Help! 1990 l98, bad idle - terrible Choking

[Aeolus702]

Corvette 90 l98 - Bad Idle - YouTube

Did a rebuild due to overheating, i think it was goosed (loud cranking noise :cry). My mechanic said he could fix it. Seems good now but now its choking sense the rebuild.

Recent Rebuild,
3 spark plugs were cracked after rebuild, have been replaced.
Broke in engine already, changed oil.
Distributor had timing corrected
Valve timing was adjusted
still having choking problem, as well as power draw.
This choking can be felt when accelerating. feels super rough and has no power behind it.

also before the rebuild oil would come out of the dipstick and cause big smoke clouds burning on the exhaust headers.

throwing out ideas about these 2 issues would be helpful, going to buy new dipstick hopefully that will fix, hoping its not major.

 

[68 4 spd]

Bad Idle

Corvette 90 l98 - Bad Idle - YouTube
sounds like maybe its leaning out check fuel pressure and scan o2 sensors did you find cylinder problem on rebuild bad piston or cylinder ?
Did a rebuild due to overheating, i think it was goosed (loud cranking noise :cry). My mechanic said he could fix it. Seems good now but now its choking sense the rebuild.

Recent Rebuild,
3 spark plugs were cracked after rebuild, have been replaced.
Broke in engine already, changed oil.
Distributor had timing corrected
Valve timing was adjusted
still having choking problem, as well as power draw.
This choking can be felt when accelerating. feels super rough and has no power behind it.

also before the rebuild oil would come out of the dipstick and cause big smoke clouds burning on the exhaust headers.

throwing out ideas about these 2 issues would be helpful, going to buy new dipstick hopefully that will fix, hoping its not major.

sounds like maybe its leaning out check fuel pressure and scan o2 sensors did you find cylinder problem on rebuild bad piston or cylinder ?

 

[gmjunkie]

Any Codes stored in ECM?

:confused

 

[WhalePirot]

gosh.. posting after Junk! I'm not worthy

I'd argue whether it was 'good' after the rebuild, but.... there could be so many things wrong here. Wow.

Oil pushed out the dipstick means the crankcase is pressurizing.. excess ring blowby? no PVC operating? Has this ceased since the "fix"?

Choking: Do you mean very rich running? Could be bad or contaminated O2 sensor (code stored), incorrect fuel pressure regulator vacuum or a bad regulator... or another sensor (TPS, MAP) bad, misadjusted or not connected.

Is this mechanic experienced with computer controlled fuel injected cars?

 

[Aeolus702]

1.Code in ECU - 32, from what i know thats the emissions. i replaced the egr(i think thats what its called) and that made the code go away.

2.for the oil, pcv's are working (did have this problem before rebuild) ill ask him about the ring blowby.

3.im pretty sure hes comfortable with electronics.

im taking it to him this weekend, ill update afterwards.

thanks guys! much appreciated! all this stuff is going beyond my capabilities

 

[Schrade]

You got vacuum leak - betcha'.

Vacuum leak.

Detection process follow to a 'T':
Originally Posted by Blade_1
Idle to warm motor. MUST BE CLOSED LOOP WARM.

Brick on GAS pedal, block TB linkage, anything to get a STEADY idle - about 2k rpms. MUST BE STEADY.

Spray starting fluid everywhere air can get sucked in, A LITTLE AT A TIME, until the motor surges. That's the leak. If it's in a tight spot, light a book of matches, blow them out quickly, and feed the smoke to the draw. Don't stop when you find one leak either. Plenum-to-runners, runners-to-intake, emissions hoses (EVAP cannister, EGR) valve covers, brake booster, EVERYWHERE. Vacuum/intake leak will make a 2012 car lope idle, and also will make a 50 year old lawnmower lope idle.

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This ain't hard. But I know of only 1 PERSON who ever got it right, and found his intake leak.

Even mechanics don't know how to get it right...