Hello everyone, I'm new to the boards. There's alot of knowlege about out trucks being passed around here, more than the dealer knows, thats for sure. I have been experiencing the same 2 problems with my truck for about a year now. Nobody seems to know whats wrong with it.

1.) If it's driven hard or you have to go up a few steep hills, the idle drops to about 300 RPM's then up to 900 over and over. The motor sounds like it is about to explode. Then when you go again, you can put the pedal all the way down and 2,000 RPM is all it will do. This will eventually clear up, about 100 yards down the road.

2.) Occasionally the RPM's also stick at 3000-3500 at WOT. With your foot still on the floor, the RPM's go DOWN! They eventually climb back up but this is terrible.

My truck has 60,000 miles now. I have replaced:
1. Plugs
2. Wires
3. Both Coils
4. Fuel Filter
5. Cleaned K&N FIPK
6. Cleaned Throttle body
7. Clamped every vacuum hose I could find.
8. Flushed Trans
9. Done 2 Fuel injector treatments in the last 1000 mi.
10. Tightened the connection on the computer

Thanks in advance anyone who takes a shot at this. Any advice is helpful at this point.

 

Beetlejuice: Off hand I have not had this problem with my truck but then again mine isn't as new as yours. Has the dealership(s) that you have taken the truck to ever checked it for any error codes that it may have keep in memory. I would probably start asking questions about the throttle position sensor, or the idle air valve. The throttle position sensor is mounted on the throttle body and is generally small and round. The idle air valve is about 3 inches long, round, on one end it has a connector. On the one side it will have a small triangle part that mounts to the throttle body. I just replaced mine. The truck started up and quit twice, then the third time I had to feather the gas pedal to keep it running. It wouldn't idle at all, it would run around 400 - 500 rpm and then up to around 1000 rpm. It was like it was missing, but I ran it by the guys at my dealership and they said that the valve was probably the problem. I replaced it for $100.00 CDN. Hopefully this solve my problem. Maybe if you have a chance, get the computer code of off the truck and then call Mike Troyer. I am not saying that he will know what the problem is but he may know of any problems with the original software on the truck. Maybe the computer needs a new level of software that you and the dealership is unaware of. Hope this helps or atleast get you on the right track. Keep us up to date on this.

Have Fun & Keep on Truckin'
Dean

 

1) EGR is stuck/not operating properly.
2) What is the year model? Any lights like 'check engine'? Could me other sensing parts (O2, vacuum, etc).

 

Just a shot in the dark...

Sounds heat related to me. Wondering if faulty catalytic converter could cause such a problem? Would think that the compuer would detect a problem. Like I said, it's a shot in the dark.

Reasoning: More exhaust thru the converters means they run hotter. In this case, could an extra hot converter somehow restrict the flow of exhaust gasses causing the symptoms?

 

I am going along with Izzyeddy on this one and saying it is the throttle position sensor or the idle air sensor. Truthvully if it's anything it should be throwing a engine code. My dad's 94 had almost the same problem as you are describing and we changed out the TPS and it cleared right up but he had a check engine light on and OBD1 scans confirmed it was the TPS. His exact problem was after the truck got to operating tempatures you could try to go up a steep hill and as you stepped on the gas the RPM's would not build and the truck would not downshift. After the TPS change same hill you could barly touch the gas and the truck would downshift and take off like it should.

 

No, there are no error codes. I had one a while ago for a misfire and relaced all that stuff in my list. The bill for one replaced spark plug came to $130. And it wasn't even gapped right- 0.42.
My cat's are ok on the outside, not saying anything about their substrate though. No exterior damage to any components.
I have all the gaskets on order to remove my throttle body, TB neck, EGR, IAC and TPS. I'm planning on checking all the components with an ohmmeter when they're off and cleaned. Anyone around here ever try this? It doesn't look hard at all but there's not much play in those small hoses to plug them back in (like the one on the top of the neck and the back of it.)
Anything else you guys can think of? I'll pull it apart at the same time. I've got the next 10 days off from work- came down with mono. Antibiotics don't do anything for cabin fever!

 

One of those systems is similar to mine. I've been having trouble with my tranny overheating. When it does, it will not shift down into 2nd like it normally does when I floor it going up a hill. In third it will be around 3000 to 3500 rpm. I also notice that if I press it a littel bit it will shift into 3rd then when I floor it, it will go down about 300 rpm. It won't go up 900 rpm like you are saying though. I'm assuming you have an automatic tranny. Next time you notice those symptoms look at the o/d light on the shift lever, if it is flashing there is something wrong with the tranny. That is how I found out mine was overheating. When it starts flashing it will store a code. I had mine scanned and it came up as an overheat condition. It only overheats after driving for slow speeds or going up and down steep hills for a period of time.