Its been a while since I've been here. I've been enjoying my '94 1500 5.2 since the plenum fix and rebuilt front end. Thank you all for the help.

Although the plenum is fixed, I still have some problems with power climbing hills at 65mph+. I'm also at 5500 ft. My truck has a 1 year old 3 inch exhaust.

The odd thing is if I have 1000-2000 lbs in the bed, I can climb the same hills in 5th gear without any difficulty. I brought the truck to the dealer for a diagnosis. They found nothing wrong except for an oil pan drip.

Does anyone have an idea why with no load I have trouble getting up the hills and carrying 1ton there are no issues ?

cheers
gary

 

My guess would be your driving style changes with a load in the bed.....

 

With that much of a load, are you driving with overdrive off? Is it not downshifting or just lugging?

 

I think he has a manual trans.

 

Sorry for the confusion. It's a 5 speed manual.

I think the issue may be my exhaust is too large for the engine. I thought a bigger pipe would work like my old diesel, but now I'm rethinking that brilliant plan.

Has anyone else seen this ?

 

What size pipe ya got on there?

 

Larger pipe equals loss of the lower end torque. On a gasser.

 

@HeyYou: pipe size is 3 inches.

@bddb1: I kind of figured out about low end torque now reading about it. Maybe under load engine scavaging changes. I'm trying to find articles on the topic.

Maybe I need a resrtictor on the end of the tail pipe ?

 

Restrictor won't help you. It's all about flow. The larger pipe probably allows the exhaust gases to cool to quickly to promote good flow. Besides, on yours, the biggest restriction is the 2" pipes to the cat, and where the pipes hit the cat itself. That was a really poor design there.....

But, I don't think that is the real problem....... Have you fixed your plenum yet?

 

Sorry for the delay in responding. I posted with my ipad, but the post didn't take.

I checked and the pipes to the cat are 2 inches. I remember the conversation with the shop telling me I'll have to change the manifold for a bigger pipe.

@HeyYou, yeah I have a Hughes plate on the stock plenum. If I need fix it again, I'm pulling the engine (changing the clutch) and putting on a mopar M-1 intake. Or just buy a new 2500.

So now I'm back to the beginning, thinking I have something else not working for me.