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7427 install, first impressions
Well, yesterday I finally got brave enough to try the 7427 pcm. I wasnt brave enough to jump in feet first and go all out. So I spent a couple hours and built a adapter from the plug from a junk 7747 ecm and some spare pigtails from a 7427. That way if it ran bad, or needed lots of tuning, I could simply unplug it and plug back in my old 7747 and drive it when I needed.
First lesson learned, dont get in a rush and install the eeprom in backwards! :laugh: I bought the moates G1 adapter, and I was so used to pin 1 being at the handle end of my zif socket like I have on my 7747, I just threw it in the same way. Turns out, pin 1 goes in away from the handle on the G1.
After I turned on the key, and the fuel pump never shut off, and I couldnt get aldl connection, I figured out the problem. I dont know if I corrupted the bin on the chip, but I didnt want to risk it. So I threw it back in the autoprom, erased it then re programmed it. I installed it and it works fine, so I didnt fry the eeprom.
Started the datalog and went for a small test drive.
After the drive, my first impression is wow. What a vast improvement. It idles smoother and better, acceration is smoother and more crisp, steady cruise is smoother, throttle response is better, and even decel is smoother and better. Light accel is better/smoother, wot accel is better/smoother. Even seems to have just a tiny bit more power. Seems pretty much all rpm ranges are better.
All this from a mildly modded stock bin. I imported my timing table from my old 7747 tune, and then just did some smoothing of the fuel maps. I also followed the steps and disabled all the trans controlls and turned off all the trans trouble codes, also disabled egr and turned off that code.
Going by the datalog, seems all cells from about map 50-20 I was rich, map 60-80 were pretty close, and map 90-100 was a touch lean. So just a few logs and tuning and I think it will be all set.
Now for the one and only problem I am having---the knock sensor. I made a small jumper wire to go in the plug for the esc to connect the knock sensor to the correct input on the pcm (using the old esc signal wire) but I am getting the knock sensor or circuit error code. So the check engine light is staying on. Its the only error code I get.
I looked up on advance autos website and looked up a 89 and a 95 chevy 1500. The knock sensor I am using is for the 89 350. When I look up the 95 1500 truck, it shows two knock sensors. One for a auto, one for a manual trans. The one it lists for the manual trans is the same part number of the one it lists for the 89 truck. The memcal I am using is of corse from a auto truck. So do I need to use the knock sensor it lists for the auto trans models? I'm thinking mabey the esc in the memcal is not seeing the knock sensor I am currently using.
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Re: 7427 install, first impressions
Subscribed since I am putting together a 427 for my sons IH Manual trans...
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Re: 7427 install, first impressions
The knock sensor I use when I convert to a '427 is a Standard Ignition KS6. The KS6 measures about 4K ohms. Most likely the knock sensor your currently using is 100K ohms? Try installing a 4K resistor instead of the current knock sensor and see if the error goes away.
Maybe you need to bypass the old ESC module mounted near the EGR valve?
dave w
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Re: 7427 install, first impressions
I have a custom install on a non chevy engine, no egr and the esc is on the firewall in my setup. But I unplugged it and installed a jumper wire between the pins in the plug to connect the knock sensor to the pcm. I will try a resistor like you mention, is it something common I can find at somewhere like radio shack? Do I just put it inline somewhere between the knock sensor and the pcm?
I had a code pop up today while doing another datalog. I dont know/cant remember if it was there yesterday or not. But on the error code list in the datalog, I am getting a error next to 36 throttle kicker failure. What does that mean? I remember seeing paramiters in the bin about throttle kicker settings, but didnt really pay attention to them.
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Re: 7427 install, first impressions
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.
Your overall first impression has got me excited to get the kids truck done! :thumbsup:
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Re: 7427 install, first impressions
Quote:
Originally Posted by EagleMark
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.
Your overall first impression has got me excited to get the kids truck done! :thumbsup:
I have to ask why wouldn't you use a parallel configuration to attain a 4K ohm resistance?
The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.
