Hello I am new to the forum. I own a 2001 Dodge ram 1500 5.2L rear wheel drive with 149,000 miles on it. This is my story I applagize in advance, quite lengthy but want to provide as much as possible to hopefully get the help I need.

It is running rich and have no top end power. The truck will struggle to get to over 70 mph with out having to engage passing gear. Sometimes it does it at lower speeds like 50 mph. When I gradually let off pedal and passing gear disengages speed drops gradually. When I set cruise control at 70 going up hill speed drops and going down hill it goes back to 70. It almost feels like there is a void in engine power. It seems to always happen when AC goes to defrost. It's a constant battle when on the highway consumes a lot of gas. When this is going on the gargling and crackling sound in throttle body is heard.

It has a quick cold start idles good and has excellent low end power.

It does consume quite a bit of oil not sure if it's from the plenum and or valve seals.

Only code I get is the notorious P1494 that this truck seems to commonly get.

I have replaced o2 sensors (NTK) new fuel pump, plugs, Genesis computer to check if it governed (it's not), throttle body gasket and cleaned, air filter gasket ( was missing). TPS sensor, ran smoke machine (1 leak found) EVAP code comes back. I sprayed it once with carb cleaner and no change I will be try starting fluid this time. Transmission checked and all gears kick in smoothly all the time. Noisy alternator replaced, differential oil change.

I purchased it for $800 single owner thinking it was a good buy if only I could find the culprit. I need help what should I look for? What order should I go with?Previous owner did not have answers other than the cat was replaced and O2 sensors a couple times. Running rich with no codes seems to be the source of my problems. Please help!

 

The oil consumption, along with the lack of power, kinda points to a clogging cat. If the plenum hasn't been fixed, that is a rather major avenue for the oil consumption. Burning oil will destroy cats, and O2 sensors fairly efficiently.

Also, at almost 150K, the timing chain is going to be rather stretched out. That effects cam timing, and will cost you power.

Did you take a look down into the intake while you had the TB off? See anything interesting??

Welcome to DF!

 

When I initially did when I first got the truck was take it to a muffler shop and had it removed to look at and run a straight pipe through it and ran it this way. Same results. Muffler shop told me is looked new which it was as the previous owner had told me he had recently replaced. I later also removed the up stream o2 sensor with it plugged in to harness to see if it would release pressure and give me more power but did not help.

​​​​​​The timing chain pulley does have some play which would demonstrate loss of power but it does not explain it running rich. I would think the vehicle could still eventually get to higher speeds gradually even with weaker timing chain. Not sure please advise.

 

O2 sensors have a great many failure modes, very few of which will actually set a code. Drive with the O2 sensor disconnected from the electrical harness. This will force the PCM to run in open loop. See if it runs any better.

 

I ran it with o2 sensors disconnected with same results. When I reach 60-70 mph it appears it's struggling with fuel. I hear the throttle bottle gargle fuel.

Starting to think it could be a vacuum leak. It kind of reminds me of the time I had taken the air filter housing on my first generation 2 1999 dodge RAM. It was dark and I had taken it apart to clean the throttle body before I headed out of town the following morning. When I hit the road it was fine but the moment I got on the highway it struggled to maintain top end speed. I drove it like this for about 60 miles until I pulled over to check what was the problem. I found that I had failed to sit the air filter housing right. This was allowing a too much air to be sucked in through the throttle body.

On this current truck that I'm trying to get the issue resolved there does not seem to be any obvious vacuum leaks. Could it be from the plenum area? Could this cause a vaccum issue and no code? Stuck injectors?

I would like to find the source of burning rich fuel and no codes. This could very well be causing the fuel leak detection pump code I get that I have been unsuccessful at clearing too.

 

I will check first down the throttle body first. Any recommendations of what I should look for or when I should check it?

 

The engine tilts toward the rear of the truck, so, oil tends to pool at the back of the intake. May have to pull the tb to see it clearly.

May want to check fuel pressure. See what it looks like at idle, and how fast it bleeds down when you shut off the engine.

 

What I meant to ask when checking for plenum oil leaks is it best checked after a long time no use to let oil pond or after so use and allow it to cool off a bit before disassembling? Does this matter or will it be obvious to see signs of oil?

I will be checking fuel pressure as well. Thanks again

 

Doesn't matter. If there is oil in there, it will be obvious once the TB is out of the way. Have a look, see what you find.