paulwall86

The car bucks when i punch the gas, when i let off it stop any ideas?

j2b4o

More info would be helpful.
Year??
"punch the gas" is WOT I assume?
Do the rpm's bomb when this happens? Does it feel like a transmission issue? Any codes? Does it at any speed? From a stop? Recent work? Sounds??

paulwall86

It is a 91 Ls400, yes the rpm does bomb but it kinda goes up and down. No the transmission was rebuilt feels more like an engine issue. No codes. It does it from a stop. No sounds that I am aware of.

trukn1

Bucking, sluggish, faint smell of gas is a strong indicator of a bad coil pack. Probably had gone bad and needs to be replaced. Remember this is an item often overlooked b/c they don't go bad often and the car IS 21 years old now.

paulwall86

Thanks for your help. I ordered one this morning, I will install it when it comes in and let you know how it went.
I plan on doing a full tuneup in June any suggestions on replacing anything else while I have the enginge uncovered, It is 21 years old.

trukn1

You have 2 coil packs on the car, not just one. Passenger side can be seen at the very top of the motor front center. Driver side is tucked on the side of the block between the block and the battery. Would be a good idea to replace both of them, as 1 goes, the other is not far behind it.

Plugs, wires, distributor cap and rotor, coolant temp sensor (will pretty much have the area uncovered, will make it easier to get to), refresh/change all the fluids, DO NOT flush the trans (just drain and fill), new serpentine belt, check the condition and operation of pulleys and you should be good to go for awhile.

paulwall86

Well I replaced the coil pack in the front of the engine and it seemed to help. It does not buck. I will keep an eye on it. Thanks