Engine Bucking

[BigLex14]

I am fairly new to this forum, i have only posted once before. My 93 es300 has recently started bucking and surging on initial acceleration. This happens especially in the morning after a cold start. It even bucks at idle at red lights when i first start to drive in the morning, it only does this in drive, when i put it in park it never bucks at all. it also does not do this after i have accelerated a while, only when i start up from a stop or when i come to a stop. it is a really violent bucking and i fear damage is being done to the engine, i have had the computer scanned and it gives no error messages. If anybody has had a similar problem or can tell me possible causes of these symptoms it would be greatly appreciated

[brucelee]

I am fairly new to this forum, i have only posted once before. My 93 es300 has recently started bucking and surging on initial acceleration. This happens especially in the morning after a cold start. It even bucks at idle at red lights when i first start to drive in the morning, it only does this in drive, when i put it in park it never bucks at all. it also does not do this after i have accelerated a while, only when i start up from a stop or when i come to a stop. it is a really violent bucking and i fear damage is being done to the engine, i have had the computer scanned and it gives no error messages. If anybody has had a similar problem or can tell me possible causes of these symptoms it would be greatly appreciated

Check out the EGR valve. My car did this form months and eventually threw a code.

Replaced the valve and the engine runs like. new.

[BigLex14]

I am fairly new to this forum, i have only posted once before. My 93 es300 has recently started bucking and surging on initial acceleration. This happens especially in the morning after a cold start. It even bucks at idle at red lights when i first start to drive in the morning, it only does this in drive, when i put it in park it never bucks at all. it also does not do this after i have accelerated a while, only when i start up from a stop or when i come to a stop. it is a really violent bucking and i fear damage is being done to the engine, i have had the computer scanned and it gives no error messages. If anybody has had a similar problem or can tell me possible causes of these symptoms it would be greatly appreciated

Check out the EGR valve. My car did this form months and eventually threw a code.

Replaced the valve and the engine runs like. new.

Thanks i'll try that

[BigLex14]

Is the EGR valve the same as the air control valve (thats what the mechanic told me it might be) and how much does the EGR valve cost to replace?

[blk_on_blk]

An EGR valve is an Exhaust-Gas Recirculation valve... it's an emmisions control system that brings in exhaust and attempts to reburn it to reduce emissioins (it also is used to pre-heat combustion chamber). It's usually just a little discrete valve that's easy to access/replace.

The IACV is the Idle Air Control Valve. This is integrated in the butterfly assembly in the air intake (just past the MAF location by the air filter box). A few months ago our '95 ES300 did the exact same thing... bucking and chugging. We had just started the car and were leaving our neighborhood, so I was luckily able to get the car back to the house. I pulled off the IACV and gave it a good cleaning (about an hour's worth of time)... it's run flawlessly since.

Since Brucelee has good results with the EGR replacement, and I had good results with the IACV cleaning, you might want to look at those two first as a solution to your problem.

[nsjoel808]

I have the exact same problem and was told it was the Throttle Position Sensor, has anyone had results in changing this?

[abutony]

I have the exact same problem and was told it was the Throttle Position Sensor, has anyone had results in changing this?

I was told the same thing today by a Car Mechanic... At first, I thought it was my battery but it's not. Every morning my car revs like crazy especially during cold start ups. Now that winter is here, it's even worse. The RPM is at 3.5 when I am driving at 35 km/hr but after a long while RPM goes down to 2. I am assuming I need a new Throttle Position Sensor. I hoping I am not the engine is not being damaged. Any comments please?