I'll try to cut the story short, so sorry if it's long in advance.

1993 Accord LX F22 automatic (if you need me to list engine mods let me know)

First bought the car about 2 years ago, it kept dying in midst drive. Replaced the distributor, all was well. Later did a full tune up, plugs, wires, fuel pump, valves, everything, which is still recent enough to say I don't need to do it again for a while longer.

Later, I had some electronics misbehaving/failing one by one in a row. 3 speakers don't work, blower motor went out, speedsensor/speedometer acting up.

Now, today was -25F with a -40F wind chill. Brand new, fully charged, well connected battery. I let it warm up today after turning it over for 15 minutes, dropped to 1.2k rpms or so and temp gauge was about halfway which is normal for it. Shifted normally and did fine until I asked it to hit the 50mph speed limit. Got to 2nd, maybe 3rd gear and spazzed out. RPMs was bouncing from 2 to 4.5 - 5 back and forth extremely quickly and roughly, the car felt like it was bouncing in all directions. Brought it to first gear, cruised for about a minute, put it back in D4 asked it to go again and without hesitation went and did fine the rest of the way back.

Went home and realized I had the wrong oil weight in the car for the season (10w instead of 5w). Had some suggestions about possibly low transmission fluid, or the fluid not being up to temp with the rest of the engine causing it to do race through the RPMs like that. Others then suggested it's either an alternator issue, or the ECU.

I'm leaning towards the the ECU since a lot of electronics have been going down the toilet lately.

Question is, what exactly could have caused the RPMs to go so wacky? And how exactly can you tell when your ECU is about to crap out?

PS, I'm going to be switching oil weights, checking the tranny oil, and testing my alternator. Also, none of my electronics went wacky when my car was racing through the RPMs.

 

My two cents: You can't tell exactly when an ECU is going bad. You've replaced a lot of parts that could cause the symptoms you're having. According to previous posts, the car was hit hard on the passenger door which is very close to the ECU. 4th Gen ECUs are cheap and easy to replace. Replace it and see if the drivability problems go away. You may want to open the TCU case and look for burned resistors and leaking capacitors while you're replacing the ECU.

 

In the meantime, if I can control the symptoms is it going to hurt it if I drive it? Daily driver...

Also, the electronics began failing even before the door got wailed on, but I'm sure that didn't help anything either

 

Probably best not to lump everything in with a bad ECU. Speakers have nothing to do with the ECU; are the speakers/headunit an aftermarket installation? If so then I'd take a hard look at that. Similarly, the blower motor going out probably has nothing to do with the ECU, although it sits right above it and the motor or the blower relay could have been damaged by the hit. Lots of threads about diagnosing/repairing blower problems. Do a search of this site.

Check out techauto(dot)awardspace(dot)com/vss(dot)html. I'm not familiar with 4th Gen ECU/TCU combo troubleshooting, but a faulty VSS can cause some of problems similar to what you're experiencing, and it's easy to access and diagnose.

 

Just seemed odd everything went out around the same time, never really considered the ECU a possibility until the RPMs acted up the other day. The stereo header/speakers entire audio setup is stock and has never been messed with. When they died I checked for both a fuse and faulty wires and everything was normal. I'm guessing now, those speakers just quit since they are marking 21 years old now. No idea how the speedometer went out, with a bit of research I did it seems the speedsensors in the 4th gens are commonly needing replacement, as well as the blower motor. The blower motor died before the hit in the door along with the other things described. I have the blower motor, resistor and relay for it that is going in it this weekend. As I said before, was just weird they all went right around the same time though.

Wish there was a way to test it without taking it to a shop

Other than I'm totally stumped. IF the ECU is the issue, it really could throw RPMs around like that? Another suggestion I got was alternator, that could do that as well?

 

Did you read that tech auto/VSS site?

 

Check for resistance from the negative battery post to the engine. Should be 1 ohm or less. If more than that you got bad connections.

 

My bad, scrolled right over the first time The VSS doesn't sound a lot like my problem, the ECU kind of maybe so I'll follow the guide on that one and the TCU sounds pretty much dead on. Thanks for showing me that! Bookmarking now!

 

One of the first things I checked, all was clear there

 

it could be the ignitor i would swap it