I have 2 symptoms that may or may not be related to each other. The first is a rough engine when I give it the gas in park. It is not immediate but after I have pressed on the gas pedal approximately 1/4 way down. Guessing, I would say at about 2500 to 3500 rpm. No roughness prior to that. Also, when the engine is cold I do not get this roughness at all. When I am stopped at a light the engine runs very rough but when I shift back to neutral it runs well.
The other symptom is a lack of response to the gas pedal after a long highway drive. Yesterday after driving continuously for 125 miles on the highway at 65 mph, I got off the ramp and came to a red light. When I gave it the gas at the green lite, I had very little acceleration even though I had the pedal half way down. The engine increased aceleration gradually until I was up to speed. After I let the engine cool down I had no problem with acceleration. This is the second time this has happened in the past month.
What's up with this????

In the past six months I have replace the plugs, wires, ignition coil, cam syc gear and cleaned the egr ports by taking the upper intake off. I add fuel injector cleaner every 1000 miles. Most of my driving is short trips with occasional trips of 100 miles or more of highway driving 2 or 3 times a month.
Aslo I changed the fuel filter 15k miles ago. I have also given the engine 2 treatments of seaform in the past 2 months.
I am leaning towards a fuel problem but I would certainly appreciate any help I could get.

Dan

 

What exactly are you working on? Year, engine size, etc.

 

sorry for the delay lxman...I had an activation problem when I changed my email. I have a 1997 4.2 automatic f-150 with 95k on it. Since I wrote my first I have found where a leaking lower intake gasket could cause the problem. I do have a vanishing coolant problem and I also experience hard starting occasionally in the mornings. I visited leakingfords.com site and the symptoms fit at least some of my problems. What do you think?
Dan

 

i know this sounds stupid but when was the last time you changed your fuel filter??? that seems to help alot when acceleration decreases, also i believe you said you had a 4.2 liter, i hate to tell you but i think that type motor is worth a bunch of crap i hate those engines every one that i have seen rode in or heard has had a bent rod or a broken one

 

Hi Dan, and welcome to FTE.

This topic or one similar to it was recently discussed in a long thread... I suggest you read through it - I think you may find some answers there:

https://www.ford-trucks.com/forums/s...ighlight=delay

I hope this helps you out.

Ryan

 

Thanks for the replys. As far as acceleration is concerned, this is a different problem. It only seems to happen after a long highway drive better than 100 miles. I decided not to take any chances. I made an appointment at the ford dealer to install a new lower intake gasket tomorrow. After reading all the problems with this gasket I decide to have it done since I don't have the time to do it myself. The dealer quoted me $600 (chicago prices) for the job. Let's see what happens after the new gasket is in place. I am suspecting that I definitely have a problem with this gasket since I am experieceing loss of coolant and hard starting. Also, since I am having this done, the dealer has agreed to change the heater hoses and thermostat at no additional labor costs, just parts. I will let you know how it runs after the repairs.

Dan

 

I hope it turns out well for you, Dan, and fixes all your problems!

Ryan

 

You might want to have them clean the MAF sensor while you're there too. it only takes a few extra minutes.

 

Well, the new lower intake gaskets were installed at the dealer yesterday. I am very lucky that I brought it in when I did since the gasket was torn in 3 places and I was definitely leaking coolant into the cylinders. Here are the symptoms and the results after the gaskets were replaced.

loosing coolant, about 1/2 galon a month.....gone.
hard starting.....gone.
rough idle.....gone.
rough running at about 2500 to 3000 rpm.....gone.
poor gas milage......gone
loud running engine....gone.
misfiring cylinder #3....gone.
poor acceleration after long highway drives.....gone

Can you see why I am so happy? If any of you have a 4.2 that has any of these problems you should seriously consider replacing the lower intake gaskets. Oh by the way, prior to replacing the gaskets I did try the usual troubleshooting for the symptoms above. I changed the fuel filter, changed all the spark plugs with motorcraft plugs, changed the wires, changed the coil pack and removed the upper intake to clean the egr ports. These never fixed the problem although they did minimise it somewhat.

I'm a happy man even after spending $600. The truck is a 1997 and has 95k on but runs very well. At least I do not have to worry about that dam gasket anymore or blowing the engine. I am going to post this response as a separate entry since so many people have these syptoms.

Thanks for all your help.

PS. I did not have the heater hoses replaced since the dealer wanted an additional $372 to do this. What's up with that? $372 for heater hoses? Also I read about the MAF sensor to late. Thanks again.

Dan