RENIX TPS Question - Simple answer needed, not the usual questions!

RickyN29 · 12-09-2006, 12:24 AM

Okay,

So, the little lever on the TPS that moves with the throttle....

If you were to push this down (like with a screw driver or something)...

Or even adjust it with the engine idling....

Should the IDLE change??

I read some people say is does, others make no mention.

Could it be that I have two defective TPS units? I can play with the lever, unplug the sensor, etc, and nothing seems any different.

**balloo93** · 12-09-2006, 12:28 AM

In theory it should. Don't know by how much though. It may affect the trans shift points as well if not set right.

Rock Kustoms · 12-09-2006, 07:32 AM

no, it will not technically change the idle. idle speed is controlled by the IAC, the IAC is activated when the TPS reads <3% open. by dialing that screw in, you crack the butterfly open therefor disabling the IAC permently. Yes, you can dial it in, and increase your idle speed, but with out the IAC system being used, the jeep now has NO adjustment for idle speed based on engine temp and air temp, which means on a cold day, with a cold motor, the jeep will idle different than a hot day w/ an already warmed up motor.

my street jeep stroker motor is set up like this, so Im not saying its a bad thing, but it requires me to have to tune the jeep quite often. the throttle body Im using doesnt have an IAC, so its pretty much my only choice.

tangofox007 · 12-09-2006, 07:48 AM

Ricky,
I will see what mine does and let you know. I have observed that the IAC pintle is retracted (which would result in a higher RPM) once the throttle is opened past a certain point. I would seem logical that this retraction is based on TPS input, but possibly not on TPS position alone.

tangofox007 · 12-09-2006, 09:44 AM

Leaving the throttle closed, I pressed down on the TPS lever. If I pressed down slowly, there was very little noticable difference the the engine speed. When I pressed the lever down rapidly, the engine stumbled somewhat then ran about the same as when the lever was in the normal position. (My TPS is only a few months old. I replaced it in an effort to eliminate the occasional high RPM at atart-up, hesitation and shudder during decelleration. The new TPS eliminated all those conditions.)

Blue XJ · 12-09-2006, 11:49 AM

It shouldn't really change the speed, it might change the amountof gas the computer puts into the motor, which might change the speed slightly.

**Matt Gertsch** · 12-09-2006, 12:28 PM

Quote:

Originally Posted by tealcherokee

my street jeep stroker motor is set up like this, so Im not saying its a bad thing, but it requires me to have to tune the jeep quite often. the throttle body Im using doesnt have an IAC, so its pretty much my only choice.

What TB are you using and how did you solve the idle stability issue?

Rock Kustoms · 12-09-2006, 01:57 PM

Quote:

Originally Posted by Matt Gertsch

What TB are you using and how did you solve the idle stability issue?

im using a 73mm SHO throttle body, and its a race jeep, so i only take it out when its nice, and usually the idle stays about the same (1250 rpm), if its off too much, i let the motor warm up, and then i adjust it

anony91xj · 12-09-2006, 05:01 PM

Yes. When the TPS senses a throttle increase, the PCM sends a signal to open the IAC. If your TPS isn't registering a closed (0%) throttle condition with your foot off the gas, the idle will be high.

I had this issue when I first did my HO swap.

RickyN29 · 12-09-2006, 05:09 PM

Interesting, thank you very much for all the replies and input.

My issue is a very low idle under certain conditions.

TPS makes no difference. IAC makes no difference. I have two of each sensor, neither makes a difference. Stumped.

For now I opened up the idle bleed screw on the throttle body and everything seems pretty decent. I know it is not the right way persay, but no more stalling or anything.

tangofox007 · 12-09-2006, 06:16 PM

Quote:

Originally Posted by anony91xj

Yes. When the TPS senses a throttle increase, the PCM sends a signal to open the IAC.

That's what I would have thought. My IAC does retract when the throttle actually opens. But it does not retract if the throttle remains closed and only the TPS lever is moved to an open throttle position. That makes me think that the ECU is using more than just the TPS input to control the IAC operation.

tangofox007 · 12-09-2006, 06:18 PM

Quote:

Originally Posted by RickyN29

My issue is a very low idle under certain conditions.

TPS makes no difference. IAC makes no difference. I have two of each sensor, neither makes a difference. Stumped.

For now I opened up the idle bleed screw on the throttle body and everything seems pretty decent. I know it is not the right way persay, but no more stalling or anything.

Have you tried cleaning the throttle body? Especially the idle air passage. Checked fuel pressure?

RickyN29 · 12-12-2006, 01:21 AM

Yep, all cleaned out, seafoamed, etc.

