Hesitation when excelerating


Asked by Jan 20, 2008 at 02:16 AM about the 1993 Lexus LS 400

Question type: Maintenance & Repair

'93 Lexus LS400 ~ Help! Mystery problem.  Hesitation, almost as if it's cutting out, on exceleration like getting on the freeway. Otherwise, starts and runs great.  Have noticed strong fuel smell from exhaust when I first start car.  Any ideas? Mechanic has checked all the obvious.

9 Answers


I would think that maybe you fuel regulator or injector o-rings are in need of replacement. a long shot might be your coils is on its way out. hope this helps and best of luck.

1 of 1 people found this helpful.

Agreed, something is causing a rich mixture which is exacerbated by the need for extra fuel on acceleration. Have it checked for fuel pressure, have plugs pulled and checked, check coil, etc. Ask mechanic to check throttle position sensor and see if the ECM is working properly.

4 of 4 people found this helpful.

Same problem here, I noticed that it goes away once the car has reached its normal operating temperature. Is the heavy gas smell is only noticable in colder weather? That is normal. Are you running 91 Octane fuel? Have you ever cleaned the carbon buildup off the interior of the throttle body? Is your air filter clean? Is this happening when you hit the "magic button" under the gas pedal? Does the car immediately downshift?

1 of 1 people found this helpful.

Had same problem a few years back - Faulty spark plug wire was the problem - at low speeds you don't notice a cylinder not firing - when you accelerate that is when you feel the loss of the cylinder - have them either checked or replaced

1 of 1 people found this helpful.

More than likely it's your fuel pump. Happened to mine. Previous owners didn't change it, I did at 133K and it was mush. After replacing ECU, the throttle position sensor, replace plugs and wires, coils, and water pump, it's good for another 200,000 miles.

3 of 3 people found this helpful.

So someone accidentally hooked my battery up wrong. Got the battery replaced correctly and also rebuilt the alternator. Now my car will not accelerate like it should. Could I somehow flooded my car. In which now I need to change my spark plugs... Any suggestions would help before I spend money on something that isnt resourceful to my needs at this moment... Note before the battery went dead and was put back in incorrectly. The car was running like it was brand new.. Also it is a Lexus ls400 1997... Any help please????

2 of 2 people found this helpful.

Nice answers. It is a thermostat of some sort. It can be all these above, except the Fuel Pump, not even close. Have them put it on the machine and I am pretty sure this is a thermostat issue, confusing the ECU

I change my spark plugs in my fuel pump in my car still doesn't start I doesn't I think it's the starter cuz it cranks what's wrong with my car

Try the Yaw sensor. I just had mine replaced for similar reason. I hope it is the problem.

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