Question on coil pack/harness and voltage/resistance

[The Dude]

I tested my coil packs and the harness attached to them. I'm getting 11.48 volts to each of the harness ends. TSRM states approximately 12 volts is the norm. Now, is there any leeway to that # and also is there something besides the harness itself that would cause a lower voltage(besides the battery I'm guessing, which tested fine)?

Also, I'll throw this out there too: I tested each coil pack and got a resistance of 0.6-0.7 ohms each while the TSRM states 0.3-0.5 is the correct range. Also tested 3 other packs and they were between 0.5-0.7 so is it safe to assume that measurement is close enough to spec or my multimeter just isn't that good (~$60 Craftsman)?

Ultimately it comes down to "Well Dude, is your car running with these numbers?", and the answer would be no. Cranks but doesn't start, no codes(had a 12 at one time and a 14 another, but they're both gone now after some tinkering and haven't come back after several start attempts), but that's something I'm not asking for help with just yet. Just need the answers to the specific questions above. One of the few things I've changed since it was last running was the coil pack harness because the clips were in very bad shape (I no longer have that harness) so I am leaning towards replacing it with a new piece now, but I don't want to pull the trigger just yet.

 

[jetjock]

Were you referencing that measurement to chassis ground, battery negative, or across the coil? Either way those numbers are fine although all they prove (unless you were across the coil) is the packs are receiving power. It's the igniter that grounds them. I hope it's bolted to the chassis because that's where it gets the ground.

Pack resistance is also OK. It's not possible to accurately measure resistance that low without special equipment and besides, the value will change based on how hot the packs are. Bottom line: Your packs aren't the cause of your no-start. The igniter or harness may be though. If you hand made it be sure it's wired correctly.

Edit: Both of the codes you mentioned would keep the engine from starting. What "tinkering" did you do to fix them?

 

[The Dude]

We're you referencing that measurement to chassis ground, battery negative, or across the coil?

Appreciate the response. I tested the coil packs from it's + to - terminals per the TSRM. I used the negative battery cable chassis ground location as the ground point for the harness test. I cleaned the ignitor bracket ground points before testing and also attempted to make a ground coming from inside the ignitor directly to the chassis to be sure but the screws are soft and stripped to hell on the case. :nono: The harness I used was a throw-in that came with my other coil pack set I pick up way back when, not self made. I think I'll look closer at that then move to the ignitor.

 

[jetjock]

You should check for actual spark. I say that because if it isn't there you should have code 14. That you don't implies you have spark, or at least the coils are being fired. If none work back towards the igniter. Check for IGt and the coil pack encoding signals coming in and test the igniter using the procedure in the book. Does the tach flicker when cranking? Getting pulses on terminal IG in the diag block?

 

[The Dude]

Beat me to my edit...

EDIT: For the code 12 I mostly played with the CPS despite the rpms always jumping while cranking. I honestly don't know what fixed them, they just stopped coming back after resetting them, which is unsettling. Now the 14 is interesting to me because it only popped up one time. I was reading(your post actually) that if the ignitor doesn't respond back to the ecu within a few seconds it'd generate an IGf then it'd throw that code. And I think that's where I'm alittle stuck. What would I check at that point? Just the spark like you said?

NM, thought about that for 10 seconds and realized how obvious that was...

 

[jetjock]

Yeah, no spark will result in a loss of IGf going back to the ECU. It'll shut the injectors down if it sees that. Pull a plug wire and hold it near ground. Better to use an old plug or a $5 spark tester. Whatever you do don't let the pack fire into an open circuit like many people do. It's very hard on the pack's internal insulation.

 

[jkendall86]

This thread intrigues me. I am having a problem with my 89 turbo not starting at times. Sometimes it won't start when cold, and a few times would not start when hot. No codes either. The last time it did it, it died while driving and would not restart until the next day when it was cold. I had a similar problem a couple years ago and it was a coil pack that failed when hot. I tested the resistance on the packs and got .2 on most and .1 on one. Did the test when the engine was cold and I have a pretty good tester, not a cheap one. I had another couple of packs from the last go round and they also tested .2, is this good enough, or do I need to replace the coil packs? I also had a spare ignitor that I threw on just to see what would happen. It still did not work, and when it did start, it started with both ignitors. So both ignitors seem to work.