ACT sensor **UPDATE**

[MOSHO92]

I did a search and could not find much...

I have been having an idle problem for a while. I sent back my Pro-M 75mm MAF to get recalibrated, and that didnt really do much. I want to to blame it on my ACT sensor.

I have three reasons for this:
-It looks cheap and easy to replace
-The problem only occurs on cold nights
-I dont know what else it could be...

Here is a description of the problem:
"When i drop it into neutral while driving (like coming to a stop sign) the revs fall normally down to about 1.5k then sometimes drops down to like 400 rpm and stutters (almost dies) then it bounces up to 1300 again and then back down to 600 and then up to ....you get the picture"


Any suggestions??? Where can i get this ACT sensor?

<small>[ September 24, 2003, 12:40 AM: Message edited by: MOSHO92 ]</small>

 

[AutoSHO]

Mine did that. The BARO sensor was at fault. Wont hurt to change the ACT, but I havent ever had one make my car run differently, but all the ones I have might be good. Have you replaced the IAB? I had an intermittant idle problem that was only certain conditions, turned out to be a bad IAB.

 

[masho95]

I'll tell you right off the bat... save your money and don't waste it on a new ACT. As for your reasoning on replacing it... flawed and based on no facts. Run your codes first and see what you have.

 

[MOSHO92]

No codes...i think ahead. Iv'e been trying to pinpoint this problem for months...

I seems like it should be the MAF, something it causing it to run rich or lean when i let off the throttle. Ive had the MAF looked at by pro-m and they say it it fine, plus when i reinstall my old MAF the problem was still there. Why would it just happen when it is cold?? Where is the error in my logic?

 

[Groo]

I had the exact same problem. You should check the tubing you're using to connect the MAF to the TB. The tubing I was using was too narrow, and it caused the same problem you describe.

 

[JaySHOguy]

Have you been resetting the computer when you swap all of these parts?
Disconnecting the battery for awhile will clear the computer and you can reset the Idle afterwards.

 

[SuperG]

I did not have any luck resetting the computer by disconnecting the battery...However, if you run the KOEO test, then disconnect the wire to the EEC Test box, re-connect it...that should do it, unless it is totally different for 92's versus 93's.

Then run the KOEO test again...

Here is one place for the instructions:

http://www.midwestsho.com/catalog/troubleshooting.php?codes=instructions

 

[sdpatt]

The oscillating idle speed is usually caused by a faulty position feedback from the idle air control valve. This is not correctable by cleaning the air flow portion of the IAC valve. Try unplugging one sensor at a time: ACT, MAP, TPS and see if the changing idle speed ceases. I think you can replace all of these and not correct the real problem though.

 

[masho95]

sdpatt:
The oscillating idle speed is usually caused by a faulty position feedback from the idle air control valve. This is not correctable by cleaning the air flow portion of the IAC valve. Try unplugging one sensor at a time: ACT, MAP, TPS and see if the changing idle speed ceases. I think you can replace all of these and not correct the real problem though.

How many times does the idle speed oscillate like that? Amd when did the problem first start? Was it after you replace something? (fidanza flywheel in mind). I've noticed with my SS 8-lb flywheel when I'm driving and drop it into neutral while slowing coming to a stop or such with the clutch out the idle drops real low and even causes the oil pressure light to come on. I think that the computer is having a problem adjusting for the mass of the flywheel and causing it to drop to low in RPM's. The flywheel is probably spinning down faster than a stock 21-lb flywheel and thus the drop. Mine only drops low once and and pretty much goes up and down a tiny bit but it settles pretty quickly. Odd that it only happens on cold nights though...

 

[MOSHO92]

Well, I checked my codes again (even though I checked them before creating this thread) and low and behold...a 157 "MAF circuit dropped below minimum voltage". Maybe Pro-M forgot to actually CHECK it before they sent it back to me and told me the problem was on my end.

I swapped out the old MAF for my pro-M, CLEARED THE COMPUTOR (something i forgot to do last time i swapped them to check doh ), and it runs fine.

Sorry for the waste of bandwidth, but thanks for all your help anyways. thumb

 

[MOSHO92]

Well, I checked my codes again (even though I checked them before creating this thread) and low and behold...a 157 "MAF circuit dropped below minimum voltage". Maybe Pro-M forgot to actually CHECK it before they sent it back to me and told me the problem was on my end.

I swapped out the old MAF for my pro-M, CLEARED THE COMPUTOR (something i forgot to do last time i swapped them to check doh ), and it runs fine.

Sorry for the waste of bandwidth, but thanks for all your help anyways. thumb

 

[HopefulSHO]

Glad to see you got it fixed. Dont be sorry, that's what the forum is for. thumb