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Re: 7427 install, first impressions
From what I have read, the auto trans vehicles were the first to use the '6395, '7427 PCMs due to E-trans control. The manual trans still used the '7747 for a few years. The '7427, 6395, and others use a different Knock sensor and the circuitry for that knock sensor is on the memcal, so there is no need for the separate ESC. I thought there was a way to use the old KS with the '7427 but i don't recall exactly how. The info is out there, you might search TGO in the TBI board. So yes easy way is to use the right KS for the Auto.
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Re: 7427 install, first impressions
Quote:
Originally Posted by Six_Shooter
Quote:
Originally Posted by EagleMark
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.
Your overall first impression has got me excited to get the kids truck done! :thumbsup:
I have to ask why wouldn't you use a parallel configuration to attain a 4K ohm resistance?
The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.
Electricity takes the path of least resistence, ie it would all go through one resister in parellel. Next time you have resisters out try it. 1k and 1k in series is 2k. 1k and 1k in parellel is 1k.
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Re: 7427 install, first impressions
Quote:
Originally Posted by EagleMark
Quote:
Originally Posted by Six_Shooter
Quote:
Originally Posted by EagleMark
Yes radio shack will have them, may need a couple depending on what sizes they have. Wire them in series (in line) to make 4K. Not parrellel (next to each other). I bought a BIG pack that has 100s of them for $5. and built VATS bypass plugs.
Your overall first impression has got me excited to get the kids truck done! :thumbsup:
I have to ask why wouldn't you use a parallel configuration to attain a 4K ohm resistance?
The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.
Electricity takes the path of least resistence, ie it would all go through one resister in parellel. Next time you have resisters out try it. 1k and 1k in series is 2k. 1k and 1k in parellel is 1k.
You would think so, but that's not entirely the case in an instance like this. ;)
Trust me, I've worked with resistors for many years. Some of the circuits I needed to trigger had an allowable tolerance of 10 ohms, and required some creative resistor combinations to get it sometimes.
If you'd have seen some of the calculations I had to go through during my Automotive Electronic Accessory Tech training, it would blow you away. The sad part is I don't quite remember how to use Kirchoff's Voltage Law anymore. I need to go through that again.
On the other hand, if you use two resistors of the same value in parallel the final resistance will always be half the original value. So there's no reason to never use resistors in parallel.
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Re: 7427 install, first impressions
Great! Now that I had it straight in my head it may not be the case always... :mad1:
I had followed on online write up to make a vats bypass and they showed and said it was OK to parallel and even showed a picture. So I added up 2 resistors parallel and FAIL! Measured them and it came out to the one resister. I then got 2 new resisters that added up to exact ohms needed in series and it was still the same amount.
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Re: 7427 install, first impressions
Quote:
Originally Posted by Six_Shooter
The 4K resistance would be to ground with the knock sensor unplugged. This is just for testing, not a permanent solution.
Oh, I was thinking yall ment to put the resister between the pcm and my current knock sensor to make it work. I would rather just install the correct sensor.
So with the parts stores showing two of them, one for auto, one for manual, with the manual one being the same part number as the one I am currently using, would I be correct in assuming I need the one they list for automatic?
Also, what about this throttle kicker error code I am getting? I cant seem to find any info on it online :confused:
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Re: 7427 install, first impressions
I use the Standard Ignition KS6 for an automatic transmission when doing the '427 PCM conversion. The parts stores are not able to look up the correct knock sensor after the '427 PCM conversion. The old ESC module needs to be completely removed from the old knock sensor circuit.
There are four wires that go to the old ESC module:
1. 12 volt with ignition switch in the on position. (Usually Pink wire with a Black Stripe)
2. Ground. (Usually a Black wire with a White Stripe)
3. Knock Sensor wire ~ from knock sensor to ESC Module. (color varies by model year)
4. Knock Sensor wire ~ from ECM to ESC Module. (color varies by year)
Solder together wires 3 and 4, and check with an ohm meter to make sure you have continuity from the ECM to the Knock Sensor.
dave w
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Re: 7427 install, first impressions
Quote:
Originally Posted by dave w
I use the Standard Ignition KS6 for an automatic transmission when doing the '427 PCM conversion. The parts stores are not able to look up the correct knock sensor after the '427 PCM conversion. The old ESC module needs to be completely removed from the old knock sensor circuit.
