Hey guys, It's been awhile since I've been around. Some of you might remember quite awhile back I was fighting an issue with my father's 1998 1500 with a 5.9 (originally 5.2).

Basically, it runs extremely rough at idle and puffs out small clouds of black smoke. It's had a complete tune up, plug wires are routed correctly following the TSB, and a brand new set of fuel injectors. Higher RPM's it does not miss but it will blow black smoke at times. The engine has only been in the truck for a year and it has missed since, however it has gotten progressively.

After fixing a transmission issue yesterday, I took it to Auto Computer Exchange in Davie, FL. I had decided the problem had to be in the PCM. To my surprise, the owner directed me to his warehouse where his manager gave me the tools to remove the PCM, then he put it on a 5.9 Durango to test run it... No issues. They then reflashed the PCM to 5.9 specs with all of the updated software. Awesome customer service.

The truck ran great after leaving ACE, however halfway back to the shop it started missing again; this time even worse than before. In first gear it doesn't want to get out of it's own way until about 1500 RPM's, then it feels relatively smooth with power.

Any ideas?

 

Well, first, Auto Computer Exchange doesn't have the best reputation....... however, since you can actually visit them in person, you are ahead of most others there....

Are you getting any codes? Even misfire codes?

 

I haven't had the chance to stick the scanner on it, but here's the original thread:

https://dodgeforum.com/forum/2nd-gen...r-misfire.html

You're right, ACE doesn't have the best reputation online... But their employees went above and beyond. I originally walked into the store front, but the owner took me aside and told me to go down to his warehouse and tell them he said to let me use their tools to take it out and they would do whatever I needed to get the truck running well. I was extremely impressed. Rather than just sell me on a new PCM, they actually took the time to tell me mine was okay and only charged me $125 to reflash it.

 

Wonder if they gave you the death flash..... (thread in FAQ section on just what that is) Even if they did though, that would not account for your symptoms. Can you do the key dance on yours to pull codes? (don't recall if that works on the 98's....) Is the CEL on??

 

Wont work on a 98 for some reason. On a side note! Not that it matters around here anymore(just thought I'd point it out to be the forum dick), but a thread title in the tech section named "It's Been Awhile..." really does not not help anyone. LOL

 

hahahahahahaha coincidentally we were just talking about this today!

 

I threw a new coil on it for S&G's, and it made no difference. Cold start it runs and drives MUCH better but not perfect; judging by the smoke I'm assuming the plugs are all fouled out after over a year of driving it like this so I'm going to say this accounts for the slight miss it still has at idle when cold.

I'm REALLY leaning towards the oxygen sensor. I unplugged the upstream sensor with it warmed up and I didn't have the severe miss/hesitation but I had no power across the power band.

When I get to the shop Monday I'll hook the scanner up to it and see what it says.

 

After driving it around with the upstream sensor unhooked, I was convinced this was the issue so I changed the sensor and spark plugs (which were fouled as I suspected). The rough idle is gone and it has tons more power. The smoke at idle and cruising is gone but it still smokes at WOT, I'm thinking that after a year of driving it with a super rich condition it's gonna take a little while to clear all the carbon out. Problem solved.

My father was pretty close to buying a new 2012; but now that his 98 is running well he'll hold onto it for as long as he can even though it has 250,000 with almost no dash or clear coat left.