Pulsing Idle
 

So my car is being really annoying now. When the car is cold everything seems fine, except no accelerated warm up. However, when the car warms up the idle likes to pulse between 1k and 1.5k rpm. This is very embarrassing in traffic and at stop lights.

So, to ad to other problems, I have a single turbo set at 13 psi, stock primaries and 1300 cc secondaries. I took the car down to Tri-Point to have them tune it and they couldn't get the car over 167 hp, no that is not a typo. They said the fuel trim and timing were fine. They suggested that my Trust car back was causing flow issues since it seems to be disintegrating inside. I am picking up a Racing Beat single tip exhaust on Monday.

Does anyone else think the bad idle might be because of the bad exhaust as well?

Also, I did notice that the plug to my IAC valve came off last weekend and kept coming off. I zip tied it on and it's still connected, but I still have this issue. I don't know if the previous owner disconnected it and reconnecting it caused this problem.

Do you have stock cats still? They could be clogged. how does it idle below 1000k? Vacuum bounce? Have you checked compression lately?

Have a down pipe, but still have the second car. Tri-point said it looked good, but the muffler was shot.

The car doesn't really idle under 1000 rpm at the moment. When it's still cool it sits at around 800 to 850

And compression is the same as when I bought it back in January 112 psi rear and 95 psi front. Tri-Points isn't to sure why that is. I suspect at some point the previous owner replaced the rear housing but not the front. Tax returns next year will bring all new housings and an Arkins over haul kit.

Vacuum leak.

Not that I've found yet. Do you have any suggestions of where to start looking? I no longer have the rats nest so there aren't nearly as many hoses.

This seems to be a real issue right now, I saw two other similar threads on this scrolling down to mine.

I just noticed an other symptom. The car idles fine when it wants to, but when it decides it wants to do this pulsing idle, it runs my rpm's up to 3k with out my putting my food on the accelerator, then it drops back down to 1 k and pulses between 1k and 1.5 k. This really sucks while being stuck in traffic or the all to common red light.

Created a video to help show the problem.

Its a vacuum leak.

Okay, a vacuum leak from a particular spot? Do you have an idea of where to check? If it was a vacuum leak wouldn't this be a constant problem instead of an intermittent one?

It really is random as to when it decides to do this. However is seem to happen more often on a hot start instead of a cold one.

Vacuum leak use the clean throttle spray and spray the vacuum hose !

Then what, then engine does something?

Idle will change when the vacuum leak ingests what amounts to fuel. I'd start around the UIM, especially around any ports. You can also use a mechanic's mirror to visually check places without removing things.

Okay, so I found some Vacuum leaks I will fix tomorrow.

These should be capped
http://i291.photobucket.com/albums/l...ps0106a975.jpg

And what is this and where is the hose that goes to it?
http://i291.photobucket.com/albums/l...psbafc9597.jpg

Cleaned the IAC tonight also. We'll see if that helps tomorrow, it didn't seem that bad.

That is your double throttle control. See link below:

Banzai Racing FD Block-Off Plates Location

Based on your photos it looks like you're overdue for a full vacuum hose job. I'm surprised TriPoint didn't catch all these missing vacuum lines. Those connections should have a vacuum line or be capped depending on your setup.

The car is a single turbo and the rats nest has been removed. This was all done prior to buying the car. I've had it since January, but the idle problem just popped up about a 3 weeks ago. Also the car dynoed at 167 hp???? This is also a condition that started about 2 months ago and is a real head scratcher. I'm going to pick up the plugs for those nipples tomorrow.

Found this on-line, but the hoses are no where near this configuration now.
Attachment 667131

You didn't find any vacuum leaks. The four pipes in the picture go straight through the the LIM for sequential turbo control and EGR. The other picture is the disconnected double throttle. With the engine running, spray carb cleaner on areas that can leak like the LIM to block. It is very common to leak there because of the crappy paper gasket. When you get the carb cleaner in the leak it will be obvious.

Will try that tomorrow if the car continues to act up. Cool thing is my cousin just started working at tri-point last week.

Humm, looks like the previous owner blocked off the ACV (air control valve)

Since it's already been disabled, and after getting your idle stabilized, you may want to consider removing the double-throttle.... How to Disable or Remove the Double Throttle

Okay, so I capped off the four nipples in the pic, I also found four more on the outside of the intake manifold close to the turbo and caped those off as well. I haven't had a need to drive the car yet so I'll post up as soon as I get the car up to operating temp. I did notice in the garage though, I still have the same problem with the deceleration. If I rev the engine up, then take my foot off the gas, as the rpm's drop, they drop to almost zero then bounce back up to about 1000 to 1100 RPM. I just cleaned the IAC valve last night, so I have no idea why it's still doing this.

http://i291.photobucket.com/albums/l...ps0106a975.jpg

http://i291.photobucket.com/albums/l...psd145111a.jpg

http://i291.photobucket.com/albums/l...psc6c0a60b.jpg

http://i291.photobucket.com/albums/l...ps38a06af1.jpg

Uploaded an other video to show what the idle is doing now

You capped off both ends of the same pipe.........4 times!