1997 XLT is misfiring.

[N3EAQ]

Hello All!

Maybe someone here can help, I'm out of ideas! I have a 97 Explorer XLT w/ about 65K miles on it.

About a year ago I started to notice that when I was sitting at idle (at lights or in traffic), especially if the headlights and/or the heater/AC blower was running, the volt meter would show very low voltage, or a non-charging condition. Around the same time I started to notice a serious misfire when I would put the SUV under load. E.g., pulling a steep hill, having a load in the back and accelerating, giving it hard pedal to pull out from a ramp or stop sign, etc..

I attempted to repair these conditions myself with the following actions, I replaced the:

Plugs,
Wires,
Coil pack,
Air Filter,
Fuel Filter,
Battery,
Alternator,
Serpentine Belt,

The above seemed to solve the issue of the misfire during the cool weather months, however I did feel that the SUV didn’t have the power it had before. Also, the low voltage/charge at idle was NOT solved. As soon as warm weather came back this year, so did the misfire!

Using my analyzer on the OBD II port all I ever read is P0303/P0305 (misfire cyl 3 & 5) which has not helped much in tracking down a solid cause. Not sure why it’s always these and only these cyl. Reporting the misfire, and never any other helpful codes!

Only seems to throw codes/miss fire when the engine is warmed up and has been running a while, let's say after about 20 miles/minutes, i.e., after the engine is good and warmed up.

I've thought about it and the MAF and O2 sensors don't make sense, or it would be more than just cyl 3 & 5, same goes for a fuel pump/pressure issue.

The wires for cyl 3 & 5 are not next to each other, so they can't be cross-sparking, these cyl. aren't next to each other physically on the engine, so it's not a gasket/valve issue.

They ARE next to each other in the firing sequence, so that may be some clue, but to what, I don't know!


IDEAS???????


Mike - Email me direct at n3eaq@n3eaq.net

 

[2000StreetRod]

read the plugs?

Congratulations on having such a low mileage 1997!

Did you "read" the spark plugs when you replaced them? Did the plugs from cylinders #3 and #5 show any abnormalities?

Which engine? Did you perform a compression test?

Have you tried adding a bottle of fuel injector cleaner to the fuel tank?

Engine misfire procedure

 

[N3EAQ]

I bought the Explorer in 2000 and gave it to my mom. She used it for a grocery hauler
until her death last year, when I got it back. I used it for commuting for a year, or it would only have 50K on it!

Yes, I looked at all the plugs when I pulled them, and they all looked the same, and fine... No compression test, but considering the signs, I wouldn't think one would be warrented. As I said, these cyl., are not adjacent... I've put many bottles and types of injector cleaners down the throat of this beast!

MK

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the stock 95-01 section.

 

[mbruffey]

Solve the charging issue first. Low battery = run like crud. No escape. You can buy a doodad that will plug right in to your cigarette lighter socket to verify that your anmeter is accurate and not giving a false reading. Or, take it to a shop to have them test the alternator output. Next, check all the connections from the battery to ground, hot. I noticed my main battery ground wire chafing on the frame (97 5.0) and put something in there to reduce that. Perhaps you have something chafing that expands enough to make a little contact after the engine compartment warms up. Ensure your battery terminals are clean and tight. Also,it's always possible you replaced a bad battery with a bad battery or a weak alternator with another weak alternator. If you do have a loose or shorting connection, that could have fried the diodes on the new alternator. LMB

P.S. The tensioner for the serpentine belt can also go "soft." Did you consider that possibility?

 

[N3EAQ]

I will have a look at the connections, Thanks!

The belt is solidly tensioned, and I have confirmed that the dash meter is indeed correct
with an outboard meter. I also had the new alternator tested. It is outputting fine, and the new battery is OK as well. Maybe there is a poor connection somewhere, so I'll go digging!