I've got a '99, 5.4, 4x4...

The idle is rougher than normal and there is a vibration in the steering wheel that's very rythmic when the engine is under load. It feels like there is a cylinder that's not firing right. It also does not seem to depend on what gear the tranny has it in.

My plugs are 20k miles old, fuel filter, oil change, new PCV valve were done about 2k miles ago. I've got 99k miles on it. I have a powerdyne SC on it but removed the drive belt to try and diagnose the problem. The problem does not seem to be as bad when the SC is disconnected.

I did have transmission shudder which a fluid/filter change fixed about 10k miles ago. This problem is not the same as the shudder problem, it feels a lot different. Also, the shudder problem only showed up when it was in overdrive.

Any ideas ?

Thanks, Ron

 

I've also been chasing a rough Idle problem on my 2000 4.6.

Dealer can't figure it out so I Did.

Make sure you have Reference Voltage going to your Cam Sensor
(wire harness) - Approx 3.35 Volts.

Cam sensor is on front of Drivers side Cylinder head.

Cam sensor's function is to control fuel injection
in relation to engine timing.

 

Thanks a lot.

I did check that after seeing your response and it looks to be ok, assuming I got the VM on the right wires. It registered a hair under 4 volts.

Upon several suggestions from some local folks I replaced the EGR valve and the DPFE sensor. Expensive stuff, and totally wasted my money. That did not fix the problem. I changed out the spark plugs again for the heck of it and that did not fix it. I cleaned the MAF sensor and also tried putting the stock MAF sensor back in and neither one of those things did anything to make the problem better or worse. Changed the fuel filter, again. No crap in the filter when I back-flushed it so there's nothing in the fuel tank but fuel. Last 3 times filling it up I went to 3 different gas stations, no difference in the engine miss. There is no check engine light and there are no error codes coming across to my scanner. I'm not losing oil or coolant so there does not appear to be any gasket leakage. Local garage checked fuel pressure and said it was fine, whatever fine means. At least they did it for free.

I'm stumped for now. The thing runs like crap.

I've got an e-brake issue I'm working on today so after I'm done with that it's back to the engine miss.

Ran awsome for 92k miles and now an issue that nobody can figure out. I'm not ready to part with it yet. It's been way too good of a vehile until now. Could not sell/trade it anyway until the problem is fixed since it's obvious there is a problem, especially when you drive it and try to accelerate.

Oh well, back to the garage for brake fun... Sometimes I wish I was at work instead of messing with this...

 

When you changed the plugs out again, how did they look?

How's the timing?

Have you ran a good in-tank injector cleaner?

After a couple of bottles at strong strength and there is a slight change, maybe it's time for FI service?

How's the gas mileage been since you noticed the idle issue- maybe it's just the IAC needin' a cleanin'.

Good luck.

 

Thanks Bill.

I did use Seafoam in the gas tank about 2 tanks ago. 2 cans in a full tank of gas. That seemend to do little or nothing. My gas mileage is not way out of line but it is a bit lower than 'normal'. Every other day it's either 70 or 45 so it's hard to guess if I'm out of line on the mileage or not.

I can try something else specifically designed at a fuel injector cleaner but I've always used seafoam with good results. Who knows...

I may also just bite the bullet and bring it in and just list all the things I tried already so I'm not paying for redundancy.

Thanks, I'll post what it is when it's figured out.

 

Oh, the plugs looked fine. Brownish and they all looked very similar in color. No obvious fouling.

I'm not certain on the timing. I've not owned a timing light or anything like that in 15 years so I'd have to have that checked.

Thanks again.

 

Keep the board posted...

Does not hurt to clean the IAC anyway and to have the base timing checked.

You did not mention- any codes??? I would think if it was missin' it would throw a code.

 

I'll clean it and take it in with a list of stuff I've done to it if that don't fix it. I have a local guy that's pretty good. I'd just rather save the bucks since I can do a lot myself and enjoy doing it myself.

No code, that's the strange thing. I've got my own OBD-II scanner and have been checking for codes and pending codes for about a month. Nothin...

It's not trans shudder (before anyone asks), I know what that's like. I had that before. It's definitely not that.

I'm going to fix my brake problem and bring it in tomorrow and see if they can figure it out. Maybe it's something really stupid that another set of eyes and ears need to experience. At this point I'm running out of options that don't cost a fortune.

Thanks again. I'll let you all know what the deal is.

 

Just a quick note. My stock plug wires cause me a simular problem like yours. The stock wires were toast at 26,000 miles.

 

99 5.4's have NO spark plug wires. Coil packs on top of plugs

 

Ok. I guess things have changed since I bought my antique in 1998.

 

Had a similiar problem with my 98 4X4. but got a code 0174 I think. It turned out to be a damaged 90 degree rubber fitting at the back of the intake manifold that comes from the PCV valve. Probably not your problem but thought I would throw it out there.

Steve

 

Does it happen when the fans are on? or all the time? If the fan blades are dirty from playing in the mud they will cause a vibration.

 

I have electric fans and was not playing in the mud.

The problem seems to come and go. I would reset the computer and it will run fine for a hundred miles or so and then the problem comes back. I still have no clode coming across. I'm clueless on this. Been working on a rear end/brake problem that's actually worse. For those of you who have rear disks read my last post in the brake message board on the BS I had to deal with on the rear drum parking brakes. Geez.... What a pain.

Anyway, now that the brake issue is fixed it's back on to this issue with the miss...

I'm running out of things to try and things to check on this one.

 

I have thought about this, (your miss problem) for a couple of hours now, and the only thing I can think of is to check your 02 sensors. It seems to me they would give a code, but maybe you have a frayed wire, or a dented sensor.

Not much help, but that's all I can think of