Very low idle....plucking my nerves

[riverst]

Hey guys,
Today the weirdest thing stated happenng. My idle went hay-wire. I turn on the truck and was sitting there for about 3-5 minutes and my RPM gage went from 800rpm down to about 400rpm. Then it went low, all the way down and the truck began to shake and the engine sounded like it was coughing. I thought the truck was going to shut off. So i thought it was the IAC valve. I went to autzone and got a brand new one with some Seafoam too. Replace the IAC and injected the Seafoam through the brake booster line. Nothing really seem to change. The seafoam made a little bit of white smoke out the tailpipe, but the engine still remain sick. later on, I was on my way to school and I was stuck in traffic, the truck begain to low idle again and I really thought it was gonna shut off. I check all the vaccum line that i knew off and they were all attached and clean the TB. Now I :roll: really dont know what to do. Im clueless to what may be causing the truck to idle so low.
I had some headers installed on friday, but I dont think that may cause the problem. I have a Stupid Jet chip- would I need to change the chip now that I have headers or it doesnt even matter. Would the chip cause the low idle. Or maybe the sparkplugs. I dont know. like I said im clueless...
Please help or I might have to check in to a psych ward.

 

[monkeydude3]

try cleaning the MAF. another thing is, do you have obdII on y our truck? I know some 1996s have it and all 97s and beyond do. In either case see if you can pull any codes. yes the computer does store some codes, and there could be some in there that haven't quite yet thrown a "check engine" condition. Some take about 3-5 instances of that happening for it to throw a check engine light.

Try checkin for codes

George

 

[riverst]

Yes, I have a OBD II port. Today I will get the codes read and clean the MAF. Can I use seafoam to clean the MAF. I have some left over.
Thanks

 

[TPLYNCH]

Check the DPFE and EGR. Make sure the lines are connected and that the DPFE didn't melt

 

[riverst]

Today i had my OBDII read and it gave a P0113 code. I look in the Hayes book and it said the "IAT circut high input". I came to the conclusion that I have a air leak some where. so I check all the vacum hoses and everything was connected except this metal tube that goes into the intake manifold was letting air escape through there. So I took the mainifold off and put some silicone around the tube and i pray that fixes the problem. ill see when I go to work tommorow.
Plus on top of that, my gas milage sucks. I get about 4 days driving to work and school. What can i do to fix that. Do you think all the aftermarket parts are decreases my fuel economy.
What is the DPFE?

 

[monkeydude3]

Do you have the 4.0L OHV engine? Try replacing your intake air temp sensor. That is the IAT code you got. If I remember correctly the higher the voltage from that the hotter your engine is (supposedly). Try replacing that sensor.

Your DPFE is a pressure sensor that senses varying pressure in the exhaust and knows relates this to your EGR valve position and tells the engine how to do that accordingly. I did an experiment today, and when you apply vacuum to the EGR valve the engine runs down just like you said. So as far as I can tell, you possibly have an EGR valve that is opening at the wrong time. Investigate that.

George

 

[riverst]

Thanks, Ill try that today after school.

 

[ExplorerOfDaMud]

mine does that sometimes and it also does that when i just start it up somtimes i was told to clean my iac and maf with electrical cleaner

 

[ExplorerOfDaMud]

but mines a 91 xlt 4.0