Engine stumbles under load, only recovers if gas released or clutch engaged
07-31-2014, 11:32 AM
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Car: 1984 Trans Am
Engine: L69
Transmission: T5
Engine stumbles under load, only recovers if gas released or clutch engaged
Hi all,
I’m having a strange and intermittent problem with my TA and I’m hoping someone will have dealt with a similar problem before or have some suggestions. I took a look through other posts but didn't see something that quite matched what is going on.
The car is a 1984, L69, WS7 – all stock.
When I am driving the car, the engine will sometimes stumble and become non-responsive. The car will start slowing down as if I have taken my foot off the gas. The RPMs don’t jump or bounce. The problem almost always happens at faster speeds (60+), but has also happened at 30-40mph. It seems to happen more frequently when the car has been driven for a while and is hot then when the engine is cold.
If I hold my foot on the gas the engine may continue to stumble, as if it’s trying to get going, but the car keeps slowing down as if I took my foot off the gas. If I press down on the accelerator there is the same lack of response.
If I take my foot off the gas and reapply it then the engine will pick up again. The car may be fine for a while or the problem may recur quickly. The longer I have been driving the car, the more likely it seems the problem will happen again sooner.
One interesting note – when the problem happens, if I keep my foot on the gas but engage the clutch – the engine RPMs drop completely (past idle speed) and the car stalls out. If I release the clutch the engine comes back to life and I can keep going (until the problem happens again). Presumably, if I hold the gas and engage the clutch the engine should rev.
The car seems basically otherwise. It’s sometimes hard to start if it’s sat for a day, but it idles OK and isn’t throwing any codes.
I’m not really sure what the problem may be. The fuel pump is new, the spark plugs and all filters were changed within the last couple months. I’m thinking maybe it could be a fault with the ignition system under load or a bad MAP, MAF or TPS?
Has anyone seen something like this before?
Thanks,
John
I’m having a strange and intermittent problem with my TA and I’m hoping someone will have dealt with a similar problem before or have some suggestions. I took a look through other posts but didn't see something that quite matched what is going on.
The car is a 1984, L69, WS7 – all stock.
When I am driving the car, the engine will sometimes stumble and become non-responsive. The car will start slowing down as if I have taken my foot off the gas. The RPMs don’t jump or bounce. The problem almost always happens at faster speeds (60+), but has also happened at 30-40mph. It seems to happen more frequently when the car has been driven for a while and is hot then when the engine is cold.
If I hold my foot on the gas the engine may continue to stumble, as if it’s trying to get going, but the car keeps slowing down as if I took my foot off the gas. If I press down on the accelerator there is the same lack of response.
If I take my foot off the gas and reapply it then the engine will pick up again. The car may be fine for a while or the problem may recur quickly. The longer I have been driving the car, the more likely it seems the problem will happen again sooner.
One interesting note – when the problem happens, if I keep my foot on the gas but engage the clutch – the engine RPMs drop completely (past idle speed) and the car stalls out. If I release the clutch the engine comes back to life and I can keep going (until the problem happens again). Presumably, if I hold the gas and engage the clutch the engine should rev.
The car seems basically otherwise. It’s sometimes hard to start if it’s sat for a day, but it idles OK and isn’t throwing any codes.
I’m not really sure what the problem may be. The fuel pump is new, the spark plugs and all filters were changed within the last couple months. I’m thinking maybe it could be a fault with the ignition system under load or a bad MAP, MAF or TPS?
Has anyone seen something like this before?
Thanks,
John
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