canman44

All,

I have a 92' SC400 that is more or less stock. It's got about 165K on it right now. I've been having this intermittent misfiring happening every so often. For instance I'll just be sitting at a light, engine is purring like a kitten and then all the sudden it's running like crap and feeling like it's misfiring. The RPM's drop down a few hundred and the jump around slightly. It doesn't feel like rhythmic like the same cylinder is misfiring. It very arrhythmic and when I step on the gas it'll hesitate and then give a good kick. I can feel it misfiring when the RPM's are hiring sometimes, but it seems to be more infrequent and less noticeable than at a stop.

Recent work on the car: Had to change the starter and battery about 6-7 months ago. The ingnition coils, wires and plugs were changed about a year ago, or maybe closer to a year and half. New inner tie rod and tires installed.

Note: This seemed to start right before the ignition coil went bad. Believe me it ran REALLY bad when the coil went bad. Had the coil, wires and plugs replaced and the problem seemed to go away for a while. It came back again and then my gf killed my battery when she left the lights on at work and had some jamoke try to jump it. He hooked the wires up backwards and fried the battery and apparently the starter too (it wasn't sounding too good and was probably about to die anyways). Had the starter replaced, seemed to take care of the misfire for a while and now it's back and driving me crazy.

Dream36

ECU! I guarantee that the capacitors are bubbling or leaking. It's a common problem with our cars and can be fixed with better components. There is a website that will replace the capacitors for $80, however they won't fix any problems you are seeing. There is a guy in Florida with an ebay store who will do a full repair with new capacitors, clean contacts, and repair the board for $150. He will also send you a unit ahead to keep your car on the road, I forgot the core charge but he will refund your account when you send your old one to him.

I have been fighting these problems for a year now. I replaced coils, wires, plugs, and TPSs only to need coils again in a couple months. Turns out it was the ECU all along. Right now I'm saving to send mine away. Hope that helps.

canman44

So you are saying that it is better to have the ECU repaired than to get a new one? What about robbing one from a wrecked SC or something? Does that sound like a viable solution? I haven't looked into replacing my ECU yet and don't know how much that might run me.

canman44

Lastly, Is there a way for me to check and confirm that, that is the problem?

canman44

Update: So I was driving my SC last night and the Check Engine Light went out, but the misfiring continued. Is this still suspect for the ECU?

What is my best option for buying an ECU or replacing capacitors? I found another thread that mentioned an ECU "rebuild" by Driftmotion where they will replace the capacitors. Anyone have any first hand experience with this?

V8drummer

iTrader: (5)

For buying an ECU you have your local junk yards or classifieds, or sending it out to be rebuilt.

The dealer will probably quote you something stupid like $1,000 for a new ECU haha.

SC400slide

iTrader: (11)

Definitely sounds like it could be the ECU. And yeah, stay away from the dealer.

canman44

Note taken. Thanks for the info. I figured the dealer price for an ECU would be outrageous. The search for a new ECU begins. Anyone know of a good write-up for removing your ECU? I've never had to remove it before. I believe that I read it is on the passenger side?

SC400slide

iTrader: (11)

The ECU is on the passenger side floorboards. Pull the carpeting up all the way in the front and pull it back some, remove the scres holding the cover on, remove the screw holding the connectors to the ECU, remove the screws holding the ECU in place, pull it out and walla. Very easy to remove.