My 98 Kota Sport V6 Magnum (don't know cid ) has been doing this for about four or five years. It never does it in the winter or summer when temps are constant hot or cold. But when the seasons change, it drives me nuts.

When the engine is cold, it seems to load up a bit, run rich, but not bad. When I go to drive, it might drive fine maybe to the end of the block, then when I go to pull out onto the main street, the engine boggs down, bucks and farts, sometimes backfires through the intake. It won't do it every day, just now and then. If I put it in neutral and race the engine up a few times, it will clear up. But you never know when this is going to happen. Maybe, just that time you thought that semi wasn't coming as fast as it was and pulled out in front of it.

I've mentioned it to many people, and pretty much get the same answer. It could be anything. I even had it happen just as I was leaving my mechanics and turned right around. Instead of going for a drive real quick, they started checking codes (showed nothing) and by the time they DID drive it, the problem was gone. It feels just like back in the good ol days when the choke would stick on that Holley duel feed. So I just dumped about $10K into the truck, and the weather is warming a bit, and it's starting this baloney again. Frustrating. Mechanics seem to not want to get involved with this, so I guess it's on me. any thoughts appreciated. Thanks.

 

My 3.9 did the same thing and at first I thought it was temperature related. I made a topic called "backfire from hell" and my problem was a bad upstream o2 sensor.

It would help if you told us what you've tried too.

Since I replaced the o2 sensor its been running great for almost a year now.

Search the thread. I have a video too.

 

Yaaaa. Haven't tried anything other than ask my mechanic to fix it. That's part of why he's not my mechanic any more. Thanks. I'll check out your thread if I find it.

Watched your video. When I first clicked on it I saw a kids head hanging out a pick up truck window driving down the highway and I thought to myself, gee, seems to be running pretty good! Then I realized it was a commercial ad on youtube LOL.

Not at all what mine is doing. My truck wont even move when it starts. If I feather the gas pedal I might make it to the side of the road. If I put it in neutral and rev it up a few times it will clear up. But with over 180K on the timing chain I don't want to do that too much. My cat was replaced a few years ago only cuz it was falling apart so they did a whole new system. Had a complete tune up at Dodge dealer for $400 a while back. From now on I don't have to get the emissions test for state inspection so I might eliminate the cat if need arises.

So, where is this 02 sensor you changed and what does it look like?

 

I'm gonna go with O2. Seeing as it dictates the air/fuel ratio, any issues with a bad AFR is usually O2 related.

 

You have 4 o2 sensors. 2 on each cat. 1 before and after each cat.

Its most likely one of your (or both) upstream sensors which are before the cat. You can easily DIY. You unscrew them with a wrench and disconnect it from the harness.

If you choose to go this route. Buy OEM sensors. I've seen a lot of problems with people who decided to cheap out on them. If you're getting and misfire codes that'll help narrow down which o2 if not both, is the culprit.

 

Damn. I had a funny feeling so I looked back. Sometimes my screen doesn't show how many pages are in a thread. I just went back and read them all. I thought there was only one at first. Ya I can do that. Being a 6 cyl I suspect there are only two. I just dumped about $10K into the truck so what's a few more bucks? It sits high enough I don't even have to jack it up to work underneath. As soon as crap stops falling from the sky here so the truck is dry, I'll get under and check it out. With over 180K on the clock I guess it deserves to replace them. I'm thrilled my truck looks and runs like new and I have no payments. Going to try to get the quick disconnect installed on my new winch power cables today. Don't have to crawl under for that. THANKS GUYS! I'm shaking my head at myself now thinking how much money I fed my mechanical shop for stuff I could have been doing myself, and finding I actually enjoy it sometimes. (When things go right)

 

If you remove both fender liners, things become really easy to work on. Both upper O2's should be an easy reach with the liners removed. Wish I could say the same for the harness connectors....on mine, they're tucked up away on top of the transmission.

 

It has 4 sensors total even on your v6.

The upstream ones are most likely ur problem. It may only be one, so buy 1 and test it out. If you're getting misfires at all, depending on which cylinders will help tell you which cat has the bad sensor.

The harnesses are a pain to get to like magnet mentioned. Even with a body lift.

Good luck.

 

try cleaning your throttle body with spray

 

Do this just as an ok I checked it

Pull off the cap and rotor now what you will see is a black cover it’s not a cover well it is but it’s also the Distributor Ignition Pickup pull it up and look inside the Distributor for dirt and debris also look at the Distributor Ignition Pickup you are holding look at the sensor look for metal shavings stuck to it as its magnetic clean all shavings off look to see if its worn also put back together see if that helps.

To blow the dirt out of the Distributor use some caned air or if you have a compressor with an air attachment blow it out that way.

Usually if the Distributor Ignition Pickup is bad it will not start but I suspect if you have a lot of metal shaving or dirt on the sensor it could function poorly.