1998 Ford F150 4.2 – I'm getting really tired of this truck. I've spent days here, can't figure out.

Trouble starting, runs rough, no power…the first time you turn the motor over it will run rough and stall (just like when you shut a car off and it kept running, as a kid we called it “dieseling”). The second time you start the truck it will run. It has no power and hesitates when you hit the gas. When on the highway and you floor it there is no acceleration. I replaced the Manifold Runner Control Valves, PVC, EGR valve, Fuel pump, fuel filter, Idle Air Control Motor, Throttle position sensor, and Air charged temperature sensor. I can’t find any vacuum leaks and the code reader spits out a useless code, I don't recall the number. I took it to a mechanic who cut open the catalytic converter and tore the guts out of it, he said something about a sensor and it appeared to be running hot, could be clogged, I don’t recall exactly why, no improvement. He removed and cleaned the injectors, said they were already clean. He’s stumped and says the timing chain may have jumped a link. Any suggestions?

 

Sorry..I meant to post to 6 cyl board

 

Please get the exact code.

Did the mechanic gut all 4 cats? Have you thought about changing the plugs and wires? MAF sensor?

 

You did check the fuel pressure? right?

 

what method are you using to check for a vacuum leak?

 

I have no way to check the fuel pressure. I'm assuming the new fuel pump and filter solved that problem.

I did replace the MAF, no improvement.

I made a visual inspection of the vacuum system, listened for leaks, and checked all the connections. There has to be a better way, someone mentioned blowing smoke into the lines. Guess I'll have to buy a cigar.

I have not replaced any of the ignition parts.....yet. That's probably next.

As far as a timing chain jump......I doubt it. Seems like it would run much worse if that were the case. Besides, it doesn't seem wise to rip the motor down to the timing chain just to check it. With my luck the chain will be lined up properly.

The mechanic did gut the cats.

I'm going to pick the truck up this AM, I'll get the exact code.

 

Parts stores should have a fuel pressure gauge in their loaner parts kit.

Use only Motorcraft parts.

You sure he did all 4 of them?

 

My mechanic said he gutted two cats.....wasn't aware of two more. It is a six cyl. Are you sure there are two more? If so, I'll take it back down to him.

I had this truck shipped to the Bahamas where I work. Point is.....getting a fuel pressure gauge would take a couple months to have shipped down.

You can add new plugs to the list of parts I've installed.

Maybe I am imagining it but the truck seems to be running slightly better...not much. Hesitates when you hit the gas and no power. At higher speeds there is no acceleration until it kicks into a lower gear and it might backfire before taking off with slow acceleration.

The check engine light is off so it's not kicking out any codes.

 

There are 2 cats on each side.

Left:



Right:



Change the plug wires.

 

I crawled under the truck. It does have 4 cats. The mechanic said they were clean so doing the other two aren't necessary.

I have new plug wires and ignition coil coming in from Nassau in a few days.

I'll let you how it goes.

 

Block off the intake with a cup in the intake tube, attempt to crank the truck. If it's got a small leak it will whistle where the engine is pulling air in from. If it's got a bug leak it might actually stumble and start running, but it should still whistle.

If the system is tight it should hold vacuum on the intake.

 

OK.....add new spark plug wires, coil pack, EGR feedback sensor, and vacuum regulator solenoid to the list of replaced parts above....

Fuel pressure is about 32 lbs.

I put a cup in the intake to listen for vacuum leaks. I don't hear any leaks and there is no whistling.

Double checked the firing order, all plugs and wire are correctly hooked upped to the coil pack.

No improvement, no codes......almost stalls when coming to a stop, I have to feather the throttle keep in going and start moving.....runs like garbage.

 

Double check your plug wire placement coming off the coil. It's not a simple 1,2,3 4,5,6

 

32 psi is a bit on the low side for fuel pressure - minimum is 28 and maximum is 40.

With the engine off, pull the vacuum line off the fuel pressure regulator. If any fuel drips out or you smell fuel, the diaphragm is cracked and the FPR needs to be replaced. Also, with the gauge hooked up pull the vacuum line, the pressure should rise at least 5 psi.

What brand plugs, wires, and coil did you use?

 

The wires are Bosch, they look like better quality than the old ones. The coil is MSD high performance. Not sure of the plugs...the mechanic put those in, I can't get a good look at them.

I'll check the fuel pressure regulator. Idle is around 35psi drops to 32ish when throttling up.

I Stopped by to see my mechanic and report my lack of progress. He's still convinced the timing chain jumped a link due to the overall lack of power. He described it in a language I can understand......comparable to the old points and distributor ignition system with a vacuum advance. The only time the truck seems to run ok is at higher speeds when I punch the gas. It will stutter and pop before kicking into a lower gear and then take off at higher RPM. The computer is throwing the spark ahead enough to slightly compensate for the jumped link. Sounds good but with my batting average on this truck who knows...........It's possible, the truck has 270K on it. I've heard of chains stretching a bit or tensioners wearing out.

I told him was going to wait a day or two on this forum to see if someone can come up with a better idea before ordering a timing chain and gears.