Different problem... Long

[j_yewchin]

Greetings everyone, I've got a bit of a different question than people normally do, although it may seem the same as other ones. by the way i type LOTS. Anywho, not too long ago I joined the club and bought a used 2001 GAGT.. I love it, but its lacking power. I used to drive these things for a living.. i bagged on quite a few 2004s. For having the same power rating, somethings missing here... VERY little power until i reach 3000 rpms. Intake and exhaust have been done... i realize this takes away a little lower end. but i CANT spin my tires unless i do a brake stand. a chevy venture does a better job laying a patch than my car can... I did that MAF screen removal trick too. It didn't really do much to be honest. My throttle response is pretty bad.. again compared with a chevy venture which was way better. i realize the gm vans have 10 more horse, but its not making THAT much of a difference. I have 70000kms. im sure the plugs are origional, but from what i've read they should be good to at least 100000. i have my doubts that the cat is clogged already. i've done various fuel system cleaners. and intake cleaner, including iac valve. i tried combustion chamber cleaner too.... slight improvement. me and my brother timed my car for 0-60.. as im sure most of you know the stock 0-60 time of these cars is 7.7 seconds. but lets just say 8.. mine took TEN... we did 2 run... its pathetic. like i said before anything above 3000rpms is fine, its got LOTS of pull then so the top end is good, but i should be making more power in the lower end. i guess i should mention that the only time the check engine light has come on is if i've left something disconnected. i've heard about pcm reprograms from the dealer but i dont think it should be necessary. by the way this is a great message board so i thought i'd ask you guys if you had any ideas or suggestions.. many of you on here are brilliant. so any tips would be greatly appreciated. have a good one, all.
JiM

[Craig99SE2]

WOW ... OK ... where to begin ...

1. Welcome
2. Intake / Exhaust DID NOT rob you of anything (i.e. low end)
3. NEVER ALTER THE MAF!!!
4. What exactly has been done. Specifics are nice ... like brands and such.

Regarding most of the things I mentioned above, SEARCH, SEARCH, SEARCH!

[j_yewchin]

yikes that was quick! hahah dont' worry i did spend lots of time searching. yeah the maf screen removal thing wasn't the best thing to do. you said you wanted brand names... i got a high flow AMSoil air filter and dropped it in my factory air box. as for exhaust there IS a resonator in there but its not the factory one. no clue on the brand on that one. i have one hooker performance muffler. thats all the info i have for ya. thanks for the fast reply!

[Craig99SE2]

So far I have gathered you have an Amsoil drop-in and a custom exhaust. Neither of which will hurt performance but give you more like 5-10 horsies.

Sounds like you got other probs ... was it a rental car that got thrashed ... get a CarFax to be sure. Other than that, hook up to a OBD-2 scanner and take a look at what is going on.

[j_yewchin]

hey. i do have a obd2 scanner at work but they'll only let me use it if its throwing a code, otherwise they'll think im just dinking around. one more note, doesn't seem to matter if computer is in closed or open loop. it'll do it all the time. the oil was overfilled when i got it by like a litre. i drained it out. i don't have any blowby currently. i guess i should mention i have a new pcv valve and fuel filter. as for the rental car thing you mentioned, as far as im concerned a person owned it. but you never know how good/bad it was driven/maintained. i'd consider doing a compression test, but with under 100000km's i think of it as unnecessary. i am switching to mobil 1 soon. but i dont think that will noticeably improve throttle response or power at all. i don't really feel like spending the time and effort on replacing the spark plugs and wires unless im sure thats whats causing the problem ... or at least i can narrow it down. i'm open to any more suggestions. thanks lots for the help so far!

[Love my GT]

I am not an expert when it comes to problems like this, but why don't you just pull the front 3 spark plugs and see what kind of shape they are in. Just my thoughts.

[Craig99SE2]

Bottom line is something is wrong with the car! You either hook it up to a scanner or else roll the dice and cross your fingers that you don't crap out!

If it is that slow ... something is seriously wrong! COuld be trans too. The Grand AM transmission is JUNK!

[j_yewchin]

so yeah... whoever suggested the plugs was right. i took out the front 3 today, while i was at it i sprayed carb cleaner in the cylinders. they were all at a .065 gap. again, my kilometerage (not mileage, its a new word, heheh ) is 70000kms. i have my doubts the plugs would last all the way to "166000kms" like the manual says. i cleaned them off... they did NOT look good... all brown and crusty, i know what they are supposed to look like and they weren't close. what a difference afterwards though, JUST from the front 3 its WAY better...i bought some bosch platinums and plan on replacing them soon.. oh joy. my friend told me to get the bosch 4+'s, but since i heard so many bad things about them i chose not to. they are pretty close to being properly gapped from the factory.. they are either at .060 or .062.. is the .062 a big deal.. should i adjust it? im going to shoot for .059 if possible.. just cuz. thanks to the two people who replied, later all.

[blackGT420]

if you want to spin your tires turn of traction control

[j_yewchin]

hahah yes i know how to turn off traction control. once it DETECTS wheel spin is when it counters it. and now that i regapped the front 3 plugs (previous post). i can spin em no problem with traction on. thanks for the thought though. i usually leave ets on, cuz i hate the bright orange light that stares back at me if i turn it off.

