Guys I am struggling here. My 1996 Dodge 2500 (5.9 V8) is sitting with what I would call a high idle or a stuck throttle. Basically it feels as if the truck is rearing to go to a point that when you put it in gear there is a bit of a lurch and as soon as you take your foot off the brake the truck begins to move (a bit more than normal). Additionally there is a high pitched blower type sound coming from the engine. When I keep the truck in park the egine seems to spit a little, condensation or something comes out of the tail pipe along with blue/white smoke.
I have replaced the airfilter and the PCV valve because I knew they needed to be done. I have done the on/off code check and return a code 13 for a MAP Sensor issue (no difference in pressure). this code appears alone. I have also tested the voltage on the throttle body sensor and I do not seem to get the smooth voltage variation you should return.
I have looked at so much my head is spinning. One thing points to bad MAP sensor, Vacuum leak or bad plenum gasket. Something else points to bad Throttle Position Sensor and of course the Idle Air Control always seems to come up with talk about idle problems.
Based on everything I am reading and the code I return I am thinking it is eithe MAP Sensor, gasket or vacuum problem. I do not want to waste time or money chasing my tail so any recommendations on a systematic approach would be appreciated. TIA

Replace the map, AND the TPS. Make sure the little vacuum hose for the MAP is in good shape. Pull the throttle body off the truck, remove the IAC motor, and clean the well it goes into. Leave the battery disconnected while you do all this, so that when you have it all back together, it can re-learn the new parts. On the first start up, turn the key to On, count to ten, THEN crank it up.

HeyYou,

Is this kind of a catch all solution or is there something with the symptoms I described that make you believe the TPS and the MAPS both need replacing?

Do you think this will take care of the smoke and gurgle/spit and the high pitched blower type noise? Or is this just a first shot and see what happens approach?

I am just curious so I know what to expect if/when I tackle this.

I am assuming that to do this I will need new gaskets for the TPS and MAPS as well as throttle body (I am assuming I need to remove the throttle body to clean the IAC motor)

Thanks for the advice and help

nah HeyYou has good advice, and I'd also replace those two items. The white smoke would potentially be alarming to me...does that smoke smell sweet? Was the truck running good before those codes popped up? Have you addressed the plenum issue yet? the IAC motor you can remove the TB, but if you don't want to do that, it is possible to do it with removing the TB, its just harder is all.

chromed95,
I have not personally taken care of the plenum issue. I purchased the truck used and I really do not know if it was previously addressed. That is what has me a little concerned. I am wondering if the blown gasket may actually be the cause of the problem. I am wondering is I would best be served doing that, but it definitely seems the most labor intensive and it seems that once you have it all apart there are several additional things worth doing (thermostat?). From what I have read the plenum gasket could cause the code I am getting and if that has blown I am wondering if that would cause the high pitched blower type sound (vacuum issues).

From what I have read a simple test is to cover the vacuum hose going to the air breather and the PVC valave. If you do not get positive vacuum (I am assuming a blowing as opposed to sucking?) then you have a leak problem. If that is the case I am thinking the plenum gasket may be the place to start.

I have not noticed the smell of the smoke. Tonight I will test the vacuum as I described and see what I get. I will also try to notice the smell of the smoke. Anything else I should look at tonight to provide you guys more information?

Bad plenum gasket won't give you very many of the symptoms you have. (no codes, no white smoke, etc.) You have more than one problem.

TPS failed your test, it needs to go. You could do that first, clear codes, and see what happens......

Map sensor *might* just be a bad vacuum line. (it is cleverly concealed under the sensor, little 90* elbow feller. gotta pull the sensor to see it.) If the little hose is good, sensor is most likely bad.

Cleaning the TB while you have it off is never a bad plan. Good chance the IAC well is choked full of crap, and the pintle simply cannot move. (it happens....)

To rule out the PCV system (blue smoke), disable it. (pull the hose off the intake, and plug the fitting on the intake.) Aftermarket PCV valves are not always the best, and may flow too much, allowing the system to suck oil. I think a higher likelihood there is blown plenum though. While the TB is off, have a look down there. If you see oil pooling. Time to start lookin' at fixing the plenum.

White smoke may just be condensation, a bit of water in the gas, or..... bad headgasket/cracked head...... Try starting the engine when it is stone cold. Grab a hold of the upper radiator hose, and if it gets solid immediately after start up, you have a head, or gasket issue. That should probably be your first priority.... figger out why it is smoking.

Smoking engine

The smoke from the exhaust was definitely not sweet smelling and the upper radiator hose was not hard right after starting the engine. I am guessing that is a good thing.

The exhaust was not smoking so bad tonight. Infact when I had the air box off there was hardly any smoke. When I reattached the airbox I got a little, but nothing too bad. I am thinking replacing the TPS and MAPS and cleaning the IAC is a good place to start.

Any other thoughts?

For whatever reason, I can't get any of the links to work.

Yes, those are both "Good Things™".

replace the tps, but, look at the little hose for the map before replacing it.

Well got the throttle body off pretty easy. Actually maybe too easy. The gasket came off in about three broken pieces it was so brittle.

Now first question is should I take the IAC valve off to clean inside the cylinder?

Also how/should I clean down inside the intake manifold?

I looked down at the plenum plate and I am not sure if whAt I am seeing is pooled oil or normal. Here are some photos for your review. I am just trying to figure out if I need to replace the plenum gasket. Thoughts?