I am going to be using Autotap to try and diagnose idle problems that I have been having with my car. I was hoping some of you would give me suggestions for certain parameters that I should check first.. I was thinking tps, egr, maf, iac.. Any other common causes?

 

What kind of idle problem does it have?

 

after the car has been driven for a little while when I come to stops it will idle down to 6 or 700 then back up to 1000 then back down. It used to be much worse than this but I have since gotten the tps where it should be and the iac looks fine too.. The problem is still there though. I am thinking the O2 sensors may be bad because I ran them directly after my header install thinking maybe some of the coating in the headers could have messed them up but i dont get codes for O2 sensors although I have before and i cleaned them with electrical cleaner and the problem cleared a little but not fully. I also wonder if it has something to do with the AS&M 54mm throttle body I have on here.. Will a bad battery cause low/ insufficient voltage codes? I had one for my MAF but im thinking it may have been caused by me unhooking the maf with the battery still hooked up.

 

after clearing codes yesterday and driving it again today I got some more codes. p0122(TPS circuit low voltage), p0135(HO2S heater circuit bank 1 sensor 1, and p1121&p1122(tps ckt. intermitten high and low voltages). What would be the cause of high and low voltage readings on the tps? I was monitoring yesterday and @ 0% it was .6v all the way to 4.8.. I did notice that for a second with the car off when i was monitoring my tps voltage changes that at 0% throttle the voltage dropped to .2v a couple of times but it never did it again after that.. I didnt notice anything over 5 though. All of these codes it gave me before only this time i got no MAF code.

 

I'm wondering if you have a short in some of the wiring that may cause multi-sensor problems. As the TPS and O2 sensors are really 2 seperate issues.... I'm not 100% sure of whether they may be close to each other, in terms of wiring, but if some part got exposed to heat, etc. and started shorting... you may have some problems.

 

Have you ever hooked up the scanner or a volt meter, turned the key on, and moved the TPS sensor slowly through the full range of motion, watching for intermittent voltage fluctuations? Do it several times, jiggling the shaft and the harness connector. Anything under 0.20V for 1-second or more at closed throttle, or over 4.90V at any other time sets the codes. Could be a faulty rheostat in the TPS, a faulty harness connector or shorts in the wiring from the PCM to the TPS sensor.

 

while checking voltage as stated by injuneer you shoud also wiggle the harness to make sure you dont have a intermittant open in the harness

 

Thanks for the suggestions guys. I have checked the voltages of everything under normal conditions ill try disturbing the wires a little bit and see what happens. As for the o2 sensor problem.. I tested the voltage of the wires at the extensions and they are both receiving 12+ so I am going to blame that on a bad o2. I also noticed the other day that the lean/rich switches of that o2 sensor were half the amount of the other one.. Will it be alright to replace only 1 o2 and leave the other in there? Or should I get 2 new sensors?

 

I did this today. I replaced the front drivers side o2 sensor after determining the wiring to the o2 sensors were good. I then tested the voltage again on the tps sensor and got the low voltage/ckt intermittent codes for it. The voltage fluctuated up and down as i pressed the wires into the harness. This is what set the codes off.. It set at .1v until I messed with the wires again.. Is there a way I can fix the harness or do I need to replace the whole thing?

 

ttt? Anyone?

 

Start with a new pigtail.

Right hand side of the page has a pigtail part # listing:

http://shbox.com/1/Parts.htm

 

i would just pull the harness you have apart and see what it looks like. if it looks ok and only one or two wires are screwed up then just fix the one you got. but do it right - solder and heat shrink

 

Are you meaning pigtail as in the connector to the tps? I think the left hand side of that page only has a part # for the tps itself..

 

Did you look at the right side of the page, under the heading:

"1993-1997 F-body Wiring Replacement Pig Tails"

 

Well I slotted a GM TPS that I had in my garage that i forgot about and those tps problems seem to have gone away.. I have another question though. I have noticed that when in gear at a stop the cars idle will fumble around a little bit from time to time.. I was watching autotap when this happened and it would read anywhere from 0 to 4 degree's of knock retard then there would be a slight stumble.. My engine shakes a decent amount when the car is at idle like that. Would this be the cause? I have some performance motor mounts that I never put on would that possibly get rid of that knock im having at idle?