TPS affects on IAC?

[imjoesnuffy]

If the TPS is bad can it throw off the IAC? Think my TPS just took a crap on me. min voltage is now .89 volts and max is 2.4 volts. I was working on the tune yesterday, checking default values and found this out. Car was idling fine prior to yesterday. Only thing changed recently was I had a bung welded into the up pipe for the ATS. I did check for vacuum leaks with brake cleaner to rule them out. None found. BLMs and INT are all over the place too.

I reset the ecm started it back up and now it wants to idle around 2000 rpms. Cut it off and restart it and it goes to 1000 rpms. IAC doesn't drop below 60 at idle hot (with the throttle stop screw unscrewed all the way).

Goose the throttle and it is slow to come back down in rpms to 1000.

My turbo oil return line just developed a crack as well. LOL, why does crap like this have to happen the week before BG??? New oil return on the way. Sources for a good TPS?

Thanks for the help in advance!

 

[TurboDave]

Well, to begin with, backing the idle stop screw (not actually correct terminology) out will raise IAC, and will definately screw up the TPS setting!!!

You've got something whacked out of adjustment and they are affecting each other, so I would suggest starting over.

Lets get the IAC screw back where it belongs, screw it IN just enough to show 1 thread on the other side of it's mounting boss.

First of all, reset your TPS this way:
Loosen both screws so you can adjust it, but not enough to allow it to move much on it's own.

Pull it as far forward against those two screws as it will go.

Tighten the two srews just enough to hold it in place.
That's your best wot adjustment.

loosen the top screw just enough so you can move the nose of the tps up or down. IN VERY SMALL AMOUNTS!! while watching your scan tool, this is your idle tps adjustment.
You should not allow the tps to move backward while your doing the "up/down" adjustment. That's why you leave the bottom screw just tight enough to prevent fore/aft movement, but allow the nose to be rotated up or down.

Now, with key on engine off, you should be able to see how close you are on your tps idle and wot adjustments, and play with it a little

TPS seldom "crap out" as you described, it's usually a combination of mis adjusted IAC and TPS.

If you decide to mess your IAC adjustment screw, remember, it will change your idle tps values every time you mess with it, so the two interact.

 

[imjoesnuffy]

Thanks for trying to sort my mess out.

OK, 1 thread showing on the other side of where the screw goes in (towards the radiator). TPS loosened up and pushed all the way forward (towards the radiator) TPS does not go below .79 volts. I followed your recommendations with getting the bottom screw snug and top screw loose still able to tilt the TPS back and forth. With the TPS tilted all the way forward it doesn't go below .79 volts.

It will go up when tilted to the rear.

I am getting 5.01 volts at the harness plug as well.

 

[BlackBandit]

Go to this link. IAC Reset Procedure It will walk you through the IAC procedure and then link you to the TPS procedure.

 

[imjoesnuffy]

Go to this link. IAC Reset Procedure It will walk you through the IAC procedure and then link you to the TPS procedure.

Blackbandit,

I can not adjust the IAC. With the screw all the way out it is idling around 1000. The IAC should be going down, correct? Idle goes up, IAC goes down. That's the way it used to work for me If I screw it in the idle goes up even further, yet the IAC still doesn't come down.

I was thinking vacuum leak giving me unmetered air, I did spray everything in carb cleaner to check. With it idling so high hard to tell if there is any fluctuation. Nothing obvious though.

 

[BlackBandit]

Maybe this will work. IAC Reset Procedure

 

[imjoesnuffy]

Scanmast readings

O2's bouncing betwee 119-642
WB 14.3 steady
AF 5
L8 29
BAT 14.1
INT Bouncing 132-141
BLM 139
MPH 00
CLT 162
ATS 80
RPM 1000
TPS .83
IAC 78
CC 0-255 loop
Pu 1.8
SP 29.2
Mal 0
MAP 0 Not hooked up on the powerlogger
Boost 0

 

[JayC]

You need to set the idle to about ~100 of what the chip is commanding the idle to be. I usually shoot for 850 in gear so I tell people to set the idle around 750. Setting it at 500 is great for stock.

