Hey Guys and Gals, Merry Christmas!

I have been having this problem for about a week now and I could really use some help!!

If the truck is cold, about 5 minutes or less after I start driving truck will sound like it is about to shift up a gear, and then it hesitates and starts making a popping or banging noise (kind of sounds like hitting two large frying pans together). It'll do this for about 10-15 seconds and then everything goes back to normal. It only happens when the engine is a "little" warm. While it's happening the RPMs jump around a little, the truck is a little jerky, and it won't rev very high even if I floor the gas peddle. It only happens at low speed, and usually when accelerating from a stop or near stop.

After it does this I can drive it around all day just fine, stop, go, highway speeds or slow back streets, however as soon as it cools down again I can only get a couple of kilometers before it happens again and I have no power until it goes back to normal.

It started happening after I took the truck on it's first long drive (about 5 hours non-stop of highway driving) since I bought it about 7 months ago. I'm really hoping it is an easy(ish) fix that I can do myself!

I took the truck to Canadian Tire (not my first choice, but it was Saturday and my mechanic is on holidays) and they could replicate the problem but could not diagnose it. They said to try a transmission place, but I have a few days until they are open. I'm not getting any codes and my check engine light isn't coming on.

It's a '99 Dakota sport, 3.9L V6 RWD Automatic with about 211 000 kilometers.

Any ideas or feedback will be greatly appreciated!!

Thanks!!!!!!!!!!!!

 

Have you had any recent work done to the truck ? I had a bronco do this once and it was a map sensor .. Did it run hot during the trip ? anything odd happen to the truck during the trip ? ( random check engine light , check gauge's light ?)

 

The only work that I had done recently was having a couple of bushings replaced and the right front stabilizer link replaced. I don't think the map sensor would have been touched, but I'll take a look at it and see if it helps. Thanks!!

 

if it looses power, I would suggest checking the compression on cylinders.

 

Hi I just wanted to chime in as youre symptoms are the same as a problem i am having with my 97. if youre check engine light is on take it to auto store for code read and see if you get a code for crank cam or pcm problems. the sensors are easy to change and i hope it fixes your problem.

 

Hey Guys, thanks for the suggestions. I'm afraid that the check engine light doesn't come on, my code reader doesn't pick up anything, and that the truck is running at normal temperature (or at least it claims to be). I've seen a video where a bad upstream O2 sensor was the culprit so I'm going to get this checked as well.

While I was poking around I found this connection dangling around. The unused connections under my hood are all secured so that they don't dangle. I'm thinking that it's possible that this is supposed to connect to something but it came loose? I can't find a fitting connector within reach, however it wouldn't be the first time I haven't been able to locate a connector (had an AC problem caused by this). Does anyone know if this is something that is supposed to be hooked up to something else, or am I grasping at straws? I'd love to figure this out as where I live stores aren't open boxing day so I'm out of luck until thursday at the earliest! (Ignore the green circle, it's the connector in the red circle that I am concerned with).

 

Actually, the symptoms you speak of does sound like what the O2 sensor system would go through once the truck is heated enough. There is a cycle of rick then lean signals to test that the sensors are adjusting and the Cat is performing well under the conditions.

I really don't know all about it, but enough to be dangerous and comment here.

I might only assume your cat is doing a great job for now.

Regarding the connector, it loooks EXACTLY like a O2 sensor connector. The fact it is so clean and not road garbled makes me think it recently came apart. No way I could get my hands up in there to change mine, so finding one that is separated may be nearly impossible. If you're 4X4 and California emissions, may have to remove the wheel well cover to find the connector; or maybe look through the opening there.

My $.02 might be correct here. Good luck!

 

If it helps, the connector is near the front right fender. I'll look to see if an 02 sensor isn't connected to anything. Thanks!

 

check on top of engine that could be a connector to one of youre ignition coils

 

Have to ask if it was dangling on the top of the engine or under? Under the truck may be the O2 sensor. Dangling on top anywhere... and my direction is sunk.

It just seems to make sense... only happens after warming then goes away after 15-20 seconds. Engine run great when still hot, all day long.

Compression would show bad performance all of the time.

Timing may not show up until after initial warm up, then be bad the entire time.

Know this: I am not an expert by any stretch of the imagination. I am an engineer by trade and mechanically inclined enough to be dangerous.

Good luck!