club.liberty.asn.au

Im back with yet another problem that is starting to cost a small fortune diagnosing. CEL came back with P0638 - Throttle control circuit range performance problem. This causes the engine light to come on and cruise will flash and a high and lumpy idle. This problem happens mostly when i put it in P [park] but recently now in nuetral and more recently in drive at a set of lights. Couple of mechanics stated throttle body as the issue. I first got it cleaned and put back in but code reappeared. I have just put in a new[ish] one i got from a parts place but im still getting the code. Im not sure where to really go from here now without spending a huge amount of money on a brand new throttle body [$2000 subaru says] and still having the same problem. Has anyone been through and solved this problem? Ive googled so much but cant find any resolved issues.
Heeelp please.

Have a read of these pdfs

http://legacygt.com/forums/showpost.php ... ostcount=2

That may as well be written in chinese. Thats hard to follow for me. Im pretty simple when it come to things like measuring volts, ohms and things. It is very detailed though.

Mate I'm having a very similar issue: viewtopic.php?f=45&t=22990
My GT just dies randomly - I'm starting to think there is a short somewhere and the extra load at night - lights etc is causing a voltage drop which in turn leads to TPS errors and the car going into limp mode. Thinking there might be a damaged relay or contact somewhere. Degreased the engine at one point and the errors started afterwards.
Good luck..
Jim.

I get no difference if lights are on or not. Im about to put in yet another throttle body and see what happens. Im getting the flashing cruise light come on randomly now too but without the cel. Worst car ive ever owned

NRV155 wrote:I get no difference if lights are on or not. Im about to put in yet another throttle body and see what happens. Im getting the flashing cruise light come on randomly now too but without the cel. Worst car ive ever owned

Didn't you get the car ridiculously cheap or something?

Most of us have had years of hassle free motoring.. Must've got a lemon eh!

Start simple. Have you checked the plugs on the throttle body. Codes are thrown when voltages are not what is expected. If the plug is dodgy then you may not be getting a clean signal. Modern cars like these many problems are more likely to be electrical rather than mechanical failure.

zch91 wrote:

NRV155 wrote:I get no difference if lights are on or not. Im about to put in yet another throttle body and see what happens. Im getting the flashing cruise light come on randomly now too but without the cel. Worst car ive ever owned

Didn't you get the car ridiculously cheap or something?

Most of us have had years of hassle free motoring.. Must've got a lemon eh!

Yeah i did. Now i know why.

Okay, ive now tried my third throttle body with no luck. It seems to still not catch idle properly and sometimes stalls. I posted a vid to show what i mean.
http://www.youtube.com/watch?feature=player_detailpage&v=tS4yzmP0SDQ

I will try to catch when it throws a CEL but its too random. I really wanted to like this car and was hoping this would be an easy fix. The lib gt, as a whole, is what i want in a car but too bad i got a lemon.

A few questions to try and help

1. Does this only happen exclusively when you're in park or neutral?

2. Does it ever stall? Or does it simply rev hunt?

3. Have you checked the engine earths are all ok? There are three on the 04 GT on both chassis rails in the engine bay. The third is on the gearbox auto pitch mount

4. Have you checked your plug at the accelerator pedal? This is the controller for your dbw settings - check the pins at your accelerator pedal.

Mick

1. No. It started in, and is more frequently happening when i put in park but has happened in neutral a handful of times and once in drive.

2. Has stalled a couple of times when i dab the accelerator. Most other times the engine light comes on and cruise control will flash and the revs jump up a bit and gets lumpy. The video is me just tapping the accelerator quickly.

3. No. Not even quite sure where they all are. I will check the ones i can find when i change my original throttle body back in tomorrow.

4. I have pulled the plug and all seems visually fine. Wouldnt it throw a throttle pedal CEL instead?

As i drive normally and take my foot off the accelerator, what you see in the video happens. It drops well below 1000 rpm and seems like it just stays alive. Does not happen in 5th gear on the M4 (110km/hr) at all though.
Subaru mechanic is my last (and expensive) resort.

NRV155 wrote:1. No. It started in, and is more frequently happening when i put in park but has happened in neutral a handful of times and once in drive.

2. Has stalled a couple of times when i dab the accelerator. Most other times the engine light comes on and cruise control will flash and the revs jump up a bit and gets lumpy. The video is me just tapping the accelerator quickly.

3. No. Not even quite sure where they all are. I will check the ones i can find when i change my original throttle body back in tomorrow.

4. I have pulled the plug and all seems visually fine. Wouldnt it throw a throttle pedal CEL instead?

As i drive normally and take my foot off the accelerator, what you see in the video happens. It drops well below 1000 rpm and seems like it just stays alive. Does not happen in 5th gear on the M4 (110km/hr) at all though.
Subaru mechanic is my last (and expensive) resort.

Wow - very difficult to isolate and diagnose. If youve changed throtte bodies that many times and its not fixed - its not your throttle body.

Could be many thinga - bad earths per above, a potential problem with the connectors to your tcu or the plugs to the auto itself (the tps talks to the tcu and transmission); could be bad wiring somewhere in the dbw system. Way too many things to diagnose without a scanner or Tactrix and without mechanically being able to inspect

Check all those before taking it elsewhere - but then again it may not be any of them

Sorry for your issue mate - it's a shit position to be in

Mick

I just read the links chaotic250 posted above

They are actually quite comprehensive and not too hard to do even if you don't have much mechanical knowledge

Try those and see how you go

Mick

My car rev hunts like that too when you give it rev of the throttle. Can also do that in neutral coming up to lights.

Never had it stall on me tho. Spoken to the tuner who did my last tune sand he said that's normal idle hunting.

Another forum member on here who is a mate has the same car as me ( 07/08 gt spec B , mines a TB Sti ftw) , both manuals and both of our cars idle hunt as well.

Doesn't throw a code tho, or cel ??

Main and reoccurring problem is first post. Throws CEL sometimes.

Just put original throttle body back in and no change at all. All the ground wires are connected properly too.
Found a stripped bolt in the curved pipe between turbo and intercooler causing the pipe to not seal properly. Thought this might be the issue but it wasnt.