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-   -   09 Cobalt - Air temp related misfire (https://ecomodder.com/forum/showthread.php/09-cobalt-air-temp-related-misfire-28537.html)

roosterk0031 03-24-2014 01:51 PM

09 Cobalt - Air temp related misfire
 
09 Cobalt XFE manual. I've had the car 2 years and think it's done it the whole time. But realized it went away this winter, back first day air temps broke 50f it did it again on the way home. Temp colder it went away.

Symptom: driving along light load 1500-2000 rpm, it stumbles for a fraction of a second, comes back on then repeats, sometimes just one, other time 5-8 times. No CEL. no codes via Scan guage. About 85,000 miles now.

It's more than a single misfire it almost feels like you hit a dip in the road as it's enough to slow the car. It's a drive by wire car.

When it happens in 3-4 gear 35 mph it really chugs, at 55 mph its just a dip by comparison. 90%+ of my driving is 55 mph.

I have doubt is cutting ignition or fuel alone would chug like it does, it's almost like the throttle is slamming shut and reopening. The SG2 display doesn't seem fast enough to catch what's going on.

Suggestions?

ksa8907 03-24-2014 02:00 PM

So the best guess I can give is pre-ignition from the higher air temps. I assume you are using a wai?

Does that car use VVT?

Best software I have had experience with is OBD2007 for data logging. I can only suggest cleaning the throttle body and appropriate sensors/air control valves, as well as check/replace spark plugs. Maybe use a higher octane and observe changes.

roosterk0031 03-24-2014 03:45 PM

All stock motor w/VVT. SG2 isn't plugged in at the moment, intake air during winter was only a couple degrees above ambient. Been running lots of different fuel blends, going with E10 87 octane for a while till I figure it out. Some days I think it's not going to make it, will do it 30 times, then gone for weeks. Didn't pick up the air temp correlation till few weeks ago, back in to 20's today and it's OK. Will see on way home it will probably do it now.

I'll was thinking data logging will be the way to go but no experience with it, will look into that.

ksa8907 03-24-2014 03:54 PM

data logging will be your friend, possibly a dying sensor.

I had an issue with a egr valve that was slow to close causing the engine to die when you let off the throttle, only way i found the problem was seeing log data of the IAT sensor reading a 100 degree change in under 10 seconds.

cbaber 03-24-2014 04:58 PM

Could also be O2 sensor or another critical sensor. You can tell if you unplug your O2 sensor. The car will run in open-loop mode, ignoring sensors like the O2 sensor. If the problem goes away, you can rule out things like plugs, ignition coils, fuel supply, etc. and focus on closed-loop components for troubleshooting.

roosterk0031 03-27-2014 02:04 PM

38 & wet this morning and all fine. I keyed off and back on to see if it would feel the same and it does, just quicker than I can do it with the key.

roosterk0031 04-28-2014 10:28 PM

Missfire is getting worst, watching the SG2 on way home, GPH went to 0 or real close at times even wasn't missing. TPS doesn't seem to change much from 25 at idle with limited sample of data seems like 35-38 on tps is where it cuts out. I'm leaning towards MAF, only if my other cobalt was closer I could swap and test. Did a couple 2nd gear to 6000 rpm pulls and it no misses, also did 5th gear up hill 1300 rpm to 2000 (55 mph) again no misfires.

roosterk0031 04-29-2014 09:23 AM

Finally got a code PO102 indicating MAF this morning. After it came on the car ran fine, it was still running closed loop wonder if the car's ignoring the signal it's receiving. Did see GPH go to 0 a couple times afterwards but not as much as before but without the misfire I wasn't looking at the SG2.

roosterk0031 04-29-2014 01:28 PM

Impala has the same part, going to swap MAF with it tonight and see if that fixes it.

roosterk0031 05-08-2014 09:33 AM

Didn't get around to swapping parts. Got a can a MAF sensor cleaner instead and used it over the weekend, I think it missed once since cleaning.

