audifirst

I am in process of solving engine problem(v6 2.8). I need your help to give me more directions what else to check
When car is cold drives fine.
When car come to full warm up it's start to acting up. Mostly noticed during stop at the lights in Drive mode, engine RPM drops down to point that engine wants to stall and then rpm comes back to normal and again the cycle starts in couple seconds.. engine hesitates when I accelerate from stop..
I have so far address
1. new spark plugs, I did check wires with ohmmeter and they were withing spec required
2. fuel filter
3. I have replace all visible rubber small hoses in engine bay as they were cracked and dried up to point when I touch it dis grated
4. I did with vagcom TBA (Throttle Body Alignment)
5. checked all sensors with ohmmeter and oxygen sensors and they are within operational specs
6. replace suction pump
7. Cleaned MAF to see if anything improves

none of them fixed problem, but after replacing suction pump as one of clips was loose and air was escaping, and cleaning MAF, surging at the stop is not as much as before, still rpm drops and hesitates, when I switch to Neutral or Parking those symptoms are less felt then before

any other suggestions, maybe I am missing anything else to check..

4Driver4

Just for fun, change your coolant temp sensor.

audifirst

one..

thanks

Kris Hansen

Have you cleaned the throttle body at all? That seems to help a lot.

audifirst

I did the cleaning tonight
this is what I have found
<img src="http://img444.imageshack.us/img444/9162/dscf0901jq0.jpg">

after cleaning much better

<img src="http://img89.imageshack.us/img89/4603/dscf0905yl3.jpg">

tommorrow I will give a longer test, so far I run in garage, it was running smoothly with some small rpm drop once a while

audifirst

today the weather was much warmer on plus side, not cold, I have notice the surging is gone ??
so now this is strange, what this could indicate.. hose or intake leak or sensor not working ..

4Driver4

<ul><li><a href="https://forums.audiworld.com/30vv6/msgs/2979.phtml">.</a></li></ul>

audifirst

and I will replace it today, and test drive it..
I will post the results.. at the same time I will do the throttle cleaning..

audifirst

I believe it was faulty, I have measure the resistance as per bentley, and it was 1200 ohms it suppose to be in 1500-2000 range at 30 degrees, the new one was at 1738 ohm
here is a picture new one on the left and old one on the right
<img src="http://img89.imageshack.us/img89/6419/dscf0909mm7.jpg">

audifirst

After cleaning Throttle intake and replacing the coolant temp, engine runs smoothly now,
no more surging/rough idle or hesitation felt, hopefully this is it.. so far it is good..