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I have a 1998 Eddie Bauer Expedition with a 5.4L engine. Lately, I have noticed that if the truck sits all night in the rain, or it is extremely humid outside, I get hesitation on take-off. This starts after about 10 mins of driving and is gone after another 30 mins of driving. I changed to super unleaded gas (ouch!). I still have the problem. In good weather (no rain and average humidity) there is no sign of the problem. I'm not getting any check engine light where I could get a code. The engine is stock with the only mod being a K & N Air Filter. This problem is driving me crazy. I hope someone else has had or seen this issue and can point me in the right direction.
Wow, that's a weird sounding problem. The only thing I can think of is the electronic control module is getting a little too damp and takes a few minutes to dry out.
I had it in the shop this morning. The removed the spark plug boots and put di-electric grease on the boots, but this has not solved the problem. My gas mileage is crappy, and this problem is driving me crazy. What is the ECM?
Try searching on startup and hesitation problems. I know I have read about this problem on here before but I do not remember what the cause was. Sorry I could not be of more help...
About 2 years ago, I replaced the pcv valve/hose assembly (the elbow bend was melted away causing rough idle). I checked this morning, and another soft rubber bend has softened and collapsed. Would this cause my problem?
Update:
Replaced the PCV assembly and the problem persist. The only difference now is that I'm finally gettting a check engine light with the code P0171 (engine running lean on bank 1).
I was speaking with a mechanic at the local shop who own a 1998 Navigator with the 5.4L engine. He was telling me that when he had this problem the solution was to replace all 4 oxygen sensors, and the problem vanished. I have had cars with bad oxygen sensors, but it didn't affect the way they run. Can someone tell me if this sounds right?
Update: I took my truck in to be diagnosed on Wed. The mechanic called me and said that he was checking the fuel injectors. He removed the #1 injector and put it back, he removed the #2 injector and put it back. He went to remove the #1 injector again, and the engine smoothed out and ran fine. I got the truck back, and it is fine with the exception of a small hesitation if I get on the gas hard. If I ease down on the gas, there is no problem at all. Any further suggestions?
Update: I took my truck in to be diagnosed on Wed. The mechanic called me and said that he was checking the fuel injectors. He removed the #1 injector and put it back, he removed the #2 injector and put it back. He went to remove the #1 injector again, and the engine smoothed out and ran fine. I got the truck back, and it is fine with the exception of a small hesitation if I get on the gas hard. If I ease down on the gas, there is no problem at all. Any further suggestions?
Why didn't he replace the #1 injector then and there? Sounds like the possibility that you have a partially clogged injector. You can run a can of Techron through the tank. Sometimes it will clean a partially clogged injector. If it doesn't fix the problem, at least it won't hurt anything. I have cleared up very minor induction problems with it in the past. Would be worth a try.
I was speaking with a mechanic at the local shop who own a 1998 Navigator with the 5.4L engine. He was telling me that when he had this problem the solution was to replace all 4 oxygen sensors, and the problem vanished. I have had cars with bad oxygen sensors, but it didn't affect the way they run. Can someone tell me if this sounds right?
The only time that I had a bad O2 sensor, the truck ran like a DOG.
I had the same problem with my 5.4L '99 EB. It would start after the truck would warm up and if i was crusing at 40mph and went to speed up it would start to hesitate and it ended up being a bad coil pack on cyl #2. The dealer replaced the pack and solved my problem.
I have a 99 F-150 Lariot and now I have a check Eng light ....had a diagnostic and was told it was my O2 sensors.....he said I had 4...I was shocked...I thought I only had two.....after reading it looks like I do have 4.....I dont think replacing them will be bad....and I need to do it soon....rough Idle and even shuts off at red lights.....
I found another vacuum leak and fixed it. That solved all of the issues with the way the truck runs. I cleared the CEL. I got it back now, with codes P0171&P1074, but no issues with the way the truck is running.
For the problem when it rains:
I've heard of some hose leakage right above #1; could cause rust, etc. You also may want to put a water hose to your windshield and check for leaks into your engine compartment. Just my 2 cents...
Why didn't he replace the #1 injector then and there? Sounds like the possibility that you have a partially clogged injector. You can run a can of Techron through the tank. Sometimes it will clean a partially clogged injector. If it doesn't fix the problem, at least it won't hurt anything. I have cleared up very minor induction problems with it in the past. Would be worth a try.
That was his rationale. He had me run the Techron through the tank before replacing the injector. The problem seems to be gone now, but I still get the P0171&P0174 codes (but the truck is running fine).