the camaro has been running rich for several months now, and i can't figure it out. i've taken it to two different shops, and all i ended up doing was wasting money.

things i've replaced:
prom
ecm
oxygen sensor
coolant temperature sensor
air filter
plug wires

things i've checked and found to be working fine:
timing is fine
plugs are almost brand new and look ok
ignition coil
running temp
spray pattern
vacuum hoses
no visible leaks
tried variety of gas

i'm running out of ideas now, all i can think of is maybe its another sensor like the MAP sensor or MAT sensor, but i doubt it. not throwing any codes, except for a rich running like every two weeks or so. the fuel pump is about 8 months old, don't have a fuel pressure gauge.

if it helps, i can smell the gas coming from the engine bay more than from the exhaust, i seriously can't use the heater because it will asphexiate me its so bad.

any ideas? its an 88 camaro 305 tbi, very few mods

 

Just a few precaustions here, but if it smells like raw fuel in the engine, then I'd suspect a fuel leak. If it smells like excessive exhaust, then an exhaust leak. Both are/can be dangerous.

Since you mention it's stronger in the engine bay and the smell is blown in through the vents, I'd concentrate under the hood for leaks as opposed to fuel management.

 

Lucas,

(Does anyone but me find the connection between "Lucas" and "Vader" a little coincidental?)

ECMs almost never go bad. Everyone is quick to blame rogue problems on the device because they don't understand it.

EPROMS almost never fail (See above).

You have replaced a lot of components that probably needed replacement anyway, with the possible exception of the CTS (and of course the ECM and EPROM). All the rest should be replaced regularly anyway.

You have tested several things that should be tested in the course of diagnosing this problem, but have missed a couple of key items. Both of the shops that you paid your good money to should have done a more thorough diagnosis. This isn't specifically related to just ThirdGens, but any car with electronic fuel injection (which is now about 90% or more of the vehicles on the road). It's sad that diagnostic skills are eroding so badly, and that shops can't seem to hire and pay a decent wage to the truly skilled technicians (which leaves me out).

As a general rule, since you already have some basic knowledge of what's happening under the hood, you probably know as much as any of the "mechanics" you paid to find your problem - you just don't have all the pretty gadgets and tools. Don't even bother taking your car to a shop that doesn't have ASE certified technicians. Even if they cost more per hour, they're going to spend a helluva lot less hours correcting your problem than the average place.

O.K., I'll get off my stump for now...

That said, you really need to check the fuel pressure with the engine running. We'll need to have the fuel pressure, MAP readings or intake vacuum readings at idle, idle RPM, and coolant temperature. With that data, there is a very good chance of solving your issues.

Any other data you can provide could be helpful, so submit anything you may have from the shops you visited and your recollection and testing. A list of your modifications, no matter how minor, might help as well.

 

thanks vader, i'd hope you'd come along.

i believe the same thing about the ecm and the eprom, i was VERY hesitant to replace it, so i talked with the guy for about 20 minutes on why he thought it was screwed up. he said something along the lines of the right inputs were going in but the right outputs were screwy. new one and prom didn't change anything though. at least i have a spare now.

btw, both shops had ASE mechanics, and they were both fairly large shops.

8mike9, i've verified there is no gas leak, the car would have already burned to the ground if there was

can i take a MAP reading with a multimeter? i'll try to find my gauge so i can get a vacuum reading, and the idle speed in park is usually around 700 rpm.

how can i check fuel pressure on a TBI? do i need to plug the return line or something?

 

Lucas,

The MAP can be tested for output voltage with a DMM (or analog meter if you have a good eye). It should output 4.8-5.0 VDC with the vacuum line disconnected, and 1.2-1.5VDC at 18" Hg. The output should be fairly linear at any point between those vacuum levels. Don't apply more than 20" Hg to the sensor if you can avoid it since the diaphragm won't survive it for long.

As for testing the fuel pressure, the TBI systems are not supplied with a Schrader valve for testing. You'll have to fit a test fixture with a valve. These usually temprarily replace the fuel filter of fit between the fuel line and TBI base. The pressure should be 11-13 PSIG at idle. Low fuel pressure on a TBI system in closed-loop tends to make for rich running, not lean, since the ECM corrects the mixture in relatively large steps. I had a TBI with a marginal fuel pump that help 7 PSI and the mixture was so rich it would almost make you cry.

 

are there any other symptoms that go along with the "smell every two weeks"... like rough idle, black smoke out the tail pipes... changes in weather hot, dry, wet, cold???

this is just to add to the things Vader suggested...

zroc

 

I have had fuel pressure problems also. The psi vary's around a pound and the needle shakes at times.

 

Did the shop you took your car too check to see that the injectors were in spec, electronically that is?

Not too long ago I had to change all 8 of my injectors. What happened was my car would stall at lights and hesitate when I pressed the gas.
The problem it seems is that 4 of the injectors where electronically damaged. The injectors themselves were clean, spraying a nice profile or spray pattern BUT electronically they were out of spec.
The test the technician did was to use his ohmmeter and check the resistance out on the injector’s contacts (pins, connectors).
For a 305, the injectors should have a resistance of 14-16 ohms. 4 of the injectors were at about 8 ohms, and the rest were in tolerance.
The computer was over compensating for the 4 bad injectors and the car was running rich because of it. Its like the old carburetor cars if it isn’t tuned just right your either running rich or lean and the car won’t run properly.

 

Correct me if im wrong, but I think he said TBI Which should only have 2 injectors.... Am i Wrong?? I have TBI and can only SEE 2 injectors, 1 fuse for each in the fuse block too... Mine runs rich as nuts every now and then too, ever since i did the exhaust, and throws O2 sensor Lean codes, so my problem is likelly just the O2 sensor, yours sounds electrical (hehe) and not in my range of mechanics, but who knows... a "gas smell" is not always just raw gas sitting there, and since you are sure there is no gas leak, it could just be coming from the throttle body itself, since the injectors just kinda flop the gas ontop of the throttle blades and then it bleeds down (from what i can see) smell the throttle body itself to see if the smell gets worse... if not there is a place somwhere else causeing the smell... Is the smell part of your problem??? good question...