Hello all.. I been a long time reader here on the forum but never actually signed up. I decided that it was about time since I started having problems of my own.

I started noticing a really bad idle only during cat warm up mode. When it was cold out I would get misfire CEL but since the weather have warmed up I only get misfire counts but no actual CEL. At first I didn't know WTH was going on so I checked everything I could check from coils, plugs, vacuum lines, to even a cr check. Everything turned out fine. I am currently trifecta tuned, so I talk to vince about it and he suggested to disable the cat warm up mode since I don't have any cats anyway. So I took his advice but the cat warm up mode is giving me problems of it's own it seems. So I went back to cat warm up mode since I only had to deal with rough idle only during the cat warm up mode. The problem now is that my normal temperature idle seem a tad rough than usual. It feel like my ac compressor is coming on and off but it's really not.

I noticed that there are tons of guys with GM's direct injection with cat warm up mode that are going through this exact problem, from now the camaro guys to some saturn guys in the past, but I haven't seen anyone find out why the cat warm up mode all of a sudden is going bonkers. I also heard that there is a TSB out from GM that supposed to fix this cat warm up misfires and rough start/idle with a reflash, but that is all I know.

As I mentioned above, I am getting massive misfire count with no CEL during the cat warm up mode on cy1 right now. I am thinking I might have bad injectors, but I just don't want to go through buying rebuild parts, injectors, and special tools and come to find out that it was not the injectors. I'm thinking If it was the injectors, then why does it only give me issues during cat warm up mode?? although I am starting to notice my idle a little more rough than usual.

I would like to hear more about this from you guys if I could.

 

Do you smell gas when your car is in the garage? Do you hear anything that sounds like popcorn popping when you're under WOT? That would be a missing injector seal. Did you see any codes for EVAP? Does your car have trouble starting after you fill it up? You could unplug the solenoid for the EVAP purge and see if it idles more smoothly. If it does, you need a new EVAP solenoid. Does your car sound like a Subaru at any time? If so, you have broken a lash adjuster and need to take off the valve cover and look at cylinder 1 rocker/lash adjuster.

 

no problem starting the car. I just started to notice my car idle a little more rough than usual on full temperature tho. no popcorn noise and no suby boxer noise. The cat warm up mode is the only time when it idle rough and actually throw misfire code in cold but it only has been showing misfire counts since the temp been warm. cylinder 1 misfire count can sometimes go into 30's. After the cat warm up mode everything seem perfect other than my normal idle seem to have gotten a little rough, almost as if my AC compression was turning on and off.

I know some peoples been fine with the cat warm up mode off but isn't that just throwing on a band aid? I don't think the cat warm up mode is just going to go bonkers on you for no obvious reason.

 

only time i get misfire sureing cat warmup is when i have the cat installed, when i run no cat downpipe it doesnt do it

 

I have not been getting any actual misfire CEL codes as the temperature around here been warming up, but my misfire history count on cy 1 sometime go up into 30's, and 1 or 2 on other cylinders. It's weird, because right after the cat warm up mode things are fine. I see that few others that had the same cat warm up mode issue found out that their teflon seal on the injector was detoriating or even fallen off. My question is, if the injectors are at fault wouldn't I have issues even after the cat warm up mode? and popcorn noise as one guy mentioned. Others are just turning off the cat warm up mode, and I don't have a problem with that since I have no cats but I would like to find out why my cat warm up mode all of a sudden is having problems. The only thing I didn't check was my injectors but I just don't want to start putting money into injectors parts and end up finding out the injectors was fine.

Where are everyone that was having this same problem?

 

where do u see this misfire count?

 

aeroforce gauge and HPT scanner misfire history log.

 

could be phantom misfire, i see misfire on dashdaq 2, but it never throws codes, and when i scan i see nothing.

 

I heard that during cat warm up mode misfire CEL do not get thrown no matter how much it really misfire. Not sure how true this is but my idle during cat warm up mode is rough, choppy, and it really does miss. Is not like my cat warm up mode idle is smooth and I am seeing misfire counts.

This is what I am exactly going through, http://www.*******************/forum...warmup-misfire gee em sport compact dot net for the missing

and this, https://www.cobaltss.net/forums/prob...please-272068/

and this, https://www.cobaltss.net/forums/prob...-codes-267040/

and this, https://www.cobaltss.net/forums/08-1...d-star-257051/

All of those peoples are having cat warm up mode issue and there's ton's of it more. Just search google for "LNF bad injector" "rough idle" "cat warm up mode" "misfire cat warm up mode" and there's ton's and ton's of it. The crazy thing about this is that I can't seem to find out why GM's cat warm up mode goes bonkers on direct injected engines. everyone seem to either have just band aided and turned the cat warm up mode off, or the cause been the injector teflon seal coming off or going bad. I don't think is the injectors for me tho..and I don't want to just turn my cat warm up mode off without knowing for sure that there's anything else wrong. There's even a how to deal with procedure on HP tuners forum and also a TSB so obviously this is a known issue. I just want to get to the bottom of it.

Thanks for the help tom..

 

Pull the injectors. You'll find out that way.

 

i dont think thats true cause iv had a code thrown at catwarmup for misfire. and mine is usually when iv been running the car, then let it sit for an hour, then run it again, then i get phantom misfire. but with no cat, its almost never. i think its the cat itself causing some messed up reading.

 

well I have no cats.

I think the only thing left to do is to pull my injectors but I wish there was a way to know for sure that the injectors are at fault here. I would hate to buy parts that need to be replaced just to pull out the injectors then find out my injectors are fine.