What issues with vacuum leaks and idle have people had?
Intake mani gasket? Injector seals? Throttle Body Gasket? Internal to brake booster or ERG system?

Let me know. Bouncing Idle and hesitation on acceleration plaguing my life! Suspecting the Intake Mani.

 

Do a positive pressure/boost leak test and find out for sure. Otherwise you are just guessing.

 

Start simple. Reset the ECU by removing fuse #6 (15 amp) from the fuse box under the hood. Wait about 30 seconds before reinstalling it, then do the idle relearn.


- Turn all electrical items OFF. (radio, wipers, heater, defogger, etc etc)

- Start the car and hold it at 3,000 RPM until the radiator fan comes on, or until the coolant reaches the operating temperature of 194 °F

- Take your foot off of the accelerator and let the car idle for at least five minutes.

- Done.



Have you checked the TPS with a scan tool? The reading should be about 10% when the throttle is closed, and about 90% when it's fully opened. If it's not within spec, replace the TPS.

How dirty is the throttle body? Ever cleaned the IACV?


It's possible that your suspicion is correct, and that you do have an intake vacuum leak. Usually easy to find with a can of ether.

 

with engine running spray carb cleaner around vacuum hoses, anywhere you suspect a vacuum leak. If the rpm go up when spraying in a certain spot, there is your vacuum leak.

 

I have:
- Cleaned throttle body
- Done Idle Relearn
- Added extra electrical grounds
- used vac gauge , reading a steady 22, snap test 0 to 27 to 22
- inspected and replaced vac hoses
- used scan tool, no codes
- Bled coolant
- Cleaned out & inspect ERG system
- Replaced TPS sensor, calib. .45 -4.5 v
- Replaced both 02 sensors
- Replaced ECT sensor
- Replaced MAP sensor
- Replaced IACV valve at great expense.
- Replaced spark plugs
- Replaced timing belt to check cam/crank timing marks.

Did the carb cleaner spray down and found an area underneath intake manifold that caused the engine to nearly stall with prolonged spray. Thus i suspect the intake manifold gasket. I have the gasket on hand. I was surprised to find this after THE FIRST thing I did was a vacuum check with the gauge, which was totally normal, I could find stone cold evidence of a vacuum leak.

What I was looking for with this thread was the symptoms other people had experiences with vac leaks in different locations.

 

I've noticed that my TPS used to say 9.4% when fully closed. Since I installed a short-ram intake, my scan tool now says that my TPS is idling at 35%. The car now idles anywhere between 1,200-1,800 RPM instead of the factory set 650-700 RPM. Has anyone noticed anything weird happening since changing their factory intake to something aftermarket?

I know for sure that I didn't touch or shift the TPS, and it's bolted down tight to the throttle-body.

 

^^ reinstall the factory intake and see if your symptoms are the same.

OP, this hunting idle seems like a common problem that no one has a solution to yet. that being said, i think i'll try the idle relearn procedure. seems like something to do... esp since i've seen it mentioned in the FSM.

 

I've finally got around to trying this today. The symptoms were the same.

 

I had a cracked rubber plug on an unused vacuum port (beside PCV line) that caused a crappy idle. Hard to find, but easy to fix.

 

I just finished installing a head gasket and Helicoiling the head bolt threads. Had two head bolts pull their threads.
I found this rubber hose under the car by the left front wheel when done.
I remember seeing this before but I do not know where.
The car runs perfectly with no issues.
Help, where does it go?