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No power under load, check engine light comes on after a few revs.

3.8K views 10 replies 3 participants last post by  kamesama980  
#1 ·
Hey guys, I have a 1985 mx73 and am having a few troubles. Under load I have a severe loss of power. The check engine light comes on after a few blips of the throttle when free revving. I can't seem to make the engine light flash for diagnostic mode, could be using wrong pins, I should be jumping pins T & E1 correct? She has brand new plug wires, new dizzy cap & rotor & the plugs are only a few months old. Any advice is highly appreciated. Thanks guys, Tyler.
 
#3 ·
Man, that sucks. :(

You can also short Te1 to ground. Make sure E1 is grounded. The troubleshooting sticky at the top of the section has a few things that are required for the car to go into diagnostics mode (like AC off, O/D button in, etc) there are a lot of possibilities and we're just shooting randomly in the dark without the codes.
 
#6 ·
According to my book, press SELECT and INPUT-M keys together for 3 sec, once word DIAG disappear then press SET key for another 3 sec, then read code. No need to short pins for super monitor. I think your problem is with knock sensor. Is your engine knock? That's a typical symptom when engine detect knock.
 
#7 ·
So does E1 go to ground? you checked it with an ohmmeter? Next step is to start ohming out the wiring harness, make sure the right wires are contiguous and not shorted anywhere. Make sure E1 at the ECM plug goes to ground. Next most likely scenario is you have a bad ECM. How much is your time worth? is it cheaper for you to spend hours checking wires or start throwing parts in? Yes you're going to need a wiring diagram and I don't have it.



Except it won't light the CEL unless there's an open/short in the knock sensor wiring and won't be horribly underpowered if it hears knocking. Maybe a little less powered. Either way it's abnormal to have significant amounts of knock if everything else is working. Which it isn't since the OP says the SM doesn't work.
 
#8 ·
There isn't a knock in the engine, the only foreign sound in the engine bay is an exhaust leak at the mani. As for the wire for e1 being grounded, I checked the harness & the wire runs off into the abyss under the intake mani. Haven't tried to ohm any of the harness yet, which wires should I start with & how much resistance should be there? Thanks for the info on how to put the super monitor in diagnostic mode, but she is fried. Stays at 6:00 no matter what o try doing. I appreciate all the info & help guys, anything more you can offer I am super appreciative of. Thanks, Tyler.
 
#11 ·
put the meter on "ohms" and put one lead on E1, the other to the battery - post. should be zero ohms. Don't jumper anything when you do that.

most of the other pins go to the ECU or sensors (or more accurately, they're Teed into the wires going from the sensor to the ECU)