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[Afunk]

Hey,

I know I should probably post this in technical but no one looks there. My car, when driving around normal, not in any particular RPM range, but above the idling range, will suddenly feel like it hits fuel cut. According to the tach, the RPMs will drop very abuptly and the whole car bucks when it does. On occasion it will even throw an engine code for a few seconds like fuel cut does. Other than this, it runs fine. Idle is a little iffy and it sometimes idles at weird RPM.

I'm throwing no codes.

TPS is calibrated perfectly, throttle body was pulled of to do this.

AFM electronics were bad and it was throwing a code 31 and 11 but I changed the electronics out yesterday and it doesn't throw codes anymore and it idles dramatically better.

The whole car is grounded great with 4 guage wire.

I think it may have something to do with the CPS or coil packs, but I could be wrong...

What do you think?

Thanks,

Alex

 

[GrimJack]

Heh... looks like you've been relegated to the tech area anyhow. And lots of us read this area!

If the CEL comes on, a code should be stored in the ECU. If the idle is iffy, I'd suspect the ISC is letting air in when it shouldn't, try pulling that off and cleaning it.

 

[Afunk]

Alright, thanks, but why would it have fuel cut symptoms during above idle RPM ranges?

 

[jong]

Hmmmmm... this is a real nut jerker....

Things i would check before throwing parts at it...

1) timing, just check to make sure its on, cheap insurance for an easy fix... make sure to jumper te1 and e1 or whatever
2)ground the afm to the body. my car had similar problems, grounding the afm resolved them
3) spray all vacuum lines and intake connections, especially manifold areas, with carb cleaner or brake cleaner during idle. Listen for hesitation, sputtering, when you spray certain areas, listen also for leaks. vac. leak will cause those symptoms, a bad vacuum leak will actually increase vehicle speed w/ throttle closed ( ask me how i know)
4) what does it do during a neutral free rev of the engine? same symptoms?
5) let it idle.... if it stumbles a little at idle, carefully remove either an injector or spark wire for each cylinder 1-6. you're looking for the one that DOESN"T change the rough idle. That'll be the culprit... See when you remove a wire, the cylinder isn't firing anymore, if the idle gets more rough, then it was working, if it stays the same, it was never working, or at least not consistantly...

let me know what you find out-- if that doesn't work... house call

 

[Nick M]

If the tach drops you are likely losing the ignition pickup. In the wiring diagram I think Toyota calls it NE signal. I dont have it in front of me to check though.

Make sure the cam positioning sensor is plugged in good, and the pins are not bent over. There are also checks in the repair manual for the pick up you can do.