OKXXFE 05-13-2014 09:52 AM

Rooster, I had a similar set of problems last year from Fall till December. I remember that I had just changed my air filter (second change Stock->Wix-> now K&N). I also removed the intake silencer tube from the wheel well, just because I like intake noise, but now realize I have a free WAI! While I had it open I decided to clean my TB and MAF for first time with appropriate products. After putting it all back together and driving my normal commute, I noticed hesitation and misfire like you described especially at low speeds.
Had the codes read at parts store and bought the Haynes manual, turned out it was MAF sensor wire AND Camshaft Position Sensor (intake side I think).
I think the CPS is a job I can do myself with the repair book, but I had the dealership take care of it as I was also having a transmission trouble and still under 5yr warranty.
CobaltSS forums suggest that the life of these CPSensors is kinda short, the part is about 50-80$ and right on top of the head, real easy to get to if so inclined.

Hope it helps.

roosterk0031 05-13-2014 10:20 AM

Thanks, was browsing Cobaltss and saw that about the cam sensors and actuators as well, doesn't look to tough to change. I did about 1200 miles over the weekend and noticed the stumble only a handful of times. Nothing like it was before cleaning it. If it starts doing it consistently again I'll swap MAFs with the impala or other cobalt.

OKXXFE 05-13-2014 10:57 AM

I think when I cleaned the MAF, that I broke or screwed up the wiring to it causing my problem. Why does GM use the tiniest and flimsiest wires for their sensors, right on top of a hot engine? (rhetorical, I know it's because I only paid 12k for it new).

On another subject, I am about to replace the last two of my original tires @68k miles. How far did your OE's take you? The stock Continentals were g*d awful noisy and didn't grip AT ALL, but I do think I've gotten my investment out of them.

roosterk0031 05-13-2014 11:45 AM

Took 2 off at 40,000 going into winter they were almost to wear bars, I haven't worn out the other 2 yet, took them off going into the last winter so were probably about at 65,000 miles and still OK for summer. I'm planning on finishing them off this summer when the Nokian's wrg2's on the rear wear out but they seem to be lasting way longer than are supposed too.

I have Ecopia's on front now, I'm going to put some Nokian WRg2 or 3's on KT's cobalt this fall and use up her tires on mine during the summers. Run them all at 50+ psi.

roosterk0031 06-02-2014 02:15 PM

P0101 code today pointing to MAF, got a P0020 I think it was last week point to VVT cam sensor or actuator. It has the Impala MAF in it for about a week now, so don't think that's it. KT's cobalt was home so I should have swapped some parts with it but had other stuff to do. Each part is about $60 so don't want to just start buying without a clue of which one is really wrong.

2000mc 06-02-2014 08:38 PM

i cant pull up a p0020 for a cobalt, if it was a p0011(intake) or p0014(exh) i would try sticking a solenoid in

on the maf, assuming you have a stock intake, its hard to see if the intake tube is actually all the way on the throttle body, so its worth checking. other than air leaks, simillar to what okxxfe was saying, i'd be suspect of a broken wire inside the insulation near the maf connector

roosterk0031 06-02-2014 11:06 PM

Am thinking broken wire as well p0101 and p0102 both on way home, haven't checked yet but think both are maf. Car's all stock

OKXXFE 06-03-2014 06:57 AM

My Chilton's manual doesn't show a P0020, though the P0016/17 are
CKP-to-Intake/exhaust correlation so maybe it's not a part code but a "invalid value" code or calculation?
My codes when I had the problem were p0010 (Intake cam CMP, actuator circuit),
p0011 (Intake cam CMP, performance), and p0102 (MAF).
Good Luck!

roosterk0031 06-03-2014 09:51 AM

I'm thinking swapping cam sensors and MAF with Kt's cobalt, only take a few minutes. I haven't looked for the MAP yet. Car's at college, but USPSA match is close to there this weekend, go shooting, swap some parts and test drive home.

