Cruise control is a separate system from the EFI.
Cruise control is a separate system from the EFI.
The man who says something is impossible, is usually interrupted by the man doing it.
I converted my 89 chevy astro over to the 16197427 (vehicle was converted to a 350 TBI a few years a go). I was having problems with the knock sensor wiring, originally I connected brown and blue together as desribed in this how to. This does not work on an 89 astro. On this vehicle brown is ground and black is the signal to the ECM (now PCM). This is probably an astro specific thing but there may be other GM TBI vehicles with this discrepency so I suggest going by the pinout of the ESC module which is as follows - pin A is empty, pin B goes to +12 volt, pin C is signal to ECM, pin D is ground and pin E to knock sensor. So connect the wires at pin C and E together. Oh and thanks goes to those who pioneered this conversion and those who have worked to perfect it!
Just remember the 89 knock sensor is not gonna be the correct one for a 7427, it will need changed.
79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy
93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver
99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.
I think the knock sensor circuit re-wiring is confusing for a few reasons.
The original re-wiring information from Thridgen.org was for a passenger vehicle. The information on Thridgen.org comments pickups are similar.
(3*)= A.) Wire like 1995 P30 Step Van, ESC Module output to B7
(3*)= B.) Wire like 1995 C10 Truck, Bypass ESC (Blue to Brown) and use Late TBI/TPI 305/350 Knock sensor
The first time I did this conversion was on a 1987 1 ton 2WD dually pickup with a 454, which is at the start of this tread. Not everyone has access to the wiring diagrams for a 1995 P30 Step Van or a 1995 C10 Truck, so this creates confusion on what to do. The GM Pickup used different wire colors for the ESC module (mounted near the TBI) than the passenger vehicle, which creates confusion. Different years of GM pickup production have different wire colors for the ESC module which creates confusion.
If doing this conversion without proper wiring diagrams, I suggest the following procedure with multimeter.
Unplug the ESC module.
With the multimeter set to volts DC turn the ignition switch on, connect the negative lead of the multimeter to the battery negative connection and probe all four pins on the ESC module connector. Only one pin of the four pins will show a near battery voltage, which identifies which of the 4 wires is the ignition power wire.
Turn the ignition switch off, and disconnect the negative cable from the battery.
With the multimeter set to Ohms scale 200K, connect the negative lead of the multimeter to negative battery cable bolt on the engine block and probe the remaining three pins of the ESC module connector. One of the remaining three pins will measure nearly ZERO ohms, which then identifies the ground wire to the ESC Module. One of the remaining three pins will measure nearly 100K Ohms, which then identifies the wire going to the knock sensor.
By process of elimination the 4th pin in the ESC module is the wire that goes to the ECM. The ESC connector wire that goes to the ECM and the ESC connector wire that goes to the knock sensor are then solder spliced together. The ESC ignition power and ground wires can be left inside the ESC Module connector.
I typically use then use the old ESC module ignition power wire and the old ESC ground wire for a heated O2 sensor upgrade.
The last source of confusion is which knock sensor to use. I typically use an aftermarket knock sensor from Standard Ignition part number KS6. I've looked at some of the online aftermarket parts supplier websites; many of the 1993 ~ 1995 GM pickup make / model / year parts catalogs do not show a 4K ohm knock sensor for an automatic transmission only a 100K ohm manual transmission. The Standard Ignition knock sensor part number KS6 is a 4K ohm knock sensor that I have successfully used in the multiple conversion I've done.
dave w
Last edited by dave w; 01-11-2013 at 09:13 PM.
Yes, the multimeter method is the surefire way to figure out the knock sensor wiring. It is also how I ended up figuring it out. I believe that the pin designations on the modules are the same on passenger cars vs. trucks but the wiring colors are different. I could be wrong though, I don't have both to confirm this.
I also used the Standard Motor products KS6 knock sensor. It is working great.
I would have to agree with the people who state this conversion won't make your vehicle run better if you had the original ECM tuned right to start with, but the datalogging is so much better! There is one quirk my van had with the 7747 that has went away now, that I could never get tuned out on the 7747. On cold start at an ambient temp of around 40-50*F I would have to push the accelerator a little bit or it would just flood out with the 7747. If temperatures were colder or warmer than that range it would fire right up with just a turn of the key. Since the change to the 97427 that issue has went away. This could just be an issue with my setup, this engine is far from a stock 350 with more cam than most would consider EFI friendly, and I am sure it could have been tuned out on the 7747 but I couldn't figure it out and the conversion to the 97427 eliminated the need to figure it out. In any case there is definitely something superior about the cold start up routines in the 97427 and it is great having that problem gone after 4 years of dealing with that on daily driving.
GM loves to switch around the wire colors. I recently swapped my L31 black box to a 0411 in my 97 Express using a guide for a 97 C1500. Found several discrepencies with that swap as well.Originally Posted by d21turbo
The 427 swap was very new when I wrote that guide on TGO, very few had done it and the info was scattered across numerous posts and sites. I swapped my 83 G20 first using a 92 G20 harness, followed by th 87 GMC Jimmy 2.8 and a RS Camaro.
Having done 3 different swap, all on well tuned setups, I have to say the newer 7427 has noticeably better driveability than an earler TBI ECM. They ran smoother, were more responsive, responded to changing conditions better and just all around performed better. The real improvement was E-transmissions however.
I will also add I have a 95 G-series calibration I found with the a/c high pressure switch active and I believe the 95 trucks used them too.
Last edited by Fast355; 02-17-2013 at 12:13 PM.
Chris how did you find this website?!?! That's it, Fast has made his arrival, time to shut the forum down! LOL JK man, glad to have you on here with your EFI-veteran status!
I agree on trying to eliminate the confusion on the knock sensor wiring when upgrading from the 747 ECM to the 7427 PCM, I went through the same thing myself. Blue to brown gives you two grounds on some GM vehicles (which obviously won't work b/c that's only half of the circuit). The multimeter is the only surefire way. It also doesn't help that the wire colors underhood are further obscured by fading/grime accumulation.
Also, I'm not as learned as some of the guys on here, but I have to agree, with what little I know, that the 7427 does indeed have better cold start routines, and also is just better all around in my opinion. Perhaps part of this is the additional resolution on things like fuel tables?
Last edited by CDeeZ; 02-26-2013 at 06:44 AM.
Homemade injector flow bench: https://www.youtube.com/watch?v=e_g9K0VEsfE
http://www.youtube.com/watch?v=zBYMtJO0pX8
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