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Discussion Starter · #1 ·
I know what you're thinking... "Great, another one of these" but honestly, I don't know where to look next to figure out why this car won't start. It's at a buddy's house and I'm purchasing the car but in it's current state, it just won't start. Here's the rundown:

'90 AWD Turbo
known-good ECU (non-eprom, stock ECU was fried)
RC 550cc injectors
2G MAF
UICP, LICP, 3" Buschur tb
B16G

Here's the situation - back in December, the car died. I think they had it towed back to their house and it sat since then. We discovered the burnt ECU and found a local one and installed it. Car fired up and ran. Turned off the car, put it all back together, car won't start. Fast forward a week. Car starts fine after sitting. Turn off car, try to turn car back on, car won't start. Fast forward two days. In a very strange twist, the car won't start so I start checking for spark (we have had spark/fuel this entire time) and pull plug and wire from cylinder 4 and let them hang by the engine block. Friend in the car doesn't know those are missing so he cranks it. It starts... doesn't run well but it started and ran. Put everything back together, car won't start. Pull plug from cyl 4, car starts. Plug it back in, car won't start. We found an abrasion on that plug wire so we replaced it. I had left at that point so I don't know if it started with the new plug. Get there today to pick it up and my buddy had it running from a cold start for about 30 minutes. Turn it off, button everything back up, car won't start. Figuring it was bad gas we hard-wired the pump and pumped all of the gas out of it and put 4 gallons of brand new gas in it. Still won't start. Pull out the plugs, they're fuel-soaked. He has a spark plug cleaner (which by the way is one of the coolest tools ever, thanks Harbor Freight) so we get them all clean and put it all back together, still won't start. So, seriously... what...the...fuck? This entire time, it will "run" if we spray Starting Fluid into the manifold. It doesn't stay running, but you can hear it running so long as it has starting fluid coming in.

In all, we have a new ECU in the thing, we're soaking the plugs with fuel, we have spark on all cylinders, it just won't fire up when warm/sort of warm. What are we missing here, any ideas?
 

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Try some new plugs and see if it fires. Old one are soaked with fuel and may be fouled. Also check the timing on the car make sure it's in line and not out of time.
 

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Discussion Starter · #3 ·
Thanks for the suggestions. We have some new NGK's laying around so I can have him try those. We figured cleaning the ones that were in it would do but you never know.

As a side note - is the firing order on the coil pack the same on a '90 as on every other 1G?
 

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Try this: (be careful though) Remove all spark plugs and cover any plug wires. Make sure fuel can get nowhere near them! Once the spark plugs are out, crank the motor. This will shoot all the fuel out of the cylinders. After this is down, install new plugs and try to start it.
 

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Also try adjusting the cam postion sensor on the side. I had a simlar problem ended up being that. Also check the timing belt, maybe it jumped.
 

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Discussion Starter · #7 ·
I will try the suggestions - thank you! As for the cam position sensor, if I'm remembering right, that's the greenish thing on the side of cyl #4 that adjusts ignition timing correct? If so, we're reading 3 degrees advance on our timing light and we have adjusted it. The timing belt is brand new and the car has not run under any load since it was installed, it has just idled. As a precaution, we'll take the t-belt cover off and verify it's still on correctly at TDC. Thanks again guys - also, since it was cheap, I picked up a new coolant temp sensor just to eliminate that as a possibility. I also found out that the car does not have the fuel pressure solenoid at all anymore, not sure if that matters. My suggestion is to put it back on since it doesn't hurt anything to be on the car.
 

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This is the OP on my buddy's account - we have found something, but don't yet know what's causing it. We have no fuel now... we went so far as to take the rail/injectors out, plug everything back together and held the injectors in place with our hands while his fiance tried to start the car and we have fuel behind the injectors, just not coming out of them at all. We tested each injector at 2.3 ohms and I tried to test them at the clip by the resistor box but I'm coming up with 25-28 ohms out of that clip on each injector. The resistor box is testing out at 6.5 ohm and we're wondering if that's low enough to fry the old ECU and possibly the one we have in the car right now? We're almost out of ideas here... we've had the car running so I haven't been pointing the finger to the ECU but now we can't get it to start whatsoever, cold, hot, or otherwise. We replaced the coolant temp sensor but that didn't fix it. We also tried a set of known-good 950cc injectors and they have no fuel coming out of them either.
 

