Issue with misfire during cold start only - Page 3

JamesNoBrakes · 02-12-2019, 10:34 PM

Dealer covered it, replaced the spark plugs, they were fouled with lots of carbon deposits. They said there was an evap leak and that also contributed...also "bad gas", but I doubt at least some of this. I'm going to look a little harder at it tomorrow or sometime later, I have a hard time believing a fitting was loose with the catch can, as all of those things were well tightened with clamps, etc., but again, I'll have to look into it. No charge, car is back, runs smooth, got it "cold" from the dealer at 35F, just smooth as could be driving home. Nice to have it back.

sadpanda · 02-13-2019, 10:37 AM

You threatened lemon proceedings on a modded car? Then your dealer put plugs in and 'fixed' your mod for free? I'm no apologist or fan boy but I'd ease up on the rhetoric... Sounds like you are being well taken care of.

The others experiencing cold start misfire should signal ZERO mod vs 'light mods'.

JamesNoBrakes · 02-13-2019, 11:03 PM

Quote:

Originally Posted by sadpanda

You threatened lemon proceedings on a modded car? Then your dealer put plugs in and 'fixed' your mod for free? I'm no apologist or fan boy but I'd ease up on the rhetoric... Sounds like you are being well taken care of.

The others experiencing cold start misfire should signal ZERO mod vs 'light mods'.

Oh, there are lots of good tidbits I left out, like how a few days ago the customer service rep called to tell me that my car was fixed, service was complete, and it was being towed by roadside assistance from 150 miles away...(when it's supposed to be 5 miles away at the dealer).

There were lots of dropped-balls. At one point, they accused me of having the car "sitting for one year without driving", which caused "bad gas", when I didn't even own it for one year and the longest it ever sat in one place was at the dealer for this very problem. Then I asked them if they could tell the difference between bad gas from sitting and bad gas from a dispensary. They said yes, then said it was the latter due to how it looked. I asked them then why did they accuse me of the former if they knew the difference? I also supplied my fuel receipts showing I put "top tier" fuel in it the entire time.

gmw0181 · 02-24-2019, 07:10 AM

Quote:

Originally Posted by EMTNLSS

So i'm having this issue where I seem to be getting a misfire mainly in cylinder #7 and maybe #8 only during the cold start sequence. I'll log it with hp tuners and it'll misfire for most of the cold start sequence then once it calms down it'll show no misfires. I went out and drove it around going to redline and everything and got pretty much no misfires. Maybe like 1 or 2 but I feel like that's normal.

I've checked the wire and it seems fine. I replaced the spark plug with the OEM ACDelco one and it's still misfiring. I'm thinking about switching the coil to another cylinder and see if the misfire switches. Any ideas on why it would only misfire during a cold start? Mods are in my sig. Thanks!

I too had a misfire at cold idle. I looked for a vacuum leak and found my PCV hose loose not snapped down. It look ok but I pushed it down it snapped/locked on to the fitting.

EMTNLSS · 02-26-2019, 03:05 PM

I don't seem to have any vacuum leaks.

After logging a few cold starts I feel like it's the injectors. The misfires will only happen when Injector Pulse Width 2 is happening. As soon as that's done my misfires stop.

02-12-2019, 10:34 PM	#29
JamesNoBrakes Drives: 2SS 1LE Join Date: Oct 2011 Location: AK Posts: 2,301	Dealer covered it, replaced the spark plugs, they were fouled with lots of carbon deposits. They said there was an evap leak and that also contributed...also "bad gas", but I doubt at least some of this. I'm going to look a little harder at it tomorrow or sometime later, I have a hard time believing a fitting was loose with the catch can, as all of those things were well tightened with clamps, etc., but again, I'll have to look into it. No charge, car is back, runs smooth, got it "cold" from the dealer at 35F, just smooth as could be driving home. Nice to have it back. __________________ Everything happens for a reason, except when it doesn't, but even then, you can, in hindsight, fabricate a reason that satisfies your belief system. 2018 2SS 1LE 2023 Colorado ZR2 2022 Stinger GT-line AWD

02-26-2019, 03:05 PM	#33
EMTNLSS Drives: 2016 Hyper Blue 2SS Join Date: Feb 2016 Location: Layton, UT Posts: 498	I don't seem to have any vacuum leaks. After logging a few cold starts I feel like it's the injectors. The misfires will only happen when Injector Pulse Width 2 is happening. As soon as that's done my misfires stop. __________________ 2SS Hyper Blue Metallic \| A8 \| Jet Black Interior \| NPP Exhaust Current Mods: Catch Can \| aFe Lowering Springs \| GM 2nd Gen Splitter \| Hotchkis Sway Bars \| MRR FS02 Wheels \| Flowmaster Exhaust \| Dark Tail Lights \| Diode Dynamics Sidemarkers \| Roto Fab \| Solar TB \| PRAY Ported IM \| BMR \| PRAY Tune Upcoming Mods:

02-13-2019, 10:37 AM	#30
sadpanda Drives: 2014 ATS 2.0T 6MT Join Date: Mar 2018 Location: ohio Posts: 66	You threatened lemon proceedings on a modded car? Then your dealer put plugs in and 'fixed' your mod for free? I'm no apologist or fan boy but I'd ease up on the rhetoric... Sounds like you are being well taken care of. The others experiencing cold start misfire should signal ZERO mod vs 'light mods'.

User Name		Remember Me?
Password