irregular speed
Thread Starter
|
Mountain Pass
Joined: Jul 2005
Posts: 113
Likes: 0
irregular speed
I've been trouble shooting this truck since June and with the help of the members of this forum I've managed to fix a lot of problems. Thank you !!
I've swapped most sensors and/or tested them. I did find plugged vacuum lines etc. Those were replaced and all the others checked to see if they hold vacuum. The problem is that the truck doesn't hold a constant speed, at any speed. It is constantly speeding up and slowing down unless I'm accellerating. It also tries to die when I slow down and turn. Fuel pressure,timing, and vacuum are correct. I do reset the computer every time I change anything but can only drive it 1-3 miles due to the tags. The only code I get is a 12. I've checked for vacuum leaks and swapped the IAC, and tested the O2 sensor. This is getting old.
Any other ideas out there ?
I've swapped most sensors and/or tested them. I did find plugged vacuum lines etc. Those were replaced and all the others checked to see if they hold vacuum. The problem is that the truck doesn't hold a constant speed, at any speed. It is constantly speeding up and slowing down unless I'm accellerating. It also tries to die when I slow down and turn. Fuel pressure,timing, and vacuum are correct. I do reset the computer every time I change anything but can only drive it 1-3 miles due to the tags. The only code I get is a 12. I've checked for vacuum leaks and swapped the IAC, and tested the O2 sensor. This is getting old.
Any other ideas out there ?
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
The "also wants to die when I slow down & turn" part, kinda makes me want to suspect something is going on with the EGR system, but thats just a wild guess.
Which year, engine, tranny, miles, ect, are we talking about here.
Kinda bring us up to date on the repairs you've done so far!!!!
Did this present problem begin slowly over time, or suddenly, after some event???
Which year, engine, tranny, miles, ect, are we talking about here.
Kinda bring us up to date on the repairs you've done so far!!!!
Did this present problem begin slowly over time, or suddenly, after some event???
Thread Starter
|
Mountain Pass
Joined: Jul 2005
Posts: 113
Likes: 0
Gee, I'm sorry! Excuse me for being a bonehead! I did mean to input that info. I'm talking about a 1986 ranger with EFI, a 2.9, and AT. I don't really know the miles, figure high mileage. It has done this since I bought it. I had a melted hose in the gas tank that starved it for gas, replaced both fuel filters, tuned it, repaced the distributor module, both u-joints, muffler and pipe, gutted the cat(for now-it was plugged). The O2 sensor is in front of the cat so that isn't a cause.
I did have an EGR problem and it was a plugged line to the EGR control valve. Both have been changed.
I keep wondering if the problem is the speed control sensor ?
I get a code 12 and this is what my book says: 12= vacuum leak/TB base idle off/idle air valve dirty or bad, EGR stuck open.
I did have an EGR problem and it was a plugged line to the EGR control valve. Both have been changed.
I keep wondering if the problem is the speed control sensor ?
I get a code 12 and this is what my book says: 12= vacuum leak/TB base idle off/idle air valve dirty or bad, EGR stuck open.
Last edited by Wildpony2000; Apr 9, 2006 at 10:44 AM. Reason: forgot info
Thread Starter
|
Mountain Pass
Joined: Jul 2005
Posts: 113
Likes: 0
Today I exchanged the IAC and tested - still a code 12, removed the EGR valve, tested it, plugged one vacuum line to it at a time and ran tests. Both times I got a code 33. Hooked it up right and the 33 went away. I tightened the manifold bolts and tested the vacuum lines again. Am I missing something simple here ?
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
OK, good testing, at least the computer is awake with regards to the EGR being on line.
I'm not familar with your year/model EGR system, but does it have a DPFE valve controlling the EGR???? If so check it too, as on later models with a DPFE, it controls when & how much the EGR is suppsed to open & if it screws up & calls for EGR when you don't need it, things can act as you've described.
The DPFE is a common problem on later models.
I've heard that earlier models of the DPFE can sometimes be cleaned up of carbon, so they'll work ok, but later models don't clean up well & have to be replaced when bad.
I'd continue to work the code 12 until it's put right.
Not saying you might not have a acting out speed sensor, but imo it's not likely figuring in on the surge problem.
The O2 sensor could though, if it's lazy on feedback to the computer.
The computer uses it's signal to judge how it's doing on adjusting the fuel injectors "on" pulse. So if it's slow in signaling whats going on, the computer is always playing catch up!!!!
Just some thoughts for pondering!!!
Maybe someone with detailed knowledge of your year/model will chime in with some detailed info.
Do you have a repair manual????
Let us know how it goes
I'm not familar with your year/model EGR system, but does it have a DPFE valve controlling the EGR???? If so check it too, as on later models with a DPFE, it controls when & how much the EGR is suppsed to open & if it screws up & calls for EGR when you don't need it, things can act as you've described.
The DPFE is a common problem on later models.
I've heard that earlier models of the DPFE can sometimes be cleaned up of carbon, so they'll work ok, but later models don't clean up well & have to be replaced when bad.
I'd continue to work the code 12 until it's put right.
Not saying you might not have a acting out speed sensor, but imo it's not likely figuring in on the surge problem.
The O2 sensor could though, if it's lazy on feedback to the computer.
The computer uses it's signal to judge how it's doing on adjusting the fuel injectors "on" pulse. So if it's slow in signaling whats going on, the computer is always playing catch up!!!!
Just some thoughts for pondering!!!
