I just got to 140,000 the truck is running a little sluggish but still solid as a rock. Suggestions for a complete tune-up??? i have gone through plenty of threads but still not sure what's best for my 98 any help is helpful???!!

 

Besides the obvious (spark plug change (use motorcraft platinum plugs!), air and fuel filters I would go with an additional do-it-yourself jobs that may help out your sluggishness.
When I had to do my '98 5.4 with around 110k or so, I included the following besides what I mentioned above.
First thing is to disconnect your negative terminal from your battery. (This will reset the computer when you reconnect the battery.)
When changing the air filter (assuming your doing the tune-up yourself) I cleaned the Mass Air Flow sensor located on the other side of the air intake tube. If you look at it you will see two nodes sticking out into the middle of the tube, these should be silver looking! (mine were black!). These need to be cleaned, to clean I take off the tube and spray the little nodes with Brake-Kleen. (or any good approved electrical parts cleaner). Don't actually touch them, just use the cleaner and let air dry, the can't become contaminated. I then re-attach the air intake tube.
Another issue you may have is carbon buildup within the intake manifold and other parts (ie IAC, EGR valves etc.) A really good product is called SeaFoam, it is a petroleum based cleaner that can be put into gasoline, oil or into one of your vacuum lines. This product cleans off carbon deposits and helps sticky valves etc. I found this at NAPA auto parts and it works great!. You can put a third of the can into the oil, a third into the brake booster vacuum line and a third into your gas tank. You would then want to get an oil change soon after b/c it loosens up deposits.
Just my two cents, and I'm sure many here have there ways of improving there tune-ups.
Good luck!!
Phil

 

Phil, Thanks for taking the time to explain everything i will try the Seafoam product. Thanks again.

 

No problem, give another post when you have completed the work! I'd like to hear how everything went.

Phil

 

andrews-777,
You mention that you would like to do a complete tune-up. I had purchased my 99 Expy used and it just passed 100000 so I did the following.

Change front and rear differential fluids. This is suprisingly easy. The front has a drain and fill plug. The rear only has a fill plug, so I pulled off the cover(mine had 12 bolts) and let it drain completely. Then I added the 70-140 and 4 oz friction modifier. Clean both mating surfaces of the differental and cover and then put RTV gasket sealant on completely and bolt the cover back on.
Transmission fluid and filter. This just requires removing the pan from the tranny and once the fluid has drained, swapping the filter with a new one. Bolt back on the pan and fill to specs.
Transfer case. I believe that this one has a drain and fill plug like the front differential, so quite easy there.
Fuel filter. Having the line disconnect tool (from any autopart store - I think 5/16") makes this a 10 minute job.
Spark plugs. I decided to attack this based mostly on people's post and the cost to have the dealer do it. It took me about 4 hours, 2 1/2 were on the drivers which I started first. I was pretty cautious as I unbolted the fuel line and go used to the location of the plugs. Next time shouldn't take more than 2 total.
I used this forum and the Haynes manual (section 1 mostly) to do the above. I am definitely a novice and the most difficult job was the spark plugs, but I am glad I did it.
Hope this helpls.

 

I would also recommend that you clean the throttle body and change the Oxygen sensors. You have over 100k miles. I would change the sensors and you should see some better improvement. I would also remove, clean and lube the IAC and EGR valve

I agree with the above suggestion to use Seafoam but would not put it in the gas unless you are taking a long road trip and can burn it all out at higway speeds/temps. I sucked it through the PCV valve and it worked great, when I added the remainder to the gas tank it pinged like a can full of forks falling down a metal staircase for the whole tank. It worked great but ran like crap until it was gone.

 

jbabbler,
How much of a PITA is changing the o2 sensors? I'm pretty sure mine haven't been changed? As far as the SeaFoam I was cracking up with your comment, I only used approx 4 oz or about a third of the can in the gas, and I used the brake booster line for the intake. Maybe the pcv valve route would give me better results? b/c I'm still getting that annoying ping while accelerating, and I'm thinking it could be the o2 sensors even though I'm not throwing any codes.

Phil

 

Pinging is caused by pre-detonation. If its real bad and you've already done everything you can think of, I would start looking at the DPFE sensor or the EGR valve. If the EGR valve is staying closed you will get heavy pinging. As for the O2 sensors, they are easy if you take your time a route the wires properly so as to protect them from rubbing and heat sources.

Good Luck

 

I copied this from another thread:
have a '98 Expy with the 5.4L and was also experiencing detonation under load. It wasn't severe, but it was annoying. It was worse when the AC was on, and also very noticeable after the 2-3 shift. I tried all the usual tricks, cleaned MAF, replaced EGR valve, replaced DPFE sensor, none of these worked. Also, the problem lessened, but did not go away, when I burned higher octane gas.

Finally, I called the Service Dept. at a local dealer and talked to a very knowledgeable writer. I explained to him what I had done and how much time and money I had spent troubleshooting this problem. He told me to bring it in and they would check to see if I was showing any codes (I wasn't) and try to re-program the engine Program Control Module per TSB 001203A. It would cost me $40. BINGO!! No more ping, and I even tried to load it heavily. I turned on the AC, let the tranny shift into OD, let the rpm's drop to about 1500, then floored the accelerator just enough to make sure the tranny didn't kick down. No ping, everyone happy.

I know this applies to the 5.4L, maybe someone can check and see if this TSB also applies to the 4.6L. Heck, maybe someone can link us to the TSB.

I also have pinging on my 5.4. I changed the DPFE sensor to get rid of the code I was getting but it still pings under load. I may try the reprogramming route.

 

Most pinging in Ford's with the Mass Air Flow sensor (MAF) is the MAF sensor itself, air filter surrounding rubbers are breaking and splitting, letting dirt get caught onto the MAF and sending incorrect readings to the computer about the amount of air that is going into the engine, therefore it cannot deliver the correct amount of fuel at a given computation, you might not even get a code even with a bad ping, I do not clean MAF anymore, I asked the Tech teacher at our last meeting about cleaning Ford's MAF, he has done the precedure with a Q-tip and alcohol but does not suggest cleaning them at all, there is a chemical on the wires and cleaners take it off. His title is senior technical advisor, not some shop class. .02 Broken Wire