cold start almost stall

I have an issue where when I start my car after sitting for hours, it'll start right up, sit at 1000ish RPM for a second or two then drop like a rock down to 3-400 occasionally stalling. It starts right up the second time, every time. It happens every time i let the car sit overnight, the first start of the day is a guarantee. You can let it sit a hour and it'll be fine, I'm lost on this one. I primed the fuel pump using scanner a few times to rule out delayed fuel pressure, and same result. I read somewhere someone with a similar issue had to change there injector offset from vacuum to MAP, in my case the car wouldn't start, but there's no data for id1300s i don't believe for vs MAP.
Also have a issue where fuel trims want to go negative on cold starts, until it makes it up to operating temp, to where they then fall in line. This hasn't bothered me as much but its still odd, and possibly related to the start problem? Id appreciate any input.

The starting issue started after I changed the fuel system to a return, boost referenced setup, with id1300s put in at the same time.

edit : just noticed the commanded EQ shoots rich, while its falling on its face.. down in the .6 lambda range, then goes back to .8 after it finds idle again, I cant seem to find the section on where you adjust commanded EQ for warmup, and I don't know if that's the cause, or the effect of the issue. Also noticed it recovers as the alternator starts charging, if you take a look at the voltage in the PID list. I've been having issues where the car will bog for a second when the radiator fans kick on, so a failing alternator is a possibility.
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Your injector data is wrong, It's a matter of copy and paste from ID. Find your matching tables and input their values.

Your flow rate vs pressure is set at 36.9 lb/hr with 1300cc injectors? There should be like 3x that much flow rate

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Originally Posted by rabbs88

Your injector data is wrong, It's a matter of copy and paste from ID. Find your matching tables and input their values.

Your flow rate vs pressure is set at 36.9 lb/hr with 1300cc injectors? There should be like 3x that much flow rate

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They are scaled 25%, with a 67.5 limit. Airflow tables halved and stoich x2

In your data log, can't really tell anything about your fueling. Your narrowbands aren't active and there's no wideband input.

Also in your data log after startup, you lose almost all your manifold vacuum before it recovers. That's very odd. Not sure what's causing that.

Looks like your tune file is "MAF only". I'd dial in the VVE and set it up normal.

Startup airflow is lower than original in half the table. I'd put that back to stock. Most of the time that table needs increased, not decreased.

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Originally Posted by edcmat-l1

In your data log, can't really tell anything about your fueling. Your narrowbands aren't active and there's no wideband input.

Also in your data log after startup, you lose almost all your manifold vacuum before it recovers. That's very odd. Not sure what's causing that.

Looks like your tune file is "MAF only". I'd dial in the VVE and set it up normal.

Startup airflow is lower than original in half the table. I'd put that back to stock. Most of the time that table needs increased, not decreased.

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Yeah my fault on the wideband, Im assuming its loosing vacuum because the BOV is opening. Ive also been slowly chipping away at the VVE using dynaair. Ill try playing with the startup airflow and get a proper log with wideband.

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Originally Posted by 8aHemi

Yeah my fault on the wideband, Im assuming its loosing vacuum because the BOV is opening. Ive also been slowly chipping away at the VVE using dynaair. Ill try playing with the startup airflow and get a proper log with wideband.

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The only way that loss of vacuum can be attributed to the BOV opening is if the BOV is in the intake manifold. The MAP sensor is sensing the pressure in the manifold, not the pressure ahead of the throttle body.

Heres 2 logs, the first one is a cold start, but the ambient temp was in the 70s, and the second one was after work, probably 50 degrees maybe 40s. First log it started fine, second log it started and bogged but recovered quicker. 6 hours later I started it and it fell on its face hard struggling to recover from the dip, surging in the 3-400 range for a few seconds. unfortunately I do not have a log of this. I cant get my wideband to warmup fast enough as its powered by the same source of the radio, which turns off and on to aid in cranking. Ill have to run a jumper from battery or something to keep wideband powered during cranking. Putting the startup airflow to stock didnt seem to help the issue, it just causes a spike to 2000rpm and it slowly falls to idle.

