Here is my dilemma (all specs are in my sig)

I have been working on a problem for about a year now that is bugging me. About 150 to 200 miles after resetting the PCM my truck will not idle/die if I am at a slow speed, like in a parking lot, and let off the gas. Sometimes it will almost die (go below 500 rpm's) and then go back up to normal idle (around 700 or 800 rpm's)and sometimes it will just die. If I reset the PCM it works perfect for another 150 to 200 miles and then the problem starts all over again.

Trying to fix this problem, I have
[ul][*]replaced Plenum gasket (I didn't use the hughes kit [:@]...I think it is going bad again [sm=headbang.gif]....saving for the hughes kit )[*]replaced IAC[*]replaced header gasket (incase I was sucking air)[*]Icleaned O2 sensors[*]I cleaned all the TB[*]I checked the TPS for .7v and cleaned it[*]put fuel injector cleaner in it (sea foam, techron, and lucas oils)[*]replaced the plugs with autolite 3923's [/ul]
[ol][/ol]

The truck runs perfect even when this problem is going on except for the scenario I stated above. I don't think I am running rich because I get 16 MPG in town and 19 MPG on the highway.

ANY IDEAS OR HELP is appreciated.

Brad

 

You get some bad-*** mileage there.

My suggestion is to check the evap purge solenoid and the hoses that are routed to it. If they are routed backwards (which I did when I reassembled my engine) the engine will not idle properly. Also, could your charcoal filter have been flooded with gas at one time? I know mine is saturated and I'm planning to crack it open, replace the charcoal, and seal it up. This is just off of the top of my head.

 

ok I found the evap purge selenoid last night and looked at the hoses, they are all hard plastic to the TB and to somewhere under the cab of the truck could one of these be the problem?
[ul][*]connecting the hard pastic lineto the TB it is a rubber hose and it slid on and off the TB pretty easily(is not a super tight fit)[*]coming off the evap selenoid going under the cab I also have about 6" of rubber hose before connecting to the hard plastic line (is not a super tight fit)[/ul]
Which way do the hoses go and is there a way to test the evap selenoid?
I am not sure what the charcoal filter is or where it is?

Brad

 

Sounds about right with the evap purge solenoid hoses. Have you downloaded the FSM (Field Service Manual) from the DIY thread? It is invaluable. The charcoal filter is located on the frame rail on the driver's side, literally under the door. You would have to cut it open to know if it is saturated or not. I plan on saving money by getting a plastic welding kit, cutting it open, replacing the charcoal, and welding it shut again.

 

Yes I have the manual on my hard drive and I agree it is a life saver.

So there is no way to check/test the selenoid or the charcoal filter?

Brad

 

I am unsure about how to test the solenoid. You're going to hate this, but check every damned ground wire out there. That's the number one problem with modern cars. Too much is dependant upon the computer system and proper voltages. As for the filter, there's not much to test. Open it up.

 

I was having idle problems with my truck until I located the cracked vacuum line that was causing it. Don't know if this is causing your problem, but it was a major PITA for me.

 

Where was the cracked vacuum line at...I am also having the dreaded AC going to defrosters problem so this could be a fix...I have ran most if not all the vacuum lines and replaced most of them.

Question: How tight should the vacuum lines be when connecting them to whatever it is they connect to? the reason i ask is I have some lines (mainly boot connectors) that slide on and off easy but still require pushing/pulling off.

Brad

 

I would get your battery and alt checked. If you alt is going bad it doesn't work good enough at low rpm to run the truck.


Just a warning though, after you get them tested let your battery set on the charger overnight. Those tests always seem to kill the batteries. Its happened to quite a few people including me.

 

I know you said you checked the TPS, but this problem points to it. I had a Ranger that did the same thing.