1UZFEric

Alright guys- I've done a fair amount of research and have found several threads that sound like a similar problem as what I'm experiencing, but I'm yet to find anyone who posted their solution...

93 SC4, 128k miles. I've had the car for a little over a year and it's always shown a code 13. I'm assuming this has been the case long before I bought the car because I discovered the CEL bulb had been intentionally broken but anyway. It's always run like a top- absolutely no hiccups, ever. I'd checked the routing of the plug and coil wires and cam position sensor wires and they all appeared to be correct without any sign of tampering, so I've always been a little stumped as to the source of the CEL. Regardless, about 2 weeks ago I went to crank it up after a week or so of leaving it parked and it was misfiring, extremely down on power and was running super rich, so I shut it down and started investigating. There were no new CEL's at the time it started running poorly, but the code 13 was still present. The timing belt doesn't appear to have skipped a tooth which was my first thought. The coils and igniters all appear to be working properly, as disconnecting any of them causes the engine to die immediately. I did find that the passenger side camshaft position sensor had failed (resistance test showed an open circuit), so I ordered a factory replacement, along with a new rotor for the passenger side since the original was cracked.

Unfortunately after waiting over a week for the parts, I installed them today only to discover the only thing that's changed is that the code 13 is no longer present; the car doesn't appear to care if the sensor is plugged in or not, it misfires regardless. I tested the new sensor and it is within spec, as is the driver side camshaft position sensor. I also pulled the cover off the ECM to inspect for leaking capacitors and didn't see any evidence of this. One thing I have noticed pertaining to the camshaft position sensor wiring for the side I replaced is that some coolant has leaked from the thermostat housing onto the CPS wiring, but after wiping it clean, it doesn't appear to have visually penetrated the wiring loom.

I'm stumped. I've read alot of people have had trouble with the fuel controller, but that seems to typically cause a no-start condition. Same goes with the crankshaft position sensor. The car starts and idles every time without fail; it's just not firing/injecting on at least 2 cylinders (the front and rear cylinders on the driver side). My next step is going to be to pull plug wires again one by one and determine if it's spark or fuel that's missing, but beyond that I'm not sure where to look next.

Ali SC3

iTrader: (10)

drivers side rotor? i would check it.

1UZFEric

Ali - PM me your address cause I needa mail you a 6 pack! Turns out there were a few issues w/ the driver side distributor/coil. Not sure what the turn of events was, but the distributor contacts had a significant amount of carbon buildup, the coil wire was welded to the distributor, the rotor button was cracked and probably near the end of its' usable life, and last but not least the coil itself was faulty. I hadn't suspected this before because both coils ohmed out the same so I assumed all was good, but upon close inspection, the coil had a crack in the top of it.

One distributor, rotor button, coil wire and a donor coil from a 96 LS4 later, she's running strong.

Thanks guys.

Ali SC3

iTrader: (10)

haha np, glad that helped you go in the right direction usually when one falls apart you are on borrowed time with the other. might be the least words I have ever written that lead to a fix.. lol. good luck enjoy it!

1UZFEric

Yeah, in the end the roundabout way in which I ended up finding the problem resulted in new rotor buttons on both sides which I likely never would have known needed to be replaced until it was too late..and I fixed my CEL along the way

Ali SC3

iTrader: (10)

Yup, new caps and rotors on a distributor motor go a long way it is probably the weakest point of the Toyota ignition system of that generation. Everyone who has owned one for long enough thinking they don't have to replace them usually end up in a parking lot or on the side of the road with half their cylinders misfiring. Been there done that I much prefer not getting run over trying to push the car to the side of the road when that happens I just replace them when I get one of these type of cars. The V8 at least usually they go one at a time and you can still drive it to somewhere safe sort of, but the I6 only has one distributor and when it goes even if you are lucky enough to have 1 or 2 cylinders working you still get nowhere quick.

My only advice to anyone stuck out there if it happens to you is to give the distributor cap a small whack with something plastic (don't break it) and sometimes that will give you enough time to move the car a very short distance. Kind of like the starter trick.