Engine runs rough

Problem: engine runs rough.
Dodge Durango, 1999
5.9L V8
87,000 miles
Misfire on cylinder 8 problem. I have a trouble code reading device to test and reset the check engine light.
Replaced the following:
Spark plugs
Plug wires
Distributor cap
Distributor rotor
Removed the fuel injector from cylinder 8, it was fouled with what looked like carbon deposits. I clean it and swapped it with cylinder 6 injector. I still get cylinder 8 misfire error codes being generated.
I compression tested the engine, here are the results:
Cylinder, Pressure in PSI
1 - 150
2 - 130
3 - 150
4 - 150
5 - 140
6 - 150
7 - 135
8 - 100 - 110, added a little oil to cylinder then 115

Any ideas??

--Gordon

Hi Gordon,
I have a misfire code on cylinder number 8 on my 99 Durango too. I have replced the intake manifold gaket and Replaced the following:
Spark plugs
Plug wires
Distributor cap
Distributor rotor

What was the solution?
Please letme know..

Thanks,





Problem: engine runs rough.
Dodge Durango, 1999
5.9L V8
87,000 miles
Misfire on cylinder 8 problem. I have a trouble code reading device to test and reset the check engine light.
Replaced the following:
Spark plugs
Plug wires
Distributor cap
Distributor rotor
Removed the fuel injector from cylinder 8, it was fouled with what looked like carbon deposits. I clean it and swapped it with cylinder 6 injector. I still get cylinder 8 misfire error codes being generated.
I compression tested the engine, here are the results:
Cylinder, Pressure in PSI
1 - 150
2 - 130
3 - 150
4 - 150
5 - 140
6 - 150
7 - 135
8 - 100 - 110, added a little oil to cylinder then 115

Any ideas??

--Gordon

I have a 99 Durango that has been the best truck I ever had...unti 2 weeks after I bought it after the lease was up! Now it is the biggest piece of shit I ever got behind the wheele of!

If I were you, I would drain the oil and drop the oil pan to check for a sludge build up. It will eventually happen to your truck, since you are experiencing misfire problems it won't hurt to check into it now....

The sludge will block the oil pump filter so it will not send oil to the upper half of the motor resulting in you having to buy a new motor...$5,000! been there done that! at only 50,000 miles!

I have a 98 Grand Cherokee with the 5.9 V8. Also had the cylinder 8 misfire. My mechanic simply replaced the spark plugs and it has been good ever since, knock on wood. This happened about 2 or 3 months ago.

The sludge will get you...!

Missing? #8? ok, change the plug... ignore it... it's not going to go away until the sludge takes it all away.

Use thinner oil. Change more often.

I'm serious.

check for a weak ignition coil/ignitor.

it's simple to avoid sludge:change oil regularly.

Try some combustion chamber cleaner. If it is a carbon problem that will help. I've seen a few of the 5.9 with cracked cylinder heads, always the outsie chamber.

Gordon, atthehelm,

My friend has a '99 Durango, 5.9L, with the exact same problem you describe. He has changed the plugs and wires and cap, and the problem is still there. We even checked the new plug in #8 and it's VERY clean -- looks just like #4.

Drove it cold last night, and holy cow it ran strong! Thought the cap and wires fixed the problem, until the problem reappeared a few minutes later, after some warm-up. So the behavior helps me rule out two things which the dealer suggested: It's not the "bed pan" (intake) gasket, since the effect of a vacuum leak would be minimized at WOT with fuel injection (and that's where the problem occurs worst), and it's not a plugged catalytic converter, since it ran so strong when cold.

So, what did you learn on yours?
Thanks!!
Jeff

check the injectors there part of the ingnition system too

The reason is most likely a blown intake or the head is cracked between the valves, both concerns are fairly common.

check for a burnt exhaust valve, bad valve seat

A user replied about his #8 cylinder misfire from another message forum and did everything you guys did. Plugs, wires, etc. Later he had his fuel injection system inspected and found it was the fuel injection rail going to #8. So the rail was replaced and problem went away.

I recently had the same problem. I have a '01 5.9L R/T w/ 60,000 miles on it. I took it in originally because it was skipping. We put a new Distributor, Rotor, Wires, Plugs, etc on it. Ran great for about a week, then starting doing the same thing again. Took it in and the #1 Plug was flattened. This was cause by the rod I believe hitting it. Needless to say it is getting a new motor. Quote is up to $6200 as of now. Thanks god for the extended warranty I purchased.