Take a look at this idle [video]

[merqury]

I've been having this idle problem since I bought the car (95 Talon TSi AWD). I changed the ISC and alternator & checked all vac lines. I also upt in new plugs and wires, that didnt change a thing. The previous owner didnt know jack about this car, do you think cams would cause this kind of idling?

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[JayRolla]

I would do a boost leak test. May be a leak behind the TB.

 

[JFZERO ECLIPSE]

Yes, cams would cause that kind of idling.

Also you said that you replaced the alternator, and thus when you do so you should disconnect the battery. It is possible that you wiped the ecu's memory so it will have to "re-learn". My old 95 TSi AWD did the exact same thing when I had disconnected the battery.

Off Topic

Also, I'm noticing a Tial BOV in there with the recirculation port blocked off. I'm hopeing you have some form of manamgement to deal with the venting problems that you may recieve I myself vent with a Tial but the GM MAF helps me with them problems

 

[merqury]

How long does this re-learning last? This has been going on for quite a while now.

The Tial (ebay knockoff i think) is vented. I have the stock pipe and BOV - would putting those back on make a diff? The BOV doesnt hold pressure at idle does it?

 

[JayRolla]

No cams would not cause it to do that. At least not that bad. Also just recirculate that BOV for other reasons. I would do a boost leak test. Have you tried to adjust the idle to see if it does anything?

 

[merqury]

Yes I tried adjusting the idle screw, no difference. Also when I turn on the AC the idle drops lower and cluster lights start dimming.

I've seen videos of DSMs with cams that sound really similar - the jerking idle.

I will do a boost leak test soon. I have a leak in the exhaust as you can probably hear but I dont think this would affect idling.

 

[JayRolla]

My mechanic runs FP3x's and his idle is not choppy like that. Almost one of the biggest cams for our car.

 

[thegchild04]

I have 272's and my car sounds nothing like that, your car sounds like it has something very wrong with it, did you buy it with that idle problem?

 

[merqury]

The idle problem wasnt there when I bought it, however I dont remember exactly. I got a CEL P0505 - Idle Control System so I changed the ISC valve.

I checked compression, its fine across all four cylinders. It boosts fine too. What else could be wrong?

 

[JayRolla]

Check to make sure timing is right. Timing being off can cause all kinds of wierd idle problems.

 

[merqury]

The throttle response is great, so my mechanic and I assumed timing is right. Plus there's no problems at all when driving. Also in the vfaq here it says make sure idle is right before testing the timing.

I think my car sounds very similar to this - http://youtube.com/watch?v=S3rM0IZe3hM

 

[400awhpgsx]

I disagree. Your video and that video sound very different. Do you have any sort of engine management? What sort of aftermarket parts do you have on the car? You might want to look at getting a tune possibly?

 

[merqury]

I just put in a new air filter cone, didnt even put the intake pipe in yet (Injen). Also the Upper IC pipe with the Tial on it that you can see in the video. That's about it. I dont have any engine management system.

 

[JayRolla]

His car also sounds a little more choppy than it should with 272's. His timing may be off also.

When I said to check timing I meant to make sure the timing belt is on correctly.

 

[eboy0]

Mine sounds very, very simular to yours! I don't have a video, but I can post up a sound clip.
I also get alot of hissing sound from the intake manifold, but no boost leaks... Replaced my ISC motor aswell, and managing my stuff with DSMLink, I'm down to about 800rpm and its a bit choppy like that.
Last thing the previous owner did to this car was a timing belt change, so that may be what's wrong with both of our cars.

 

[merqury]

So what exactly is wrong with the timing belt..do I have to change it now?

EDIT: This sounds familiar - http://s19.photobucket.com/albums/b158/ShaneW700/Stock GSX/?action=view&current=shanew2.flv

 

[merqury]

So I put the stock upper IC pipe & BOV and recirculated the BOV. Now it feels a bit better but the idle's still choppy.

I'm running out of options. Would this be caused by a faulty ECU (leaking capacitors etc) or an exhaust leak?

 

[TSIfreek]

Check the cam timing sounds like there off. It sounds like stock cams that are not timed straight up. Hp cams are not that consitant and dont sound like that. Any engine codes??

 

[Killa_dsm]

If you think its cams, why dont you just pull your valve cover and check?

 

[merqury]

I only keep getting the code P0505 - Idle Control System Malfunction.

 

[TSIfreek]

I forgot to add check all the vacume lines to make sure they are all conected a vacume leak will cause this as well. A boost leak test would be perfect for this and will pin point it very quickly if there is a big leak. I would also try a know good IAC even though you have replace it. Get back with us letting us know what you found that was the problem.

 

[Eclipsethis90]

My 90 sounded like that after i set my intake cam off a tooth following a rushed timing belt change.

 

[merqury]

I already checked all vac lines and boost. However I will probably do a boost leak test soon.

I suspect the timing but I dont have the tools/knowledge to fix it. How hard is it/what kind of tools are required?

 

[merqury]

I did a boost leak test and found a huge leak at the ISC. The mechanic forgot to put the o-ring there. I put in a new o-ring and it tests fine now - up to 15 psi. I also put in a new 3" exhaust, so no more exhaust leaks. This took care of the rough idle. It idles pretty smooth now.

However a new problem has come up. It starts surging now - goes from 1000-2000 and then drops back down. It only happens once or twice when at idle and then idles constant at around 1100. Does it take a while for the ECU to learn the new setup or is there something else wrong?

 

[TSIfreek]

Did you disconect the battery to reset the ECU? Also check your TPS setting at idle it should be at 10% at idle (at least on a 1g). Did you move the BISS screw at all when you were having problems?