Dereke

so ive been having this headache of a problem. car is idling rough and stumbling when i speed up. changed plugs wires cap rotor fuel filter ran sea foam through the intake and gas. messed with tps and maf. here is the strange part.

everything i touch fixes the car for the first drive. then if i shut it off and start it back up it starts to run like garbage again. the tps adjustment seemed to help the most but with the tps maxed to the right it idles high but ran great for a day. now its running like junk again so i put it back.

possible ecu problem? my car is a 93, what year cars can i get an ecu from that will work for me?

thanks

PureDrifter

iTrader: (10)

93-94 only iirc.

j stuff

iTrader: (5)

im having similar problem

i can hit 80+ mph if i go VERY steady and accelerate slow but right when i put more than a granny driver worth of throttle on it it starts to surge/hiccup/hesitate whatever you want to call it.

Im thinkin of doing all you did first then lookin for an ecu

1993Ls400s

I am having some of the same problems. When idling the car seems to be almost like its hopping. u can feel it like its making u bounce up and down slightly,and the tach needle is jumping slightly.. when driving the car,it has hesitation, and when u get up to 45 to say 55 the car will suddenly start bucking severely,i mean really bad! It doesn't do it hardly at all with overdrive off because it seems to depend on where the rpms are at. when its in idle i can rev it up to around 1500 rpm lil less lil higher u can feel the motor like surging. i am about fed up, i cant take much more,i have spent a fortune in the last week on parts. I have had it to 3 mechanics and no one can fig it out. no cel on or nothing,they hooked it to a code reader and said there where no codes in it... I have replaced the fuel pump, spark plug wires, spark plugs, distributor caps, distributor rotors, and the camshaft position sensors, not only that, i went to the junk yard and tried 3 diff mafs! The funny thing is though, the car runs great with the maf unplugged!!! i checked the connector it's fine. I don't like running with maf unplugged because it smells like its making it run rich. i just don't understand what it could be. i am starting to think its the ECU/ECM. Someone else said maybe oxygen sensors, but wouldn't that throw a code? anyways who knows, i feel ya, this is very frustrating hopefully someone here can lead us in the right direction of what to do.

Oh yea, and when you floor it, the car is fine, lots of power smooth as silk..

Dereke

yeah exactly what my car is doing except i tried unplugging the maf and it made my car really sluggish. im really leaning twards the ecu at this point and it seems like a pretty common problem.

Photoinc

Hey,

Had this problem with my 93 LS, it turned out to be the connector to the camposition sensors. They are so old and rotten from the heat of the engine, they stop getting a good connection. The shop working on the car ended up removing the connectors and crimped the wires together on both sensors, have not had that problem since.
I can confirm this with him tomorrow, and get back to you.
This problem first showed up when I changed the starter on that car, and at that time I changed all the wires and plugs, when we got it back together, there was this bucking problem. It kind of went away on its own, for several years then recently, I had the timing belt done, and this problem showed up again.

I'll find out tomorrow.

David
98 LS 400
93 LS 400

Dereke

yeah for sure let us know.

Photoinc

So I talked to my mechanic today.
He said he cleaned the connectors with brake fluid, then zip tied one of them together, the other was falling apart so he, took the wires out of the connector, plugged them together, then sealed them individually. Then another issue came up.....the car started fine, but ran like a pig, had no power, we changed the coils for both banks of the engine, now the car runs like a champ.

It's worth a shot to DIY

David
98 LS 400
93 LS 400

Rocan

you have my name...

Photoinc

Your name is David Too??

Rocan

guess so

Just thinking, if your car has a busted ecu, it WONT be able to throw a code

Dereke

changed coils? my car only has one coil.. you mean the caps and rotors?

1993Ls400s

I went and bought a new Maf, didn't help nothing at all. i read on here somewhere that the maf is somehow works with the o2 sensors. Because when i unplug the maf the car runs great. But if the 02's were bad wouldn't it throw a check engine light and a code???

Photoinc

No I mean coils. My mechanic said there is a coil for each bank of the engine. Makes sense to me if there are two distributors.
I changed the starter on this car, and replaced the wires, cap and rotors, but I'll be damned if I remember beyond a doubt that it has two coils.
Anybody??

The main issue of the missing in the engine, was corrected by the fixing of the wires to the distributors, or cam position sensors

1993Ls400s

There are 2 coils.