I was actually working on my buddies mustang who was having an issue with idle. Any adjustment of the TPS resulted in a significance idle change.

Believe it or not, i am thinking that both TPS units I have tried are defective. Or, possibly, but unlikely, damage between the sensor, and the wiring to the ECU.

When I get some extra mulla, I will buy yet another TPS.

12-09-2006, 07:48 AM	#4
tangofox007 Web Wheeler Join Date: May 2005 Location: GA Posts: 5,933 Profile Gallery Classifieds My Jeeps	Ricky, I will see what mine does and let you know. I have observed that the IAC pintle is retracted (which would result in a higher RPM) once the throttle is opened past a certain point. I would seem logical that this retraction is based on TPS input, but possibly not on TPS position alone. Last edited by tangofox007; 12-09-2006 at 09:45 AM..

12-09-2006, 05:01 PM	#9
anony91xj Registered User Join Date: Dec 2004 Location: North Jersey Posts: 2,742 Profile Gallery Classifieds My Jeeps	Yes. When the TPS senses a throttle increase, the PCM sends a signal to open the IAC. If your TPS isn't registering a closed (0%) throttle condition with your foot off the gas, the idle will be high. I had this issue when I first did my HO swap. __________________ 1997 VW Jetta - Daily Beater <---Totaled, seeking replacement DD 2004 GMC Envoy - Wife's Ride

12-09-2006, 05:09 PM	#10
RickyN29 Registered User Join Date: Apr 2004 Location: San Jose, CA Posts: 1,487 Profile Gallery Classifieds My Jeeps	Interesting, thank you very much for all the replies and input. My issue is a very low idle under certain conditions. TPS makes no difference. IAC makes no difference. I have two of each sensor, neither makes a difference. Stumped. For now I opened up the idle bleed screw on the throttle body and everything seems pretty decent. I know it is not the right way persay, but no more stalling or anything. __________________ 1990 XJ Laredo 4x4 Auto Rusty's ~6" Lift Dana30/Dana44 3.55's Pacer Wheels/High-Tec Retreads 31" MT KargoMaster Safari Rack CSF Open Cooling System Conversion Hayden Tranny Cooler Flowmaster 40 Delta & High-Flo Cat PORC SYE / FRT DS Combo *The Doors are off again for summer!

12-12-2006, 01:21 AM	#13
RickyN29 Registered User Join Date: Apr 2004 Location: San Jose, CA Posts: 1,487 Profile Gallery Classifieds My Jeeps	Yep, all cleaned out, seafoamed, etc. I was actually working on my buddies mustang who was having an issue with idle. Any adjustment of the TPS resulted in a significance idle change. Believe it or not, i am thinking that both TPS units I have tried are defective. Or, possibly, but unlikely, damage between the sensor, and the wiring to the ECU. When I get some extra mulla, I will buy yet another TPS. __________________ 1990 XJ Laredo 4x4 Auto Rusty's ~6" Lift Dana30/Dana44 3.55's Pacer Wheels/High-Tec Retreads 31" MT KargoMaster Safari Rack CSF Open Cooling System Conversion Hayden Tranny Cooler Flowmaster 40 Delta & High-Flo Cat PORC SYE / FRT DS Combo *The Doors are off again for summer!

12-09-2006, 07:32 AM	#3
Rock Kustoms Registered User Join Date: Feb 2005 Location: Wolcott, CT Posts: 3,848 Profile Gallery Classifieds My Jeeps	no, it will not technically change the idle. idle speed is controlled by the IAC, the IAC is activated when the TPS reads <3% open. by dialing that screw in, you crack the butterfly open therefor disabling the IAC permently. Yes, you can dial it in, and increase your idle speed, but with out the IAC system being used, the jeep now has NO adjustment for idle speed based on engine temp and air temp, which means on a cold day, with a cold motor, the jeep will idle different than a hot day w/ an already warmed up motor. my street jeep stroker motor is set up like this, so Im not saying its a bad thing, but it requires me to have to tune the jeep quite often. the throttle body Im using doesnt have an IAC, so its pretty much my only choice.

12-09-2006, 09:44 AM	#5
tangofox007 Web Wheeler Join Date: May 2005 Location: GA Posts: 5,933 Profile Gallery Classifieds My Jeeps	Leaving the throttle closed, I pressed down on the TPS lever. If I pressed down slowly, there was very little noticable difference the the engine speed. When I pressed the lever down rapidly, the engine stumbled somewhat then ran about the same as when the lever was in the normal position. (My TPS is only a few months old. I replaced it in an effort to eliminate the occasional high RPM at atart-up, hesitation and shudder during decelleration. The new TPS eliminated all those conditions.)