Just want to start off that I have a tuner currently working on this car, I just don't want to pester him with questions if this is a mechanical issue on my end so I figured i'd come here first while he works out the rest of the tune. This car has been tuned by 3 different people at this point (2 in my ownership), after the last tune I have had a very horrible cold start mixed with some pretty poor driveability, bad enough I've put maybe 2k miles on the car in the last 10 years of ownership. My current tuner has rectified the driveability issues and planned to look at the warmup issues once we finish up the tune, Id just like to make sure this actually needs rom tweaking and not a mechanical issue that coincidentally occurred after the first guy I had retune the car (current tuner is using his own base map, not tuning off the original file). The issue I have is a very erratic and lean warm up idle, it needs babied basically until it hits closed loop and then it's good to go. The colder out it is, the worse it is and my AEM wideband will be pegged lean, sometimes with huge RPM swings up to 3k rpm and back down. It's currently 90* out in this log, and the idle stays consistent, but very lean up until closed loop takes over. It then spikes to 2500 rpm as the ISCV demand seems to start working and the o2 starts trimming fuel back down. I'm not sure the functionality of the warm up tables as I've never had to mess with them before, but I imagine it should be working the ISC before it hits closed loop. Around 190 seconds on this log you can see it take over, ISC position is pegged at 100% but idle is low, as soon as it hits closed loop it's like the ISC starts working, shoots the RPM way up and then the computer starts to trim the idle back to target. I have replaced the ISC in this car a few times with good working units (I have 2 evos, and evo ecus in multiple other cars using evo isc). I'd also like to point out that warmed up fuel trims and ISCV demand trims are very near zero, so I don't think this is an issue with the main maps, seems like a warmup table that my car just hates for whatever reason.

Relevant mods- 2.3L, hks 272 cams, FIC2150's, omni 4 bar SD, has a near new denso o2 sensor as well. Would love to hear some feedback on this as this car would be wonderful to drive if it would warm up nicely lol

 

which tune was the SD conversion? I have my own issues with mine

 

Which rom you mean? I’m on 9417 right now but it did it on 9653 with the last tuner. The original tune was a 9653 ROM as well

 

I mean I started having new issues after SD conversion was done. were all your tunes with SD?
Do you still use the PCV? if you do try blocking it off to see if it makes any difference. I was going to try this to figure things out but I just got my car and its already apart. the theory I'm chasing is the MAP can be influenced by the PCV and the IACV (and whatever leaks) and they could be chasing their tails
check your coolant temp sensor. I say this because my other car have 2 and it took me a while to figure out that the one read by the ecu was dead. Also I remember 2 different shops replaced my sensor out of the blue

 

yes all of these tunes have been on SD. This has done this with PCV and without, as I’ve run the setup both ways. Coolant temp sensor is working and reading correctly. This started after the last guy tuned it. I drove it to him with no issue, he loaded his base map (also a 9653) rom, tuned it (engine was warm as I drove it to him and it was dead of summer) and the issues started after. He was having issues with a typical lean tip in which wasn’t present on the previous tune, blamed my 1450cc injectors that I had been using problem free for a year or more before he tuned it and no issues with the drive to him. My tuner had no issues rectifying the lean tip in which was still there on the old tune when I swapped to 2150s so I’m confident it was just an issue with the first guy i had tuning it not setting SD up properly.

Either the original guy that tuned it spent a lot of time dialing in the cold starts and idle from the base Evo settings, or my car coincidentally has some mechanical failure that started as soon as the last tuner flashed his base map in

 

sorry man. Have you tried using ecuflash to compare ROMs? I'm about to use that to learn a bit on what my tuners are changing

 

Yes, I’ve compared lots of ROM files as this has been an issue for almost 10 years at this point and have been every which way I can with it. My original rom file was corrupted at some point a long time ago so I have nothing to compare to from the original file

 

I am having a similar issue to what the post says but mine is far worse in cooler weather.

What are you saying to do with the PCV? I am still trying to troubleshoot mine and I have had 2 tuners look over the tune without them finding anything they think needs to change.

 

Stupid question is your MAF plugged in? I think I read this could function as an IAT in some setups. When I got my car it wont even start. it turns out "his" tune required the MAF to be unplugged

Ryan, i'm just throwing ideas. With SD i feel my IACV is doing a lot of adjustments and I'm not sure why. Since the MAP sensor is the new piece i'm thinking its influenced by the air coming thru the PCV AND the PCV let air thru at a certain vacuum range only AND our stock PCV has a stickiness issue. SO i thought removing the PCV line or setting a higher target idle might be something worth a try.

I have never gotten a chance to start my car in cold weather so I cant tell if I will have the same starting and idling problems. If it was good with cold weather I could forward my rom/logs for you to compare

 

I have a GM IAT in my setup, so no MAF. I’ve never used the stock MAF with a SD setup. Always a GM IAT

 

Have you experimented with that IAT? I honestly dont know if i have one.

 

Maybe I'll have to give that a shot this fall. Its warm here now and the car is much better behaved. I also am flexfuel and it is better on e85 than 91 so that is what led me to think its in the tune somewhere but I am kind of at a loss.
I have logged it so many times and it just shows the idle dipping, IAC catching it and then repeating over and over. Not really a ton of info in there unfortunately.
I wish I could get my hands on a known good IAC just to test when its doing it. Mine seems fine, passes the key on test, appears to function but I have always been curious if mine is just slow to react.

 

Experimented in what way?

 

which reminds me, I have my original IACV i need try, just need new seals

 

What is different when closed loop control kicks in? Does fueling, ignition timing or does only the iacv duty cycle change. Run some logs and see what parameters change after closed loop kicks in.