There are four wires that go to the old ESC module:
1. 12 volt with ignition switch in the on position. (Usually Pink wire with a Black Stripe)
2. Ground. (Usually a Black wire with a White Stripe)
3. Knock Sensor wire ~ from knock sensor to ESC Module. (color varies by model year)
4. Knock Sensor wire ~ from ECM to ESC Module. (color varies by year)
Solder together wires 3 and 4, and check with an ohm meter to make sure you have continuity from the ECM to the Knock Sensor.
dave w
That sir is excellent information that should be in your 427 conversion article! :wtg:
Maybe it is but I don't remember it...
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Re: 7427 install, first impressions
Yes, the old esc will be completely removed from the system once I get some time. I plan on doing that when I do the ecm plug swap and get rid of my adapter harness I am using right now.
The local parts stores done have that brand of knock sensor, is there a way to cross refrence that to another brand? The monkey behind the parts counter had no luck doing so.
I did some google work on this throttle kicker failure code I am getting, and I had zero luck on finding anything. All I can find when I search throttle kicker is a bunch of stuff about carbs, when I search error code 36 I get a bunch of other error codes. And I see no pins labeled for a throttle kicker on the wiring diagrams. So for now I just turned off the error code so it doesnt come back on. :confused:
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Re: 7427 install, first impressions
What makes you think it's a "throttle kicker" error?
The most likely error is "4T60-E Shifting Error" which would be reflective of the code you're running.
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Re: 7427 install, first impressions
What's a thottle kicker?
there's a varity of codes depending on vin "?" here's one for a 92 93 chevy 5.7L Vin J
36 ECM detected less than 60 high resolution timing pulses between each low resolution pulse for 5 consecutive cycles.
other 36 codes could be MAF or DIS on a quad 4 engine.
What was your PCM out of?
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1 Attachment(s)
Re: 7427 install, first impressions
Quote:
Originally Posted by JeepsAndGuns
Yes, the old esc will be completely removed from the system once I get some time. I plan on doing that when I do the ecm plug swap and get rid of my adapter harness I am using right now.
The local parts stores done have that brand of knock sensor, is there a way to cross refrence that to another brand? The monkey behind the parts counter had no luck doing so.
Maybe this information will help? Bring an Ohm meter to make sure the knock sensor is 4K.
dave w
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Re: 7427 install, first impressions
Quote:
Originally Posted by EagleMark
What's a thottle kicker?
there's a varity of codes depending on vin "?" here's one for a 92 93 chevy 5.7L Vin J
36 ECM detected less than 60 high resolution timing pulses between each low resolution pulse for 5 consecutive cycles.
other 36 codes could be MAF or DIS on a quad 4 engine.
What was your PCM out of?
The PCM itself is from a 95 half ton truck, 350 automatic. BCC, BJYK was the chip that was in it. Right now I am using the moates G1 adapter and running a 27SF512 chip. The bin I am using is one posted up here on my last post. BMHK, witch is supposed to be for a 454 with a manual trans. It of corse uses the 0E (tunerpro V5) defination. I am also using the (tp V5) 0E datastream defination for the datalogging. Its what labels the code 36 as "throttle kicker failure" Also when looking through the bin, there are paramiters for the "throttle kicker" So, did some trucks actually use a "throttle kicker"? From what I have seen online, a throttle kicker is simply a solenoid or stepper motor that pushes aganst the throttle to open it slightly, in order to raise the idle.
It seems to run fine, well better than fine, like mentioned at the start, it runs way better than it did with the 7747, so I'm not really wanting to think its those other trouble codes (I saw those too when searching)
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Re: 7427 install, first impressions
I don't know the answers, but I'll bet the throttle kicker has something to do with the manual trans and shifting, so between shifts the engine does not go back to idle, cleaning up emmisions and making shifting easier.
EDIT: Found three for 1995
DTC - 36 MAF sensor error
DTC - 36 24x Crankshaft position sensor circuit error
DTC - 36 4T60-E Shifting Error
Full list found here:
viewtopic.php?f=9&t=311
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Re: 7427 install, first impressions
Yea I found those same codes with google, they didnt really seem to fit since I dont have a maf sensor, or a 24x crank wheel. But whats that 4T60-E shifting error? Something to do with the auto trans?
