trans took a dump?

[rt91tt]

Went over a bump (rr tracks actually) and then it immediately started running not so good. I managed to limp home. It would idle fine at high RPM, but when driving any attempt to push it over 2k rpm would result in surging/oscillation behavior. So I would shift up and keep the rpm in a range that it balked along. Speedometer was intermittently inoperative during the drive home. I thought I smelled some clutch or other material at some point, but it may have been a nearby vehicle.

Have not put it up on stands yet to make sure thing are mechanically okay (wheels spin, etc). Will do so tomorrow during daylight. The symptoms (speedo working/not working on and off) make me suspect output shaft or VCU or maybe passenger side CV.

[MR2]

Electrical issue?

[rt91tt]

Electrical issue?

hmm. can't rule out electrical, but my gut tells me it's something mechanical. I'd be glad to be wrong though.

I just got the front end up on stands and there is no obvious trauma (cracked xfer case, broken shafts or CV boots, etc.). Front wheels spin in opposite directions when spun by hand, as they should.

I checked, battery voltage is ~12.5 vdc when engine is off, 14 or so when it's on. No prob there. I have had an alternator go bad before and recall a 'surging' type behavior, but this is a bit different.

Also one more thing I observed was the speedo at zero while moving at 15 mph or so, then while in neutral, adding a bit of throttle brought the speedo back momentarily. That's in-line with your electrical theory, I would think.

I removed the negative batt cable for a bit to let the ECU reset, then drove it up and down the street. Same behavior. ECU is giving the all clear code.

I swapped in my spare ECU, same behavior.

Also another thing (first thing actually) I checked was whether the air intake tube had popped off. It's on securely.

Don't know if it matters, but I filled up the gas tank today about 5 miles later this began. I tend to doubt bad gas though.

[MR2]

oddly I had something similar and it was the MAS..I somehow got water or something into it's sensor...your speedo not working is odd too! did any lights come on in the dash? don't suppose you have a logger?

[rt91tt]

oddly I had something similar and it was the MAS..I somehow got water or something into it's sensor...your speedo not working is odd too! did any lights come on in the dash? don't suppose you have a logger?

No CIL illumination, ECU code reads normal with an analog multimeter. I don't have a datalogger unfortunately. maybe it's time it invest in a cheap one, any recommendations?

[rt91tt]

It was the ECS. Unplugging ECS wiring harness restored normal engine operation.

I recapped the ECS for good measure (could have just left it unplugged, but hey).