all A8 BINs should already be setup as 4 cylinders.... it was only ever used on the Quad4.
Printable View
all A8 BINs should already be setup as 4 cylinders.... it was only ever used on the Quad4.
This link is to the tread I started when I began testing the 8708 for TBI http://www.gearhead-efi.com/Fuel-Inj...ECM-8B-for-TBI
dave w
So it may be a bad ICM/IDI? I'm still thinking I'm starting with a V6 bin... that was the 7727 ECM we pulled the same day... ah shit! I guess I'm doing worse then I thought...
Is there any reason you couldn't drop other code, such as $8D, $A1, etc into that ECM (8707)? I know those codes aren't native to that ECM, but it might work.
All the Q4 cals are for 4 cylinders. There is no cylinder constant and changing the cal for 6 or 8 cylinders takes some work.Quote:
all A8 BINs should already be setup as 4 cylinders.... it was only ever used on the Quad4.
The issue with the 8707 and other code is this: It appears that ecm has additional hardware which requires specific code before the injectors will trigger. Testing by myself and a few others with $58 clearly show the injectors won't fire when a reference pulse is applied. I don't believe that anyone has followed through to determine exactly what's happening though. And even though $58 didn't work, I don't know of anyone who's tried other code. I've warned about the potential problem before but I don't think anyone's taken up the challenge.Quote:
Is there any reason you couldn't drop other code, such as $8D, $A1, etc into that ECM (8707)? I know those codes aren't native to that ECM, but it might work.
Mark, if you can do it, compare the crank sensor A/C pulses to the REF pulses heading to the ecm. If the crank sensor voltage isn't high enough the ICM won't generate a REF signal and you'll see pulse in but not pulse out. I realize that the diagram I posted earlier (in this thread?) can be tricky to follow but your scope traces should match what's in that picture. I think you said that you changed the crank sensor to the 2.2 version? Might want to double check that as well.
I may have partial disassemblies around from one of the Q4 codes. lmk if you need it and I'll dig around tonight.
Ok, so there is some hardware interface issues. Could it be as simple as changing some of the addressing of the ports?
I know this is beyond the scope of this project, just a side thought.
No need for dissasmblies now thanks!Quote:
Originally Posted by 1project2many
My scope is 2 channel but never ran them both. Will give it a shot later when I get done with appointments.
Glad you mentioned voltage! It may be an issue as well with battery mounted in rear. Batt power to power distribution block is run off starter bolt. Batt is new optima and charger had it at 100% when I found the changing spark timing, but that means nothing if voltage is low.
Well this thing is beating me up. Here is where I'm at.
First I can get spark with 2 spark testers to 1-4 or 2-3. Both will spark once or sometimes twice, then if keep cranking nothing.
Batt is fully charged, pink/black circuits to ECM, Ignition and injectors will only go to 10.86 during crank.
Voltage tests to ECM pins with key on are all within spec
Noid lights do not flash.
Crank sensor is 956 ohm, within 800 to 1200 range. AC voltage at cranking is 1.3 MV which is much more then 300 MV spec.
Wave form on Oscilloscope is similar to Reference from my MAC O-scope but not as high or low. Signal looks good and can see the double notch on crank trigger, this signal is steady for as long as you want to crank.
One of the FSM tests ends at replace ICM, we had this one tested and is good. But replaced it anyways and same situation.
Another question is a ICM test I have seen on internet you tube etc... remove coils and use a test light on terminals that go into coils. It should light up, but mine does not? If I run ground to engine it does? When doing this if engine is cranked the test light should blink. Mine does not...
is the ECM detecting a speed high enough to kick out of bypass mode after 1 or 2 revolutions? and the ECM not commanding spark?
That is a direct possibility! Hmmm... maybe if I disconnect bypass?
Little out of my element here, you guys know more about these older pcms than I do, but I came across this that specifically says not to hook up to 1x on that pcm.
http://www.thirdgen.org/techboard/di...ing-100-a.html
i knew funstick had mentioned using one before, but i thought we had all decided he liked to blow things out of proportion and otherwise wasn't a source of verifiable information?
It was mentioned earlier in this thread that when questioned he disappeared and has not been seen since?
Now I do have another failed ICM test. If you look at this video at 3.42 seconds, my test light blinks a little once in awhile?
http://www.wellsve.com/video_gmcylmisfire.html
I was going to suggest disconnecting the bypass wire (tan/black) and testing for spark again. The ICM should have spark when the engine is cranking in that situation, or even running, just on base timing.
I will do this when I am starting a DIS conversion for the first time. This will ensure that the ignition is working and that the fuel is close, if it starts. It sounds like the ECM is not getting a DRP though. What does TP show for RPM while cranking? What does an O-scope show on the REF HI and/or EST wires while cranking? Screen caps of the O-scope would be great.
TP shows 0 RPM when cranking.