Pulsating Idle

[tjh]

Pulsating Idle

Idle bounces from 500 rpm to 1000rpm "only when in gear ". (but not every-time I put the vehicle in gear)

If I release the brake pedal while its doing the pulse thing, it will pull the vehicle along with a bouncy rhythm that matches the revs , up until I accelerate past 1000 rpm.

What Ive tried thus far : Cleaned MAF
Cleaned TB
Cleaned EGR pipe
Replaced TPS
Replaced IACV
Replaced EGRV
Replaced FPR
Replaced FPR vacuum line
Replaced Fuel filter
No dice yet !

Symptoms have progressed into idle hanging up at 2000 rpm after accelerating .
I recently unplugged the pressure switch for the power steering and have not had the Idle hang up again ...Yet .
The idle still continues to pulsate , only when in gear , but not all the time , and it happens more frequently when in reverse .

Intake manifold appears to be in good condition , I will be testing it for leaks .

What,where, else should I be looking ?

[VX crazy]

Vacuum line maybe??????? We get some weird problems, I wish everything had a specific code!

Pulsating Idle

Idle bounces from 500 rpm to 1000rpm "only when in gear ". (but not every-time I put the vehicle in gear)

If I release the brake pedal while its doing the pulse thing, it will pull the vehicle along with a bouncy rhythm that matches the revs , up until I accelerate past 1000 rpm.

What Ive tried thus far : Cleaned MAF
Cleaned TB
Cleaned EGR pipe
Replaced TPS
Replaced IACV
Replaced EGRV
Replaced FPR
Replaced Fuel filter
No dice yet !

Symptoms have progressed into idle hanging up at 2000 rpm after accelerating .
I recently unplugged the pressure switch for the power steering and have not had the Idle hang up again ...Yet .
The idle still continues to pulsate , only when in gear , but not all the time , and it happens more frequently when in reverse .

Intake manifold appears to be in good condition , I will be testing it for leaks .

What,where, else should I be looking ?

[djvx]

did you try to pull a code?

[tjh]

did you try to pull a code?

Yes, suposedly everything is hunky dory.

[blacksambo]

Spray carb cleaner around the common chamber gasket areas and see if the idle lifts. If so, cahnge those gaskets and torque to 13lbs, not 18lbs.

[Triathlete]

The above is a definate possibility. Also check your gas cap...although this usually only causes issues when warm.

[tjh]

Spray carb cleaner around the common chamber gasket areas and see if the idle lifts. If so, cahnge those gaskets and torque to 13lbs, not 18lbs.

Right O , next on my list . NOTE TO SELF : Purchase torque wrench .

The above is a definate possibility. Also check your gas cap...although this usually only causes issues when warm.

What am I checking for ?

Thank you for the leads .

[Triathlete]

Either not on tight or leaking (hard to check without a cap tester though.

[tjh]

Either not on tight or leaking (hard to check without a cap tester though.

I just made a google ! that's a pricey little gadget .

[SilverBullet75]

Couple other checks:
- Intake Manifold gasket
- Make sure all electrical connectors are plugged in tightly.
......I know it sounds elementary, but when working in the engine comp., things can bump loose. (Speaking from experience)

- Check for Nervous Leg-bounce. Can cause Idle fluctuations.

Can't think of anything else off hand.... anyone else?

[Triathlete]

I just made a google ! that's a pricey little gadget .

The cap or the tester?
If the tester...ours get tested as part of our required emissions tests.

[tjh]

The cap or the tester?
If the tester...ours get tested as part of our required emissions tests.

The fuel cap of-course $36.23 that's outrageous .

Heck the tester is only like $2391.99 , I mean that's like couch change .

A required test ? ha doesn't exist here !

[tjh]

I sprayed carb cleaner all around the intake/throttle body , no increase in idle.


High Idle returned to day . When the motor started the high idle I popped open the hood, and grabbed the shaft that the accelerator cable is attached to . I was going to increase the throttle , but the weight of my hand on the shaft caused the idle to return to normal. There was no discernible downward movement of the shaft. I increased the throttle and it returned to high idle, and then I pushed down on the shaft and Idle went back to normal. I cant detect any downward movement of the shaft .
What is going on ? How do I fix it ?

I still get pulsating idle when in gear . When I engage a gear the Idle will drop to about 500 rpm and then return to 750 most of the time . Other times it will just bounce from 500 to 1000 rpm ,over and over and over.

[tjh]

During a high idle episode , I pulled the plug on the TPS while the engine was running,and the idle immediately returned to normal.

Could the TPS be the culprit?

[Grif]

During a high idle episode , I pulled the plug on the TPS while the engine was running,and the idle immediately returned to normal.

Could the TPS be the culprit?

I would say quite possible yes. I replaced mine when I was having idle issues, easy to do and a cheap available part, so its an easy enough test.