2001 Dodge Ram Van 1500 5.2 - 150k

For the past few months around 1 out of every 10 starts the engine idles really rough/runs rich and when I rev it a little bit it will chug and almost die completely. I usually just turn it off, wait a good 10 seconds, put it in the ON position for a couple of seconds and start it and normally it fires up and runs just fine.

In the past month I replaced the MAP sensor, IAC valve, TPS sensor and took off the throttle body and cleaned it. Same issue is still happening, with no check engine/codes.

I had the fuel pump replaced about 7 years ago and just tested it last week and it read fine. I replaced the crankshaft sensor about 5 years about when I was chasing down an issue that ended up being the dreaded PCM. I also replaced the ignition coil 2 years ago then again over the summer (was initially sold a bad one).

Any help/trouble shooting would be great, thanks!

 

I had a similar issue and stumbled on the solution by accident. I had a poor connection on the fuel pump relay under the hood in the electrical box. Mine is a 1999 model.

 

Did you buy a new relay or how did you fix the connection?

 

Split the box and put a new spade connector on the wire end. Someone missed the spade and bent it all up. Easy fix once i figured it out

 

Great, I'll take a look. Appreciate it.

 

Sounds similar to what my 01 was doing. Does it just do this after a hot start but runs ok on a cold start?

If the coolant temp was above 100 F and the van has been sitting for 30 minutes to three hours it would start but one minute later would start flooding out. Popping cracking backfiring through the throttle body .

Either I could floor it for 30 seconds or shut the ignition off and restart and it was fine.

If I started the engine within 15 minutes it was ok. Seems the window of time was 30 minutes to 3 hours.

Took some readings with an app on my phone and a device I plugged into my obd2 port and discovered the O2 sensor was not producing voltage when this was happening. Once the engine started running fine the 02 sensor was producing voltage.

I replaced the bank 1 O2 sensor ( the one before the cat) and it seemed to fix the problem.

My logic is if the coolant is above 100F the system goes into a closed loop one minute after starting . If the heating element in the sensor is burned out, the sensor wont read voltage and the ECU starts dumping excess fuel into the engine until the exhaust heats up the sensor.

Because the heating element is controller by a relay and not the ECU you will never get an OBD II code or check engine light.

I'm just speculating on this. I'm not an expert. Try a new O2 sensor before the cat and see if this fixes the problem. I got mine off eBay for around $25.

It just worked for me.
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It doesn't matter if its hot/warm/cold, it just seems to be random. I also replaced both O2 sensors about a year and a half ago, I figure if it was one of those it would spit out a code at me. It's been a hard one to figure out.

 

Only the OEM/NTK/Denso 02 sensors work correctly. I, and many others, have had similar issues with Bosch and other generic ones.

 

Ill check what kind I bought, do you think that would effect my fuel efficiency, I feel like that past few months its using more gas than normal.

 

Yes. As I remember I got down to 8-9mpg and was wondering why...
The main issue I was dealing with was backfiring. I also had poor acceleration, gas mileage was down, and general stalling at weird times.
After it would backfire it wouldn't start for awhile.
Maybe this could help? I hope so

Also I had no codes too. The Bosch I had in there was the worst. I also had issues with a generic one I tried one time too.