I looked last night, and both tuner pro version 5 0E and 0D definations and adx files say 36 is throttle kicker failure. And both have paramiters in the bin for a throttle kicker. So is it possiable they have been miss labeled by the person who made the definations?
I even went as far as calling the local chevy dealer and asked parts if there was a throttle kicker on any of the 95 model trucks. He had never even heard of a throttle kicker, and could find nothing of the sorts in his parts program. I then talked to one of the shop techs and he seemed to think mabey it was used on like the kodiak HD trucks that had a pto, as a way to run the engine at fast idle. I transfered back over to parts cause he said he could look up the BCC. All he could pull up was that it was a 5 speed bin, but had no info on what that BCC was originally supposed to be for. (this is the BMHK bcc, just fyi)
One thing I might try, is to load up the BJYK bin (350 auto) that I made up and see if the code sets when driving with that bin. Just depends if I have time this weekend.
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Re: 7427 install, first impressions
Well I think I have figured out this throttle kicker issue, well sort of, if we really want to call it a issue.
I have noticed the last few times I have drove it, it wanted to stumble, kinda almost stall as I was pulling out from a dead stop. This was only while letting out on the clutch to pull out, if it was a rolling start, it wouldnt do it. I had to give it more throttle to pull out than I should. I thought this was odd as it didnt do it the first few times I drove it, even more so odd as the first few times I drove it, it actually pulled out better than it did with the old 7747. The issue seemed to appear as I was tuning my fuel maps. I was starting to think there was some issue with either fuel or spark starting to show itself.
As I was driving back home from a friends house, it hit me :idea: . Back when I first started getting that error code, I noticed once or twice, the code for iac failure was on too. I thought that was very odd, as the iac was working perfectly fine. So I just ignored that code. When it hit me, I realaized the pulling out issue started about the same time I turned off the error code for the throttle kicker failure. But thinking it was a external bolt on part that was not being used (like the egr valve), I went to paramiters for the throttle kicker and set the enable temp to max so it would never turn on (just lke I did the egr) And then turned off the error code for it.
So I figured, mabey this had something do do with the pulling out issue. So I went back into the bin, and set the enable temp back to what it was stock. I then test drove and the pulling out issue is gone. I watched my datalog dash while pulling out, and when you do so, it must sense from the engine load increasing and rpm dropping slightly, that you are trying to pull out, cause when I am pulling out, it openes the iac up a significant ammount, I guess thats the "kick" It opens it up to give you more throttle and air to give it a extra kittle kick when pulling out.
Only one last issue, I am still getting that iac failure error code. The check engine light is not on, but the error code is showing on the error code list in the data log. I find this very odd, as the iac is working perfectly fine. Could the error code simply be stored in the memory, and just show up now every time I drive it? I hear that you have to have these un plugged from power for several days to clear the memory, is that true? I went ahead and unplugged it and I am leaving it unplugged untill next weekend when I get some more time to do some more tuning.
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Re: 7427 install, first impressions
Quote:
Originally Posted by JeepsAndGuns
Well I think I have figured out this throttle kicker issue, well sort of, if we really want to call it a issue.
Only one last issue, I am still getting that iac failure error code. The check engine light is not on, but the error code is showing on the error code list in the data log. I find this very odd, as the iac is working perfectly fine. Could the error code simply be stored in the memory, and just show up now every time I drive it? I hear that you have to have these un plugged from power for several days to clear the memory, is that true? I went ahead and unplugged it and I am leaving it unplugged untill next weekend when I get some more time to do some more tuning.
I usually need to adjust the IAC / Throttle minimum air to about 10 ~ 15 steps with the engine fully warmed up and parked in neutral. There are several methods to adjust the minimum air. My minimum air adjustment method is NOT the conventional method. I simply adjust the throttle stop screw, while watching the data log, with the engine running, fully warmed up and parked in neutral.
The memory will clear after 30 seconds or less after disconnecting the power from the PCM.
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Re: 7427 install, first impressions
I do what dave w does, but when done TPS voltage should be under 1.0 volt. Optimum is .54. but told from pioneers on Thirdgen anything under 1.0 volt is fine.
