I have the 97, 4.6, 4x4, 180,000 miles, screw. I have a misfire issue that comes and goes. The shop usually says misfire on 1 and 3 and I have had the coils replaced, plugs replaced, three times. New O2 sensors, new temp sensor, new MAF sensor, hi-flow cats, and the K & N cold air intake.

The problem is the misfire issue which comes and goes. All the changes I list above is the result of three different shops diagnosis. However, the misfire comes and goes. The truck really purrs when not misfiring and runs about 16 mpg.

There once was a post about turning the truck iginition on for three seconds without starting the truck, then turning the key off, then repeating a number of times. This seems to make the truck run smoother more often than misfiring. I have been going through this ritual since I read the post and am happy the truck runs better.

If someone can remind me of what the cure listed was on this post I would appreciate it. I plan on replacing the coil packs in a couple of weeks with either Accel or MSD.

 

Is this supposed to be a one time fix or a do it on a regular basis fix????? and when you say "a number of times" do you mean 5 times or 12 times....

 

I usually do it three times then the truck will start and run okay.

The things is, I don't want to have to do this everytime I start my truck, but the post I read before recommended a fix for this, but I do't remember what it was.

 

This procedure is often suggested when weak fuel pump problems are suspected. It allows fuel rail pressure to build by cycling the pump several times to correct for either a fuel line restriction (ie, filter), excessive pump leakdown, or a weak pump.

A fuel pressure guage would be useful in determining if, in fact, you have a fuel pressure/delivery problem (which I'd tend to discount). If you did, you'd notice other symptoms of low pressure as soon as the engine started.

Can anyone remember which portion of the intake gets the EGR inlet flow and which cylinders get the bulk of the EGR flow? Perhaps there is unwanted flow that is dumping into those particular cylinders and leaning them out.


Steve

 

cycling the igntion runs the fuel pump. It takes less than a second to build pressure but can take 5-10 seconds to push the air out of the fuel rail and into the return line. Most likely is the fuel pressure regulator or the fuel pump. Less likely is a fuel line or injectors that leak fuel. Injectors can dribble a little fuel into the intake. the fuel pressure regulator and injector leaks will also usually cause an extended crank on warm/hot start after sitting 15-45 minutes. after long sit start good. You can pull the vacuum line off the fuel pressure regulator and if any fuel is present its bad. you could possibly have a restricted pressure line but that would set lean codes and power loss. and least likely the fuel could boin in the rail causing air to form. some models of vehicles have TSB's refering to this like 2000-03 Cherokee 4.0. Don't know if ford does. realy best to have a fuel pressure guage to quickly and accurately troubleshoot this. I don't think changing the coils on this stock motor will make anything you can feel. Most think it does, the plecebo effect

 

Thanks, now I have something to work on other than coil packs. This truck runs excellent when it isn't misfiring. I just ran 100 mph behind an Impala the other day for about 10 miles. The guy was probably surprised to see such an old truck running right on his tail.

Thanks for the info.