Hey guys,

Recently the cars CAS went out and we finally got a new one that we put in.

My friends car is having issues with idling properly and stalling often. It used to happen after he would reset the ecu that it wouldn't idle right, it would have an erratic idle and die when he came to a stop. But since we replaced the CAS it doesn't even idle enough to stay running unless he holds the throttle at a certain amount. And if he doesn't watch it, it constantly dies when driving at low speeds.

Its had this problem before and after the CAS went out.

I've been trying to figure it out as i've been working with his crappy tune that he got a while ago from a shop in our area.


His mods are as follows:
Greddy t67 25g turbo kit
PE 780cc injectors
Ebay FMIC
3inch piping
Greddy type R BOV (VTA)
a custom made intake pipe
stock maf with an adapter for a cone filter
3inch CBE w/stock DP
stock ecu
255lph Walbro

Im not the most experienced with the stock ECU and im still learning. I tried to make some adjustments to the idle but it doesn't seem to help.

Some things i noticed in the tune were that his injects are scalled at 655's or something so i was just wondering if that might have anything to do with it or if theres any reason to do that.

My real question is before we go looking at getting some more experienced tuning help is if something other then his bad tune could be causing all this?

I wasn't sure if it could be a dirty MAF.

Any help is much appreciated!

 

Hey i know what it is. It happened to my 03 i fixed it today. It is the IAC they go bad for some reason in the 03 year. Lots of people have this problem but not to many people find the answere. I did some searching and replaced it and it fixed it no prblems at all now. It costs around 450 for the part take it to the dealer and they can test to see if it is the IAC.

 

I would for sure check the IAC, the little plastic teeth break on the earlier model year evos. If they do, nothing you put into the idle tables will do anything as there is nothing there to make the changes.

 

This is interesting as my car does this too. It at first would do it badly when I reset the battery/ECU, but after a while it would stop. The weird thing with mine though is it would continue with my IX valve, but would stop when I put my Forge DV in.

 

If it is the IAC, its fairly easy to take out and check. I noticed this on a friends Evo, where mine was fine. I just chalked the damage to his as being due to the Meth injection he was running..

Anyway, if you look at the valve, its basically a stepper motor with a cone that moves in and out into the seat of the idle circuit on the throttlebody. If you look at that cone, it should be held in place by three grooves, and there should be three "Teeth" that fit into the groove, when it gets worn, those teeth are gone and it can rotate. If it can rotate, it can't move in and out when the stepper motor rotates.


Its an easy enough thing to check.

Another possibility is the cam angle sensor is 180 degrees out of phase, since you said it wasn't as bad before it was replaced I would look there first.

The CAS sensor is what is used (In conjunction with the Crank sensor) to determine the ignition events and synchronize the ECU when you first crank it.. The fact that the Ignition has two coils, each paired as wasted spark (each coil fires two cylinders) the car will run, but will have odd issues that can be hard to track down.

The later posts are "airflow related" as different DV's open at different levels of engine vacuum, in doing that, it can drastically alter the airflow through the MAF sensor, which can also cause idle problems. Its important to be able to log the sensor data (RPM, fuel trims, IACV Position, Ignition, and MAF Frequency) as their dead giveaways to some issues.

 

Wow you guys are awesome. I will check that IAC as soon as we get the chance.

I also read from other people about having the BOV too tight can cause some problems so ill try loosening it to see if it helps too. He wants to do recir but we are going to have to rig up some stuff first with his intake pipe.

I'll be sure to do some logging to see whats going on as well.

Again many thanks!!!

 

Excuse my double post but can you buy just the IAC or do you have to buy the whole throttle body? My friend called a dealer and they said it comes with the throttle body.

 

I'm sure that the IAC can be bought separately.

The part number is 1450A069.

Here is a pic.

 

was it your iac?

 

At this point I am just going to assume that it is since he didn't come back looking for more help.

 

In that picture above can some actually tell me what the IAC is it the module right under the main valve of the intake mani?

 

wre can i get iac for a good price

 

hi there,
the info here is very well documented about the IAC being the culprit.

Can anyone please document with pictures:

1. how to remove the IAC?
2. how to check the IAC for the teeth/guides?

 

1. The IAC is removed by unclipping the harness connector, and removing three screws/bolts that hold it to the T/B.

2. Did you read any of the thread?

 

1) so does that mean i dont have to touch the piping to the throttle body? I'll be amazed if that's the case.

2) yes i did and it was good but i needed more of a run through as i'm not so mech versed and my mech's far away .