Hi all,

I am still trying to finish up wiring up my 2.9 L out of a '88 going into a '84 BII.
I don't get spark when turning over the engine. But, when I release the key I'll get an intermitent spark.
On certain rotations or attempts I'll get one cylinder ignition even. What is happening here? I have tested coil, module, wiring in run and in start position. Everything is showing power with my test light.
Can bad grounding cause this to happen?
Any and all help is appreciated.

Hawkeye

 

Iam reaching out being ignorent but I'll hope it makes sense, did you move the 2.9 into the 84 with the fuel injection system intact?, I know a 2.8 and 2.9 were the same for the most part with fuel injection used on the 2.9 and hydrolic lifters instead of mechanical on 2.8. past that I did not know how many other difference's there were as I never traded one into another. Did you try a remote starter switch at the starter solenoid to see then if you got steady spark with the key on? If kept E.F.I system when you wirred in the newer P.C.M. did you make sure the P.C.M. ground pins 40 and 60 (double check me on that) was connected to the negative bat post or other secure ground? A simple test would be to check for a 5 volt signal to the T.P.S. or Egr sensor, there will be no voltage if P.C.M. is not grounded.

 

If it comes down to it I have a "known good" 88 b2 2.9 computer if you need one and find yours is bad. It is for a manual transmission though so keep that in mind if yours is a auto, it will not work with a auto tranny.

 

Well first off thanks for responding.
I transfered the entire 2.9 system into the truck, from the gas tank, pumps and lines. The wiring harnesses, engine, and computer. All from the donor truck. My carbureted 2.8 was dead. I got the whole donor for 300.00. It was an Automatic. I have a manual trans. To the best of my knowledge, going by my printed out wiring diagrams as well as Haynes and Chiltons books that I have, I think my wiring is correct. I intend to double check my grounds to frame and body. I have traced the 20 pin to the engine block, the 40 and 60 pins junction out near the fender well relays and then a single wire goes to the negative post at the battery. The '88 engine didn't have the EGR.

Hawkeye

 

I have a computer from an automatic. That is what the donor was.
Well I don't know what will happen later when I start to debug my setup, after I get it to run. But.. pin 30 is shown on my diagrams to go to either neutral safety switch on a automatic. Or, to both a clutch engage switch and a neutral sense switch. So my thoughts have been that I would run a wire to them when I got the engine to run. If I run into trouble I very well may take you up on your offer.
Thanks for that by the way.

Hawkeye

 

The computer for the auto should work for a manual, the check engine lite would likely be on all the time though.

No response from the shift solenoids in the tranny so the cel would come on and stay on. Other than that I don't see why it wouldn't work if it is "good" otherwise.

And yea you should be able to work out the neutral safety switch with no problem.

But I have one if you need it.

One other thought, did you test for power out of the ignition switch itself in the "run" position? I see you listed some things you tested but not that.

The BK/LG wire is the "run" wire out of the ignition switch, the R/LB is the "start" wire.

The BK/LG at the ignition switch should have 12v in it with the key in the "run" position in a 84, if not the ignition switch itself is likely to be your problem.

 

Yes I did check those both.

Now for the good news.
I retraced all my grounds for pins 20, 40, and 60. Also pin 49 (Hego ground). The fuel pump ground. Then the body, engine and frame grounds. I found two that I don't like, the braided ones running from engine to body and the other to the frame. Quick threw together one of each from some battery cable I have laying around and BINGO!! I have spark, and I mean serious spark. It's operating in the correct fashion as well not when the key is being turned off. Also picked up more speed in my starters crank speed as well.
I want to thank both of you for helping me on this. You got me thinking and helped me work it out.
Man... am I relieved.

Hawkeye

 

[QUOTE=danr1;6391804] "The computer for the auto should work for a manual, the check engine lite would likely be on all the time though.

No response from the shift solenoids in the tranny so the cel would come on and stay on. Other than that I don't see why it wouldn't work if it is "good" otherwise.

And yea you should be able to work out the neutral safety switch with no problem.

But I have one if you need it."







One other thing, I'm puzzled why the CEL would be on. If the same pin is used on both types of trans. Then they released two computers, one used for Manual and one for Auto? I thought I'd be able to run the wire to the switches and the computer would get the proper info returned.

Hawkeye

 

You can install resistors as jumpers in place of the solenoids to keep the CEL off. I'm not sure what the resistance you would need is, but it needs to be about the same resistance as a good solenoid.

 

Well that sounds easy enough. Is there any way you can find out what resistance I am going to need or does anyone here know? Thanks.

Hawkeye

 

No I do not know what value they are but I do have a couple that are out of a A4LD, I'll try and get a measurement and get back to you.

(Manual transmissions do not have shift solenoids, you're thinking "neutral safety switch/clutch pedal lock out" I think)

Should be easy enough to do, fool the computer to think the tranny that is not there did if fact "shift". Lol!

You will have to do it twice, once for "torque converter lock up" and once for "shift to overdrive".

 

Cool. I'll be anxious to hear what you find.
Thanks for the input.

Hawkeye

 

Well lets see, not sure if this will help but this is what I found.

Unenergized I got a resistance of 29 to 30.3ohm, energized it goes to -415. If I reverse the leads it goes to polarity reversed on the meter.

Diode test showed 030Mv unenergized and polarity reversed or "reversed" when energized.

My good Amprobe meter died and I grabbed a cheapy the day it happen off the shelf. The only one they had at the hardware store and hadn't remembered to order a good quality one yet to replace it. I have a pretty good idea I did it right but the instructions for this thing is a joke, wanted to make sure I had it set right. It doesn't have the options my Amprobe meter had either, Diode and continuity test are the same setting on this one. The good meter had a separate setting for testing for each among other differences. Twain piece of junk anyway.....

I had the other one for years, could work it with my eyes closed just about.

Anyway from what I see it "sees" the solenoid when "deenergized" as in not shifted into overdrive or TC lock up and not when it is in TC lockup and has shifted to OD? Sound right to you electronic wizards out there?

 

Cool. I'll talk this over with a couple of the mechanics at work. They are better with electrical than I am. Thank you for doing this.

Hawkeye

 

Sounds like a wiring nightmare, let me throw a much simpler thought in here. If the starter motor pulls too much current, there is nothing left for the ignition system, untill the key is released. The same can hold true for a battery not up to par. I like to start simple then jump into the maze as we might call it. kotzy