I have a 2002 Screw w/ 5.4 which had a rough idle for just one day. No check engine lights and now it is running fine. Would there be any codes to look for if no light came on? Any ideas what might have caused it?

Thanks.

 

you may of had some bad gas. i have heard so some people having that problem before. as far as the mil light. i was told that if the light has came on and then went off. the coded is held there for 1 drive cycle. which i beleave is around 50 miles. it may be around 20 mile. i was have been told both by different people.

furrby

 

The engine didn't get wet did it? This can short out the ignition coils.

 

No the engine did not get wet. I was wondering if it might have been bad gas or a plugged fuel filter, but it wasn't lacking power so I don't think that was the problem. I was thinking it might have been the gas, but it didn't run that way for the whole tank, only part of it. It also seemed to run rough at 1500-2000 RPM as well which makes me think it might have been the gas, but why it didn't do that for the whole tank has me baffled. Anyways I was just wondering what else it might be if the check engine light didn't come on. Thanks.

 

The codes will stay there until cleared !
if you have a scanner that can pull misfire codes,(not all scanners can do it) go in an chk for them.It will tell you which cylinders were bad at the time.
Other things can cause misfire,gas,dirty injectors,ckp sensor flaky,or a loose spark plug in the hole. Cop's are the common failure with 5.4,6.8 liter engines.

If your having rough idle or surging idle the IAC valve could be a problem.
Rich

 

I had sporadic misfiring with my 4.6 - I had it to two different dealerships 5 times and they could not find the problem. It only misfired on start up after it sat overnight or long enough for the engine to cool off during the day. After talking to one Ford mechanic, it became apparent what the problem was - the gasoline. The mechanic told me BP puts an additive in their gasoline that will coagulate on the injector nozzles as the engine cools off. When the engine is started, one (or possibly more) injector will not work properly, causing a misfire and eventually the SERVICE ENGINE SOON light begins to flash and a code is stored in the computer. After you drive a few miles (less than 4 in my case), the engine would start running fine. Apparently, the pressure from the fuel pump was enough to cause the "blockage" to be cleared, the gasoline starts to flow and the engine returns to normal operation, However, the SERVICE ENGINE SOON light stays on and will not clear. Now that the mech. pointed that out, I can recall have the problem within a few days after I put BP in my van. I have switched gasoline and have not had the problem since. Hope this helps some of you guys if you are trying to run down a misfire.

 

TNelson408, I think what you have described might have been the problem. It seems to fit with the symptoms I was seeing. I haven't seen the problem since and have been filling in gas at the all the same places. I guess they can get a bad batch. Thanks for providing the info Tnelson408, it makes me feel a lot better about what happened.

 

Had a 5.4 with same issue, I took it to mechanic and had the meter put on it. Gave me an error code stating Cylinder 2 misfire. He said it was likely the coil and gave me an estimate of $175 to fix it. I went to a auto parts store and bought the coil myself and changed it in less than 20 minutes. Part cost me $48 + tax. Pays to do it yourself.

 

I don't know if it's my area's formulation is different, but I run BP about half the time in my 4.6L modulars and V10, and never had a problem like that

It isn't so much reading "misfire codes" as being able to read the misfire COUNTERS. There is a memory location in the computer that keeps count of individual cylinder's misfires. I don't think they stay there forever either, at least, in my experience with 4.6L's, they don't stay there for very long.

Anyway, get it checked, maybe Autozone can read them ?

art k.

 

Probably you are in the process of "blowing a plug" Compression on that cylinder not what it should be.

Rush, Rush to a Ford service dealer! Have them inspect!!!!!

 

I, like you, used BP about half the time, that is why it took so long to figure out. Last year, the engine did it once and I figured I got some gas with water or something in it. This year, it did it repeatedly and it was always 2 to 3 days after I put BP gas in. I have not used BP since may and have not had the problem again. That seems to have been my issue anyway.

The first time it acted up was about at about 120K miles; I had replaced the plugs and wires at 100K. At one point when the SERVICE light came on, I was able to get to a dealer and they indicated there was a misfire on #7, so I replaced that plug again. But it was not the plug afterall, it was the gas.