Took the car for a spin; first time it had been driven in months. Went to the grocery store, and the car didn't start when I came back out. Felt like there was no fuel. I figured my warm start enrichment settings were wonky, so let the car cool down a bit. Sure enough, started up after 10 minutes or so of sitting. It hadn't been a long drive over, and I don't think coolant was fully up to temp, but pretty sure IAT was.

Anyway, this gives me some motivation to get my PalmEdit worked out, so I can change cranking settings in a pinch without lugging around a laptop constantly. Anybody use PalmEdit?

 

I doubt warm up has anything to do with it not wanting to start up after driving.

 

You do. Having a palm in the glovebox to make adjustments whenever for whatever is a nice option.

 

Man, setup some serious IAT based enrichment to conquer that IAT heatsoak. Make sure your cranking settings are not averaging CLT and IAT as well that will cause some serious issues.
These are my current IAT based enrichment values. Scott uses like 2 times the correction I do but this is working for me right now. I only do this to keep my idle stable as the sensor heat soaks at idle sometimes. Shouldn't have anything to do with it not starting unless you're averaging the two.

 

this is what i was using, mine would heatsoak like crazy within 30secs of shutting off the car and I'd no fuel. this put me at 13:1 for a few moments after cranking until the temps dropped down, i used to have a nice log of it but lost it when i dropped my laptop.

 

Thanks guys; I'll take a look tonight at what's going on with my current settings, and give these things a try.

 

is this the coolant related air density table you guys are posting?

 

yes, but it's setup for AIT corrections, not CLT.

 

So it puts more fuel in the hotter the air?

 

The more I look at things, the more I think I was just in a spot of untuned cranking pulse widths. It was a short drive, so coolant was in that "warmer than ambient, but not fully warmed up" zone that hadn't ever been tuned. I may try out Scott's cranking PWM values he posted a while back; same engine and injectors I have.

 

Yeah I get it.

Sort of, but in an opposite approach. It doesn't allow a fuel cut due to an artificial IAT reading.

 

Computer thinks the air is hot, when it actually is cold and cuts back the fuel. So it just adds more fuel.

 

Well, my intake temperature is always between ambient (9c, 48f today) and never goes over 26c (79f) and my table looks like this... does it need changing?

 

I only use the IAT enrichments for idle correction i have them disabled by 1800 RPM i think. I think the default option disables it by like 3k rpm?

 

i have mine weening out starting at 1500RPM and fully off at 2000RPM.

I also only have AIT corrections on past 85°F, i don't want the rest of the fuel map touched by them. As it looks above, at 50°F you're getting 5% more fuel. at 70°F your have 21% more fuel...the whole purpose is for heat soaked hot starts, not full time enrichments.

 

I guess you could use this for intercooler heatsoak after running lots of BOOOSSSSTTTTT but that's not really an issue considering how fast they cool off once out of boost. Maybe on the track this would be necessary. Adding 10% once your IAT temps are above 100-110 or something like that. You could even set it up that way considering your IATs would only be that high at idle, before starting, or under lots of hot n heavy boostin.

 

Well, these are my MSPNP default IAT corrections, so I'm thinking it wasn't IAT heatsoak.

 

I hate to bring this back from the dead, but it was my thread originally, so

Anyway...I noticed after some hard driving that my idle is pretty rich. Well, quite rich. Like, 11:1 rich. I'm thinking this is a direct result of the awfully high IAT correction values from the mspnp base map that I posted earlier. I'm posting here for a sanity check: am I off base about this?

My IAT was only ~80°F +/- 5°F, which would still increase fuel by a significant amount based on my table. I think I'll try something closer to Brain's table tonight.

 

I'm going to say yes, knock them down my 10 unit a piece and see if that's good enough.

 

Feel free to give me the MS-n00b smackdown, but I thought cranking enrichments didn't have anything to do with idle or anything once the engine was running.