1987 - 1996 F150 & Larger F-Series Trucks1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks
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This is what is going on. Thanksgiving weekend, I replaced the radiator, and fuel filter. A few days later, I started to notice that the truck was running rougher than it normally does. It hasn't had a smooth idle since I bought it just over a year ago.
It got to the point where while on the highway, around 55-65mph, that if I gave it more gas, I would get some serious vibration. Thought maybe it was torque converter shudder. Had the tranny flushed at jiffy Lube and it was still there. I took it to the local transmission shop (one of the best around), and they said that it was an engine problem. I pulled the codes... got EGR not detected opening, and not enough input from VSS. The next day, I pulled all the plugs, regapped them, some were .050-.055, when they should be .042-.046. Also, replaced the VSS. Got rid of the VSS error code, but still no change in the way it runs. Replace the cap, rotar, and wires. still no change. replaced the MAP sensor, replaced the EGR valve ( had a bad diaphram), replced the EVP, and put in new spark plugs, still no change. I have also run 2 tanks with marval mystery oil, and that seems to help, not running as rough on the highway. Still have a ping when I give it more gas. Took it to the ford dealer... the said I might have a valve that isn't seating properly.
Did I mention really bad mpg... its really suckin down that gas
Today, I put in 93 octane, the ping is almost gone. also, I check the fuel pressure that checks out ok, about 33-43psi.
i do have an exhaust leak, not sure where (yet), if at the manifold, could this be part of the problem?
What else could be the problem? I havn't checked the timing yet, I assume that the computer compensates for it being off if it is off.
Any help would be greatly aappreciated. Thanks in advance.
Hi, thanks for the reply.
I have pulled the codes, and it still a 33 EGR not detected opening. i was going to check the timing last night, but I can't find my timing light. Gonna borrow one from a freind tonight.
As for the vacuum, i do know that I have a vacuum reserve canister that leaks, I disponnexted that and plugged that line, and still the same problems.
I had it in to the garage... got a good deal goin here, since I know the mechanic. We have replaced the coil, and the TFI module, had the engine cleaned with the motor vac, and still have the problems. Today, checked the compression. That checks ok. Going to change the O2 sensor. still bad. I dented it while putting in the new one. also going to replace the throttle body gasket, and the IAC gasket. engine is still misfiring.
I am starting to think that the computer may be going bad. anybody else had this type of problem????
I'm getting tired of throwing money, time and parts at this thing!
Yup, the same problems. still getting the 33 (egr not detected opening) and 41 Hego detects lean. My mechanic says that he tested the o2 sensor, it switches for little bit and then goes to lean and stays there. I have an ACT sensor kicking around, I may as well put that in to.
Right now, I just happy that the copression test was OK! Thats a good sign. I have the new O2 sensor to put in tomorrow. I really have to get this truck running right real soon, before we get more snow, since this is the only truck I have for plowing.
Ok, replaced the O2 sensor, thats no longer an issue. Also, replaced both vac reserve cans, Still get the misfire under load. Pulled the codes... get a 32. EVP circuit below minimum voltage. At least I know why the egr wasn't opening... the vac canister on the passenger side had a hole rotted in it the size of a quater!
Still doing the misfire under load. I'm getting sick of this... maaybe time for a new truck LOL
I had the same problem with the egr showing no flow. Check to see if you have vacuum at the egr hose at the egr valve from idle to 2500rpm. If you don't then one of 3 things is the problem.
1) EGR solenoid isn't getting power
2) EGR solenoid isn't getting vacuum
3) EGR soleniod is stuck - no vac to egr valve
In my case it was the 3rd one. There is a mini air cleaner inside the cap of the solenoid. Over time it breaks down and gets sucked into the valve causing it to stick. I took mine apart, cleaned it, re-assembled it with a "new" foam air cleaner inside the cap. No more egr code.
Now if I could only find the what is causing the stumble.........
I think I figured out the egr problem. Wasn't getting vac to the solenoids. Big hole in a vac reserve canister.
I still have the ping and the stumble. I think that the next step is going to be replacing the computer. Can the computer itself be tested? I have one price from Napa... $128+tax I hate to throw more money at it and find out that the new part(s) are not the problem... I'm starting to run out of options... my mechanic is also leaning towards it being the computer. Any thoughts?
The experiences I've had with computers is when they fail, they fail. But bad grounds will drive them nuts. I wouldn't throw money that way just yet. This stumbling seems to be a common problem the older Fords. I've changed wires, plugs, rotor, cap and it ran perfect for 2 days and has started the same stumble again. All of my old plugs were running lean so I'm going to replace all of the vac lines for the heck of it, most of them are hard as a rock. The weird part of the problem now is it runs fine until it warms up. I know it will be something stupid that I've been looking at but haven't noticed.
Once it gets past 2000rpms the stumbling is almost non existent.
What rpm range is your's stumbling at?
If you're getting a ping, then your timing is probably off. The computer cannot compensate for incorrect timing. It has to be set right. 10* BTDC.
If you have a valve that's not seating correctly, a wet/dry compression test will prove that very quickly. Typical dealer response. That's why I steer people away from the dealerships.
An EGR valve not opening will cause one hell of a ping and rough running. I have been there, done that.
I wonder if the dealer was not talking about a cylinder valve but instead the EGR valve?
Make sure the vacuum lines for the entire EGR circuit are good, right from the vacuum port on the plenum. Make sure that vacuum reservoir is not rusted through (coffee can). That EGR valve has to open to cool combustion at highway speed so you don't ping.
Wish I read your last post before i bought the computer and put it in. It does seem to run a bit better. not pinging as much, and the stumble isn't like it was. not sure about what rpms the stubming starts/stops. I don't have a tach. Ot seems like when it shifts into OD, under a load, going up a hill, its worse. Maybe I can return this computer to another Napa, and say that I didn't install it, got it for $117 plus $78 core charge. In the mean time, I'll drive it for a day and see what codes I get, if any.
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