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I have a 1996 Ford F250 Powerstroke, automatic with 220K miles, but in great shape. Less that a year ago I had all new injectors put in with new glow plugs and new wire harnesses. I live in Oklahoma.
Problem: When I start the truck the rpm’s jump up and down violently for about 30 seconds. If I hold my foot on the throttle just a small amount for that 30 seconds the problem will not happen, but it does seem like it is trying to idle at very low rpm’s for a minute or two after that. The truck seems to run perfect other that this problem.
<O This problem happens every time I start the truck. It does not depend on the temperature outside or how worm the truck is. The symptoms are always the same. I can drive it 8 hours, turn it off and immediately hit the starter again and it will do exactly the same.
<O The problem started 4k miles ago shortly after I changed the oil and my normal diesel mechanic thought it was because I used 30wt synthetic oil, but told me the next time to use 10w40. It now has Rotella 15w40 in it, but the problem did not change at all.
<O A friend from out of state put a scan tool on it and it had 3 codes. #1 was the exhaust pressure sensor, so we cleaned out the tube that was plugged going to the sensor and the code went away. The other two codes were transmission codes #2 was the speed sensor and #3 was the selector position sensor (I may have the terms not exactly correct) We could not do anything about those two codes, but did not think that they were related to this problem.
<O Several other diesel mechanics have had other theories. One said that it could be the high pressure oil pump; another said it could be the Cam Position Sensor. I wonder if it could be something like the Throttle Position Sensor????
Last edited by magnessqh; Feb 26, 2007 at 02:00 PM.
Reason: missing word
I doubt it's the high pressure oil pump failing, but it may very well be in the HPOP's control system.....namely the ICP (injection control pressure) sensor, or the IPR (injection pressure regulator) valve.
The IPR is what is controlling the amount of pressure the pump delivers and the ICP is what measures that pressure.
Thanks , What should I do from here? Is there an easy test that I can do, or should I consider replacing one or both of them? What about the cost and hastle involved?
There are two things that I would do, first I would go and disconnect the ICP When you do this the truck will still fire, and the computer will be in limp mode. (the ICP is located directly behind the AC pump it is screwed into the high pressure oil rail at a 45 degree angle) While you are there down in the valley of the engine on the back of the HPOP is the IPR there is a cheep looking brass nut and a brass looking solenoid with some wires going to it check them out to see if they are loose. I would not bet on a CPS right now, but I would definitely buy one for a spare. (speaking from experience)
that is all the first thing that I would do, the second is I would search the forum for "loping" and read up as that is the description of your problem.
I saw your post on my previous loping idle thread. I will answer here as it will be more help. I would be willing to bet that the transmission selector switch may be causing your lope. When I was researching this problem a few months ago I found a few posts on another forum of a guy who had a lope and a bad selector switch and it fixed the lope when he replaced the sensor. I would try to diagnose the switch first. hopefully somebody here has a procedure they can send you to check it out and then if its the sensor its self replace it. One thing I remember the guy saying is that he could start his truck in neutral and lope would not happen.
I disconnected the ICP and tried to start it, but no change. I did try to start it in neutral, and BINGO, it started normal. I will get a transmission selector switch and let you know if that fixes it permanently. Thanks so much!!!
What about the transmission speed sensor code that we got. Where and how can I fix it, while I am down there? I know the selector sensor is on the side and an easy r&r, but what about the speed sensor?
Good call Beggsy. That's why you get the big bucks!
Originally Posted by tjbeggs
I saw your post on my previous loping idle thread. I will answer here as it will be more help. I would be willing to bet that the transmission selector switch may be causing your lope. When I was researching this problem a few months ago I found a few posts on another forum of a guy who had a lope and a bad selector switch and it fixed the lope when he replaced the sensor. I would try to diagnose the switch first. hopefully somebody here has a procedure they can send you to check it out and then if its the sensor its self replace it. One thing I remember the guy saying is that he could start his truck in neutral and lope would not happen.
Nice call. Repped. Turned an irritating situation into a clear-cut diagnosis with a simple fix. Keep up the good work Tim.
On the vehicle speed sensor I would clean off the case with gasoline and then blow off around the VSS and pull it out and clean it off. They always end up having a bunch of greasy, metallic-like gunk on them and it works better when it's cleaned off.
Hey guys, Last night I cleaned and adjusted my old Transmission Selector Sensor, but it did not help the situation, so I replaced it and it now works great. It starts in Park and Neutral with no more ROMP ROMP ROMP!!!!!
I also removed and cleaned the Speed Sensor, even though it did not look overly dirty or gunked up. The truck shifts better than it has in the 3 years I have owned it. The previous owner told me that the transmission had a fresh rebuild with a shift kit, which was the reason for the harsh shifts. No more harsh shifts. I can not say thank you enough.
p.s. I talked to my friend from Ohio who put the scan tool on it and he is amazed that this was the problem and fix. Thanks Again!!!!!!!!!!!!!!!
thanks guys glad to hear things are good to go now. I still have the romps in my truck. perhaps I need to follow my own advice and get that sensor. I just figured mine is from the strange programming and injectors but it worth a shot. Head to the ford dealer today to pick up somebody and test drive a 6.4 for the fun of it so maybe I would check them babies out.
seen this as well, those selctor switches must be wired into everything. My friend in his 03 ranger had a selector switch issues that caused the air bag light to go on and CEL to be on as well.
No pics but the slector switch goes right on the shift lever where the shift cable attaches. I think you have the remove the cable remove a nut and pop the lever off then you can get to the sensor.