stuttering when cold ? fine when warm

[andy66]

Gotta love it. Is it like this for the stock ecu? Or only aftermarket?

[archaeic_bloke]

how severe is this issue? maybe im picturing something more severe then what u guys are experiencing?... I envision the full on clutch shuffle dance kinda thing, or is it more subtle?

[M13]

it's pretty noticeable, but not undrivable lol. Just don't take it over 4000 until thermostat opens, and car's drivability changes completely.

[nelsonmxmarc]

It's like the ultimate turbo lag - intermittent, then disappears..

[beacher1B0]

My HCR does the same thing. I didnt think anything was wrong with our cars, just thought it was like that so umptards like us dont put too much load on a cold engine. When i pull mine out of storage Ill do a log with Nistune right from cold and we will really see whats up.

My TSI AWD would run the same way when cold. Not that we can really compare the two.

I would say its not that severe but just enough to let you know thats your engines not happy and is holding back.

[nelsonmxmarc]

Nistune won't tell you per se. You can only physically view and manipulate the cold start timing and fuel maps, can't log them. It'll come up as fuel and timing regardless.

[Skym]

Nelson is correct, there's a warmup ignition timing table stock ECU uses up until coolant temp reaches around 65 degrees that pulls ignition timing alot to protect engine. If above 3000rpm or load goes above a certain value, this table should be ignored and ECU uses ignition map. I always warm engine up before driving, so don't encounter the problem related to this table.

Sometimes stuttering can be due too airleak behind MAF, as it gets 2x airsources instead of one (intake hose clamp on MAF is loose or cuts inbetween ribs on rubber intake piping or under intake hose clamp, etc). It happens mainly when exiting motorway (from my experience) and goes away with throttle (sounds, feels similar to failed coilpacks).

[andy66]

A/M ecu's have the same feature built in to ? or just the stock ones ?

[beacher1B0]

Nistune won't tell you per se. You can only physically view and manipulate the cold start timing and fuel maps, can't log them. It'll come up as fuel and timing regardless.

Ahh, learned something 2day.
Forgive me, Im still a Nistune newbie.

And 99.9% I dont boost car cold and 80% dont drive it till warm, I love my HCR. But it does act just like Skym describes. Can feel the timing pull back till after 3000 rpm or so.

[galwin]

I used to have that problem too when the engine was cold, specifically when the turbos were cold. At the time I was also experiencing sputtering/popping at 5k-6k RPMs, I tried checking all the coils, electrical taped the coils, and I gapped my spark plugs closer, and my high RPM sputtering disappeared, also along side with that, the heavy hesitation at cold start was gone too. I can feel the motor vibrate a bit as I get near boost when cold, but its definitely alot better.

[kelaog]

Coolant temperature sensor after the thermostat generates a signal, Boom.Car knows it's open.

Fancy thermocouples damn!

[Skym]

andy66, only noticed that table on stock ECU. Aftermarket ECU tuning software I've looked at doesn't seem to have this table. I think Link, ViPEC ECU's have the raising revlimiter thing like I think that BMW? has on one of their cars. With the dash + raising revlimiter, has red bars or similar on rev counter that turn off as engine warmsup, so tells you how far you can rev engine.