[blackGT420]

the light does get pretty annoying, I hate the window wash one!! I always think something is wrong at first cuz of the beep

[j_yewchin]

yes the beep can freak you out.. the cadillacs i used to drive had a back up sensor on them (im sure you guys know what im talking about) and it would always DING if you got too close to something. anytime i'm backing a car out at work the low fuel warning chime always comes on and i nail the brakes everytime, . bit of an update though. i did install those bosch platinum plugs.. the back 3 plugs arent as terrible as everyone makes them out to be. #1 took the longest (the one closest to the alternator). cars WAY smoother, and YES i have no problem spinning away now. funny though, there seems to be a stuttering at 1200rpms while driving... if im going slow enough i can notice it. seems like a very small misfire or something... i wouldnt doubt it based on what i've heard about these plugs. everybody elses care idles at 600 right? my idle seems to be SLIGHTLY rougher.. i can see the engine move a little both ways while idling, but i dont think its a problem. if i start running into problems with these plugs i'll post to inform you guys. peace out

[j_yewchin]

OUCH! just when i thought the bosch's were doinga good job... BOOM the check engine light comes on. took about 200 kms. code that came out was random cylinder misfire. took out the plugs and they were already blackish... pretty sick for being in a week or two. i disagreed with everyone when they said stay away from bosch in gm engines, i thought it was just the +4's t hat were troublesome, but i had the regular platinums and they made my car stutter and misfire. i bought ac delco rapidfires and put them in.. VERY big difference. quite efficient spark plugs. the gm dealer wanted 15 $ canadian for each platinum ac delco plug. and the list price on the rapidfires werer 10 $.. i told him i worked across the street at another dealership and he chopped it down to 7.40 a peice. total cost was under 50 dollars for a plug thats better than the stockers. highly recommended. just thought i'd post this on here to help anyone decide what plugs to get.

[tranceokido]

50$ for spark plugs! OMFG are you crazy! That is way to much for some spark plugs. They better be superman spark plugs with a lifetime warranty or something. ****..I go to wall-world and buy some autolite plat tipped plugs and all my cars have fun great on them. I have not replaced them on the GA yet though.

[j_yewchin]

hahahah no im not crazy, the 20 dollar bosch ones were just crap. now im just sticking with ac delco. hey, least i didn't get the 15 dollar ones thats 90 bucks... plus tax! . yeah they are pretty good spark plugs. nothing special but it runs like a top compared to that german designed crap. talk to you later.

[tranceokido]

autolite isn't german...I am sure you could of been just fine with those. But no biggie..now you know.

[j_yewchin]

ANYWAYS... havn't really got this fixed. small update though. i swapped in a maf with a screen on it and reset the computer nicely since then. SMALL improvement in fuel economy. still no low end power whatsoever though. just got the computer scanned, no codes except failure to comunicate with bcm (only once that showed up, i have NO idea why). still desperate for some advice, tried almost everything i can think of. thanks people have a good one

[atc3434]

Did these plugs end up crappy like your first replaced set. My Bosch Platinums have served 20k so far and are going strong, so I don't beleive the line on the Bosch plugs being a poor choice for this car. My guess, is that its a plugged cat or O2 sensor. My $$ are on an O2 sensor. The MAF screen is good to have back on. Just for the record, my GA isn't a tire roasting machine, but it scoots along pretty good. Sure, if you turn of trac control and mash it from a stop it'll spin em a little, but don't expect to light em up and burn em down the street. GM's pcm programing still limits wheelspin, even with traction control off. Something to keep in mind.

Another thing to keep in mind, is the with the CAI, you might notice a little bit slow throttle response right on the very bottom of the powerband. The increased airflow doesn't build a lot of velocity for the air going into the engine as fast as the smaller diameter stock piping, so the very lowend does seem less responsive.

[j_yewchin]

nice, quick reply! my throttle response has gotten better lately, but i usually never hear a sucking sound if i rev it and put my ear by the intake. it should slurp a little bit. i really dont think its bringing in enough air. im agreeing with you on the cat or the o2 sensor( s). because when i had those boschs in it was misfiring for about 200+ kms, so that MIGHT have been enough time to roast the cat. i have my doubts though.. either way its warranty, as long as i can prove somethings wrong.. for any edmontonians im working at/getting my warranty work done at petersen pontiac in sherwood park. they are pretty cool. i was thinking about taking an O2 sensor out and seeing how covered it is. was also thinking about cleaning it off with brake cleaner or something, as it might be slow, or "lazy". and to answer your question about the plugs i have in... the rapidfires look fine, i had the front 3 out to double check the gap not too long ago, still decent. i think its possible that they might have given me the wrong heat range of plug... i'm not sure how many ranges rapidfires have, but that would explain why i lose a lot of power as my car warms up a little. getting this bad of fuel economy is frustrating, thanks for helping out, atc3434!

[atc3434]

I would really put money on the O2 sensor if your fuel ecconomy is in the crapper. Plus, you said you really notice the power loss once the car warms up. I'm betting that once it goes closed loop and is really leaning on O2 readings for its fuel and spark trim, thats when you notice the power go away. A scan tool really could help you figure it out, I'm not sure that you can take the sensor out and clean it, but it probably wouldn't hurt anything. I doubt that you have the wrong heat range, or that if you did it would cause you power loss. Heat ranges are for keeping the plug hot enough to burn off anything that would cause it to foul but not so hot as it causes detonation. You're not getting a lot of pre-ignition are you? And one other thought, I know this sounds like a no-brainer, but the air filter is clean, right?