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My car is a 2003 Chevy impala 3.4 L v6. It has 60k miles on it. Car runs good except for a somewhat Intermittent issue on the interstate. After driving for a bit on the highway when I press the gas pedal in and put a small load on the engine the car will randomly feel like it loses power and then gains it back, like a surge almost. I’ve noticed that this problem goes away when I very slightly press the brake while keeping my foot on the gas. Could it be misfiring and not throwing a code? Or is this a transmission problem? I recently changed transmission fluid and filter but the car did this before I just didn’t pay much attention till now. Thank you.
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It doesn’t feel like a downshift, I’m not sure how to describe it other than it feels like it loses power and then goes back to normal. Like a surge. I don’t think its a gear slip because I know what that feels like because of my old truck that slipped. The transmission fluid is at the right level and is bright red with no metal pieces, it also shifts perfectly fine. I’m gonna clean the MAF and see what that does.
Pressing the brake pedal disables the torque converter clutch from locking. You need a scan tool that can display tcc slip speed, which is a GM specific PID. I have experienced the exact surging you describe on a 1997 Lumina and it too was a TCC issue.
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Could be fuel pressure regulator. I have an 03 malibu that experienced the same thing (although this wouldn’t explain the braking correction you described). When the fuel pressure regulator starts going bad, you don’t get the right amount of fuel to the rails and randomly will experience that loss of power if the fuel is being backed up through the vacuum line due to a bad valve inside of it. Generally at some point though you will smell fuel or even see it. It’s a long shot, but pretty common in those GM 3.1, 3.4’s, and 3.8’s.
Let us know what you find out!
[quote=”danielthechskid” post=186545]Pressing the brake pedal disables the torque converter clutch from locking. You need a scan tool that can display tcc slip speed, which is a GM specific PID. I have experienced the exact surging you describe on a 1997 Lumina and it too was a TCC issue.[/quote]
+1 with possible TCC problem. Usually TCC problems manifest as a stall when stopping due to the TCC remaining engaged when it should be disengaged. This sounds like it could be the opposite condition where the TCC is remaining disengaged when it should be engaged. The TCC is designed to engage to provide hydraulic drive during acceleration and then disengage to allow cruise. It sounds to me like it is behaving ‘slowly’. This can be caused by a sludgy solenoid which delays its reaction, or it may not be the solenoid at all, but a fluid pressure problem caused by a blockage or restriction in the valve body.Just now seeing yalls replies, well I noticed that it doesn’t correct every time with the brakes. I will check the fuel pressure reg soon, I did recently change the transmission fluid and filter but I’m not sure how that would cause this. The fluid level is correct and the fluid is bright red along with no burning smells. I will say though that I somewhat remember it doing this before the fluid change. Any ideas on how to see if it really is the torque converter? Should I just take it to a shop and ask them to check it out? I should also mention that it is not just 4th gear(overdrive) that this occurs in, it will happen intermittently in situations where I am coasting and apply light load to the engine. Which makes me lean away from the converter clutch since it only locks in 4th but any insight is appreciated.
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