Cranks, runs rough for a bit, then dies

[intheshadows]

Cranks strong, battery tests good, alternator tests good, fuel getting to the engine, no ECU codes.....gotta be ignition related right?

 

Plugs newish, wires newish, rotor and cap newish, coil age unknown but looks like it was replaced before I got the car.

 

She'll crank, run for a few seconds like its missing or the timing is terrible, then it dies. Gassing it will keep it running for a few seconds, but it pulsates and still dies. It ran like a boss until I parked it, and now this starting problem. I got it started and running once, and it ran and drove around the neighborhood normally but I havent been able to get it to start since.

 

Also, my brake lights suddenly do not work. They worked yesterday, now they dont, both of em. Dont know if its a coincidence or not. I smell something burning inside the car maybe. Dont know if its in my head, but it didnt smell like that yesterday.

 

I've been having terrible rust problems and this might be related. I yanked out my AIV after it rusted out everything beneath it, but I fear it may have done some collateral damage. I found this grounding strap on a rusted area, which probably isnt grounding too nicely, what is this for? I'm going to relocate it.

 

 

That stuff is under the coil itself.

 

 

Here's the coil resting on top of the intake, with the plug and the box that was connected to the coil. What is this, the transistor? Where the red outline is, its rusted like crazy, so this probably causing some problems. The broken brake lights and burning smell in the cabin I find hard to relate to this. Perhaps my ECU is fried; have you guys ever seen blown or leaky capacitors or ECU troubles cause this behavior?

 

What do you guys think? Thanks!!

 

 

[aj503]

Think that grounding strap is for the coil, mine was in similar shape and I was having similar issues. Replaced the coil and it seemed to solve the problem... The thing circled in red is the ignition control module. How long does it run before it craps out, when I was dealing with it it would stop giving me spark after the truck heated up.

 

87 XE red/red 3+3+33's=my finder

[intheshadows]

I figured that was the ICM, but my parts diagrams looks different. That little ICM box has been rusted and looking like crap since I got the car.

 

She'll sputter for about 5 seconds after cranking before dying.

[aj503]

Gotcha, yeah mine looked pretty poor but I just cleaned it all up and even with the rotted out brackets/ grounding strap mine still fires right up and runs every day. Might test the coil?

 

87 XE red/red 3+3+33's=my finder

[intheshadows]

Well it appears the problem is the mass air flow sensor (hotwire modulator?) on the side of the TBI unit. One of the filaments is damaged, so I'm guessing this is why she runs so poorly. Problem is, this part is hard to find and expensive!

 

Got an OEM used one on order off of fleabay coming in and crossing my fingers.

[intheshadows]

Finally got back to this. Found all kinds of nasty blue copper wiring corrosion around the TBI unit for the TPS and injectors. Fixed what I could see and checked any connectors I could get to in the entire engine and cleaned them up like new. Injector O ring was crumbly and leaking, replaced and is OK now. Inspected wiring harness and SEEMS to be ok but I didnt tear all the way through.

 

MAF replaced due to a broken filament with an OEM pull, TPS and harness/wiring (aftermarket) replaced due to heavy corrosion on the pins. Still no luck getting her up and running. Cranks mostly, catches sometimes, and it ran again ONCE after I did this work. It ran and sounded great for all of 5 seconds before it sputtered and died (RPMs were on the high side, have been fiddling with the distributor position and idle screw).

 

It checks OK for spark to the distributor with some irregularities. Seems to cut out or act up randomly but I cant say for sure. Cap/rotor (aftermarket) swapped again. ICM and coil (aftermarket) swapped in and out with no noticeable difference. ECU also swapped in and out with no change.

 

I'm out of ideas other than the distributor/CPS at this point. Any way to definitively test these guys out before I fork out more cash? I suppose the aftermarket parts could be pure junk as well. Very frustrating.

 

 

[intheshadows]

The spark I'm getting out of the coil starts out blue and strong then fades to orange rather quickly. I have 2 coils and they both behave the same.

 

I went and double checked the aftermarket ICM for spark, and I get no spark at the coil. Same coil that was just sparking with my old ratty ICM. Went out to the local NAPA for another aftermarket unit. Same thing, no spark. Aftermarket ICMs look to be the same manufacturer and the plug that fits into the coil just doesnt fit nicely but looks passable side by side with the old ICM. Could I have two bad aftermarket units or what the heck is going on with this no spark? I really want to try and swap the connector but I dont think theyll take it back as a return once I do that.

 

I'm getting battery voltage at the ICM-->coil on all three ICMs across the two wires, but only the old ratty ICM creates a spark to feed the dizzy.

 

I did the diagnostic from the FSM on the crank angle sensor in the distributor and it seems to be working fine. I did all the ignition tests from the FSM too and it passes only with the old ratty ICM, grounds, signals, OK. Still behaves the same, sputters and doesnt catch.

 

What to try, go OEM on the ICM? Would a bad ICM cause a weak spark or is that the coils fault?