1990 Chevy Corvette Lean Burn Miss

Tiny
VETT 90
  • MEMBER
  • 1990 CHEVROLET CORVETTE
  • V8
  • 2WD
  • AUTOMATIC
  • 85,000 MILES
1990 Corvette Convertible Recent Repairs
Full set of new Fuel injectors CVU Fuel Injector (Org Replacment)
Computer PCM
Plugs
Plug Wires
Cap
Rotor
Fuel Filters
Air Filters
Oil, Oil Filter
Injector within 1 0hm, fuel pressure within specs, EGR smoke tested ok (can't test under intake)

Continues to have lean burn miss at idle. More prevalent when engine cold. Less when warmed up or at speed mild surging.
Has anyonre had simliar issues with approx. Same year vett. Any suggestions?
I have had in 3 different shops and spent a ton of money with no results.
Do you
have the same problem?
Yes
No
Tuesday, August 11th, 2009 AT 5:11 PM

4 Replies

Tiny
DR LOOT
  • EXPERT
The first thing I would have changed would have been the oxygen sensor. Did you forget to mention that, or are you saying that three different shops overlooked that?

Good Luck.
Dr. Loot's Assistant
Was this
answer
helpful?
Yes
No
Wednesday, August 12th, 2009 AT 12:31 AM
Tiny
VETT 90
  • MEMBER
O2 sensor was replaced sorry I forgot to list that.
Was this
answer
helpful?
Yes
No
Friday, August 14th, 2009 AT 12:09 PM
Tiny
VETT 90
  • MEMBER
Compression is good accross all cylinders and there are not any computer codes coming up.
Was this
answer
helpful?
Yes
No
Friday, August 14th, 2009 AT 12:17 PM
Tiny
DR LOOT
  • EXPERT
Well, with all that you have listed, I'd expect that the problem would have been solved. So, we have to conclude that it's something we haven't thought of, or that some of the parts you paid to have changed weren't properly changed, if at all. But, assuming that they were, at this point, I would go to the shotgun approach. We need more data. Here are some ideas (and, at this point, I'm stumped so I'm shooting in the dark hoping to stumble across something):

1) try boosting your octane to a 100 or more with some of the available fuel additives. See if that makes a difference.

2) get an emissions test station to verify that your car is actually running lean at idle.

3)try pulling a spark plug wire and connecting it to a grounded plug external. Do that for each cylinder. If the miss is entirely located in one cylinder, you may be able to hear the difference.

4) on the possibility that your injectors weren't really changed, get a stethoscope and listen to each one. Maybe you can detect a difference.

5) spray starting fluid (carefully, have a fire extinguisher on hand) around the intake manifold and listen for a change in the engine idle. This can help locate a vacuum leak.

6) run some BG44K through your fuel system. If you have an injector that is not properly misting the fuel, this could help it.

7) do a leak down test to determine the health of your intake valves

That's all I can think of at the moment.

Good Luck
Dr. Loot's Assistant
Was this
answer
helpful?
Yes
No
Monday, August 17th, 2009 AT 10:50 PM

Please login or register to post a reply.

Recommended Guides