RPM's jumping and other problems [Archive] - GrandAmGT.com Forum

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laura56083
01-14-2008, 12:10 PM
I have a 2000 grand am gt with 99,000 miles. I've been having lots of problems with the car and no one seems to understand what's going on. The worst thing is my RPM's decide to jump up and down all the time. I'll be comig to a stop with my foot on the brake and my rpm's jump up and my car wants to take off. I was wondering if anyone else had the same problem? The other thing is a clicking noise that sounds like my directionals are always on and sometimes it looks like smoke comes from the steering wheel.. I know I'm not seeing things lol. The OTHER thing is... everytime I hit a bump it I have this really loud rattling noise coming from my rear passenger side. It's been getting louder and louder. I have subs in my trunk and I KNOW it's not those because I've had them in there for 2 years and this noise just started a few months ago.

I hope someone can help with some things!!

Panacea
01-14-2008, 04:09 PM
Rattling is probably strut mounts. It's common on these cars.

The turn signal noise is the turn signal switch itself (don't bother replacing the hazard switch cause it's not going to fix it).

NorKoastal
01-14-2008, 04:52 PM
I have a 2000 grand am gt with 99,000 miles. I've been having lots of problems with the car and no one seems to understand what's going on. The worst thing is my RPM's decide to jump up and down all the time. I'll be comig to a stop with my foot on the brake and my rpm's jump up and my car wants to take off. I was wondering if anyone else had the same problem? The other thing is a clicking noise that sounds like my directionals are always on and sometimes it looks like smoke comes from the steering wheel.. I know I'm not seeing things lol. The OTHER thing is... everytime I hit a bump it I have this really loud rattling noise coming from my rear passenger side. It's been getting louder and louder. I have subs in my trunk and I KNOW it's not those because I've had them in there for 2 years and this noise just started a few months ago.

I hope someone can help with some things!!

The jumpy idle could be caused by a faulty TPS sensor.. Throttle position sensor.. When the thing goes bad your idle will be jumpy and then the car will all of a sudden rev really high and stick there... This doesnt happen every start but will begin to happen often... The part is around $35-50 depending on where you go to replace it (dealer, autozone)

jackal2000
01-14-2008, 10:15 PM
The jumpy idle could be caused by a faulty TPS sensor.. Throttle position sensor.. When the thing goes bad your idle will be jumpy and then the car will all of a sudden rev really high and stick there... This doesnt happen every start but will begin to happen often... The part is around $35-50 depending on where you go to replace it (dealer, autozone)

gmpartsdirect.com has them for $30 plus shipping. i had this same problem a while back.

laura56083
01-16-2008, 09:53 AM
hey guys..i tried a new TPS and its still doing the same thing..im so lost;crap

NorKoastal
01-16-2008, 02:20 PM
hey guys..i tried a new TPS and its still doing the same thing..im so lost;crap Im thinking you might have a cracked hose somewhere causing a vacumn leak or possibly its the IAC sensor (above the TPS) that is acting up...

Hopefully its one of these two..

Just to make sure have you checked/changed all of the spark plugs recently?
Check your coil packs (where the spark plugs meet at the top of the motor). Make sure they arent too beat up looking and also pull the wires (one at a time) to make sure the post are clean and not rusted/dirty..

Has the PCV been changed recently.. Sometime the hose that pipes into the PCV will get cracked on the 90 degree bend.. This will cause a vacumn leak.

I)ark-ChiLD
01-19-2008, 09:57 AM
its your MAF(Mass Air Flow) Sensor. Have it cleaned or replaced. I had the same problem 2 weeks ago.

2000amgt
11-11-2008, 10:52 AM
im having the same problem, did you ever get your problem resolved laura?

GrandAmGTTT
12-31-2008, 09:13 AM
Does it stall out at a low RPM?

