I bought a '98 F150 a couple days ago. It has 134K miles on a 4.2L V6. It seemed to start and run fine on test drive. I did notice when I bought it that all the radio stations had been cleared, which led me to believe the battery had recently been dead.

About 25 miles into my drive home, I stopped and got gas. I put in Premium because the P/O said the truck had been sitting awhile. I thought adding premium would help any potential issues with old gas. A few minutes later into my drive, the "Check Engine" light came on. I dumped in a bottle of Lucas in the hope of cleaning injectors or other potentially offending fuel components. The truck still started and ran well.

Later in the day I took it to Goodyear for new tires, and when I went to start it up to leave, the engine cranked but would not start. It seemed not to be getting fire. One of the guys pulled wire loose and watched while I cranked. He said for about a second it did not have spark, but then it did, and started up. Since then, it has been hard to start and sometimes rough idle at start. Other times it starts right up and runs fine.

I had the codes pulled at Autozone, and it came up P0171. In an effort to clear them, I replaced the o2 sensor on the passenger side after the catalytic converter. I also replaced the coil. Neither of the changes made a difference in the performance or in clearing the code.

I read that I could remove a battery cable for 15 minutes to clear the codes, so I did. It worked, and I now believe it is likely the P/O did the same thing before I bought it. The bottom line is that I need to get the truck inspected and make it reliable. I would appreciate any thoughts or insight into this problem.

Thanks

 

That could could also mean that the MAF is dirty. Especially if you have an oiled air filter (like a K&N). Since you said that replacing the O2 didn't do the trick I'd go after the MAF next. What you can do is reach in and unplug the MAF, to force the computer into failure mode. By disconnecting the battery, you're also putting the ECM into a 'learning' mode and for a couple of miles it will only half trust it's sensors. But once you drive for a while the problem should come back.

If that's the case you may be able to get away with just cleaning the MAF. Otherwise it's about $180 for a new one, and you should be back in business.

mark

 

Thanks for the reply.

I pulled out the MAF, and it looks like new. I blew off the filaments anyway, and this made no difference. My understanding is that if this were the case, both banks would have been throwing codes. In my case it is only bank 1. Also, I don't think this would result in the sudden bout of intermittent hard starting. However, I am open to re-education.

 

Whoops... That's my fault I should have read that you didn't have P0174 (unless you have a bad O2 on that side too). In that case you could have a vacuum leak somewhere after the MAF. I'd also check the fuel pressure on bank 1.

 

Interesting comment, "a delayed spark and then the engine started". Could you clarify that for me? Perhaps I miss read the statement. Continue to look for things that can cause the lean condition on bank 1 (passenger side). Sorry for the needless O2 replacement. Most everyone falls into that trap.

 

Thanks for the replies guys.

I was in the cab and one of the tire guys from Goodyear was under the hood. He told me to crank it. I did, and he shook his head no, then said, well there it goes. Then the engine started. It was as if there was no spark for the first few revolutions.

Update: I had to get it inspected, so I pulled the battery cable off. I replaced it after 15 minutes, and the CEL is off, and I have had no further starting problems. I was able to get it inspected.

I wonder if putting in the Premium over the old gas, then adding the Lucas oil immediately afterward threw the computer off.

I appreciate any thoughts.

 

As far as the premium vs regular thing, I usually side with those who say that premium makes little difference unless you're running high compression. Higher octane means that it's harder to ignite, which is a good and bad thing. It means less chances of pre-detonation (engine knock/ping) but it also means that you're probably gonna have a harder time cold starting. I'm sure someone will disagree.

Mixing octanes is fine, and you'll come up with a number somewhere in the middle. (There's some math involved and I really don't care to look and figure it out. That's why I'm not a scientist.) Some stations in fact blend their midgrade gas from 87 and 91 octane at the pump.

About the truck... it's 100% now or is it still having intermittent issues?

 

Thanks for the replies. I am aware that mixing octanes is okay, but I also know the computer will recalculate engine parameters based upon what is in there. I have only started the truck a half dozen times since the reset. I guess I will see what develops the next couple days.