Hey guys, today I bought a fuel pressure guage when I went to get oil, so I tested my fuel pressure today.... 35 PSI at idle, when my sister touched the throttle (maybe 2.5k RPMs or so, 3 max) it jumped to 40. I think my fuel pump is just fine.
Here is what happens... at idle my SES will come on, if I idle long enough. It will turn off after I pull away and get the revs up a little. I think that is my idle SES code (says it isn't w/ 125 RPM of desired RPM at idle).
Now, the second isntance the SES will come on is when after cruising on the highway I hit the break to either exit, or slow down more then 5 or so MPH from my cruising speed.

Anyone have any ideas? IAC?
Thanks,
Douglas

 

I think you might need to replace the float in your vaccumm modulator, that or it could be the dumaflachie adjustments are set at negative top center southward.

If that doesnt work, I suggest a big hammer.. just start hitting things until it works.

No, but seriously Does it do anything strange when you first turn on the car? And also, if you are cruising, and it turns on, do you experience any drivability problems?

-Roshambo

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-Joe
1988 Pontiac Trans Am WS6 - 305 TPI, 700R4, 3.23 Posi, Digital Dash, Leather Seats, Maui Blue with Silver GFX, T-tops, Tinted Glass, Gutted MAF, TB Coolant Bypass, K&N Cone Filter, No Cat, 3" exhaust from Y-pipe back, MSD Super Coil, Accel 8mm wires, L98 Aluminum Heads, Ported and Polished Plenum, Siamesed Intake, Aluminum Driveshaft, Edelbrock 3 point Strut Tower Brace


[This message has been edited by Roshambo (edited November 15, 2001).]

 

What codes are you getting?

 

Sometimes codes do not show! I would check the voltage on the tps sensor. It should be between .05-.49 i think. Anyway, my tps sensor went bad and i checked for any codes and it did not show any, even with a scan tool! I checked the voltage with a volt/ohm meeter and found the problem. Your fuel psi should be at 43.5, make sure you pull the vacume line off the FPR when you read the pressure. Good luck! And what is the status of your car since it was hit?

 

DOH! I forgot to pull that line off. Oh well, I check it again tomorrow and see whats up.
Actually, it used to be after the SES light came on drivability got better... my guess is it went into limp home mode. We'll see what it does when I drive it tonight.
Where is the TPS sensor on the 3.1s?
Thanks!
Douglas
P.S. The car is partially fixed, and may be as fixed as it every gets w/ me. Might sell it as a project car, or something. Not 100% sure, but will probably have a 85/86 TA within the year.

 

Actually, Doug you are going into "Safe Mode", not "Limp Mode". In Limp Mode, the ECM is ignored and you run solely on the "hardware" on the Memcal. It basically has enough programming to allow you to safely pull the over to the side of the road.

Safe Mode is generally when you have an errant sensor (triggering an SES code). The ECM will use a default (example, if your CTS is bad, the ECM will try and use the MAT sensor, and if not, will use a "default value").

If your car runs BETTER in Safe Mode, then that definitely points to an errant sensor as you car should run worst in Safe Mode is all the sensors are operating properly. A buddy had a problem where the idle would be excessively high. Disconnecting the MAP sensor made the idle run better. This immediately told me that either his MAP sensor was bad or that he had a vacuum leak. Turned out to be a vacuum leak, the gasket under his TBI to be exact.

But you REALLY need to get a scan tool to properly diagnose these EFI cars...sorry no way around it. A "code reader" is basically useless as you MAY be getting a code due to the ECM compensating for some other "flaky" sensor which causes ANOTHER sensor to go outside of "predefined limits" and thus trigger an SES code.

A scan tool will allow you to see all of the readings of the various sensors, and often you can see one of the sensor are not giving readings in a "normal range". It may be because it is trying to compensate for another sensor, or it may indicate that this is indeed the bad sensor.

Also, while NONE of the sensors may be actually bad, they can help (due to there readings) to eliminate some possiblities and zero in on the real problem. Just like my buddy that had the vacuum leak. The scan tool didn't directly show that we had a vacuum leak, but it did indicate that we were getting "unusual" MAP readings, which allowed us to zero in on the problem.

Though my Diacom + was an expensive investment (the regular Diacom is half the price and more than adequate for diagnosing problems IMO), it has paid for itself in assisting me diagnose problems with my car. And INVALUABLE in my eprom burning when "user error" has caused SES codes.

My offer still stands if you want to come to Kamloops.