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Discussion Starter · #10 ·
So here's the newest twist in this ugly tale - we unplugged injector #1 and plugged in a known-good injector to see if it would "click" when we turned the car over. We tried and it did... 5 seconds later the car started up just fine (obviously running only 3 cylinders at this point). After plugging in the actual injector in the fuel rail, it ran fine and we let it warm up. Sure enough, we turned the car off and it would not start again. We tried our "clicking" test again and when it wouldn't fire up, the known-good injector wasn't even trying to open (it wasn't "clicking" anymore). Sooooo... what would cause the injectors to intermittently not open? I'm guessing it's the ECU but how would a bad ECU be able to start the car every so often and also, what fried the other ECU? When the first ECU went bad, it didn't just die of old age, it died of a melted circuit board (see pictures here). My only guess right now is that resistor box, but that's a wild guess.
 

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Go around and check some of the grounds on the car. I've never seen it happen on a car, but on ATV's, a bad ground is the culprit for stuff like this.
 

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My only guess right now is that resistor box, but that's a wild guess.
..You need a new ECU ... when a section of the momboard takes a dump like that, it takes out then entire momboard.

True, make sure that all grounds - the battery to chassis, the block to chassis and even the exhaust grounding strap from chassis to the pipe attached to the CAT are solid and intact. An open ground spell deep trouble for ECU's
 

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Discussion Starter · #13 ·
Thank you for the suggestions guys. We are going to try and find a local, running 90 AWD to swap this ECU into to see if it will run a known-good car. Other than that, I have the MPI Relay on the way based on a resolution to a very similar issue I was just told about today. I'll keep everyone posted.
 

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90 percent sure that the ecu is your problem, but the bigger question you should try and answer is what caused it to fry up? you really need to search around for any loose grounds or bad leads. if one thing goes wrong with it, you can pretty much kiss it goooooodbye.
 

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Discussion Starter · #15 ·
You are absolutely right. I *think* I know what fried it. We checked out the CAS last night and ended up having to rewire it completely. The wires at the point where they are secured to the body of the sensor (it's a little metal clip that screws into the CAS) and just inside the connector were frayed, brittle, and exposed. I could easily see that shorting out to the ECU. After we rewired it, the car fired right up but once we let it turn off to the point the MPI Relay clicked off, the car would no longer start. Right after it started and had warmed up to about 1/4 warm, I turned the key off and restarted the motor and it fired right back up. After we left it off until the relay "clicked", it would not restart. I should also note that the CAS we rewired was not the CAS on the car - we rewired a spare (the spare was cut off a harness very poorly some years ago). If the MPI Relay doesn't fix the car (we have one coming), we are going to try and find a local '90 AWD to swap my ECU into as that will be safer than trying their ECU in my car if indeed something is frying them.
 

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Discussion Starter · #16 · (Edited)
Well, we can now add the MPI Relay to the list of things we've tried, to no avail. I am now on the lookout for a '90 AWD that I can "borrow" locally for an hour or so to try the ECU we currently have in my car in a "known-good" car to see if the problem surfaces there too. If anyone has any friends in or around the South Bend/Mishawaka/Elkhart/Niles area in Indiana/Michigan, I'll offer the same reward to them if they can drop by my buddies house for a little bit.

On a different note, we now have what looks to be a new "symptom" - we can now predict when the car will start (sounds crazy right?)! We're not sure if it was the "priming" of the car that makes this happen, but after we attempted to start the car about 25-30 times, every so often we start to hear the ISC motor just going nuts. It also goes nuts on our meter with the outside pins all fluctuating wildly with voltage. Once this scenario occurs, the motor will start on the next try like clock work. We also pulled the CAS during this situation and spinning it fires the pump and the injectors. This is sounding more and more like an ECU and I really appreciate everyone who has suggested that but just know that in my current financial situation, I can't really afford to spend $150-ish + on what may be a good guess, but is still just really a guess. Also, since I already have $75 into what could be a bad ECU, it makes it doubly frustrating. Anyway, that's my story...
 

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Well, picking things apart on the car just to see what will happen isn't the best thing to do, but test that dang ECU before you put too much effort into it.

Oh ya, if you aren't broke, you aren't a true dsm'er.

haha.
 

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53066talonawd said:
Well, picking things apart on the car just to see what will happen isn't the best thing to do, but test that dang ECU before you put too much effort into it.

Oh ya, if you aren't broke, you aren't a true dsm'er.

haha.
On the contrary I think he is doing the right thing. You never want to go out and blame the ECU directly for a problem. ECU's aren't cheap. He is diagnosing it properly. The more clues he gets, the more he can blame the ECU. Also eliminating certain systems or components allows him to save money. that way he just doesn't throw money away replacing stuff that isnt needed..........yet.

To the OP. Very interesting problem you have here. Have you searched for any wire chaffing or damage? You mentioned you have a spare CAS that was poorly installed:confused:? Have you taken out the new spark plugs to see if they are still drenched with fuel?

I'll be watching this thread for any updates. Any updates by any chance?
 
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