What JeepsandGuns is saying about throttle kicker has been my suspicion the entire time that there is more in the chip different for manual than just turning off the auto trans. I was told this by a Detroit EFI engineer to always start with a manual bin for manual trans as there is differences in chip. But not apparent in anyones hacks, that I have seen so far.
Since there are 100 things in IAC logic it would be plausible. Since we know even before EFI that contraptions were made to slow throttle to idle when shifting on carburetors cars for EPA/Emissions reasons it would be silly to think they are not in EFI programming.
EDIT: Yes the error code will be stored even after the problem is fixed. There is a paremeter that clears error codes after so many starts and not receiving an error. Just disconect PCM or batterey, I always give one minute, I do not know actual time needed, but one minute always works on any I have done.
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Re: 7427 install, first impressions
What did you do for the adapter? Just whack out the recieving plug from the 1227747?
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Re: 7427 install, first impressions
Yep, I found someone with a fried 7747 and just de sodered the female plug from the main board, then sodered the wire directly to the pins. It was actually a roal pain in the ass to make, but I was just very intimadated by the pcm and I just wanted to be able to plug my old ecm back in and be able to drive it if the tuning process took a long time.
Ha, I never plugged the old 7747 back in once I plugged in the 7427.
I do have a couple questions about the wiring change over diagram. I saw no input for the crank signal (7747 pin C9), I didnt notice this when making the adapter, but when I swapped all the pins into the pcm plugs last night, I had that left over. I figure the pcm doesnt use this? If not I will just remove it from the harness.
Also, the 7747 had two power inputs, B1 and C16. But the 7427 only had one, I'm guessing the other one just gets removed?
And last, are the 7427 pins E14 and F14 inputs or outputs? The diagram shows both of those pins going to the old pin C14. But there is only 1 C14. So do I need to splice into the old C14 wire and add another wire so I can hook one to E14 and the other to F14? Thats what I did on the adapter, I just tied both together and connected it to pin C14
http://img.photobucket.com/albums/v6...0-02092120.jpg
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Re: 7427 install, first impressions
The '7427 does not use a crank signal input. Originally this would have been connected through the 3A "CNK" or "CRNK" fuse in the fuse panel.
The others I have to look at the at the wiring diagrams to remember before commenting.
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Re: 7427 install, first impressions
Quote:
Originally Posted by JeepsAndGuns
I do have a couple questions about the wiring change over diagram. I saw no input for the crank signal (7747 pin C9), I didnt notice this when making the adapter, but when I swapped all the pins into the pcm plugs last night, I had that left over. I figure the pcm doesnt use this? If not I will just remove it from the harness.
Also, the 7747 had two power inputs, B1 and C16. But the 7427 only had one, I'm guessing the other one just gets removed?
And last, are the 7427 pins E14 and F14 inputs or outputs? The diagram shows both of those pins going to the old pin C14. But there is only 1 C14. So do I need to splice into the old C14 wire and add another wire so I can hook one to E14 and the other to F14? Thats what I did on the adapter, I just tied both together and connected it to pin C14
The below information is directly from the notes on Thridgen.org
Old C14 is a 5 Volt Reference and goes to New E14.
Old B1 Battery Volts - goes to New E16
Old C16 Battery Volts - goes to New E13 (Input in place of Brake Switch)
**F14 is not listed in the notes from Thridgen.org.
***1994 Wiring Schematic I have shows F14 as a TPS 5V Reference.
****On the '427 conversions I've done F14 is not wired, nothing going there, not needed for anything!
dave w
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Re: 7427 install, first impressions
Taking notes as I build the 427 system for sons truck... yes I am procrastinating...
[attachment=0:pcy1jgip]427.jpg[/attachment:pcy1jgip]
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Re: 7427 install, first impressions
Quote:
Originally Posted by dave w
The below information is directly from the notes on Thridgen.org
Old C14 is a 5 Volt Reference and goes to New E14.
