KenMathisHD

Hey y'all! We just finished doing the oil pan, timing cover and intake gaskets on my 94, and after finding and waiting for some other parts that broke when it came off I finally got her together and running last night - it was so nice hearing her fire up after about a month and a half of sitting. Once she started though, she started missing pretty bad and ran so rich it made my eyes water. I fired her up again this morning since it was pitch black last night and left her run until she got into a closed loop to see what she'd do. Idle in open loop she wavers between 800 and 900 rpms and shakes pretty bad, with some lag in the throttle response. Closed loop she idles up to 1050 and wavers between that and 975 - still shaking though not as much with it idling up, and still running pig rich. The parts aside from the above gaskets that have been replaced are the opti (the other one drowned in oil), the ICM (figured it was time), the EGR Solenoid Controller, and the Schrader valve on the fuel rail. I've got a video of her idling that I'll post up on youtube and link here, and I'm using Tunerpro Rt to try and read her codes.

Has anyone else run into this when doing the timing over or intake gasket?

Thanks!
Ken

KenMathisHD

KenMathisHD

bump

twichy2011

I just fixed a problem where my vette was running super rich. What does the o2 sensor data look like? What are he fuel trims. My problem stemmed from the drivers side o2 giving the computer a false lean condition. Also could be opti as well. O2 readings should oscillate between 100-900 with a high frequency. If you want, log the data and export the csv file and post to here. Maybe check for a vacuum leak at the intake using a propane torch (unlit) and run the gas around where the intake mounts to the head, and around the injectors.

Best of luck!

Connor

KenMathisHD

twichy2011

When you click record on tuner pro, and then click stop when you’re done you’ll save an xdl. After you’ve saved an xdl you can load log file and when you have it loaded you can export as csv. If you want you can post both or just the xdl.

To check fuel trims you want to look at left and right INT (Integrator) and left long term and right long term.
All you have to do for the propane trick is to get the gas flowing so you can hear it and run the tip of the torch close to where the intake and the heads meet. If there is a leak the gas will be sucked in and you will notice a change in RPM

Connor

KenMathisHD

I've exported to .csv now but the file size is too big to upload directly, and the .xdl file type isn't supported by the forum site. I'm gonna upload them to docs or dropbox and shoot up a link to them here

KenMathisHD

https://drive.google.com/open?id=1xK...LnRACxxrGkDO1b - .xdl

https://drive.google.com/open?id=1K9...wysc7sm6z52ZGD - .csv

MatthewMiller

I am guessing it's not O2 sensors, because the problem is actually worse (per Ken's description) when cold, in open-loop mode. When my one of O2 sensors **** the bed, it ran fine when cold in open-loop, and only started running rough and rich once it warmed up and began closed-loop mode.

I'm guessing something hasn't sealed correctly with the intake, or you have a bad injector or something like that. I seriously doubt it's the opti: if it were, you should also be getting a bad tach signal and no signal to the injectors and plugs. If you have an IR thermometer gun, you could try aiming it at each exhaust primary to see if they are all at similar temperature. If one of them is significantly colder than the others, then you've narrowed down the search.

KenMathisHD

Just got some more time to look at the data log, both int sides stay at 128 until closed loop, then left goes to about 140 average and right to 180 average, with right getting as high as 194 and left getting as high as about 150 - there's an average difference of 30 between the two sides throughout the log, though I should also mention that during the recording the engine is revved a few times to see how the data changes.

KenMathisHD

With the IR gun, do you point it at the headers where they reach the exhaust ports, or elsewhere? The ones on her look like they join the middle two cylinders in one tube - how would you use the IR gun to figure out if the middle cylinders are missing?

MatthewMiller

As close the heads as you can get, probably. Yeah, I forgot that the stock manifolds are joined in the middle. I guess try to do each side as best you can.

KenMathisHD

Tom400CFI

Don't need to get it up to temp; run it for 30 seconds from "cold" and the pipes will be about as hot as they'll get (idling) and you can get decent readings.

Is your CTS showing values that "jibe"?

KenMathisHD

Tom400CFI

Coolant temp sensor. By "jibe" I mean, does it seem to mesh with common sense evidence: when you turn the key on "cold" does the CTS read, say, 50-70°F when it's 60°F outside? When it's fully warmed up and the t-stat opens, is the CTS reading ~200°F or so? If those numbers align, or "jibe", that is believable. OTOH, if you turned the key on, it's 85°F where the car is sitting....and your CTS reads 40°F...now you got a problem. That reading is too far off and that would make your car run rich.

Since you have or are going to be using an IR temp gun in your exhaust, you can check the CTS as the engine warms and see if it's aligned, or if it "jibes" with your IR gun readings from the head or water pump housing.

PatternDayTrader

This is the problem.
The ecm thinks its running lean and so its correcting rich. Really rich. Did you not connect the maf sensor or something ?

PatternDayTrader

Make dam sure you don't have two plug wires crossed. A misfiring cylinder just pumps o2 into the exhaust which will cause the ecm to correct rich.

twichy2011

I just got a chance to take a chance to look at the log file. First thing that I noticed is that you have what seems like a bunch of knock. Both of your O2 sensors are staying lean, either they are lazy, or they are telling the truth. If you could take another log running down the road it would help diagnose those.

Thanks,

Connor Coughlin

KenMathisHD