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12-08-2010
Please Help!
Have a 05 Grand Prix. Sometimes it chuggs when driving. Slow or fast......But the kicker is, When I shut the motor off and re-start it, everythings OK? No engine light......???? I cleaned the MAF....but still chuggs. Pissing me off......Any Suggestions?
12-08-2010
Fuel Filter clogged? Fuel injectors dirty? Just suggestions
12-08-2010
Did you only clean the MAF? What about the throttle body itself? Is the air intake good and clear, filter? Even the type of filter can be more of a problem than a help. I tried a Purolator once that was so restrictive the car couldn't breathe very well.
Beyond that, whens the last time plugs, wires, PCV had any attention?
Have you had a scanner on it to see if it's throwing any codes that aren't triggering the MIL?
Just some thoughts..
12-11-2010
I have the same problem in my 05 GP GT. No codes, no check engine light, MAF is clean, new plugs, new filter, throttle body clean. I have checked everything I could think of. Just as the original post, if you restart the car it acts fine. It is very intermittent.
12-11-2010
Seems like the practical next step would be to check to see if the O2 sensors are working correctly and beyond that, the actual injectors. The thinking is the O2 sensors measurements are what tells the PCM to control fuel/air mixture and how much to feed the injectors. Fuel pressure could factor in but I dunno.
Another thought is something more simplistic is if any sort of injector cleaner has been run through the system or been running cheap fuel. Stuff like chevron's techron or shells v-power helps keep this in order but again, with the corn gas we've been getting stuck with isn't the best thing for injectors in the first place.
12-20-2010
I have exactly the same issue with my 05 too, and yes a restart (even a rolling restart) will completely fix it, until the next time it randomly pops up. And if I don't restart it, it will keep doing the same crazy random "misses" all day long.
I did try an experiment last week, where I unplugged the MAF. This forces the computer to run guesstimates rather than input from the sensor. So far, it's been running fine (yes, the MIL light is on now). If it continues to run without the misses for 2-3 weeks, I will gamble and buy and new MAF. (yes, I already tried to clean it for those about to ask)
12-21-2010
Thanks for keeping me advised on this. It's been a real pain in my A*S! If this works for you, can you keep my informed (steele286@comcast.net). If not.......I'll just run the damn car into a tree. LOL
Thanks!
Steve
12-23-2010
have ya tryd plug wires or coils?
02-02-2011
Update: So I ran the car for 8 weeks with the MAF unplugged - the problem was completely gone. Yes, without a MAF plugged in, the SES light was on, and yes when you start it up on a cold morning it hunts a bit for idle speed and might stumble just a bit when cold, but with the chugging normally happening once or twice a week, this was a clear win.
So, I bought a new MAF - installed it - the chugging was back the next day!
So either by disconnecting the MAF, it forced the computer to also ignore other sensor readings (and maybe one of those other sensors is causing the problem) or maybe the computer programming in the 05's is a bit flawed. I only say this because the two other guys mentioning this issue also has 05's and I have not heard any "mee too's" from other years.
Anyone else have input? (and anyone want to buy a barely used MAF?)
02-03-2011
Again as I said before, you should run the gambit on sensors in the chain and make sure they are functioning within tolerances. Make sure stuff like PCV value is okay, throttle body is clean and clear. There are SO MANY things the computer makes adjustments on caused by sensor readings. If they're bogus, you'll have trouble.
I'm running a stock '05 computer and haven't had the problems you're describing.
02-03-2011
ok guys, here it is. the cat. i have the same thing going on with my 97 and ive been discussing this with some guys. let me guess, when its cold and running high to warm up at a grand it doesnt do it, but after it warms up and goes into open loop it starts to "chug" but more like bogs right, but it doesnt do it all the time. its the cat, its backing up exhaust into the engine and cant reburn burnt fuel so it "chugs" or "bogs" down. believe me, it aint your injectors specially being newer cars. granted it wouldnt hurt to check your plugs and other routine maintenance. im getting ready to install headers and delete my cat.
02-04-2011
VERY good chance that could be a factor. But based on he pulled the MAF and it worked better on default tables means there could be something wicky about the MAP, PCV, and/or EGR?Originally Posted by taman86
02-04-2011
A plugged cat would make a chugging like that, but what both Steel286 and I both noticed is that an engine restart "fixes it". - Seriously - car acting all jittery and wierd at all RPM's - kick it into neutral while still cruising, restart engine, kick back to drive, and the problem is gone. I don't see that being cat in my case. Also, at least 90% of the time I drive it, it runs perfect. Gotta be a messed up sensor.
02-04-2011
Oh yeah, new plugs, wires and throttle body cleaned. Didn't try coils, but I can't see it given the rolling restart "fixes" it. Cleaned all grounds. No SES light and no codes present.
02-03-2011
damn Gorecki, just glancing over the thread again i noticed you're running tr55's. just curious as to why if you're not pushing alot of air through or fuel and you're stock? jw is all
02-04-2011
The TR55GP is a standard temperature platinum plug, essentially a stock alternative to delcos. I use NGK plugs and K&N Filters on all of my bikes so I simply went the same direction on my GP. Have to admit once I ditched the stocker stuff for what I have, I clearly have more power on demand and when I punch it over 3k on the tach and keep going I can tell it’s breathing much better and firing more smoothly. Really simple stuff made pretty noticeable differences.
02-05-2011
thats interesting but i guess the newer cars or maybe just being n/a is it. being s/c, the tr55's are two heat ranges colder and should be used when we force more air into the motor. on my t/a with a cam and intake i was running tr-6's, but i should've went to stock plugs or maybe even hotter when i went with larger injectors to make sure i was getting a good burn.The TR55GP is a standard temperature platinum plug, essentially a stock alternative to delcos. I use NGK plugs and K&N Filters on all of my bikes so I simply went the same direction on my GP. Have to admit once I ditched the stocker stuff for what I have, I clearly have more power on demand and when I punch it over 3k on the tach and keep going I can tell it’s breathing much better and firing more smoothly. Really simple stuff made pretty noticeable differences.
02-11-2011
hey boys mine has the same problem and had a cat replacement done 1 month ago. Chugging still happens. I tried the disconnect battery tick for at least 5 hrs (I leave it overnight and that cures it for about 1week and a half then the chugging rado0mly appears). I read 04 and 05 have this problem with no know cure so was wondering if an 06 or up pcm swap would fix it. Keep up the feed back cause im sure 1 of us will come up with the fix. too bad cause this is pissing me off to the point of trading the car in for an import
02-11-2011
ps also my key restart still fixes it
02-05-2011
right, if you unplug any air monitoring sensor (iat, maf, map, 02, etc.) forces the computer to go into closed loop mode which means it goes into speed density or relies on a preset fuel and spark tables without adjusting. with that, the preset fuel tables are rich to make sure the engine doesnt get damaged. more fuel being forced down a clogged cat means no chug, same as first start up while in warm up mode. but wierd though that if you turn the car off and turn it back on and the problem is gone, maybe a map or 02 sensor. try having the car scanned while its doing that. also, the computer wont throw a code unless there is a problem for an extended period of time
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