Maybe someone with detailed knowledge of your year/model will chime in with some detailed info.
Do you have a repair manual????
Let us know how it goes
Thread Starter
|
Mountain Pass
Joined: Jul 2005
Posts: 113
Likes: 0
Thanks PawPaw.
No this year does not have a DPFE sensor, it has a EGR Valve Position Sensor and an EGR position sensor which I've swapped out with 2 others. The only change was after I found the the vacuum lines going from it to the EGR was plugged by a sloppy splice job (siliconed the rubber vacuum lines together).
The O2 was my next step, it has an after market and I need to get the connector also. No telling what type it is.
I do have both a repair manual and a set of Mitchell auto repair CDs.
No this year does not have a DPFE sensor, it has a EGR Valve Position Sensor and an EGR position sensor which I've swapped out with 2 others. The only change was after I found the the vacuum lines going from it to the EGR was plugged by a sloppy splice job (siliconed the rubber vacuum lines together).
The O2 was my next step, it has an after market and I need to get the connector also. No telling what type it is.
I do have both a repair manual and a set of Mitchell auto repair CDs.
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
I know you've said it's done the surge thing since you've had it, but did you have this "surge" problem before you gutted the cat????
Trending Topics
Thread Starter
|
Mountain Pass
Joined: Jul 2005
Posts: 113
Likes: 0
PawPaw, yes, and the only O2 sensor (1) is before the cat. Before I gutted it it would only run for about 3 miles, lose power, and die. Your suggestion about the O2 sensor being sluggish makes sense and is on the code 12 list. I have tested it so I do know its working, but not if its sluggish.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Thread Starter
|
Mountain Pass
Joined: Jul 2005
Posts: 113
Likes: 0
I bought an OEM style Bosch Oxygen sensor from AutoZone for $39.99+tax and got a code 12 technical repair
readout. Then I went to Pic-a-part and got the connector ($16 ordered from NAPA) for the $2 entry fee.
I wired in the connector to this code:
My Chassis wiring is:
: Light Brown -> chassis 12v -> sensor white
: Dark Brown/Black -> chassis ground -> sensor white
: Light Green -> chassis signal -> sensor signal
The Mitchell CD wiring diagram shows:
Dark Green/yellow stripe as ignition
Dark Green/purple stripe as signal
Black/light green stripe as ground
The connector wiring is:
Dark Green/yellow (ignition ?)
Light Green/purple stripe (signal ?)
Black/light green stripe (ground ?)
That's how I wired it.
1st test: KOEO 11 10 11
KOER 12, 42
Hmmm, bad O2 sensor ? I just changed it. Maybe I should try reversing the wires ?
I think I'll clear it and test it again.
2nd test: same codes.
changed the signal wire and the ground wire.
3rd test: 12, 41
hmmm.
Any comments ?
readout. Then I went to Pic-a-part and got the connector ($16 ordered from NAPA) for the $2 entry fee.
I wired in the connector to this code:
My Chassis wiring is:
: Light Brown -> chassis 12v -> sensor white
: Dark Brown/Black -> chassis ground -> sensor white
: Light Green -> chassis signal -> sensor signal
The Mitchell CD wiring diagram shows:
Dark Green/yellow stripe as ignition
Dark Green/purple stripe as signal
Black/light green stripe as ground
The connector wiring is:
Dark Green/yellow (ignition ?)
Light Green/purple stripe (signal ?)
Black/light green stripe (ground ?)
That's how I wired it.
1st test: KOEO 11 10 11
KOER 12, 42
Hmmm, bad O2 sensor ? I just changed it. Maybe I should try reversing the wires ?
I think I'll clear it and test it again.
2nd test: same codes.
changed the signal wire and the ground wire.
3rd test: 12, 41
hmmm.
Any comments ?
Thread Starter
|
Mountain Pass
Joined: Jul 2005
Posts: 113
Likes: 0
4/19/2006; I rotated out the MAP sensor and it tested the same.
I also found that the wiring by where I was splicing in the connector had been painted, apparently to match the 2 white and 1 black wires on a universal O2 sensor. I traced them back to their source and re-wired them to matched colors.
2nd test; 12 and 41 is gone
I rotated out the EGR control valve.
3rd test; 12 and 42.
4/20/2006;
Looking at the wires and my schematic it looks like I switched 2 wires on the O2 so I changed them and came up with codes 12 & 42 again.
I checked both IAC valves (the original and a spare) for resistance and they measured within specs. I checked the supply voltage and it seems to be the same as the battery voltage. So I guess my IAC is good.
I checked for vacuum leaks using the propane method - no change in engine speed.
I don't know where to hook up my handheld tach to set the throttle body idle speed.
If that's not it then I guess its time to start throwing parts at it.
I also found that the wiring by where I was splicing in the connector had been painted, apparently to match the 2 white and 1 black wires on a universal O2 sensor. I traced them back to their source and re-wired them to matched colors.
2nd test; 12 and 41 is gone
I rotated out the EGR control valve.
3rd test; 12 and 42.
4/20/2006;
Looking at the wires and my schematic it looks like I switched 2 wires on the O2 so I changed them and came up with codes 12 & 42 again.
I checked both IAC valves (the original and a spare) for resistance and they measured within specs. I checked the supply voltage and it seems to be the same as the battery voltage. So I guess my IAC is good.
I checked for vacuum leaks using the propane method - no change in engine speed.
I don't know where to hook up my handheld tach to set the throttle body idle speed.
If that's not it then I guess its time to start throwing parts at it.