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You have way too much idle timing in it that's one of the reasons it shoots to 2000 at startup. You need to knock 10 degrees out of your idle timing. 28 degrees is drastically too high. And you don't have enough timing in your high octane table @ idle. That table is actually lower than your idle table. It needs to be higher. That's probably contributing to your problem especially on a cold drive-away where it's going to switch from the idle table to the HO table as soon as the car starts moving.

Neither of those logs did it fall on it's face. Once the narrowbands get some heat in them they're showing plenty rich. I'd try pulling some open loop fuel out of those tables.

changing timing around as suggested just resulted in a rough idle, but It did the same thing. When you refer to OL fueling, is there a seperate tab for that, I figured the VVE / MAF took care of OL then CL adds trims ontop of that.

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When it happens the throttle blade opens some, the MAP goes high, loses vacuum, and then it recovers and the blade closes up again. I'd be taking fuel out of cranking fuel and the open loop tables both. It's probably just overly rich right after it fires and it's too cold to burn the shit so it's gagging on it.

The timing action looks more normal now. To smooth the idle out some make the over/under tables less aggressive.

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Originally Posted by edcmat-l1

When it happens the throttle blade opens some, the MAP goes high, loses vacuum, and then it recovers and the blade closes up again. I'd be taking fuel out of cranking fuel and the open loop tables both. It's probably just overly rich right after it fires and it's too cold to burn the shit so it's gagging on it.

The timing action looks more normal now. To smooth the idle out some make the over/under tables less aggressive.

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Where can I find the open loop tables? Is that separate from normal maf/vve?

Only thing I can find is the open loop in gear and park tables for alchohol and gasoline, looking at them id assume a higher number is leaner? On the cranking fuel table I read somewhere it?s against time since last run, I took the whole table x .8, if that doesn?t do it I?m gonna try and make the values the same against time from last run, see if that will do anything. Maybe it wasn?t necessarily a cold start issue but an off time issue? Seems it won?t do it if you restart it right after it has problems, but it will have issues if you let it sit say 6 hours.

Here you go.

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Originally Posted by edcmat-l1

Here you go.

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So I would have to raise the OL tables to lean it out and lower the cranking table, correct? Why would it be targeting 2-3x EQ in the OL tables, wouldn?t that be so lean it wouldn?t even run?

I lowered both tables a good amount and no luck. I mis understood eq ratio thinking it was lambda. I am kind of wondering if I need a check valve in my fuel system as pressure does drop to 0 key off. Pump manufacturer said that is normal though.

Checked fuel pressure while cranking, its a steady ~58 the whole time, Today i tried deflood mode in an attempt to see if maybe the injectors were leaking overnight. It had the hardest time starting ive seen yet after de flood, which may be a coincidence. This time around however i was able to throttle my way out of the surging area.Attachment 145260


Ive taken a good bit out of both OL and cranking fuel, no joy. the first start attempt in this log was deflood, second one it stalled on its own, and the last crank i got it to stay running via pedalling it.

When the wideband finally warmed up it was reading .8 lambda, and tapered up to 1.0, but it was once again already recovered.

Today I put the car on jumper cables, and it started no issue. It is pretty warm today though, and my fuel trims are 25% for some reason. Reset them and its back to near 0 across the board. I think my alternator or battery or both is weak causing issues after starting. Finally got a log with the wideband powered the whole time, and its pretty close. After a few seconds of running its about 20% rich, but the trims are 20% lean. Last night i had the car in accessory for a while with the radio going and then started it, where it threw the trims lean. Seems like lower voltage = lean condition.Attachment 145282

Update : replaced both alternator, as well as battery and it no longer struggled to start, instead it would start then instantly die. I raised my cranking VE and all is well. I was under the impression I had to halve that table when scaling airflow models, once I thought about it i realized that's incorrect, as its a percentage of VE, which was already halved. I was essentially halving a already halved airflow model.