I have a 1999 Dodge Durango 5.9L V8. Only on cold starts, it will hesitate to start and when it does start the idle will bounce between 400 and 1000. Sometimes it will stall out and we can restart it. After about 3 or 4 tries, it will start and run fine. If we drive it somewhere and stop for a bit, then get back in and start it while it's warm, it will start right up and drive just fine. It does seem to be off a little in timing so I am going to fix that, but it also seems to run a little rich from the smell of the exhaust. So far, I have:
1. Checked IAC. It's beautiful and has been replaced recently.
2. Checked Throttle Body. Not dirty and no carbon build up really. I cleaned what was there, but nothing much or severe.
3. Checked battery. sitting at 12.5 while off and 13.7 when on and running. So not the battery or alternator.
4. This truck from what I have read up on, does not have an EGR valve. So that can't be it.
5. One thing I did notice though was the throttle body cover, when I took it off, the gasket between the throttle body and the cover was broke apart and when I picked it up, it just broke apart more.
6. Spark plugs and wires are all new

Also I have been reading a little bit more and have a few possibilities. Let me know what you think...
1. O2 Sensor
2. Fuel Injection Cold Start Valve Plug
3. PCV Valve
4. Distributor Cap and Rotor
5. M.A.P. Sensor
6. Throttle Position Sensor
7. Air Charge Temp Sensor
8. Coolant Temp Sensor
*There is no MAF sensor in this truck and from what I have read no EGR valve either.

Please any help would be greatly appreciated.

 

There has to be an EGR as that is a Federal Requirement. The MAP is another name for the MAF. TPS wouldn't do it because it'd be a continuous issue regardless of temperature (in fact, it'd probably be worse hot as the housing would expand pulling the contact away from the slide rail).

Do you have a Check Engine light? If it was in the Emissions side that would illuminate.

You say the plugs are new, were they gapped properly?

It wouldn't be timing either as the roughness would again be continuous or it wouldn't run at all.

Does the crankcase vent sound like it's exhausting when the engine is shut off after running? If not, it wouldn't be that either.

Cap and rotor . . . hmmm, do you know when they were last changed? The cap is a bear to get at, hiding behind the throttle body underneath the firewall overhang.

You say it's surging when cold, have you had the compression checked?

As it runs fine at Normal Operating Temperature, it's not the fuel delivery system either. To be safe though: when was the last time the fuel filter was changed? Have you (or anybody else) fed it the wrong octane/type of fuel? Has an injector cleaner been run through the system from tank to rail and back?

The throttle body cover rarely gets removed, so the paper gasket crumbling is expected. With the air filter being in a seperate box, unless something goes wrong with the TB itself there's no need to remove it.

 

a couple of things that i need to correct here

1) there is NOT an EGR valve on any of the 1st generation durangos

2) MAP and MAF sensors perform similar functions but are NOT the same thing, it is possible to have both, these trucks dont have both however.

3) O2 sensors are emissions side they VERY FREQUENTLY go bad without setting of a CEL

4) fuel filter on these trucks is a part of the fuel pump it is considered a lifetime part and cannot be changed without dropping the fuel tank and changing the fuel pump

 

As shrpshtr has stated and I have read and had checked through dodge, no 1st gen durangos had the egr valve. And the 1st gens do not have an maf sensor. Only the map sensor. I have heard that it could be a small hole in the vacuum hose line and that when cold that hose expends thus making the hole wide enough to allow an escape, but when hot, it shrinks up and seals the hole. I do not know if this is true but will be checking all of my hoses today. If that's not the case, then I don't know what to look at next. Like I stated, the iac is brand new. I have checked the fuel lines and they seem good, the only thing I can think of with that though is like someone said, I would have a lot more problems than hard cold starts if it was a fuel problem. Yesterday though, I noticed that when idling the rims stay high enough to keep the truck running, but they still bounce between 800 and 1200. Driving is fine, it's only idling. On cold starts it will start and shut down. And when it finally starts and runs, the idle bounces from 300 to 1000 for about 15 seconds. I have to rev it to keep it running and once it's warmed up it seems fine. The plugs were all gapped correctly, all new plugs, all new wires, new iac... Checking the map sensor and hoses today. If not those, what should I look at next?

 

Also I am having a 4wd issue too... The shifter is stuck in 2wd. I cannot move it into any 4wd gear. What are the possibilities for this problem?

 

Aight, I stand corrected.

If it's a pinhole as you mentioned, I'd attach a vacuum pump to the system as see if it holds vacuum cold. Generally you can hear a leak as a suction noise -kinda like the sound one gets when sticking their hand over a vacuum cleaner hose.

There should be a cold-idle bypass valve on the throttle body (it's supposed to open when cold, close when hot) and if it's not working properly it will cause stalling/hard starts cold. My formatting on that word means I haven't taken a really good look at my ma's Durango to see if there is one present.

If it's there, check the passage for blockage and the condition of the valve. It's a generic way for the PCM to control the idle without moving the butterfly itself.

 

Ok... So I did some digging and I think it's a vacuum leak. I say this because on the power brake booster itself is a valve coming out. It's green and black. When I started the durango, it did it's normal rough start thing and idled rough too. It was idling finally around 600rpms... I unhooked one of the hoses coming off and then the other one too and after each one, the rpms went up to normal at 800. I called a dealership I used to work for and talked to the top trusted mechanic. He told me I basically just diagnosed the engine myself and that the engine is simply not getting enough air. Any ideas? I know the IAC is good and new and I know the throttle body is clean... No holes or leaks in the hoses. Anything else I can check?

 

1) the cold idle valve is the IAC valve, it opens up more when cold than when the engine is hot.

2)if he thinks you are not getting enough air the #1 place i would look is for a clogged air filter i dont recall you mentioning this in the posts (i could have missed it)

3) 800 rpms is a little high for idling on these trucks but not too bad.

 

I originally thought 800 rpms was high too, but then I have checked the service manuals and talked to a few service techs at the dealership and they all say 700-800 is where it should be. 600 is low for the 5.9L V8. For the 5.2 and V6, it should be 600. I have checked my throttle body and air filter. Both are clean, good and ready to go. I'm starting to lose hop of finding this out without having to pay a high diagnosis cost.

 

***UPDATE*** I took the durango to a dealership I used to work for. A buddy there hooked it up to a $2000 computer and did a real diagnostic. Found out the IAC isn't working properly. He checked the IAC and told me it was brand new, which I already new and should work fine. He then told me it's one of 2 things at that point. Either the wiring from the PCM to the IAC is bad, which I hope it is, or the PCM itself is bad. I will find out and let you all know but thatnk you for the help. Through this experience though I have learned a lot about working on dodges. Good knowledge. He also told me a trick and said to get by for a while until I can get a new PCM or wiring, was to increase the idle level. This was done very easily. Take off the air intake and throttle body cover. Should be one bolt and then the air filter cover clips. Then on the left side of the throttle body you'll see where the accelerator cables are attached. Part of the throttle body assembly itself is a round bump thats just above those cables. On the back side of that bump is a screw. If you can find a way to unscrew it about a turn or 2, it is a stopper for the accelerator cable and sets it so it sits open a little more. I did that and now my durango sits at 750rpms when idling and it also is running smoother and braking better. This will have to do until I can find the part I need. Thanks for al of your help though guys.