I'm new here, but have a little bit of experience changing parts. Diagnosis is a weak point for me, so hopefully someone can help. I have a 1999 Dodge Ram 1500 with the 5.9L engine. Most of the time it runs decently, but from time to time it runs very rough, though usually for a brief time.

Here is what I've done/determined so far:

1) It seems to be more likely to have this problem when the engine is cold.

2) When the problem occurs and I have the truck idling, the engine will start to lose RPM's and will start to make a giant sucking noise. If I let it continue, it will run very rough, still with the noise of a mighty rushing wind, but also with a very heavy, labored chugging noise coming from the exhaust. There is also a popping noise that will occur, but I believe it's internal to the engine because I don't hear it coming through the exhaust. Occasionally it will idle down and chug so much it stalls.
3) If I am driving when the problem occurs it will suddenly have no power. If I push the gas harder, it does not help; I just get a very hesitant and jerky response, and generally hear the same popping that I mentioned earlier. When driving, the problem is much more pronounced going up hills or under load (towing) than going downhill or on the level without a load. If I am going up hill and the problem occurs...I can shift into neutral and rev the engine without a problem. Usually I do this a few times until it goes away.

So far, to eliminate various possibilities suggested by two mechanics, I did the following:

1) Cap & Rotor
2) Plugs and wires

I did not expect either of these to cure the problem, and they did not. All these items were old enough to justify replacement, so it wasn't a waste.

After replacing the plugs and wires, I started the engine and it commenced acting up. This time I had the hood open, so I checked, and the strong "rushing wind" noise was sucking in through the air filter housing. I didn't get the housing off in time to discover whether the butterfly valves were open or closed, but generally when I start up they're closed.

This morning I started it up, and it started to suck air, but resolved itself before it got really loud or bad. At any rate, the sucking was coming from the location I labeled on the attached photo.

I guess my ultimate question is: Does anyone know the source of my problems?

Thanks,

Kevin

 

i do believe that sucking noise is from you sensor opening up your tb trying to keep you engine rolling. which means, you're getting a bad signal from some place along the line. i would personally check your front o2 sensor to see if its working properly.

 

Sounds like it could be the IAC?

 

What your pointing at is the IAC, (Idle Air Control)

How was the gasket around the filter housing?

Ryan

 

I found instructions online for cleaning the IAC. Do you think that would work, or should I just replace it?

 

just replace it ..depending on the miles you have on it. if low try cleanning it first.

 

remove old IAC and check the well where the pintle slides in/out. if you have a lot of gunk buildup on the pintle or in the well, you can clean that. you can also poke a wire through the well into tb to make sure the hole is open. if you have gunk, try cleaning it. if there's not a lot of visible gunk, then cleaning is not going to do any good and i'd replace it. if the new one fixes the problem, throw the old one away as bad. if the new one does not fix the problem, then keep the old one as a spare part.

be aware that there's an interaction between IAC and TPS, and its sometimes difficult to nail down the problem. i replaced 2 or 3 perfectly good IAC's before i found out my surging idle was a bad TPS.

edit - the IAC is the small black motor on the back of the TB. don't twist, push, or pull on the pintle.

 

Hi there i realize this was a few tears ago now but i am having the exact same issue!! I have replaced the IAC and TPS and still no luck what did u find was your problem? Thanks