Hi gang. My LNF will be kind of jumpy on a cold start at idle. I live in Wisconsin so it's consistently about 70 degrees F+ at this point. So the coolant will be around 75, I'll start it and let it sit and until the coolant gets to about 120-130 it will be jumpy but then once its there, everything is perfectly fine and smooth. The rpms will fluctuate between 900-1100, like it's misfiring almost, and the boost gauge will read -11 to -15. It's been doing it for a couple months now and I've mostly been ignoring it. Tryed cat warmup and that wasn't it. Car has 85k miles on it. Just changed plugs and yes they are gapped at stock gap.

Mods: K&N intake, zzp upper charge pipe, tune by KMO43 on 91, ZZP catless DP and muffler delete.

Just cleaned the intake valves too thinking that that might fix it - it did not.

I'll try and post a log with HPT tomorrow, but let me know if you anyone has had similar problems or any words of advice!

Thanks,
splash

 

Check for any boost/vacuum leaks and then get your tune updated.

 

i've checked for boost leaks, came up with nothing. And Kevin has tried to update the tune a few times and nothing has changed.

 

Only because i had something similar, check your ground connections. Mine was loose and it did that.

 

Where are the ground connections? :9 you just mean the ground terminal on the battery?

 

also one behind the driver headlight and another attached to the engine block/bellhousing bolt. That one sits about 5 o'clock from the oil filter.

 

Are the grounds like super obvious to see? If not, would you mind posting a picture?

 

here is the log. it gets normal around a coolant temp of 108 degrees.

 

They're definitely not obvious and i don't have a picture. If it goes normal after warming up a little then it's probably not the ground. If you still want to check you can get your volt meter and test the fuse box post with the engine block. If the voltage is less than 13 you know that's the issue. That's when I figured mine out.

 

I think my ground may be loose on the bell housing. If I grab it, I can move it fairly easily. But what do you tighten exactly? The cable going that connects to it?

 

tighten the bolt or nut. the ground cable slips onto the shaft, then the nut or bolt (can't remember which) is tightened into the housing.

 

Tightened the ground. Still no change. I really don't know what to do at this point.

 

Depends on the frequency of the oscillations but i've had something similar on mine when i started tuning it myself and turned off cat light off.

I had 2 different problems:
1) When cold started (got worst the lower the temp) , with the cat light off turned off, it sounded like a big cam car, struggling to idle, "lopey" the frequency of the oscillations were about 2 to 3 Hz, so the rpm would bounce up and down about 2-3 times per second, so fairly quick and fairly erratic.
Solution: it was my fault, even though you turn off the cat light off feature, the cams still follow the cat light off tables, which had overlap, once i turned off the cams in the cat light off tables, it got a lot better.

2) when cold started (worst at colder temps but it did it every time it was cold started) it would have this very very slow oscillation, like 0.2 to 0.3 Hz, so it would take about 3-5 seconds to oscillate the rpm up and down bouncing from about 700 rpm to about 1100 rpm, for about the first 20 to 30 seconds of idle. as soon as the coolant warmed up a little, it idled perfectly. this kinda sounds like what you have.
Solution: Although my fuel trims were good, STFT usually about +/- 2, maybe +/- 4, LTFT also low, it turns out that once i re-calibrated the MAF, especially around the low air flow region, it stopped doing it, so my advice to you: recalibrate your MAF. maybe it's dirty, maybe it just aged, maybe it's on its way out.

also something else that gave me bad cold start idle when i forgot to plug in the PCV hose, or it didn't seat it correctly, maybe you broke off that stupid plastic nipple on your intake.

I couldn't open your log because i have an older version of HPTuners, haven't upgraded yet.

 

Good to hear!

Kevin actually sent me another tune update today and this one fixed it I think. It idled very well in the first cold start since I flashed the tune on. I'll see tomorrow on that cold start if it's gone for good!

 

The cold start issue is fixed. It's running like a dream!

 

splash,

For the benefit of the forum could you / "Kevin" let us know what was wrong, and how it was fixed.

Thanks

 

Kevin adjusted the low air flow frequency on the MAF table as far as I know. If that sounds right. I'm having another issue now thought actually, it's not lopey. It's running like it wants to stall on a cold start until I give it some gas and then it goes away.

 

post up some data?

 

there is a log showing the current issue.

 

I have had this problem during tuning before. My car has a hard time tuning the low part of the table perfectly. I have to get a really good log or two to make it run like stock.

My car isn't heavily modified so staying close to stock helps me a lot especially for idle.

 

I'm gonna try flashing the stock tune on it to see if that helps for starting.

 

Flashing the stock tune back on fixed the cold start issue. So I've been running that, waiting for Kevin to send me an update of my current tune. Hopefully that'll do it.