Might buy a 2002 4.0 if I can figure out why it runs rough and stalls

[mechjames]

I'm interested in picking up a 2002 explorer with 246,000km on it. I went to check it out today and the guy thought it might have been the fuel pump. I was under the impression that it would crank and not start.

I gave it a crank and it did start, but idled really rough. I give it a bit of gas and the revs come up a little bit, if you give it more gas it will just bog down to idle and sometimes stall. When it warmed up it would stall at idle and I could barely keep it running.

It might have made a little timing chain rattle when it first started up but we got it to idle til it warmed up and the motor was pretty quiet. The truck had been sitting a few weeks though without starting. I did not see a check engine light, but I tried plugging in a cheap bluetooth ELM327 code reader I have paired to my phone, but could not connect to the truck's ECU with it. I have had this issue with my cheapo ELM327 bluetooth reader on some vehicles (it's picky on what it connects to, you get what you pay for on ebay for $15) so I'm going to bring a friend who has an autoenguinity and see if we might be able to pick up on something.

They guy did have the battery disconnected when I got there so it's possible it might not have ran long enough to throw a code either. SES light comes on with acc on before starting, so it's not burnt out.

Does this sound like a cam/crank sensor issue, maybe TPS? I can pick the truck up for a grand or less, so it might be worth the gamble. This guy bought it as a project but has no time to figure it out and is moving.

I had a friend who had timing chain issues but his truck was just noisy but running fine. Since he has never heard it running fine before (bought it as a project), is there any issues with the timing chain issues that the 4.0 SOHC has that could cause it to run like this? Max RPM before it bogs out was about 1500-2000.

Thanks

 

[Number4]

Uh, no. 2002 was the first year and had the most issues. Issues they worked out through the next few model years. You may end up putting a new engine in it. So unless your getting it for $500 I'd look else where.

 

[Styx]

Sounds more like a mass air problem or a vacuum leak to me... Timing chains are a problem with them but if its cheep and in good shape body wise go for it... I picked mine up for very cheep as it had 400,000 km on it... had a new tranny and the engine was great and its a full load EB...

Cheers Randy...

 

[mechjames]

The guy is asking 999 and I might be able to get him down to 700-800. The body is really nice.

I unplugged the MAF to see if the computer would run it in a limp mode and it didn't really help.
Can the timing chains skip a tooth or two on these trucks? Plugged up catalytic converters maybe?

 

[esclamada]

it's a gamble, it could just be basic tune-up lacking on this truck. things like fuel filter, cleaning the maf, new plugs, etc. Since the battery was disconnected for a long time, it won't give out code if the catalytic is bad most of the time. It really depends on how much are you willing to spend more on the truck to keep it running. That 700-800 might double or triple (quadruple) the cost of actually having it running fine.

remember the '02 has more issues than starting (with that kind of mileage, you know the odds)



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