Well on a friends 91 Z 305 TPI (if ya can call these mods it had K&Ns, a flowmaster muffler,and a TB coolant bypass. thats it everything else is stock) the TPS voltage is set to at .58-.59 volts at closed trottle at WOT it is at 4.35 volts.

What happens is that when ya come to a stop the rpms drop to about 500 then kick up too about 700 then steadys itself out about 600 rpm.. Also too this doesnt happen everytime ya stop.. Just randomly.. Like it wont do it for a day or 2 then it will do it very time ya stop then it would do it 3 outta 10 times ya stop.. Oh yeah and it seems todo this when the car is warmed up to operating temp too. Wither it be just coming off the highway or in ciity driving.

Ive been trying to figure out the idle prob on it for quite sometime now. So far everything checks out to be in great working order. The car has a new IAC, new plugs, spark plug wires ohmed out fine, good amount of spark, the pick up in the dist is fine, module is fine, fuel pump is fine (ran 2 15.3's at the track with it this past saturday at VIR) and I think that is everything.

Only thing that I havent checked is that MAP sensor, the CTS (the fans work fine so I assume that the CTS is fine) and the MAT (or IAT)

Any other ideas would be great cause this has me stumped.

Kat



[This message has been edited by Kat (edited July 31, 2001).]

 

Oh yeah and there isnt any vaccum leaks.. Even tho the hoses look kinda eeehhh, they need to be replaced but I know that isnt the prob.

Kat

 

btt

Kat

 

For what it's worth...

I just checked my TPS voltage on Sunday and got basically the same readings... Those numbers look normal to me.

 

Hey Kat, might be time to pull the TB and clean it all out, as well as the IAC passages. TB gasket kit is about 10 bucks.

 

Mike I did do that when I replaced the IAC

Kat

 

I am having problems with my IAC valve.I can't get it to idle right. I have gone thru 2 new IAC valves and still doesn't idle correct.IT gets fine until the coolent gets to 220 and the fan starts.but when i start it,either cold or hot,it idles crazy,sometimes it dies.

 

Manuel did ya set the min idle right?

Kat

 

Try wd40 on linkage, both on TB and inside gas pedal

------------------
'91 Camaro 3.1 t-tops 44k original.
'98 GMC Sonoma excab 4.3 auto 35k.

 

When you installed the TB Bypass, you affect the way the engine performs it calculations for various things, including the idle.

To stabalize the idle, the IAC is "migrating" to a step count that is vastly different than "initial" IAC Step Counts defined within the eprom. Do you have a non-stock t-stat (ie. not 195*?), if so, you also have caused the IAC Learn to not function as the CTS temp is lower than the minimum for the IAC Learn.

I had a similar problem, and the only way I could fix it was modifying the IAC Step Counts vs Coolant Temperature Table inside the eprom. Then my idle was very stable and would almost instantly go to the Idle Speed Vs Coolant Temp settings, which is ALSO defined inside your eprom.

 

Alex it defantly isnt the gas pedal stickin cause I already did that the other day hehe

Glenn I belive the car does have a 180* t-stat in it..

Damn I was hoping that it wasnt in the chip at all..

Well time for me to spend the cash on some prom burning stuff.

Thanks

Kat

 

You didn't mention whether you have relocated MAT, but if you do, that even further compounds things with an SD car.

The good news is that there is a lot of info on SD cars. I have even come up with correction factors for the MAT so you can "optimally" run a relocated MAT on an SD car with a TB Bypass. Now my ECM can accurately use the information on the incoming air temperature to calculate the proper injection pulse widths. Whether my engine is hot or cold, I am not plagued with the "poor performance when you let the hot engine sit about 10 minutes and restart it on a hot day" that my car previously had.

 

Nope that MAT isnt relocated, it is still in the bottom of the upper plenium.

Glenn is there anyway that I can get a copy of that .bin file to look at?

Also to do you have ICQ or anything of the sort?

Thanks again

Kat

[This message has been edited by Kat (edited August 02, 2001).]