Old B1 Battery Volts - goes to New E16
Old C16 Battery Volts - goes to New E13 (Input in place of Brake Switch)
**F14 is not listed in the notes from Thridgen.org.
***1994 Wiring Schematic I have shows F14 as a TPS 5V Reference.
****On the '427 conversions I've done F14 is not wired, nothing going there, not needed for anything!
dave w
I wasnt sure about the E14 and F14, thats why I wanted to check. Seems I remember on the 7747 system, the 5 volt refrence from the ecm goes out in the harness and then splits off and connects to the tps and map, where it appears on the original pcm harness, it must run them seperate.
I forgot to ask about that brake switch input (E13) I have had nothing connected to that pin the whole time I have been running my adapter. Everything has seemed to be ok. The diagram I have says its power when brakes are not applied, and no power when brakes are applied. So I guess its just been thinking I have had the brakes on all this time...lol
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Re: 7427 install, first impressions
The brake wire your talking about, I beleive is for lockup converter. Hence no brakes means it has power to lockup, brakes applied and unlock. It is needed for 700R4 on 7747. IIRC. I don't see a need for it on a manual... unless the 427 does something differant.
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Re: 7427 install, first impressions
Well I got my first 427 from scratch running on the bench today and this seems to be the 427 beginner thread so I have a couple questions.
Does the 427 act differently then the 7747 in that when turned on the check engine light comes on and stays on without a blink?
Does the 427 act differently then the 7747 in that when turned on the fuel pump runs continuously? No prime then off?
That's what mine is doing and I'm not sure if I have something wired wrong?
Check engine light goes off when I spin the distributor and I do have spark, injector firing, IAC moving all looking good but have not hooked up for data yet.
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Re: 7427 install, first impressions
I cannot tell you about my check engine light as I don't have it hooked up, but as far as the fuel pump running there is a parameter for time for fuel pump to run before DRP, I suggest check that to make sure it's not set to something unreasonable. I think mine primes for five seconds. I just remembered I will be driving the Camaro to work tomorrow, I can put the DMM on the CEL wire and see about that in the morning.
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Re: 7427 install, first impressions
Cool! Someone may know for sure. But I am used to seeing the flash of check engine light and fuel pump (hanging on wall) turning on, then off till run. So this is all new to me.
I'll be hooking up the AutoProm tonight and starting with one of these manual bin files 1Project2Many gave us earlier. Then get to use the sweet Defs that 93V8S10 built for TP. I'm excited to finally get this far.
Oh yeah there's an update for TunerPro V5 that fixed the data tracing!!! This is like the best day ever!!!
:jfj: :jfj: :jfj: :jfj: :jfj: :jfj:
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Re: 7427 install, first impressions
In comparing a BMHK OE Manual bin to a BJDR OE Auto bin, the manual has Flag set for Throttle Kicker and the Auto does not!
Haven't looked at the millions of other things in IAC logic but I think starting with a manual bin is going to be much better!
EDIT: WOW! Lots of IAC and other changes from Manual to Auto!!! Although the BMHK I started with was for a 7.4L all I have changed so far is TBI LBS Per HR and Cylinder Volume, unchecked a few flags like EGR, disabled EGR via temp. Should be a good starting point for the new IH engine.
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1 Attachment(s)
Re: 7427 install, first impressions
Quote:
Originally Posted by dave w
Quote:
Originally Posted by JeepsAndGuns
I do have a couple questions about the wiring change over diagram. I saw no input for the crank signal (7747 pin C9), I didnt notice this when making the adapter, but when I swapped all the pins into the pcm plugs last night, I had that left over. I figure the pcm doesnt use this? If not I will just remove it from the harness.
Also, the 7747 had two power inputs, B1 and C16. But the 7427 only had one, I'm guessing the other one just gets removed?
And last, are the 7427 pins E14 and F14 inputs or outputs? The diagram shows both of those pins going to the old pin C14. But there is only 1 C14. So do I need to splice into the old C14 wire and add another wire so I can hook one to E14 and the other to F14? Thats what I did on the adapter, I just tied both together and connected it to pin C14
The below information is directly from the notes on Thridgen.org
Old C14 is a 5 Volt Reference and goes to New E14.