 

[imjoesnuffy]

Maybe this will work. IAC Reset Procedure

Tried that as well. Grounded out the ALDL, fans turned on.

I could get it to idle around 500 with the IAC disconnected before start up. Cut it off and reconnect IAC, ignition on, TPS won't budge below .83 volts. Start it and it goes back to the same old thing???

One thing of note: WB went rich to 12.9 at idle when I restarted it following these procedures.

Turbotweak chip idle set at 850 in park I believe. I tried setting it at 850 as well with the above procedure, same results.

 

[imjoesnuffy]

After the last round of IAC resets. Reflashed the ECM. Idle set at 850 with the IAC disconnected, TPS stuck at .81 volts.

Engine running idles at 1050 rpms, IAC stuck at 78, tps at .81

 

[86george]

After the last round of IAC resets. Reflashed the ECM. Idle set at 850 with the IAC disconnected, TPS stuck at .81 volts.

Engine running idles at 1050 rpms, IAC stuck at 78, tps at .8 /QUOTE] I had the same problem on my car a couple months ago. I couldn't get the iac,tps,idle and throttle blade to match up.I had cleaned the iac and cavity did the reset and coudn't get the idle,tps and iac back where they belonged.I first thought i was getting to much unmetered air so i capped the pcv valve and that helped some.The iac was orignal so it was the next suspect. Got the iac and pcv from local Buick dealer was surprised they had them. Solved the high idle,iac,tps problem.Iac was about a $100 with tax , ouch. Good luck with yours.

 

[imjoesnuffy]

After the last round of IAC resets. Reflashed the ECM. Idle set at 850 with the IAC disconnected, TPS stuck at .81 volts.

Engine running idles at 1050 rpms, IAC stuck at 78, tps at .8 /QUOTE] I had the same problem on my car a couple months ago. I couldn't get the iac,tps,idle and throttle blade to match up.I had cleaned the iac and cavity did the reset and coudn't get the idle,tps and iac back where they belonged.I first thought i was getting to much unmetered air so i capped the pcv valve and that helped some.The iac was orignal so it was the next suspect. Got the iac and pcv from local Buick dealer was surprised they had them. Solved the high idle,iac,tps problem.Iac was about a $100 with tax , ouch. Good luck with yours.

I am running a check valve in line with the PCV. It is very snug down in the grommet in the manifold. Might have to try a different IAC. Still doesn't explain why the tps wont move???

 

[BlackBandit]

Have you checked your grounds from the block to the body? If that's not it you might want to try another tps.

 

[imjoesnuffy]

I have the caspers ground stretcher kit on my car. I will double check them to make sure none came loose.

 

[JayC]

I have the caspers ground stretcher kit on my car. I will double check them to make sure none came loose.

You also might want to add a ground to the TPS plug.

 

[FORREST]

Tps

Just a thought.I had a problem once like this,it turned out to the split pin that
drives the TPS would not make complete contact with the arm on the TPS sensor.

 

[DavzGN]

Only thing changed recently was I had a bung welded into the up pipe for the ATS.

This is probably a dumb question but was the up pipe removed from the car when the bung was welded on? If it was on the car, welding can mess up electronics.

David

 

[imjoesnuffy]

This is probably a dumb question but was the up pipe removed from the car when the bung was welded on? If it was on the car, welding can mess up electronics.

David

LOL, yes it was removed. Good question though. Took the entire throttle body off today, cleaned it inside and out, to include the IAC. Didn't see anything surprising. Reconnected everything, car is now idling better. Idle will actually adjust off of the screw at this point. IAC appears to be stuck at 175 now. No luck with the IAC reset procedures above either. When I took the TB apart the IAC pintle was not all the way out.

I have yet to the TPS voltage go below .79 or 2.78 volts maxed.

Grounds were tight. I haven't tried adding a ground to the TPS yet.