hi all. so we have a 99 e250 with the 5.4l, about 175k miles.

was misfiring and throwing codes about a year ago, so i replaced all the cops and spark plugs and the engine ran great again. fast forward to now, we haven't been driving the van much but want to start driving it again, it hesitates and stumbles again.

my dad took it to the shop to fix it(i'm short on time at the moment), and they replaced the egr valve and they detected a misfire on cylinder 6, so they replaced the plug on that cylinder. still misfires, but is not throwing any codes.

seems to run fine/no misfire when dead cold, or at least thats what i noticed earlier today. but once warm, misfires maybe in one cylinder. still driveable but lacks power, hesitates. seems like all the cylinders are running, i pulled each connector off of the cop while engine is running and each makes the engine miss, so that seems to me like all the cop are working, at idle at least. but you still notice a hesitation at idle, like its not as smooth as it should be.

what should i check next? fuel injectors? its not throwing any codes at the moment so that makes it harder. and the van is so hard to work on since you have to access most of the engine from inside.

what do you guys think?

 

Sounds like a low grade misfire. Do a scan for misfires with a mode6 scanner to find the cylinder thats giving you the problem. More than likely a COP problem but with that many miles it could also be a valve problem.

 

This sounds exactly like my problem. Very similar vehicle too, '98 E250 van, 5.4L, 184k miles. I'm thinking my cat may have went bad, but I'm currently waiting for the computer to throw some codes.

 

2001 F250 5.4 SD 264,000KM
I have the same problem but I get it while driving... massive hesitation. I do all my maintenance religiously and the only thing I can guess the problem is EGR, Cat, bad sensor or something I don't want to even speak of....Im waiting for a friend to find his reader so I can see what codes are stored.

 

I have a similar problem:
2000 Ford F250 4X4 5.4L 2Valve "PI" w/Auto Trans
Cold starts: ( +3 degrees Fahrenheit ) the truck runs great. No loss of power, no hesitation. No diagnostic trouble codes.
Warms up: Starts to hesitate, still no check engine light or codes.
Operating temperature: Runs like crap, rough idle, hesitates. No codes.
Highway speeds: Bucks and jerks so hard that the dash rattles, revving the engine and dropping a gear temporarily relieves the problem. Still no check engine light or codes.

My original diagnosis was water in the fuel (common problem here) and it seemed to get worse as the fuel level dropped in the tank. However, I pressure tested the fuel system and found 35psi @ idle and 40psi under load, well within Ford's specifications of 28 - 45psi at the fuel rail. Then I refilled the tank and ran 2 bottles of Iso-Heet (water remover ) through it and replaced the fuel filter. Still no results. At this point, I kind of have to rule out water in the fuel as the source of the problem.

Today, I had a friend put Ford's New Generation Star (NGS) tester on it and drive the crap out of it. All he found was a cyl 5 misfire in the computer's history (once apon a time). No current codes or misfires.

Some of the things I have ruled out include:
Vacuum leak - scoured over every hose, found no leaks.
Transmission - problem remains in every gear, even P, N, and R.
Air restriction - replaced filter, checked tubes, found no restrictions
Exhaust restriction - checked exhaust system, found no restrictions
Fuel system - fully tested, see above
I have also pressure tested the coolant system to rule out a head gasket or similar problem and everything checked out fine. And just for good measure, I changed the oil and used a Motorcraft filter and oil.
At this point, I have only a few suspects left: the Mass Airflow Sensor could be on it's way out or there could be a problem with the spark plugs or coils (just replaced all the plugs a year ago when I had the engine apart).
This is a very frustrating problem and maybe I'll try to tackle it this weekend. Anyways, sorry for the rambling on and I hope you get yours figured out! I'll post back if I make any progress.
-Jeff

 

Im thinking the EGR is the cause of my problems...Im replacing the valve in a few weeks keep you posted.

 

Yesterday my van threw a code for a misfire in the #7 cylinder. Replaced the coil pack and it's all good now. Well, at least until another one goes bad...

 

Today, I put the scan tool back on it and low and behold, the old misfire code popped up (cyl 5 misfire). After I cleared it, it came right back. For some reason, it still runs great when it's cold and the check engine light has still not come on. I think it's time to change the coils and plugs. Does anyone have a recomendation for some high-quality spark plugs? And has anyone had any luck with the ACCEL coil units? I hear they are alot cheaper than OEM.
-*o*- REWASDRTY

 

My son put the Accel coils on his '01 Cobra and a few months later told me he wishes he had stayed with the Motorcraft/Autolite units as there was a noticable loss in performance and he tells me that a lot of people in the various Mustang and Cobra boards are changing back to the OEM coils. I have stayed with the OEM units with no problems. But my son says I'm old and probably would not notice a difference.

 

Gonna take your advice on this one... just got the new OE unit in and will try to find time to install it. Wish me luck!
-*o*- REWASDRTY

 

I'm having the same problem with my 97 Expy 5.4L. Cylinder #5 code came up, I replaced the COP, spark plug, and even the injector. Now there are no codes present, but still the misfire. It's barely noticeable at idle, but anytime you put a load on it, misfire. Pulled a few plugs, burning very lean and hot according to a friend. I cant find a vacuum or fluid leak. I do hear and have heard some rattling in the cats. I have no idea if they could be blocked. I have 149,000 miles.

 

As for plugs use either Motorcraft or Autolite double platinum plugs for the best results.

 

If you bought a tankful of contaminated fuel you could mess up your cats and may need to have a sniffer test done by a qualified shop or mechanic to find out what is in the exhaust gasses being emitted. A clogged fuel filter could cause a lean condition in your engine as well as damage to your injectors. I would check/replace your fuel filter first.

 

Thanks Moto Mel and LxMan1. I just got off the phone with Advance Auto. I will be heading there after work tomorrow for the MC plugs and a new fuel filter.

 

Do the filter first and try to run it if it clears up you will know that it was fuel related, then do the plugs and your truck should really run better. Making two changes at one time is never a good idea because you will never know for sure what helped the most. When you get the filter off see if you can blow through it backwards and see what comes out. One more thing, just in case you don't know it, it takes a special tool to remove the filter from the line. If you don't already own one I'm sure the kind people at Advance will be glad to sell you one. I don't think they loan them .