Rough Idle and Bad Accel

[kile]

Forgive me if this has been addressed and solved but I did some general digging and found nothing relatable.

02 4.7 Ram 1500. It started off being reeeaaalllyy hesitant when I would accelerate and I would have to lift off the pedal, then slowly go back on it before it gave me any power, otherwise if I stayed down, it would take about 2 seconds then launch like Elon Musk's rocket.

Soon after it started having really rough idle issues. If I was stationary too long it would chug a lot, drop below 500rpm, then boost itself to 1250, down to 1000, then repeat until it eventually choked itself and shut off. Turned right back on and would do it again about 30-45 seconds later.

I let it sit for a few weeks while I just used my other car. Started it back up recently to test drive it cause I missed it and it would shut off if my foot was not on the throttle while moving. It shut off twice as soon as i let off the throttle and let the RPMs drop. Almost hit my neighbors mailbox. Parked it, came here. Fuel issue? Sensor? Really need this truck fixed. I'm Not a mechanic, but if pointed in a general direction, I can do it. Any help would be great, or at least point me in the right direction to a related post. Thanks.

 

[NCRaineman]

No CEL?

Remember... to run an engine needs three things. Fuel, air and spark. If the engine isn't running it's either not getting one of these things or getting them at the wrong time.

I see it's a 2002... how many miles?

My old '88 Chevy truck had similar idling and running issues a few years back. Turned out the rings on two pistons were shot so there was no compression on 2 cylinders... my V8 was trying to run as a V6.

 

[Fitz-0518]

I would suggest first things first. The condition you are experiencing can be caused by so many different electrical, air or fuel parts. You do not want to start throwing parts at your truck. Get your truck scanned by a competent tech with a professional scanner. If that is not in budget, at least get a OBD scanner and see if any codes have been set. Look up the codes and focus on what parts they relate to. Would really like to see you get a good run scan that can tell you exactly what your truck is suffering from.

 

[kile]

No CEL?

Remember... to run an engine needs three things. Fuel, air and spark. If the engine isn't running it's either not getting one of these things or getting them at the wrong time.

I see it's a 2002... how many miles?

I believe I'm up in the 190k range. It used to run like a top though, interior is mint except for the dash too. Also, I have a CEL, but when I ran the codes a while back it was just a O2 sensor cause I had bad cats, I have since straight piped it.

I would suggest first things first. The condition you are experiencing can be caused by so many different electrical, air or fuel parts. You do not want to start throwing parts at your truck. Get your truck scanned by a competent tech with a professional scanner. If that is not in budget, at least get a OBD scanner and see if any codes have been set. Look up the codes and focus on what parts they relate to. Would really like to see you get a good run scan that can tell you exactly what your truck is suffering from.

I'll probably end up leaving right now to go buy one. Will update.

 

[kile]

Finally got around to reading the codes. P0442 and 0455 for a small/large evap leak. Which sounds bout right cause there is a small smell of fuel vapor and a little vacuum leak somewhere. Gas cap doesn't seem like an issue cause I always tighten mine up because I understand the codes that can be thrown out with a loose cap.

 

[Fitz-0518]

Finally got around to reading the codes. P0442 and 0455 for a small/large evap leak. Which sounds bout right cause there is a small smell of fuel vapor and a little vacuum leak somewhere. Gas cap doesn't seem like an issue cause I always tighten mine up because I understand the codes that can be thrown out with a loose cap.

2002 original gas cap?? If so I would replace. I use Gates or Stant. Clear codes and see. This is the most common reason for those codes. If not, you have a leak in either the small hoses or possibly the neck fill hose. Smoke test can tell you that.

 

[kile]

2002 original gas cap?? If so I would replace. I use Gates or Stant. Clear codes and see. This is the most common reason for those codes. If not, you have a leak in either the small hoses or possibly the neck fill hose. Smoke test can tell you that.

Ran into a small issue before I get to that evap leak. Freeze plug blew out, replaced it, refilled coolant, and started up the truck to see how that went. HORRIBLE, I had fluid pouring out my exhaust and I'm confident it was coolant. Blown gasket? But that wouldnt make sense to me cause it was fine before and I've only moved it twice about 20 feet.

 

[Fitz-0518]

Ran into a small issue before I get to that evap leak. Freeze plug blew out, replaced it, refilled coolant, and started up the truck to see how that went. HORRIBLE, I had fluid pouring out my exhaust and I'm confident it was coolant. Blown gasket? But that wouldnt make sense to me cause it was fine before and I've only moved it twice about 20 feet.

My "first" thought is the same as yours. Head gasket. I would keep an eye on this thread. I am hoping others, maybe one of the techs, will see it and give you some suggestions.

 

[SYKRAMMAN]

What’s the prognosis op?

 

[HemiDrew]

Could it be the Idel air control valve?

 

[Mark Wood]

Bad fuel pump.

 

[Jim Tinker]

I have a problem a little like the OP... I have a new engine 6k on it... 2004 3.7, when starting the idle is rough, not quite as bad as a miss fire, but almost... after the engine reaches operating temp the engine smooths out by 85 percent or so.....

new plugs, new coils, new mass air flow sensor, thats about it...

thanks