Corvette C4 Forum 1984 through 1996

Help 90 L98 won't start

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Old Jun 24, 2007 | 11:11 PM
  #11  
cwb's Avatar
cwb
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Joined: May 2007
Posts: 1,567
From: eastern NC
Default RE: Help 90 L98 won't start

ORIGINAL: djack



ECM is new.



Just out of curiousity, where did you get the ECM?
 
Old Jun 25, 2007 | 10:03 AM
  #12  
86 Ironhead's Avatar
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Default RE: Help 90 L98 won't start

You have gas (36lbs at the injectors), You have spark, and timing is correct. You pinch off a vacuum line and the car starts but won't run pass idle. No code displayed. I suspectvacuum line trouble. Start blocking off hoses with golf tee's or caps, and borrow a vacuum gauge at autozone or checkers.

Sounds like a fuel issue or fuel mixture issue.
 
Old Jun 25, 2007 | 02:44 PM
  #13  
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cwb
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From: eastern NC
Default RE: Help 90 L98 won't start

ORIGINAL: 86 Ironhead

You have gas (36lbs at the injectors), You have spark, and timing is correct. You pinch off a vacuum line and the car starts but won't run pass idle. No code displayed. I suspectvacuum line trouble. Start blocking off hoses with golf tee's or caps, and borrow a vacuum gauge at autozone or checkers.

Sounds like a fuel issue or fuel mixture issue.
This is what I'm guessin' too, Iron, OR, his ECM was not programmed for his application... Vacuum will cause a ton of problems, and won't set off diag's, or will set off the wrong ones.
 
Old Jun 26, 2007 | 03:31 PM
  #14  
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Default RE: Help 90 L98 won't start

Would check the injectors. Easy to do and 90 Multitec were bad ones.
 
Old Jul 2, 2007 | 09:25 PM
  #15  
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Default RE: Help 90 L98 won't start

the way to tell if the timing chain has jumped is to check the distributor rotor at compression stroke onTDC. then pull a rocker cover, and check that number one rockers are both loose. that means that the distributor, run by the cam, is in position to fire, the rockers are loose, which means the cam is in position to fire, and the crank timing mark is on #1 TDC, piston at the top of the bore. if all 3 check out, no additional dissassembly required.
as long as you are in there, does it still have the nylon cam gear? if so, take it out and replace it with a good metal gear set, and a new chain. your engine will thank you for it with crisp acceleration, and diminished spark scatter.
 
Old Jul 3, 2007 | 05:34 PM
  #16  
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Default RE: Help 90 L98 won't start

so your car won't start......
ok, listen up
1986 coupe....
my car got warm, outside temp is 115 degrees, I went to the auto parts store, when I came out, and tried to start it, it refused to even turn over.
The starter wouldn't engage, and the lights all transferred into the start mode. (like normal)
I checked for codes, and I had two. 34, (maf low volts), and42, (ignition module not functioning). When it cooled off, it started like a champ. I started it 3 times, and let it run, and at 198 degrees, shut it off,...same thing. no starter. I dis-connected the battery, hooked it back up after 5 minutes, locked the car, unlocked the car, reset the hatch and outside door locks, locked the car, unlocked it with a key, then locked it, and tried to set off the alarm, and nothing. no horn, nothing! Like the vats had disabled the car, except no horn.
I played with the neutral start switch, ohmed the key, ohmed my wife's key, (1178 vs 1167). Someone suggested I put the key in the freezer to change the resistance, I did, and nothing.
When it cooled down to 157degrees, vrooom, started like normal. I still had the check engine light, so right before I was opening the hood for the 30th time, the engine started hunting at idle. Then I opened the hood, and unplugged the est module. the computer picked a default timing, and the idle was rock solid. Soooo....
I had it towed back to where I work. I went home, and got an est module, plugged it in, and I started it cold, warm, hot, you name it.
All fixed.
I think the est module must have a path to the computer that makes it act like the vats kicked in. no starter, and no injectors.
When it starts now, it acts normal. And I switched keys with my wife. after all, I have been using this one for 10 years, and she only used hers twice.
So if you have a problem starting it, unplug the ignition module, and the computer will default, and see if all is well.
 
Old Jul 3, 2007 | 06:14 PM
  #17  
cwb's Avatar
cwb
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Joined: May 2007
Posts: 1,567
From: eastern NC
Default RE: Help 90 L98 won't start

ORIGINAL: coupeguy2001

I think the est module must have a path to the computer that makes it act like the vats kicked in. no starter, and no injectors.
[sm=exactly.gif]

I'veposted before about variables' inter-relationship several times in different words coupe. I'm just passin' gas.

Almost every remote variable has some subset of variables that it is dependant on, before the computer does ITS' thing.

He said his evap purge solenoid was bad, and vacuum blocked off. There ain't NO TELLIN' what functions can be thrown off by that, even if that's actually correct in his case.
 
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