paulwall86

Hey guys,

I have a 1991 LS400, I had an incident today with my car. When I went to drive the car would act as if it was running out of gas. It would start and Idle fine, but when I started to drive it would act up and the rpms would jump from 0 to 1000 any idea?

I recently replaced a coil pack. The one near the clutch fan in the front of the engine about 3 weeks ago.

I put the old coil pack back in after this started happening this afternoon. I havent driven it for more than a mile since I replaced it with the old one.

My battery terminal is kind of loose too

Would this cause this issue or could I be in bigger trouble?

LexterLS40

How loose is it ?
It should be tight and firm any movement is a battery failure and can't be fixed by us, so you must replace the battery. Because everytime it drops below 11 V some ECU get wrong ideas and pass wrong instructions to important elements.

The LS prefers an constant 12,8 volt and even that is hard with all the accesoires full on.
Also you msut check the voltage when iddling and when engine is off see what the generator says.

Lexter

Luxurexus

Does it still act up after you switched back to the old packs? I replaced mine today, If there not plugged in correctly the car wont start so its probably not the issue. What does your car normally idle at? And what do you mean by act up besides the rpm fluctuation? Did you replace the spark plugs and wires when changing the coils?

paulwall86

I did not change the spark plugs. When I put the old coil pack in, it is no longer acting as If it is running out of gas. The rpms jump up and down when I hit the gas and I can't accelerate. The car idles at around 500

steve2006

Just wondered why you replaced the top coil 3 weeks ago were you having the same problem as you are now?
The drivers side coil above the AC compressor generally has a higher failure rate due to it's location have you checked this one?

trukn1

Is normally a good idea to change both of them. Drivers side is most likely the problem.

Luxurexus

I just replaced my coil packs last weekend and it sounds exactly like the problem I was having. Replace your driver side coil pack, you will have to remove the battery tray to get to it but its not hard. Be careful removing it, as im sure you know they have a sensor clipped to them and if you brake the clip its a pain to plug those prongs in and they may jiggle loose while driving. Your problem should clear up. I recommend replacing your plugs and wires as well.