Metallman56
12-31-2008, 11:42 AM
its your MAF(Mass Air Flow) Sensor. Have it cleaned or replaced. I had the same problem 2 weeks ago.

x2, mine does the exact same thing when my clapm for the CAI comes loose. its a b*tch to get it on there right sometimes.

zukiracer19
12-31-2008, 07:38 PM
Clean your MAF, you can get the cleaner at autozone(MAF CLEANER), could be tps, Also thinking a bad o2 sensor could do this too

RPO3
01-02-2009, 01:28 AM
Ive Had The Same Prob...
Makes It Seem Like I Dont Know How To Drive...haha

fromoe
01-02-2009, 02:13 PM
Clean your MAF, you can get the cleaner at autozone(MAF CLEANER), could be tps, Also thinking a bad o2 sensor could do this too

had the same problem a couple years ago. it was the O2 sensor on the fritz

Bonzo'97GaGt
05-12-2010, 01:03 AM
Does it stall out at a low RPM?
I'm having the same problem. At one point the CEL did come on indicating that the TPS was bad. Replaced that and still having the same problem. The idle will jump around, rev past 3000, then drop to a low RPM and stall. I will try cleaning out the MAF next, but are there any other possible causes?

AaronGTR
05-12-2010, 03:34 PM
Dirty MAF, faulty TPS sensor, faulty IAC valve, vacuum leak somewhere, fouled or worn out O2 sensor... all of those can cause the rpm to jump around.

carlos m.
05-16-2010, 10:54 PM
Maybe we all have been ignoring the fuel pressure regulator as the culprit. The fuel pressure regulator has a diaphram inside that if cracked, broken or with a hole in it; raw fuel could be sucked into the manifold by the vacuum hose attached to the fuel pressure regulator itself. The raw fuel mixed with correct fuel-air inside the combustion chamber(s); would cause the upstream oxygen sensor to tell the computer to lean the mixture in relation to engine load-- at same time the downstream oxygen sensor feeds back the info to the computer , that the correct air-fuel ratio was acheived. That is why when you throttle back--it stops surging.

AaronGTR
05-17-2010, 03:53 PM
Maybe we all have been ignoring the fuel pressure regulator as the culprit. The fuel pressure regulator has a diaphram inside that if cracked, broken or with a hole in it; raw fuel could be sucked into the manifold by the vacuum hose attached to the fuel pressure regulator itself. The raw fuel mixed with correct fuel-air inside the combustion chamber(s); would cause the upstream oxygen sensor to tell the computer to lean the mixture in relation to engine load-- at same time the downstream oxygen sensor feeds back the info to the computer , that the correct air-fuel ratio was acheived. That is why when you throttle back--it stops surging.


Usually if the diaphragm is bad you'll see fuel leaking around the hose on top because the fuel pressure is pretty high.

Also you've got the operation of the O2 sensors wrong. The "upstream" O2 sensor, or rather the primary or "bank 1" sensor which is before the cat, makes fuel corrections to the mixture after combustion, and has nothing to do with throttle input or engine load. The MAF sensor does that. The second O2 sensor, the one after the cat, only tells the computer if the cat is working properly and doesn't have anything to do with fuel adjustments at all.

2000GAGT
06-01-2010, 10:40 PM
hey thats good to know! i was wondering about that second O2 if it had any involvement with the fuel adjustments. I just ran my data logger and on a line graph my Bank1-S2 is more or less a flat line with the occasional jump about twice per screen and the upstream, Bank1-S1 is doing the usual quick up and down.

What do you think would cuz my car to create a major hesitation at WOT?
At about 5K it will jerk and the RPM will shoot down to around 3K then come back really fast and hold but very noticeable loss of power all around.
No engine codes, fuel pressure is good and seems to have a good A/F reading. Spark plugs are from last fall and wires are about one month old. Ignition control module is also about 6 months old. Possibly coils? or maybe not even an ignition problem...
I am running really rich, like a 12-11.5:1 A/F and have a 28lb injectors with a reprogram

AaronGTR
06-02-2010, 03:38 PM
Well, if that's your engine in your avatar pic.... using an RSM kit with no MAF sensor, there is your problem right there. MAF sensor is required for proper fuel metering and as a measurement of engine load used by the transmission programming. 100% positive that is causing your problem. Modify the kit to put the MAF sensor back in, and get it reprogrammed.

