Hooray, I'm posting about another issue I'm having with the evo!

This past weekend my buddy helped me get new balljoints put in the car. Drove it home and everything was fine. Took it out to dinner yesterday, fine. Drove it to work this morning, fine. At lunch today I went to go out for lunch and the car wouldn't idle. It would crank, fire, then immediately stall out. It will run if I push the throttle down, but as soon as I let go it's dead. Tried unplugging the MAF, same issue but it would throw codes. With the MAF plugged in no codes are thrown. Tried unplugging the battery for a while, same issue. Let the car sit for a while, same issue. So went back in to the office and did some googling and suspected the IAC. Unfortunately I didn't have my tools with me like I usually do. So I found someone with a leatherman and a found a multi meter and went to town diagnosing the IAC. I got it out of the TB and had a buddy turn the key to the ON position. The thing moved in a little. Then he turned the car off and it moved back out. Now it looked like the little fins around the cone were damaged or broken. I forgot to take pictures, but I can post some up later perhaps. So then I measured the resistance between pins 1&2, 2&3, 4&5, and 5&6. It's supposed to read between 28 and 31, but all my readings were like 27.6 - 27.9 at best. None of them read the minimum of 28. I'm guessing that means my IAC is on it's way out? So I put it all back together and started playing with the BISS. Turned it all the way down, same issue. Backed it out a lot and eventually got it to idle on it's own. I'm hoping it stays this way to drive home after work, but ultimately I need to fix this issue. Any help is much appreciated!

For some background, the car is 99% stock. Haven't performed any engine modifications recently. Only work I did was replacing the ball joints and tie rod ends.

 

Well I'm sure you know that messing with the suspension isn't going to effect the engines performance. I've seen similar issues with as you already said the iac going bad and the fuel pump going out too. The difference in resistance you are seeing isn't big enough to concern me personally. Your multimeter could be the difference there really. Also it is very possible you shook something lose while doing the suspension work and now have a boost leak that wasn't there before. That would definitely be my first thing to check is for a boost leak.

 

Boost leak!

 

Mmmm. Boost leak. If you don't have the boost leak tester then just check the entire area for unplugged vacuum lines.

 

Haha, yes I know the suspension does not affect this. It was added merely as a reference to what happened and how this problem presented itself. I did a visual inspection in the parking lot at work of vacuum hoses and didn't see anything out of the ordinary. I moved wiggled some vacuum hoses to check if they were loose and didn't see anything. Didn't notice any loose intercooler pipes either. But with all the hammering that was done getting the ball joints in, perhaps a coupler got loose under the car that I couldn't see.

 

Sorry, but I just thought about that as I posted it. If something got loose, I would have had trouble starting the car this morning, right? It started up fine twice yesterday and fine this morning. Then it sat in the parking lot at work for about 4 hours or so before the issue presented itself.

 

Update on this. Got the car back in to the garage after work to tighten down everything properly since I had makeshift tools to use at work. While I was there I checked the IC piping under the car. It appeared the lower IC pipe was loose where it connects with the intercooler. So I adjusted and re-tightened. When I started the car, the RPMs were high, over 2k RPM. So I turned the BISS back down to roughly what it used to be. Car idled fine, just under 1k RPM. I even turned the car off, then on again to confirm. It idled great! I thought that was the issue.

After I got home, I went to stop by my buddy's house to drop something off. The car idled so quietly, and so I look at the RPMs and they are at like 600-700 RPM. Upon first start up the car BARELY caught idle. It was too low. So I adjusted the BISS a bit higher to get the RPMs around the 1k mark.

Fast forward to this morning. I decide I'm bringing the laptop to log and get some data. I go to start the car this morning in the cold and I get the same issue where it won't idle. I back out the BISS a bit, try again, same thing. Back it out more, start the car, give it some throttle for a few seconds, then it catches idle at maybe 900 RPM. But keep in mind it's like 20 degrees out and the first time I am starting the car. It should be idling higher at least for a few seconds. So I start the logger and drive to work. When the car is warm and idling in the parking lot, it's idling at like 1.5k RPM.

Unfortunately this morning I didn't bother to check what EvoScan was logging, so I don't think I got anything useful, but I've attached it to this post anyway. I'll log again when I go out for lunch. Is there anything specific you guys can think of that I should log to help figure this out? I'm wondering if it's the IAC motor getting stuck sometimes, or if maybe the ecu temp sensor is shot?

EDIT: It appears the log is too big to upload on here even in CSV format. Here is a link to it uploaded on another forum: http://njdsm.org/forums/attachment.p...8&d=1395749680

 

Just throwing this out there...

Sounds exactly like what happened to my Saturn I had about 10 yrs ago. A temp sensor was the culprit. That little POS made the car think it was warm/cold when it wasn't and threw off everything making the car idle funny, sometimes not start, and generally be a spastic mess. It was a cheap and simple fix!

 

That's what I'm leaning towards now. I originally thought it was the IAC, but the car does idle on it's own and the motor appears to work. It obviously looks like it SHOULD be replaced anyway, but for $300 I'll wait until it's dead.

Temp sensor is cheap. I may order one anyway and continue diagnosing.

 

That's how I do things too haha

 

Yea, looks like the local parts stores have the sensor in stock for like $20. It's not OEM, but it will work.

 

The temperature sensor should be replaced with an oem one. They're only like $55 anyways. The iac valve can be replaced with an aftermarket one off of a Chrysler sebring and will work just fine and costs only around $50-$75 not the $300 oem one. Just a heads up.

 

Sounds like you may have an acute on chronic type problem. I'd be willing to bet the iac is part culprit, but there's probably some underlying problems elsewhere. Have you done a proper boost leak test? It may reveal another contributing factor. Another thing just to check (only because it caused me so much trouble on my talon) would be your fuel filter and plug wires. No they don't directly effect idle, but they can make slot of small problems worse.

 

If this is not done then there is no point reading this thread.

 

At least replacing the current sensor with the $20 one can let me know if that is in fact the issue. Good to know about the IAC!! I did NOT want to drop $300 on this thing if it was in fact the issue.

Plug wires are relatively new, and plugs are even newer. I have not checked the fuel filter in a while, and while that may contribute, the car runs fine otherwise so I would not suspect a fueling issue.

I have not done a boost leak test since the last time the intake track was altered, but that doesn't mean something may have changed during that time by just driving the car. Unfortunately I don't have the time to do that at the moment, but hopefully over the weekend I can get to that. Might as well wait until I put the new LICP on anyway.