I need O2 sensor help, please come in!

metalman

Registered User
I have a few symptoms that could be related and today I just thought it could be bad O2 sensors. What do you think?

1) On cold engine starts, it stalls a couple times before heating up. Or I have to raise the idle so it doesn't stall until it warms up.

2) I feel the car has bad gas mileage.

3) When the car does warm up, the exhuast smell is very rich.

I figured if the computer was reading lean conditions it would flood the cylinders w/ more gas to compensate- IE stalling on cold engine, crappy gas mileage and a rich exhuast smell.

What do you think. Any other ideas to these symptoms. Thanks,

Metalman
 
its not the O2's because the comp ignores the O'2s signal on cold engine startup, sooooooo......if your engine stalls at cold startup you more than likely have vac leaks causing your problem.
 
Reads like you have a SC.

These are common problems with SCs vac leak or sudden temp change can cause stalling. All SCs run rich. Yeah SCs get 16 MPG. GOOD LUCK.
 
I scanned for codes about 3 months ago. I haven't checked codes since. I'll check from vacuum leaks. I bought the car last spring and it has the same O2 sensors on a 167,000 mile engine. I might change them soon anyway.
As you can see from my signature I have done a lot of mods and worked on my motor often, so it could be a vacuum leak-If I have to guess it'll be around my raised top. Thanks for the help guys,

Metalman

On second thought...I have a dented cat. A piece of concrete smashed into it while I was driving. The cat is not broken, no rattling, I had a muffler joint check it out. But if it is dented, maybe that could be the culprite of my symptoms???
 
Depends on how bad the cat is smashed as to wether its internaly damaged or not. Here's 2 possable scenario's for the mashed cat.
1. The cat was hit in an area where the catalyst blocks are breaking the blocks up, that would reduce backpressure thus giving you a drop in boost pressure. (that would explain the 2 psi boost drop)......or.....
2. The cat was not hit in the area of the blocks resulting in no internal cat damage and no change in backpressure or boost pressure.

Really neither one of those scenario's is going to cause an over rich air fuel ratio, so that kinda excludes the cats as a possable cause of your problem.
The vac leak is the most probable culprit in my mind because it will cause every symptom you have described and a vac leak is 1 of the most common problems on the SC engine. My money is on the vac leak.
 
I once had symptons simular to yours.And I to had a hard time finding it.
It turned out to be a seeping head gasket.(not blown)It would only leak
on cold start ups, until warmed then run just fine.Then when it was
under boost it would leak.It wasent until it got to the point that it would
leak under boost before I found the problem.I never did blow the head
gasket before I fix it.It took me close to a year to find.

So it may be possible that you have a head gasket getting weak,if they
are old.I had 82,000 miles on my head gaskets.My gasket looked like
the anti-freeze and finaly ate the gasket up in one small spot.

Randy
 
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I just COMPLETELY rebuild my engine in October of '03, just over a year ago. I did everything all new gaskets everywhere, new water pump, oil pump, new cam and crank bearings, new piston rings, valve stem seals, head p/p, 3 angle valve job, the block was decked, the cylinders were honed. I hope my head gaskets aren't leaking after only, at most, 10,000...,maybe less.

Due to the mass of mods I've done this year, I'd hope to venture on the vacuum leaks :) All the mods in my signature were done from March of this year with the exception of the rebuild and the p/p. I'll check it out hopefully tomorrow.

Thanks for the replys guys.

Metalman
 
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