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early 99 rough idle

8K views 20 replies 6 participants last post by  zpd307 
#1 ·
i just bought an early 1999 f250 7.3 liter...when u let the truck idle it seems like it misses or has an erratic idle...if u first start it and dont touch the acceleration pedal it idles fine..if u riv it up then let it idle it starts missing or loping...runs fine if its rived up over 1100 rpms or so...can anybody help... Ive checked the icp sensor...if u unplug it..it idles worse so i dont think thats the problem...any input would be greatly helpful...thanks
 
#2 ·
Have you checked for any DTC's to see if there are any stored codes?

Does it matter if it is cold or warmed up?

Does it matter if it is in gear or without load?
 
#4 · (Edited)
yes i have checkes for codes...it has a bunch of the that come up...p0750,p0755,p0734,p1754,p0231,p0603,p0478,p0470,p1747,p0720,p0541....yea i know theres alot..some of them are about the transmission...but its a 6 speed and it works fine...there were 4 new injectors put in the truck b4 i baught it and all the other ones checkesd out fine..the truck does it worse if its warmed up...it only does it if it is not under a load..ya just bairly let out the clutch to take off and it smooths rite out....the truck still has stock exhaust and the factory air box..i have an edge evolution programmer for it....truck is still set on stock untill i pipe it and open up the airbox...thanks for the help.....
 
#5 ·
P0750 Shift Solenoid 1 Malfunction
P0755 Shift Solenoid B Malfunction
P0734 Gear 4 Incorrect ratio
P1754 CCS (Solenoid) Circuit Malfunction
P0231 Fuel Pump Relay Driver Circuit Failure
P0603 Internal Control Module KAM Error
P0478 Exhaust Pressure Control Valve High Input
P0470 Exhaust Back Pressure Sensor Circuit Malfunction
P1747 EPC Solenoid Short Circuit
P0720 OSS Sensor Circuit Malfunction
P0541 Manifold Intake Air Heater


OK, you say it has an edge and a 6 speed. Pull the PCM out and give me the code. Also, put the PCM back in "stock" and remove the edge. See how it runs.

It sounds like you have the wrong pcm OR your edge is screwing the truck up. All the Auto trans codes and the AIH is leading me down that path. Your early 99 didn't have a AIH.

As of right now, only the P0231 is concerning me. If you are having fueling issues, the problems you are describing can be caused by that. But it is hard to tell with all the random codes.



 
#8 ·
I don't think that any of the codes are from the injectors\HPOP system. I think that the OP has the wrong tuning or wrong PCM for the truck.

The relay circuit code is the only odd one that is throwing me off.
Well I know the 603 is from having the main injector harness apart while key on cranking (after doing injectors). The 478 is from the red vacuum line being unplugged off of boost bypass diaphragm and the 470 is from the EBPV being unplugged. I am thinking the other stuff is from having the wrong computer and it not knowing where stuff is. Probably a PMT1 . . . :dunno:
 
#6 ·
The codes need to be cleared and run the truck for a day then check for codes again. Alot of those are from doing the injectors. As Dirk said, you shouldn't have an AIH(air intake heater) plug on that truck. Make sure they used all AB injectors when they did the install as well. Depending on how long ago they did the injector replacement you could have air in the HPOP system and when it is passing over the ICP sensor you are getting that roughness. Hard to say at this point . . .
 
#10 ·
Yea something odd is going on to have auto codes on a manual trans
 
#11 ·
I wonder if the truck was converted and they didn't change the PCM?
 
#13 ·
im thinkin its the programmer also....i also have a 2000 f250 with a 7.3 and the auto trans code are from it probably..i took the edge outa it and put it in the 99...i called edge and they said that the programmer would work in the 99...its an edge evelution pt number 15001 i think....when i went to look at the truck it was running fine..after i put the edge in it it started acting up..and the water in fuel lite is on now...whitch i didnt think nothing of that because it does the same thing in the 2000 but when u set it back to stock the lite goes off....i set the 99 back to stock and took the programmer out of the truck..the water in fuel lite is still on...and its idleing rough ever since i tried programming it...it still has stock exhaust on it and the stock airbox...i just wanted to try the edge to see if it would work....and it did..programmed the truck fine...then i reset it to stock and put the programmer back in the 2000...is there anyway to reset the computer??i tried disconecting the batteries...that didnt work....im stumped on this one....thanks for the help.i aprecate it
 
#16 ·
It sounds like the edge isn't putting the "stock" file back on the pcm. I would call them and see if they can help. There is no way to reset the PCM once a OBDII style programmer has written a file to the PCM.



If you had a "chip", you could just remove it.



 
#19 ·
Cheap mods? Meh. Not really. Once the truck is running right, I can get you setup with a tuner to get you some more power.

Your early99 has AB code injectors which put out about 120cc. The later models use AD injectors which are 140cc. Not too much difference.



 
#21 ·
yes you can change computers. go to the early 99 discussion. there is plenty of info on which computer to get.
 
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