I just bought this truck. I took a gamble when I bought it. It was sold as-is,runs and drives, no further information. '06 4x4 quad cab long bed for $4800, I took my chances... Anyway, the engine (4.7L V8) sounds smooth, no knocking or tapping, maybe a slight miss, but really it sounds good. I put it in Drive, and can barely move on a flat surface. Speeds top out at about 5mph. The truck has no ***** at all. And I hear a very loud hissing sound when I try to accelerate, but I cannot visually see a vacuum leak anywhere. I get 2 Errors P0068(MAS and TPS sensor) and P0113(Intake Air Temperature Sensor). My scanner won't read the codes, it can't connect for some reason, I read these by the "triple key turn" technique. The truck was sitting for a few months before I bought it. It literally has only been in my driveway for 3 hours so I did not look it over completely yet. I just want to know if these 2 errors would cause the truck to run like this?

Also, In neutral, I can't rev the engine. It bounces between like 1500-2500RPM if I hold the gas all the way down. Is that maybe a safety feature or something? Other than this one, the newest truck I've ever owned was a '97 so I don't know the electronics on these newer ones yet.

 

There is a rev limiter for P&N and each gear.

You can removeband try to clean the IAT it should be a bright blue color, be gentle with it and don't use anything too harsh to clean it. I used wd40 on mine, it cleaned up nice.

I would begin by removing the air box and remove and clean the throttle body ( again watch what you use) that will give you better visibility to see where a vacuum leak may be. You can clean the tps with the throttle body out also, you can also just try resetting the tps. Turn key to On( don't start it ) wit for all the dinging to stop press the gas pedal to the floor and then to rest position smoothly. Turn key to off. Try and start it and see if it's any better.

 

I cleaned the sensors and throttle body with WD40. Everything cleaned up very nice. I put everything back together and reset the TPS. No changes. The truck still idles very rough and will barely move. Still alot of hissing, and I checked everywhere that I could while the truck was running and I can't locate the hissing. I can hear it better from under the truck, I think it's on the backside of the engine, but it's dark now, it will have to wait until tomorrow.

I started it a few times, it seems that it likes to backfire when it first starts up, and it will run for 1-3 seconds after I turn the key off until it stumbles and stutters off. Is that another symptom of the engine codes that I'm getting?

 

Clean the TB and sensors with brake cleaner, not oil. Sounds like it has some tranny issues. The hissing may be coming from the evaporative emissions canister. Kinda sounds like the plug wires are out of place, but I believe there aren't any. Wonder if it's possible for the coil packs to be connected to the wrong cylinders?

 

I had tons of problems in gm a few years back, TPS sensor could be your problem, i hope its easier to replace in this truck than it was in my 1990 grand prix, it was on the back of the block, had to get way up in a tight spot to get it in w/ no view at all. (unless I could have pulled the engine)

Did you replace the throttle position sensor yet?

 

It's very possible that the coil packs are on the wrong cylinders, but wouldn't that give me a different engine code? I think I should have random misfires if they are messed up.

I checked the ohms on the TPS and they seemed fine but I'll try replacing it anyway since I have an extra one.

Another thought, my scanner can't connect to the PCM, any chance the PCM is bad and it's not reading the sensors at all?

 

Another thought, my scanner can't connect to the PCM, any chance the PCM is bad and it's not reading the sensors at all?

You probably need an adapter cable for your scanner, dodge did not follow the wiring standard.

 

Coil packs can go on any cylinder. And the wires that connect to them should be labled and positioned to each cylinder. 1357 2468 etc. You would be getting a misfire code if one of these wasnt working properly (most of the time)

 

Another thing to check.... Did you check to make sure the transmission has fluid in it? I've seen vehicles with next to no transmission fluid that would rev up, and when the torque convertor finally caught, the vehicle would move for a split second at about 5 mph.

 

Tranny fluid is at the right level, although there is a delay before it goes into gear, maybe the filter needs changed? TPS has weird resistance between the 2 outer pins, one is ground, on a new pin its like 7 ohms, old one is 2 ohms. I drove it in my yard and got a new error of P0123 (Throttle Position Sensor High Voltage). I put a new TPS in and now it no longer idles rough, but still not a drop of power. I have the battery disconnected now, hopefully that will clear my codes and maybe give me a new one to work with.