Out of the blue driving today, I accelerate from a light and the car stutters for a sec, loss of power CEL kicks on and the idle surges up to ~1500 (not fluctuating).

The car is obviously in limp mode, no more vtec and it sounds and runs like ****. It smells REALLY rich, way more than normal starting richness.

I cannot figure out what is wrong, I reset the ECU with no results, all cylinders seem to be firing, all wiring looks ok, I don't know where to start... The only thing out of the ordinary was the oil was a tad on the low side (just a hair below the bottom mark on the dipstick) but nothing excessive, I added more anyway (last changed about 2000 miles ago)...

I tried to check the CEL and it just stays solid, I have the jumper shorted with a paper clip. I have never had any problems getting the CEL to show up before, I've checked it a dozen times before from issues when I first installed the motor... I can't figure out why the jumper is not making it show the code...

The Car:
1993 Civic EX
JDM D15B vtec-e ~10k since install
Original p28 ECU chipped w/ the stock d15z1 maps

 

Check the thermostat ground. Look at it really closely, i've seen the wires half break off where they're crimped into the ring terminal causing an intermitant ground.

 

I think it might be a bad ecu.

 

Hmm I just went out and looked around the thermo it all looks ok, ground looks solid :-/. I'm going to pull the ECU and look at it I guess.

 

That's what it sounds like to me too. If you can't pull the CEL, obviously something isn't right with the ECU.


Try using another ECU, or putting your ECU in a different car.

 

Blech, I just took apart the ECU, everything looks fine still, no swollen caps or fried transistors apparent. I dont exactly have an extra ecu I can just try, but I'll see what I can do.

What I did notice on the way home though, when I first started the car, I gave it a slight rev to pull out of my parking space and the cluster and everything flickered and you could hear a click under the dash, it only did it once... I don't know whats going on.

 

simple vacume leak?

 

That wouldn't cause it to go in to limp mode I wouldn't think, would it (I don't know, not being a smartass)?

Because I was going to and forgot to test that it was the IACV opening up setting the idle at 1500 not air going in to a faulty FITV causing problems... the FITV came w/ the engine from JDM land who knows if its still good


edit:
btw does anyone have a list of ALL the things that will cause limpmode (not all cels make it go in to limp mode afaik)

 

I still say check that thermost ground a little harder. Start the engine, grab the engine harness near the thermostat and start moving it around, if the car shuts off you've found your problem.

 

Hmm I took a good look at it this morning... I'm leaning toward the ECU... I'm picking up a virgin p28 today after work if things work out.

I've read on pgmfi a solid cel is likely being caused by:

a bad fuse underhood, all looked fine.

bad map sensor (5v shorted), I haven't actually checked this out w/ a multimeter yet but unplugging the map just causes the idle to get worse, but still no cel retrieved

Or the thermo ground which looks fine to me... Moving it around causes nothing, I loosened it and then tightened it back up, looks fine.

 

ECU it is... Threw a stock P28 in there, phew... So relieved... Its throwing code 19 since its an automatic and it has the d16z6 maps instead of the d15b vtec-e... But I can fix that... Soooooo relieved. $50 fix.

edit: $76 fix, $26 for a ECU chip kit shipped from moates