1992 P/U 3.0 V-6 Mystery Problem - Help

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mtrdud

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Well the problem persists. I have searched FAQ, read countless FSM pages and fixes and I can figure this problem out. My 1992 P/U 4x4 with a 3.0 V-6 will do the following: Upon first starting it up it will start and run fine. It will even rev up fine. After the initial few minutes of running and after I assume the fuel from the cold start injector does it's part, the truck will not ruv up without cutting out and stumbling. I can attempt to pump the gas and it cuts out and will stumble and seems to be "surging". After a bit up stumbling on acceleration and if you pump the accelerator, it will eventually clear up and runs great from then on. It will only do this until it clears up.
What I KNOW it is NOT because I have replaced: FUEL PUMP - I had my other one warrantied - DID NOT fix the problem, COLD START INJECTOR (replaced mine at the advice of a Toyota Tech) - DID NOT fix the problem, FUEL PRESSURE REGULATOR - DID NOT fix the problem.

I have tried the diagnostic box with the damn blinking engine symbols. I can't make any sense out of counting the blinks. Anyways, does anybody have any useful suggestions before I throw any more cash at this??

Thanks
 
3.0 Help

It only blinkled when I jumped it at the diagnostic box. NOT before. Again, I can't make sense out of the blinking anyways. I may be counting wrong but it just blinks forever and doesn't seem to have any pauses to seperate codes. In other words if the blinking DOES mean anything when I jump it I can't make sense of it.
 
If you have a repetitive constant blinking, then that is the "all is good" from the engine ECU.

Have you tried the TPS?

How about the Air Flow Sensor on the top of the airbox?

Do you have access to a Factory Service Manual?
 
3.0 Trouble

The AFM and the TPS were my next areas to check. I do have access to the online 3.0 manual on here. I checked the AFM with an voltmeter and it did not check out right as the FSM calls for however I have never felt the greatest using a volt meter checking ohms. How reliable is that check anyways? Could the TPS or the AFM cause something to be off ONCE and the clear up the rest of the day?? I'm about to pull my hair out with this.
 
UPDATE

OK, update: Ipulled the AFM off so I could check it well. It checked within spec with the volt meter. I then checked the TPS again. It checked out until I checked it with the throttle open. It did not check out properly. It actually showed nothing if I was reading it right. Like I said I'm no expert with a volt meter but I feel I was doing everything right. Also with the truck running I disconnected the TPS. At idle I noticed it was rough with it disconnected and smooth with it connected. With the throttled opened up there was NO difference either way. Does this mean it's bad?? Does any of this make sense?
 
Id replace the tps if it's not checking properly. That "is" the way to test them I work at the dealer and that's how we check them. Are you checking the resistance also ? Id also ohm the coolant temp sensor. The temp sensor tells the computer when to activate the cold start injector. And when to turn it off. Also if you have a air bubble in the cooling system at the sensor that will also fubar the readings. Juat top of the coolant. Best way to check is check it cold then drive it till hot them test at running temp. If either of the two are not with in spec. Replace it. You should also ohm the wiring harness from the sensor's to ECM to make sure a rat hasn't eaten throu it. (overheat also).
 
3.0 Problems

I have not replaced the TPS yet. Got ot hinking about this and if the TPS was bad wouldn't it be bad ALL of the time and not just initially as the problem is now? I'm gonna clean my throttle body real well and see if that makes a difference. You would think if something is wrong with the TPS I would be getting a code?? BTW do you guys totally remove your throttle body to clean it or do the best you can with it on the vehicle?
Thanks
 
mtrdud said:
I have not replaced the TPS yet. Got ot hinking about this and if the TPS was bad wouldn't it be bad ALL of the time and not just initially as the problem is now? I'm gonna clean my throttle body real well and see if that makes a difference. You would think if something is wrong with the TPS I would be getting a code?? BTW do you guys totally remove your throttle body to clean it or do the best you can with it on the vehicle?
Thanks
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i had a bad one on my 22re and it took a while for it to send a code to the computer. i do not know why but i fought with it for a month trying to figure out what was wrong, i pulled the codes daily and there would be nothing, then one day the check engine light came on, pulled the code and it was the tps. i do not know if the 3.0 are the same or not.
 
3.0 Problems

Well I plan on pulling the throttle body off and giving it a GOOD cleaning. I will probably go ahead and replace the TPS while I'm at it. What's a few more bucks! The part that throws me is that after it clears up it runs great. Go figure. I love this truck but I hate when I can't figure one out like this.
 
3.0 Problems

Well I may have found the problem. I will find out for sure in the morning when I start it up. I was checking over the EGR set-up and found that the vacuum line that runs from the bottom of the actuator to the EGR had worn in two and was basically not connected at all. This might explain the problem happening once at a colder temperature. Anyways we will see. Update to follow.
 
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