4AGE: rpms jumping

[halo07]

my 85 mr2 i just bought has been running really bad. when ever im driving, the tac will flutter a lot. the rpms will jump around and cause the car to jerk a lot. we have replaced the distributor, cap and rotor and put new spark plugs in it and nothing has helped. we even tried to replace the ECM and that didn't help ether.

[Luni]

Coil, ignitor.

[halo07]

how do you know if its bad, i checked it like it says to in my book, but it looks good. it runs good some days and runs really bad others....like when its really hot out. when it jerks really bad its like the engine is missing. please help!

[Gairloch]

Could a bad O2 sensor cause behavior like this?

[Luni]

It might, but its my understanding if it was, and you unplugged the sensor the car would still run and it wouldnt be erratic anymore.

Same goes for TPS as well. I guess check those.

[pinamr2]

check for loose grounds or not enough grounds.

[halo07]

do you haft to do anything else after you unplug the o2 sensor, or can you run it with no sensor at all?

[halo07]

oh and what would be a good turbo engine swap?

[Sam1]

I have been running with my o2 sensor unplugged for about a month :|

[halo07]

i unpluged it and it still is doing the same thing. what else could be causing that? when im stoped at a light and the car is ideling, the tac will flutter and the rpms will drop down to like 600 and it sounds like its going to stall. sometimes when im trying to drive, the check engine light will come on and all the other lights will blink, then the car will start jerking a lot, when i try and switch gear it helps sometimes but normaly it dosn't. im at a loss on this one, no one can figure it out.

[Gairloch]

If you're getting a CEL pull the code and see what it's bitching about. That's where I'd start.

[halo07]

thats what i did, its saying code 6. the distributor is fine but it said something about a distributor circuit.

[hosh]

Sounds like a bad ground or a vacuum leak.

[msmr2]

My '87 does this alot too. And it does stall time to time. I took it to the go-to guy for Toyotas here in town, and he was stumped. I thought it definately was a vacuum leak, but it turns out it's not. I don't know what else it could be..

[Gairloch]

halo7, have you taken any further steps to diagnose this?

[halo07]

were about to replace the fuel filter, and i have checked all the ignition and it seems to be fine. its almost like its missfiring when it jerks like that.

[sliverstorm]

check timing?

If the engine says dizzy system has a problem, that sounds possible to me. If I were you I'd check it out. Maybe grab a voltmeter to test the power the coil is putting out, and check how much juice is coming out of the spark plug wires? I don't like all the talk ppl give about replacing spark plug wires (seems like a lot of $ for nothing) but maybe you need new ones. You could find a MKI owner and borrow his wires for a minute, hell maybe you could even borrow his coil or use jumper wires to feed off his coil and see how you do.

[halo07]

yeah i wish i could find someone near me that would let me check out his mk1 and see if i could find the problem, but i dont know anyone around me that has a mr2. um right now my batter is about dead, so i haft to replace that before i can work on it anymore. we push started it the other day and drove it to autozone and got some injector cleaner. after we put that in we drove the piss out of it. like every time the car would start to jerk i would just keep on the gas till it went away. but after a little driving the car cleaned up a lot so im really thinking its a fuel problem. so hopefully a new fuel filter will help.