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Acceleration Problem past 3500rpms

A

adcolvin1988

New member
I’ve looked all through this forum and haven’t found a similar problem to the one I’m having.

My car is a 2002 GP GT, mods include 3" downpipe, resonator, no mufflers, and a 9" open cone air filter.

At in town speeds 0-40mph the vehicle behaves normal accelerating through the gears with equal appropriate acceleration. Accelerating to highway speeds 40-75 the car won’t rev past 4000rpms and all acceleration is lost after 3500rpms all while the RPMs continue to rise (but not exceeding 4000rpms) according to throttle position. In order to achieve highway speeds you have to feather the throttle, tricking the computer you want a different gear in order to achieve sufficient speed without high revs and the PCM killing sending fuel into the engine. You can floor it and the engine responds but will rev high without equal acceleration. If the throttle is left open allowing the engine to rev high for more than 15 seconds it will throw the "service engine soon" light on, but then goes off after you let off the throttle.

I was thinking it could be a clogged Cat, the torque converter, abused transmission, or maybe the MAF is bad.

Any insight into the issue would be much appreciated.

Additional symptoms: Terrible gas mileage, and a loud sucking noise coming from my air filter during idle
 
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If the check engine light came on, you have a code thrown. Figure out the code and then go from there.

Sounds like it may be a misfire issue.

You maybe also have a clogged cat.
 
Fivefingerdeathpunch said:
If the check engine light came on, you have a code thrown. Figure out the code and then go from there.

Sounds like it may be a misfire issue.

You maybe also have a clogged cat.
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I just replaced the Cat, lol.

I'll take it to a shop and have them check the code. Thank you.

Five Finger Death Punch, Woot Woot!!! Good band.
 
Check your coolant level. Have you fixed your UIM? Early on when mine failed it would drive around fine until you gave it the beans, then it would miss like crazy and not want to accelerate.
 
I've seen an issue before where the icm was having issues supplying enough spark in the higher rpm range. If you have one to swap might be worth a shot.

Edit... Now that I read it if im getting this right it sounds like a slipping trans. Probably a long shift max adapt code.

Sent using my Galaxy SIII on Tapatalk 2
 
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nos4blood70 said:
Check your coolant level. Have you fixed your UIM? Early on when mine failed it would drive around fine until you gave it the beans, then it would miss like crazy and not want to accelerate.
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Coolant level is good. I haven’t fixed my UIM, any write up you could refer me to?

rperry435 said:
I've seen an issue before where the icm was having issues supplying enough spark in the higher rpm range. If you have one to swap might be worth a shot.

Edit... Now that I read it if im getting this right it sounds like a slipping trans. Probably a long shift max adapt code.

Sent using my Galaxy SIII on Tapatalk 2
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The spark plug wires have been changed recently but the ICM might be the problem. I’m going to have it taken to my local shop and have the codes read to find out what’s up. The long shift occurs but never shifts to the next gear because the speed of the vehicle isn’t sufficient for the computer to initiate a shift.

What about a vacuum leak?
 


Sounds like the trans is slipping to me. Maby the clutch disks are takeing a dump for 2nd gear. If you hammer on it from say 10mph in 1st gear dose it still slip at the 3500 rpm range. If not could be your 2nd gear disks worn out. Not enuf of them left to bite to. When you go to get on the highway at about 45-50 mph your car should kick into 3rd gear. If your going easy on it. From there you can give it just enuf gas to speed up without downshifting. It may be a pain to get on the highway but it will save what is left of your 2nd gear disks. For my car 3rd gear kicks in at about 90ish at WOT.
 
izup69 said:
Sounds like the trans is slipping to me. Maby the clutch disks are takeing a dump for 2nd gear. If you hammer on it from say 10mph in 1st gear dose it still slip at the 3500 rpm range. If not could be your 2nd gear disks worn out. Not enuf of them left to bite to. When you go to get on the highway at about 45-50 mph your car should kick into 3rd gear. If your going easy on it. From there you can give it just enuf gas to speed up without downshifting. It may be a pain to get on the highway but it will save what is left of your 2nd gear disks. For my car 3rd gear kicks in at about 90ish at WOT.
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It feels like a long shift, until I let off the gas it will shift. I tested it by physically shifting into 1[SUP]st[/SUP], 2[SUP]nd[/SUP], & 3[SUP]rd[/SUP] gear and it exacted the same symptoms of high revs with no acceleration.

I’m frustrated because I took it to Oreilly Auto Parts to see if they would read my engine code, but because the light isn’t actually on, they won’t read it. I need a place to start lol. I might just take it to a auto shop and have them do a full diagnostic on it.

Could my fuel filter need replaced?
 
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So my car threw a P0300 the other day. I can't decide what to replace first. I've got a list of stuff I can replace, Spark Plugs & Wires, Ignition Coils & ICM, Oxygen Sensors, Fuel Injectors, Exhaust Valves, Catalytic Converter (no point it's brand new), EGR valve, camshaft position sensor, or the worst case scenario my Computer is Defective!!! AH!!!

Symptoms:
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.


Anyone had this code thrown and where did you start?
 
Seachicken said:
spark load test, check for vac leaks, fuel pressure?

DTC P0300
Engine Misfire Detected
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Thank you, I might take the upper intake manifold off entirely just to check for cracks causing excess air into the engine. The thing that confuses me is, I'm getting terrible gas mileage, 10 - 12 miles per gallon and I'm driving her extremely gentle. if it's running lean why the terrible mileage?

I also checked my transmission fluid and it is brown and burnt smelling, I'm concerned it's also a transmission problem.
 


if the pcm saw the car was lean it would probly try and "flood" the cylinders.

take your tran pan off and change the filter, put dexVI back in too, then after 500miles drain the pan agian, and fill up agian, NO FLUSHING
fix a known problem first
 
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Seachicken said:
if the pcm saw the car was lean it would probly try and "flood" the cylinders.

take your tran pan off and change the filter, put dexVI back in too, then after 500miles drain the pan agian, and fill up agian, NO FLUSHING
fix a know problem first
Click to expand...

Thank You. Gotta wait till payday to do it, lol.
 
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