Hey, all. Just starting my tuning journey. I have ECMLink running a 2.4 7-bolt with 16G boost set to 19psi using pump gas.

I'm having problems with a hard cold start, *very* hard hot start. Idle has a surge in it but seems mostly stable once it starts. I'm aware of no vacuum leaks.

It runs "fine" during cruise.

Decelerating into a stop sign or a light, and sometimes very slow around parking lots it will stall and be difficult to restart. Doubly so in hot weather-- the hotter it is the worse the problem becomes. I got stalled and stuck in traffic at a light for several cycles last August, eventually it seemed to cool down enough to start up and then it drove on like nothing ever happened.

Still running stock O2, which I understand isn't proper, but I'm also not trying to do anything serious yet, just get the car trustworthy. Hoping to get a new exhaust here soon with a proper bung for the wideband.

The instability feels a lot like a fuel pressure problem, so I've been chasing mechanical explanations for a while, but now I'm on known good parts running stock fuel pressure with a clean filter and I'm reckoning with the fact that it ran fine on the previous (smaller) injectors.

Attached one log, #1 is starting through 30 seconds or so of cold idle.

Injector data sheet is here: https://fuelinjectorclinic.com/pages/universal-injector-tuning-data?injector=775cc
My current settings are here: https://www.dsmtuners.com/threads/daddys-zoom-car.550432/#post-153963890
Using -40% and 300 deadband.

Second log: #2 is 30 seconds or so of idle after it's warmed up.

I have the load factor set to 83.2% to account for the 2.4l displacement.

I'm not sure of the compression ratio, but I believe it's between 1G and 2G stock values.

What do I look for?

I would highly recommend getting a wideband before going too much further. You should be able to get idle and cruising dialed in without it but I wouldn't go into boost without the wideband.
Besides that, it would seem to me that you need to get your throttle body dialed in. On your #2 log at operating temp your ISCPosition is reading 0 when it should be around 30 or so at idle. If you've never messed with the throttle body adjustments, this site is probably one of the better guides out there:

Tony1094 said:

I would highly recommend getting a wideband before going too much further.

Click to expand...

Will do.

Tony1094 said:

Besides that, it would seem to me that you need to get your throttle body dialed in.

Click to expand...

Ok, thanks. I've rebuilt the throttle body to get the leaks out and experienced some odd behavior while adjusting the BISS, The ISC position seemed to move either full open or full closed. I started with the BISS full closed and very slowly opened it until the ISC started moving. ISC moved slowly to the other extreme, so I slowly closed the BISS until it started moving again and it moved back to the other end. ISCPosition wouldn't stabilize in the middle of its range.

Perhaps I skipped a step-- I'll go back and run the whole procedure in that link and post another log.

How much does the BISS move between ISC fully open and ISC fully closed?

rdeis said:

Will do.


Ok, thanks. I've rebuilt the throttle body to get the leaks out and experienced some odd behavior while adjusting the BISS, The ISC position seemed to move either full open or full closed. I started with the BISS full closed and very slowly opened it until the ISC started moving. ISC moved slowly to the other extreme, so I slowly closed the BISS until it started moving again and it moved back to the other end. ISCPosition wouldn't stabilize in the middle of its range.

Perhaps I skipped a step-- I'll go back and run the whole procedure in that link and post another log.

Click to expand...

I struggled with my ISC for a while, too. Bypassing the FIAV along with the AO-Custom PTFE gaskets ended up getting it sorted out for me.

Is the car on Speed Density or is the MAF Stock?

Under your ECU Inputs tab you have a GM3 Bar as your Baro and a Wideband as your front o2.. If you are on speed density you need to set that as your BaseMAF type under the MAFComp Tab and check the Disable MAF Comp with SD Operations. If you're not on speed density change that back to "Undefined" along with the Wideband Pin assignments.


You will most definitely need a Wideband to continue tuning.

You can try and click the "Enable Hot Start Enrichment" under the Misc tab and see if that fixes your hot start issues.

Stock 1G MAF. Ack! Those pins must be left over from ecu’s previous owner.

Ok, ECU inputs tab wide band and baro set to undefined.

Misc tab hot start enrichment enabled.

Hmm, this is new: BISS is tight and it’s idling around 820 with 0 ISC and 140 LearnedIeAdjust. Must have picked up a vacuum leak? Or set the idle switch too tight readjusting the throttle body... Prolly that..

Just noticed something: Should the ISC move with the throttle? (see log)

ok, better and a little smarter. I backed out the idle switch 1/4 turn and now the BISS matters again. And I took a close look at the plots and the ISC comes up after I bump the throttle and then slowly drops after it closes, which makes intuitive sense.

I can’t get the ISC to stay put. I thought I had it nice and solid finally at 45, walked away for a few minutes, and when I came back it was at 120! But it is at least moving predictably during normal driving, so maybe that's good for now?

Finally took the car out and drove up the street, captured a short log of it showing knock under very mild acceleration and stalling at the stop sign. I changed the global trim from -40 to -32 and the knock mostly went away and it didn't stall at the next stop sign, huzzah! So maybe most of the problem is just too lean in the global settings? Anyhow, I got to work without further incident and I'll post the current log this evening after I get home.

Acceleration feels "flat", if that says anything useful. Looking forward to getting it stable, then I'll be off to get a new exhaust and the wideband!