One last problem and this truck is perfect!

[channingd]

Well, in my eyes at least.

So, all new sensors installed except O2 sensor.

New ECM installed.

Truck is running very well now except once it is warm, upon letting off the throttle, the idle will take a nose dive. Most of the time it will recover pretty quick and then have a nice idle. Sometimes it won't recover quick enough and trip the oil pressure switch telling the ECM to shut off the fuel relay. (This would explain why previous owner bypassd fuel relay and wired the fuel pump to a switch in the cab.)


I'm thinking it must be block IAV passages but wanted to get your opinions first. If census agrees, I'm just going to buy a rebuilt throttle body setup.

Thanks

[notyo_cheez]

Something's blocking the air flow. Don't know if this TBI application has an idle air control of some sort but it seems to me it's starved for air. My $0.02

[channingd]

I was kind of on that path too, but I checked all that and everything is fine on the air side.

The funny thing is too, is that it doesn't do it every time. And if I actually gun the motor before coming to a stop, it actually does okay. I know it has to be something with the tbi control because of that. If it were mechanical it would do it almost every time. Correct me if I'm wrong, but I think that if it can run good, and it does sometimes, then the mechanical part is fine. This is a thinking problem. Something is letting the idle go to low for maybe 1 second, that's all, then bang, up to normal idle. Unless it stalls at which point I have to restart and then it does not have any problem at all for around 45 seconds to a minute. Idles like a champ and coming to stop runs to a nice idle.

If I keep my foot laying on the throttle, just the weight of my foot is enough to make it run fine. Weird, I know.

[notyo_cheez]

Timing?

Really hard to tell sight unseen. Cam and crank position sensors not receiving a signal or intermittent signal interruptions might cause this too, and may not produce a CEL (check engine light). Timing chain might be stretching, don't know how many miles are on your engine. Not sure if this generation of plants still used the plastic gears or not.

Fuel Pump? It may be in the early stages of heading south. It can idle fine all day until you push the throttle and volume demand goes up and it won't respond immediately, this can happen with either electric or mechanical pumps. Sock might have boogers in it. Tank might have contaminants in it. Regulator might be failing?

Just sharing what I know or what experience has taught me to look for when there's a problem. As I have learned the engine needs three things to run: air, fuel, and spark.

[channingd]

Timing is at 0 degrees. Now someone told me it should be a 4 degrees at my elevation over 5000 ft. (?) But it right now is at zero.

Throttle response is great. Truck will spin tires if you give it gas too hard.

Changed fuel filter, air filter, distributor and rotar. Have not changed spark wires or plugs yet. I have them. Just haven't done it.

[notyo_cheez]

Try new cables for the sparkies and report back. Could be one is arcing...

[channingd]

I will do that this week and new spark plugs plus I pick up a new O2 sensor.

I'm really not feeling the spark or wires due to the fact it's not all the time and I don't have a miss. This is a real specific problem. Let off gas and engine tries to die even knocks once or twice then comes to where it should be and is fine til next time you let off the gas.

I'm kind of stumped.

[1LowToy]

I had the same problem on my Dakota. I had low or no idle after getting of the freeway at times. The problem was intermittent. I took off the throttle position sensor and manually made it take the full sweep of the switch. Put it back on and no more problems. A new one is in order for me next failure.

[channingd]

Put a brand new throttle position sensor. Not that the o'riely's one can't be bad right out of the box.