Mac0083
06-02-2010, 04:08 PM
Aaron, click the pic of his avatar and it shows a bigger, different pic. in that setup, there is a MAF just in front of the TB
http://www.grandamgt.com/forum/customprofilepics/profilepic6241_4.gif
btw Steven, NICE!!!
dyno numbers yet?

2000GAGT
06-03-2010, 02:32 PM
thanks mac!

yea sorry the avatar pic is a little old. and yes Aaron i know all about the wonders of no MAF and the trouble it causes. that first pic was taken when it was installed and the second pic is what it looks like now and it gets a very smooth idle and A/F with the MAF right in front of the throttle.

BUT with and without the charger connected to the system (so charger doesnt make a different connected or disconnected and returning to old intake) my car runs like ass accelerating hard or lightly. Im going to check the compression today. It almost sounds like i can hear the exhaust pulses more like a manifold is loose or something.

if it helps the symptom developed somewhere between installing 28lb injectors, fixing a wire to the MAP smashed from reinstalling the manifold, testing/starting the charger when it was first installed with out the MAF to see if it would idle (pretty sure it was dumping fuel out my tail pipes).

I've checked with my scan tool and all the sensors i can check seem to be working. It idles fine but seems to take a little more gas to accelerate and cruise on freeways.
Like i said it has this condition and during WOT it just seems to stumble and once or twice the RPMs will shoot down from around 5K to about 3K and then jump right back up.

If it also helps, this car is very modified/replaced meaning there is really not much under the hood that came with the car new. Different transmission, different engine, boosting, etc. Pretty much the only thing factory is the exhaust and the rims, don't laugh! :) So could it be because of the exhaust?? the chasis does have 206k miles! yea its a lot but the car normally drives like its got 50k. (i've replaced everything over the years, sentimental value i just dont let it die) the tranny has 95k and the engine has 46k.
Can a clogged catalytic converter cause something like this? I also noticed if i rev it up i can peak 8 psi versus during WOT i hit about 5-6 psi if that is anyhow related.

I know its a lot of info but any ideas are very greatly appreciated!!

2000GAGT
06-05-2010, 11:18 AM
so i figured out the stumbling at higher RPM. ignition control module was bad, took it to oriellys and had it tested. Got a new one and it sees to have power back.

Still have the weird noise from under the hood which sounds like i can hear the exhaust pulses or something. I checked my compression and every cylinder was 170+ with two at 180 PSI. I can hear it the most by the left side on the front exhaust manifold. i dont think the bolts could have come loose but i guess i will check.

Mac0083
06-05-2010, 04:02 PM
maybe a cracked header?

ItsMeScottG
10-23-2013, 04:28 PM
I replaced myTPS sensor and that didn't fix the issue. I'm replacing my IAC sensor tonight. I'd that doesn't resolve this issue, what should my next step be?

Starglow
10-23-2013, 05:28 PM
I replaced myTPS sensor and that didn't fix the issue. I'm replacing my IAC sensor tonight. I'd that doesn't resolve this issue, what should my next step be?

It appears that you have revived a very old thread, so I assume you have the same issues as the OP?

Make sure you clean inside the IAC hole on the TB if you take out the IAC. If you install a brand new one, the pintle position needs to be calibrated with the PCM but I can't remember the exact procedure at the moment.

If that doesn't work then suspect the IAT sensor or MAF sensor. The PCM controls the idle, so it's seeing something it doesn't like and it's trying to compensate for it by raising the idle speed. No stored SES codes?

ItsMeScottG
10-23-2013, 05:43 PM
No ses codes, all dash lights are also off, car randomly increases in RPM and accelerates at the same time.

Starglow
10-23-2013, 06:21 PM
No ses codes, all dash lights are also off, car randomly increases in RPM and accelerates at the same time.

Try cleaning the MAF and see if that helps any. Use MAF cleaner.

ItsMeScottG
10-23-2013, 06:37 PM
Try cleaning the MAF and see if that helps any. Use MAF cleaner.

Well I just cleaned my MAF while I installed my new IAC sensor using CRC MAF cleaner. My car seems to start up more instantly now. I'm going to have to drive it around for a little while to see if the issue has been resolved.

ItsMeScottG
12-08-2013, 08:52 PM
Well its been a few months and I can verify that changing my IAC fully resolved this issue