lancerMRguy

iTrader: (2)

Okay,
So for the past 2 weeks now I have been struggling with this stupid idle problem. I am about ready to blow the damn car up. I will paypal anyone who gives me the correct diagnosis and solution 10 bucks! Here is the symptoms and back story

Car was tuned for all the mods in my sig for 93 Octane on the east coast. Car ran perfect and great for 3 weeks. I drove it across country, and when I hit Texas and switched to 91 octane ran like ****. I am now in Arizona 5000ft elevation and had it retuned for 91.

Here is the problem:
When coming to a stop from just normal crusing the RPMs will drop to around 3-400 the car sounds like its choking, the A/F will read 10.0 after a few seconds the RPMs will go back up to around 800 and A/F will read 14.5-15.0.

When coming off a WOT boost the car will also drop to 3-400 RPMs but the A/F will read -- or sit at 18.9 for a while about 5-10 seconds before slowly settling back in the 14.5-15.5 range.

Also while sitting at idle once the car returns to around 800 RPMs the vacuum is only reading at about 13-15 when it used to read 18.

For the record while driving the car runs great, hold boost (21-22lbs) at WOT under partial throttle will slowly taper off, but thats normal im guessing.

I have checked all hoses and pipes. I brought the car to Mitsubishi who looked at it hooked it up and said all the sensors check out fine. I have played with just about everything I can think of and I am really starting to get pissed off. I am unhooking the battery tomorrow when it stops raining to try and see if resetting the ECU and having it relearn the elevation will help. Any help things I should be looking at?

Win yourself 10 dollars and make me want to drive the Evo again instead of being pissed off everytime i get in it.

FloopyDisk

iTrader: (6)

Take it to a tuner, it may need to be reflashed.

lancerMRguy

iTrader: (2)

I have been working with Tamer on fixing the issue and he reflashed it from 93-91 octane and made some adjustments, still working with him to figure it out. Just wanted to see if anyone else ever had this problem and maybe knew what was going on.

Fuze49

iTrader: (3)

I would say it is the tune itself but you already had it tuned to 91 again. It might just be the ECU needing a reflash to correct the idle again. I've heard of similar problems but all from people using octane they weren't tuned for but you are tuned for it.

lancerMRguy

iTrader: (2)

yeah thats what I cant figure out. Its been corrected for 91 so it should be fine. There is no knock or anything else while boosting either. The worst part is I dont want to have it taken somewhere for any major work if it is the flash because in less than a month I will be back on the east coast running 93 again.

1d10t

iTrader: (19)

I suspect maybe the idle control motor sticking or something like that. Before it warms up, (idle at1300-1500) does it drop off then? It goes rich because the engine thinks there should be air in there thats not there, and then stables when idle returns. And youre sure you have no vacuum/boost leaks? Always ask for the shop foreman when you go to the dealer, thats their best tech btw.

lancerMRguy

iTrader: (2)

yeah, it start up at about 13-1500 initially then settles down, but the idle drops occur when its warm and i come to a stop. If I have a vacuum/boost leak its the best one I have ever seen cause all the hoses and clamps are on tight and I dont seeany damaged hoses. I want to bring it somewhere good besides Mitsu for a good look but I never have any time or weekdays to bring it anywhere. Its realy starting to annoy the **** out of me I always think its gonna stall when I come to a stop.

tephra

iTrader: (6)

vacuum leak?

4WS Tuning

iTrader: (73)

Couple more ideas... The problem is it'll be corrected for a day or two, then itll revert back to the problem. It was a problem that started over night so that makes it even harder to track down.

Input would be great!

Bump!

John F

Take off the idle control valve and give it a good clean.

TouringBubble

iTrader: (2)

I'm working on a car with similar issues. We're making progress by leaning the low load cells (referenced when going to neutral/clutch in while moving) to get rid of the rich condition. This specific car has large injectors though. With stock injectors I haven't seen this issue.

We are also tuning the desired ISCV based on logs which seems to have helped as well. the Desired ISCV drive table is the one that needed tweaking ... it's referenced when the car tries to idle while speed > 0. I haven't touched the 3D stepper map.

I will recommend cleaning the ISCV to my customer as well ... I hadn't considered that.

The lean AFR when the idle drops could be misfire related ... if the O2 isn't being burned the WB can read lean. I'm not sure why it would slowly return to stoich over 5 or so seconds though. Maybe it is a dirty idle control valve.

TouringBubble

iTrader: (2)

The vacuum difference you noted could very well be a leak and that will play havoc with your idle. It would be best to invest $10 or so and build a leak tester and do it right. you'd be amazed what you will find.

scheides

iTrader: (10)

+1, do a boost leak test!

Are you for sure on stock injectors? Perhaps your latencies are goofed up a bit with the altitude....check your LTFT's and make sure everything is peachy! If you correct it and then it comes back a day or two later, that sounds fuel trim related.

lancerMRguy

iTrader: (2)

I will have to go out and buy the materials for the boost leak test this weekend. I have had it checked by about 5 different people including Mitsu with nothing found but maybe something will pop up.

JohnBradley

iTrader: (30)

So I take it its not throwing any codes?