Low End Power Surging [Archive] - GrandAmGT.com Forum

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02GT_SkyHigh
12-04-2010, 09:18 PM
Hey so im completely stumped here as to what is going on. The car is having very sluggish response in low end and is doing alot of un-necessary downshifting that it had never done before. The car like surges during the rpm curve when i hold the throttle at one place. After searching I found some direction but nothing on exactly what the problem is <a href="http://www.grandamgt.com/forum/showthread.php?t=71781&highlight=weak+low+end">Here</a>Im not throwing any codes, and In July it got new gaskets all around. This has been going on for about 2 months now. About a month ago i changed the tranny filter and got some new fluid in there, then last week I got some MAF cleaner, and cleaned that mofo thinking this was the solution! Still the same problem. Next thing i think in going to try is my Fuel filter then possibly injectors. This is driving me insane! I was told Throttle Position Sensor possibly.
This is takeoff from a dead stop. holding the throttle about half way down, its a quiet vid turn up your volume. but listen, i hold the throttle in one place and the engine surges from 2500 to 3200 rpm.
http://i21.photobucket.com/albums/b276/Skyler1356/th_VID00004-20101117-0724.jpg (http://s21.photobucket.com/albums/b276/Skyler1356/?action=view&current=VID00004-20101117-0724.mp4)
This one is in going up a slight incline, i drive it everyday to work so i know what it feels like. now its always searching down a gear to get power instead of pulling in 3rd or 4th.
http://i21.photobucket.com/albums/b276/Skyler1356/th_VID00008-20101204-1349.jpg (http://s21.photobucket.com/albums/b276/Skyler1356/?action=view&current=VID00008-20101204-1349.mp4)

02GT_SkyHigh
12-10-2010, 10:25 PM
So not much help here. i just bought a new magnaflow cat, hoping to get it by tuesday. I got my fingers crossed here and i get to freshen up my welding skills :)

Sparky'sGA01
12-11-2010, 02:03 AM
im having the exact same problem. but mine are way more constant.. mine has never done it until i got a used modified PCM off here.. i dont know if thats what it is but man is it really annoying. its like it cant decide what gear it wants to be in. and mine will do it enough to shut off my cruise and everything as well.. very very annoying.

AaronGTR
12-11-2010, 07:26 AM
It's hard to say... could be a lot of things. If the car is "hunting around" for gears, it could certainly be a throttle position sensor problem. The computer uses the TPS, vehicle speed, and engine RPM to determine upshift and downshift points.

could also be a clogged cat, but usually if that gets bad enough to cause major loss of power it also causes misfires and will typically set a code. Same with the fuel filter. Regardless, if the fuel filter hasn't been changed in 30k miles or more I'd change it anyway.

02GT_SkyHigh
12-11-2010, 10:53 AM
i have a new fuel filter its been raining bad lately. the best way to describe it is its like i have a car-full of friends. when it upshifts, it seems to loose the power that rolls over from the other gear, its fighting to get back to 3krpm. there is a strange whistling/sucking sound coming out of my CAI when the power surges. Im hoping to get this cat and on haul balls. This is where I got some direction.
http://www.grandamgt.com/forum/showthread.php?p=1135708#poststop

02GT_SkyHigh
12-15-2010, 11:20 PM
Got the new Magnaflow cat on and all i have to say is wow! its running so damn good! my exhaust is way meaner sounding too! This should have been the first thing i did with my car when i bought it! Wow. Im still amazed! Ill get pics and a vid of the exhaust up for those who might be looking into a magnaflow muffler. Im So Excited!

PLUM_72
12-19-2010, 11:06 AM
SkyHigh, I have what I think is the same issue you have. If I'm driving down the road at say 40MPH and there is a slight incline in the road, the engine is loaded and then starts to surge a couple hundred RPM's.

I've had this issue in the past, and it's mysteriously gone away, now its back. In the past I can remember the issue developing in the winter, and going away once the temps warm up. However last winter i dont recall the issue occuring. But again, it came back with the first bit of cold weather.

It doesn't feel like a trans issue, more engine or sensor related. Curious to know what people have done. I've replaced a MAF, but no luck. The TPS sounds plausable. I've also heard some have had questionable results by disconnecting the battery to "reset" the computer. I've tried it without much luck.

AaronGTR
12-19-2010, 09:45 PM
The only thing disconnecting the battery does is reset the fuel trims, and after about 30 minutes of driving the PCM relearns the fuel trims again (based on O2 sensor readings), so yeah that wouldn't do much.

02GT_SkyHigh
12-24-2010, 03:19 PM
the issue i was having is that the car would be fine at higher rpms but it wouldnt pull that speed and torque over to the next gear, so as i go up an incline, it would downshift to 3200rpm and pull to about 4200rpm, then as soon as it shifts the power would just like bog, It would feel alot like i missed 4th and went to 5th from 3rd in a manual car. it was fairly consistent and steadily got worse, never better. i was told the TPS too but with that being one of the main controls for the CPU, if it was faulty, the problem may be way more serious. imo