Not your usual idle problem

[Robby Camero]

Ok, I also have a 90 tsi fwd which isnt listed in my profile which I use as a winter beater and she is acting very strangly. It pulls hard still but idles very badly. Studdering, and almost stalling. Trims are pegged full at 120% (90 ecu), o2 wont cycle and no error codes. I know what your all gonna try and tell me already so here is a list of things I have checked.

-intake leak test, no leaks under 28 psi
-new o2 sensor
-new fuel filter
-cleaned injectors
-relpaced almost every vaccume line with new ones
-cleaned throttle body, tried another one as well
-adjusted the base idle untill I was blue in the face, no change or efect
-checked timing FOUR TIMES, crank, cam and oil pump marks are deadly and I did the ruler check accross the cam marks
-tried two different mafs
-tried two coil packs
-replaced power transistor
-blocked EGR
-new wires, plugs etc...
-new pcv valve

heres what I havent done yet
-try another ecu
-compression test (friend lost my tester)
-swap CAS (but I should be getting a code if it faulty right?)
-Check crank sensor
-swap injectors

I am stumped! Could a dead cylender cause this problem? I know a copression test has to be done but I am just waiting for a replacement from my friend. Have fun trying to figure this one out.

Thanx

 

[ltvarney]

Didn't see ISC testing in your list man.

http://www.myzero.com/engine/surge.html

 

[Robby Camero]

Its dissconnected and I pulled the plunger out once to try it that way too. Trust me, I know all about those stupid ISC's and this is not the prob. Thanx anyways.

 

[steve]

The fact that your O2's don't cycle but you have replaced the sensor leads me to ask what your coolant temp is. Check it with a logger not the dash guage.

Steve

 

[Robby Camero]

My coolant temp sensor for the ecu in the thermo housing works fine according to my logger readings.

I am gonna try a compression test tonight.

 

[Lordpaxin]

hmm, sounds like my problem, i justposted before seeing your post, mabye you can get some ideas from my post,

i suspect knock sensor.

 

[Robby Camero]

How would the knock sensor effect idle? Could you explain your theory?

I get knock counts of 18-25 stock boost but only because of the lean condition the trims are causing. The timing isnt being pulled too too bad though.

 

[Lordpaxin]

well, to my knowledge the only thing that can affect timing, is the knock sensor, or so the manual tells me,

my theory, the knock sensor, is bad, or intermittant, or fuqqed in some whay, it sends irregular signals, causing the ecu to advance.retard timing as necessary.

on my car, watching the time light, timing would spike or drop several degrees EVERY time the idle would raise or lower there after.

 

[Robby Camero]

Timing will advance or retard with rpm change. Its normal. So if you want to set the base timing, I think you (we) have to solve the idle issue first.

 

[Lordpaxin]

yes, i agree.

and you said you replaced all your vac lines?

 

[Robby Camero]

Well most of them. I left the one for the BOV, and the ones for the waste gate actuator alone because I know they were ok.

 

[Lordpaxin]

just swapped over for new vac lines, and idle is the same. but its blowin somewhat of a grey smoke.

um...
i also noticed that the amount of time it takes the car to start idle surgin, is getting faster and faster

 

[Lordpaxin]

DO THIS

go out there start it up, and go over to the throttle body, and grab ahold of the place where the throttle cable hooks in, and see if you can close it off any better.

tell me if that doesn anything