Hi all, I asked this last year under engines and didn't get a lot of hits. I have a 1993 F150 4.9L 5 speed with @ 73,000 miles and for the most part it runs good. The problem I have is I have an intermittent miss after the engine warms up. It is more noticeable in warmer weather, which I found strange. Just gave it a complete tuneup which didn't help. I had a couple error codes pop up awhile ago
and they both referenced the EGR valve. I had taken it apart and checked and it seemed o.k. but I am wondering if that could be it. Thanks for any help.

 

Is it missing at all RPM's or only idle?

If it is just at idle, does it effect off idle throttle response or just a rough idle with an occational miss?

Have the fuel injectors ever been cleaned?

Sorry just a few questions to better help diagnose.

 

Hi Colorado, thanks for the reply! Strangly enough it is only noticeable when cruising @ 35-45 mph. It idles fine and runs strong, just a period of misses here and there. I thought maybe it was happening when the egr valve was attempting to open? Like I said it is more annoying than anything. I have run some fuel injector cleaner through a couple of times but never professionally cleaned. Thanks

 

Pull your codes again. I bet you have an o2 sensor that is starting to go bad.

 

Thanks Colorado, will do. Being almost 16 years old it probably wouldn't hurt to replace it anyway.

 

My truck with the 5.8 had a similar issue, which like you said was more of an annoyance than a real problem so I didn't do anything about it. Eventually the CEL tripped, throwing a bad O2 sensor code. Replaced that, problem vanished.

Thing is, I had to get a local shop to remove the O2 sensor off the y-pipe, it was practically welded in there. Even the right size deep socket ended up rounding off the hex, so be careful. Start spraying PBlaster on it like a month before you hope to get it off.

 

Run the engine to heat the engine and exhaust up before trying to remove the o2 sensor and it will come right out. Kind of like exhaust manifold bolts.

 

Thanks for the tips guys. Will try it sometime this weekend.

 

Just a side note this morning while driving to work I did notice a rough idle as well. I don't know if it just started or I just haven't been paying attention enough.

 

Most Fords w/ fuel injection will have an intermitten rough idle as the computer tries to lean things out as much as it can. This is pretty normal on a warm engine even on new vehicles. A intermitten rough idle on a cold engine is a problem.

 

Well, thanks for all the advice guys but sadly, and I do mean sadly, my truck was totaled coming home from work today. Once again was in the wrong place at the wrong time. Such a shame too, that was the best vehicle I ever had new or used. Time to go and drink some beer and cry. Thanks again

 

Pretty easy to come by, get another one. I bought my 1992 standard cab long bed 4x4 last year for $1200.

 

Sorry to hear that, but these trucks are dime-a-dozen around here. I can think of 3 off the top of my head I've seen out for sale within about 10 miles of my house.

You shouldn't have much trouble finding another one if you need a truck. Otherwise, buy a motorcycle! They pay for themselves in a year or two in gas savings. Many newer bikes push 60 MPG, and smaller ones(<500cc) can get into the 70's. Better than 12 in one of these trucks :P