idiosyncrasies or just things to drive you crazy

[Muddy]

I have noticed several idiosyncrasies with my 1992 Vette and wondered if anyone else has seen them. They got me in a spin :s

I am getting my Vette ready for the state inspection, for the third time and noticed my water temp was a bit low the last time I had it in for the inspection. The analogue temperature gauge was at about 120 to 130F, I kind of forgot there is a digital value that can be displayed so I did not look at that value. Anyway lord and behold there was NO thermostat in my car, this must be the reason why my coolant temperature was low and my emissions are too high, I thought. So I put the new stat in (180F) and the digital value is reading between 193 and 196 or so but the analogue gauge is about where it was before I put the stat in. About 120 to 130F ,maybe a little bit higher. How accurate is the analogue display?

My electric air pump for the catalytic converters works when I start the car and I allow the car to idle with the occasional bursts on the gas pedal and does so even when the cars has reached normal operation temperature (coolant). Now if I take the car for a short spin driving it a bit hard, return and let it idle once again the electric air pump has turned off. Turn off the engine and restart it and the electric air pump is back on again. I saw some where that it is appose to turn off about 3K rpm but would have thought it should turn back on again.

Start the car from a cold engine and let it idle until it reaches normal operating temperature (coolant), with the occasional bursts on the gas pedal. The engine responds fine to the bursts on the gas pedal always returning pretty quick to the idle speed somewhere between 800 to 900 RPM. Drive the car and immediately it take a bit of time to return to the normal idle speed, even sometime staying just over a 1,000RPM.

I reconnected a wire that was cut in the wiring harness going to the ECM and now the 1 to 4 light occasional come on, is something to do with the CAGS?


Muddy:crazy

 

[69MyWay]

Yep, pretty much normal.

If you really want to get a hanle on things, order one of these actron scanners.

These things are awesome, and will give you real time data streams on the cars vital emissions and performance functions. You can look up codes, erase codes, record data, and or simply pick a string of data readings and watch them real time. You can also run some basic diagnostic tests on the car. I have the one you see below with a 84-95 cartridge, and a OBDII scan tool for my newer vehicles.

Just one time, finding, curing, and clearing the code will pay for it, vs. going to the dealer. Plus you cans see if that air pump really is cutting on and off as it should. Finally, you can watch your fuel readings, O2, TPS, etc. and determine if your idle situation is just a worn out throttle body housing, or if your car has a vacuum leak, or if it is cycling as it should.



Actron Scan Tool

 

[c4cruiser]

The analog gauge is not a linear read-out, so it's pretty hard to tell what the temp value is. I just leave the digital temp display on all the time. Temps of 193 to 200 are normal.

That idle speed sound a bit high to me. My 92 A4 idles at around 500 in either Drive or Neutral. It will occasionally idle up to around 800-1000RPM but only for a few seconds then drops to where it should be.

I assume you have a ZF in the car with the CAGS 1-4 shift light now coming on since you have spliced the wire? The easiest way to defeat CAGS is to simply disconnect the harness from the tranny. Just doing that will defeat CAGS but the light will still flash. Most Vette catalogs have a terminal connector for the wire with a resistor that will keep the light from coming on. The light should not come on at all in A4 cars.

 

[Muddy]

Thanks for the info,

69MyWay, from what you are saying it make good sense that I have to find out what my ECM is doing. Looks like I will have start saving the pennie or maybe consider using a PCB and a laptop to have a look at the ECM unit.

c4crusier, It sound like my idle is a bit screwed up, must be something wrong with the IAC unit. My cable comming from the ARS unit will not allow the throttle plate to close much more at least enough to drop the idle down to about 500rpms.

Looks like I have my work cut out for me!!!

Cheers
Muddy