Help with 3RZ Problems

[wngrog]

I have a 1997 3rz in my rock buggy.

About 6 months ago, I began having problems with the engine running rich periodically.

It would be running fine and then all of the suden, it woud run rich as if the computer was telling it to turn on the choke or something.

It first, it would happen just when the engine hit 180* and the fan would come one. I thought it was the temp sending unit, so I changed that.

That did not work so once when it did it, I unplugged the throttle body plug and replugged it and it ran great. That fix soon did not work either.

I have scanned the motor with a good OBD-II scanner and it does not throw any codes. Mind you, the wiring harness has most everything programmed out of it. I run a manual temp guage and the idiot light is only for oil pressure so I don't know if the computer will even remember a code or not.

One really wierd thing is once it was running rich and I was winching and it just killed the motor. THat made me think the car was not getting enough juice to run the computer.

I got a good charge on the battery and it still did this sporadically.

It has never stopped running with this problem until the last time out.

Last time out, the buggy died 2 times after running rough for 5-10 minutes and then it would not crank again until it cooled off. I though maybe the fuel was vapor locking the pump since it was hot that day. I changed the filter in front of the pump and it did not quit the next day, but it did still run rough at times.

The fact that it is sporatic is what is so infuriating. Any clues to what to do next?

I am about to replace the battery and the O2 sensor and see what that does.

[fastrexxx]

Got a good ground connection between the engine/frame/computer?

[wngrog]

Originally Posted by fastrexxx

Got a good ground connection between the engine/frame/computer?

Yes, but I plan on taking it off again and making sure. It sounds like a ground problem to me too seeing that it is so intermittant.

[penguinofdoom]

best bet to diagnose this is to get a obd monitor. $83 to plug your ecu into a computer and have it tell you 100% of what it's doing

http://obddiagnostics.com/index.html

btw, i was the one who originally wired this buggy for randy, but it's been a while, so i don't remember off the top of my head it's entire configuration.

it should have good grounds inside the harness.. but that might be something to check, make sure none of my splices are coming loose or anything like that.

[Propane]

Possible ignition module???

[wngrog]

Originally Posted by penguinofdoom

best bet to diagnose this is to get a obd monitor. $83 to plug your ecu into a computer and have it tell you 100% of what it's doing

http://obddiagnostics.com/index.html

btw, i was the one who originally wired this buggy for randy, but it's been a while, so i don't remember off the top of my head it's entire configuration.

it should have good grounds inside the harness.. but that might be something to check, make sure none of my splices are coming loose or anything like that.

You did a great job on this for sure.

So when I plugged in that generic OBD-II scanner, you are saying that that would not do the same job as the computer based tool you posted a link to?

I just ordered a new O2 sensor, battery and Mass Air sensor. That and checking all the grounds.

I can't test it right now, the whole thig is torn down from the engine back for new Atlas and 9" axle

[wngrog]

I read up on that computer scanner and it IS nice. I just ordered it up. Thanks!

I have had lots of questions on this harness. Do you still do them? If so, I will let others know.

[penguinofdoom]

not really, i moved, and haven't done one in a long time. i'm in school so much right now that i haven't had time to do anything else but school. i haven't even checked on here much in the past 2 years. i graduate soon though, so i might get back into it.

if you have specific questions on the harness, PM me, and i can see what i can remember..

[wngrog]

What is the firing order on a 3RZ anyway?

[toc-yo]

Got a good ground connection between the engine/frame/computer?

My 96 was doing the exact same thing and I had a bad ground (back of engine to the fire wall). I`d try that before ordering anything. Mine would run rich sometimes and would shut off when the head, brake, signal lights were turned on sometimes.
It eventually threw an engine missfire code.

[wngrog]

Thanks! I have redone all the grounds while the thing is apart.