Old B1 Battery Volts - goes to New E16
Old C16 Battery Volts - goes to New E13 (Input in place of Brake Switch)
**F14 is not listed in the notes from Thridgen.org.
***1994 Wiring Schematic I have shows F14 as a TPS 5V Reference.
****On the '427 conversions I've done F14 is not wired, nothing going there, not needed for anything!
dave w
There must be a 5 volt reference signal in the 7747 that is tied together IIRC.
I started with an OddBall harness that did not have 7747 or 427 plugs, but did have heated O2? I forget what the ECM was.
But I do have F14 Gray wire to TPS.
Just looked and 7747 does have a 5 volt reference tied from MAP to TPS. That is why a conversion from 7747 does not use F14 but 427 does...
[attachment=0:swes0ow7]747ecm7.jpg[/attachment:swes0ow7]
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Re: 7427 install, first impressions
No CEL blink and continuous running fuel pump is a sure indication of Limp Home Mode.
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Re: 7427 install, first impressions
Quote:
Originally Posted by Six_Shooter
No CEL blink and continuous running fuel pump is a sure indication of Limp Home Mode.
Well don't know what I did, now running on AutoProm not the origanal chip, but now the fuel pump comes on then off at key on just like a 7747. But the CEL does not blink. CEL goes off and stays off while drill is running the distributor. No error codes set. CEL still does not blink when I go key on? AH! May be the way I have the Test CEL wired I have hanging on the wall, Nope! The light bulb I have wired and hanging on wall blinks with a 7747, but must be to big for 427. I wired in a smaller dash type bulb, instead of a tail light bulb and it blinks when key on! Wierd?
System is running on the bench and I had a High MAP error, forgot the vacuum pump, it went away. Then I got a knock sensor error because I did not have a knock sensor hooked up nor do I have one. So I wired a few resisters in series to measure 4k and that error went away to. I did change a setting I thought was in Scalers but can't find it now? It was VSS not from DRAC or something like that. So with that changed and a 4K resister = no codes! :wtg:
EDIT: Found the Output speed not from DRAC in Flags 4L80E Tranmission Paremeters. This was unchecked, I checked it and used a 4k resister and no error code set. Have not tested for MPH.
Rewired, tested, emulated and datlogged on the bench and ready to install on the truck!
Thanks for the help! :rockon:
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Re: 7427 install, first impressions
One question on VSS signal? It's the only wire I don't have done. Wiring diagram shows 2 wires from VSSB to PCM at F12 and F13. When not using a VSSB/DRAC what one to use? Or does one go to VSS and one come back?
And I don't see any Park/Neutral switch wire on the 427 wiring diagram? But it's pretty late and I'm wore out...
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Re: 7427 install, first impressions
Wow, yall have been busy posting while I have been asleep :laugh:
To try and answer a few questions.
When I first installed my 7427 and put the eeprom in backwards, it had a constant cel and the fuel pump stayed running, so it sounds like you were in limp home mode, like mentioned above. Also I coudnt get aldl connection when I had the chip in backwards.
With everything running, yes, my cel flashes just like the old 7747 did when I turn the key on and the fuel pump cycles.
I just checked a 7747 harness I pulled from the junkyard for resale and yes, the 5 volt refrence splits off a few inches from the ecm and then goes to the map and tps. Where the 7427 seperates them.
The BMHK is the same bin I am using, I think its a good bin to start with if your running a manual. Even though its a manual bin (confirmed by a chevy dealer) I still had to change a couple settings in it according to the paramiter comments in the defination. There was one flag called something like enable shift light (or something like that, I dont have my laptop turned on right now) and it disables the auto trans controlls and sets it up for manual. Make sure thats checked, and the comments box says there is a table that has to be set to all 0, and it wasnt. So I changed it. I also went through and turned off every error code for transmission (just to be safe)
six shooter posted up good info in the vss thread. He says the pcm gets both the 40 pulse signal on F12 for trans controlls, and speed signal from the buffer on F13 for other stuff (the diagram I have says fuel cutoff) I used that diagram you have posted on here in another thread and it says to connect A10 to F12, when according to all this, it looks like it should actually be hooked to F13. I have mine hooked to F12. I will try and switch it today and report back with my findings.
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Re: 7427 install, first impressions
In re reading the 427 conversion thread, yes it looks like VSS should go to F13.
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