OKXXFE 06-03-2014 10:41 AM

I don't know that the 2.2L Cobalts have a MAP sensor? I thought it was just the flow and temp. I haven't seen it referred to in my manual.

roosterk0031 06-03-2014 11:17 AM

I don't know either, just kind of assumed they did. I haven't had to learn anything about the FI cause haven't had any problems with FI since a 94 explorer, and it was still under warranty. I think the SGII displays vacuum it so I assumed there's one.

Oriely's says I have one, and it's the same as the impala. Too bad the impala doesn't have cam position sensors. I should get a manual since I have 2 of these and plan on putting another 100k on this one, then hand it down to my son.

OKXXFE 06-03-2014 11:30 AM

Best $40 bucks a guy can spend for a car. His or Hers! I picked up the habit from my Dad who had a Haynes or Chilton for every car anyone in the family or close friends meant to keep. He saved alot of people a bunch of money in repairs through the years!

2000mc 06-03-2014 12:27 PM

Quote:

Originally Posted by roosterk0031 (Post 427773)
Too bad the impala doesn't have cam position sensors.

I've never had a bad position sensor on any of gm's vvt engines, it always comes back to solenoids/actuators/chains/timing/oil level+pressure

roosterk0031 06-03-2014 01:35 PM

Quote:

Originally Posted by OKXXFE (Post 427775)
Best $40 bucks a guy can spend for a car. His or Hers! I picked up the habit from my Dad who had a Haynes or Chilton for every car anyone in the family or close friends meant to keep. He saved alot of people a bunch of money in repairs through the years!

Used to get manuals for bikes and cars, but last 15 years haven't had to do anything on cars that I need a manual and sold the bikes, been just the simple stuff like brakes and wheel bearings.

roosterk0031 06-23-2014 04:20 PM

A few weeks ago swapped MAFs with KT's cobalt since it only has 26,000 miles, no change, developed an annoying miss first thing every morning when releasing the clutch to get it rolling. Getting P0101 regularly and occasional P0102. Last week when I got home I decided to take a close look at the wires at the MAF, took a little piece of electrical tape off the end of the loom, inspected with 5-6 wires and couldn't see any damage. Next day it did the high speed stumble 5-6 times. Been almost perfect since, no more CELs.

Debating liquid taping the wires but if I ever have to mess with them again it would make it difficult.

Kt's cobalt did get a CEL a few days later with my MAF, but she refueled and it came on shortly so I expect that's really the cause.

2000mc 06-23-2014 05:07 PM

If you have to rework that connector you'll want to replace it as a pigtail anyway

roosterk0031 06-24-2014 01:25 PM

Thanks, I just assumed I'd have to splice it together and didn't want to do that. Went searching and found new connectors with 12" of wire so I feel safe in liquid taping and maybe that will be the end of it.

Well almost, KT's cobalt threw a CEL so maybe my MAF is still bad.

roosterk0031 09-02-2015 04:13 PM

Took me just over a year to get around to it but finally fixed my problem last weekend, car ran fin 98% of the time just occasional miss/chug, sometimes a pretty big series of chugs. Nephew gave me a MAF extension to cut up and $6 of connections the CEL is gone and not a miss in a week.

Next step making it a FFV.

2000mc 09-02-2015 06:29 PM

Always nice to hear solutions / wrap-ups.

roosterk0031 09-02-2015 09:30 PM

I was 90% sure where the problem was, but was just a minor inconvience, and when the CEL was on it ran 99% fine. Plugged the SG2 into it last weekend and no MGP, AVE or GPH reading at all so I finally broke down and replaced the pigtail. Seems down on power but the butt dyno lies.

Ran into this guys site

2007 Chevrolet HHR

So I now have FFV HHR fuel map with same engine and tranny as my XFE and going enable it to make if FFV, if it works then KT's Cobalt. Today E85 might not be cheaper per mile but it will be again if at only the cost of tuner $100 I love the flexiblity. And he claims GM detunes the E85 to hurt it maybe the cost differential will be less the my current and previous GM FFV at 18%.


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