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Topic
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2002 Toyota Camry LE V6 3.0
135,000 miles
Automatic transmissionWhere to start with this —- First of all, 8 mechanics have looked at it. No one can tell me what is causing it, not even the dealership.
When I swiftly press or depress the accelerator I get a pretty sever “bump” or “jerk” feeling. When I press the accelerator, it’s one jerk. When I release, it’s one jerk followed by two smaller ones. It’s also a little delayed when accelerating. There is also a vibration I can feel in the acceleration pedal. It almost feels like something is grinding. There is nothing audible at all.
If I very slowly accelerate or decelerate it does not happen.
When on the highway and turning off cruise control, I get a pretty big jolt.
It does this when in a fixed gear, like 2 or 1. It does not do it when shifting. It does not do it in neutral or park.
It’s not as bad when going fast on the highway but it does still happen. It’s much more severe at low speeds.
The check engine light is NOT on. No mechanic can find any trouble codes.
I’ve replaced the spark plugs, cleaned the throttle body, replaced all 4 motor mounts, ran some seafoam through it.
Most mechanics first think it’s the motor mounts. When it’s not that they have no idea what it could be.
The idle is low, not sure what that could be really.
Any ideas?
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I would clean and test the MAF sensor next. The MAF can be dirty or out of spec without throwing a code.
Engine hesitation, almost by definition, usually goes back to a misfire in one or more of the cylinders. When one or more cylinders stops firing, the power cuts, and the vehicle hesitates under acceleration. The misfire is causing the hesitation; you just need to find out what’s causing the misfire. Often, it will come back to a “lean” condition,” meaning that there’s either not enough fuel or too much air going in. Clogged fuel filters, failing fuel pumps or regulators, and dirty or malfunctioning fuel injectors are the most common causes of a failure of fuel delivery. The accompanying “lean misfire” will trigger a check-engine light. On the other side, you could have a massive air leak from a bad vacuum line or intake manifold gasket. Failed intake sensors — throttle position, mass airflow, intake air temperature and manifold absolute pressure sensors included — will often cause the computer to think there’s less air going in than there really is. So, as far as its concerned, there’s a massive vacuum leak present.
It also might be the transmission, in that case…Hesitation doesn’t always come from the engine. Electronically controlled automatic transmissions are subject to the same kinds of sensor and actuator problems engines are, and have a lot of complex hardware to control. Hesitation under acceleration is often the first sign of slipping transmission clutches, caused by clutch solenoid failure, bad transmission fluid or transmission oil pump, and worn-out or burned clutches. If your vehicle only seems to hesitate in top gear, or over about 45 mph, you may have a problem with the lock-up clutches in the torque converter. Of course, low transmission fluid can also cause hesitation, both because of fluid pressure fluctuations in the transmission, and because of an empty torque converter churning up air instead of transferring power. Modern vehicles will typically self-diagnose the transmission just like the engine, but these manufacturer codes may not be readable with a generic scanner.
Thanks for the info. I did just try cleaning the MAF but no change. I guess I am just under the assumption that since it happens in a fixed gear it wouldn’t be the transmission?
I recorded my engine movement when holding down the brake in drive and giving it gas. Does this seem normal?
Try checking the rubber hose at the intake after the air box. If there is a crack it sometimes when the engine moves the hose flexes, the crack opens and causes an air leak making the engine stumble. It can be difficult to see.
I realize you state the motor mounts have been replaced, but there is a lot of motion there, enough to be stretching the upper radiator hose. Re-check the mounts, make sure the rubber hasn’t separated, and that they are torqued properly. Were the mounts replaced with OEM? Maybe have a helper rev the engine while you observe each of the mounts.
So, a big update on this. I put a can of seafoam in my gas tank. After driving for about 1/4 of a tank the problem is almost completely gone. On a scale of 1 to 10 it went from about an 8 to a 2.
I mean it may be too early to celebrate but I wonder what it will be like when this tank is empty.
I’m actually just fine with the way it’s running now!!!
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