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Power Loss

7K views 15 replies 9 participants last post by  astroturf 
#1 ·
Over the past few weeks, I've been noticing a power decrease. It's especially evident i go up the mountain by my house--routine drive for me... Anyway the power seemed much less, and the van kept wanting to upshift into lower gears to make the hill, as my speed dropped down to 40ish. To be honest, it's like an overloaded 18 wheeler when going up long hills...

What could be going on here? Here are some facts that may be related:

* Van has about 115,000 mi and probably original fuel pump

* Van has in the past year been known to throw a code--P0101--it's an MAF or ERG code

* I tried unplugging it and running like that. No changes in performance.

* I am starting to get another gear wine out of the rear end

* The tranny doesn't like to cruise at 65mph anymore -- overrun clutches I think

* Tranny fluid level is fine

* Plugs and wires are only a year old--pretty new for platinums

* Air filter (K&N) was cleaned about 5000 miles ago.

Any thoughts? All I truly know at this point is I shouldn't lose speed with the accelerator mashed to the floor...
 
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#3 ·
Hi chemist

A couple things come to mind to start with.
1-When was the fuel filter replaced last?
2-How long have you had the K&N filter system on your vehicle? The "notorious" part of any K&N system, is the oil it throws up onto the MAF sensors. Hit the MAF screen with some carb or brake cleaner but please don't touch it in anyway.

Let us know what happens, Thanks.:)
 
#5 ·
astro355 said:
Yes, K&N filters really shouldn't be used with cars with MAFs. I would get some MAF cleaner and remove the oil from the resistors.
:banghead:

Makes sense...

I really wish I had read this post earlier today. I just replaced the MAF. Anyway that did result in a significant improvement, so it was the MAF...
 
#6 ·
Hi chemist

It's a well known, un-talked about problem with it (very oily). Thanks for the update.:)
 
#8 ·
Update: The problem is only 50% solved. Going up hill I still have an issue, presenting as follows:

In 3rd and 4th gears, I got all the power I need. Once it drops to 2nd gear, you loose speed. Basically in 2nd, going uphill, if you don't floor it, you loose speed, but if you do floor it and it goes into 2nd at high RPM, you loose speed real fast... wth? :driving:
 
#9 ·
Hmm, when was the Fuel Filter and Ignition Coil replaced last chemist? Thanks
 
#11 ·
Hi chemist

If it's been in the van for 6 years, then replace it whether it's the problem or not. That's a very long time for a coil that's enclosed and exposed to that much heat. My OEM coil lasted 3 years before it needed replacing.

Here is the coil you need if you do decide to replace it:
http://www.rockauto.com/catalog/x,carco ... ttype,7060

Delco or Delphi are my only recommendations here for this application. Let us know how things work out, thanks.:)
 
#14 ·
don't know if your still looking for answers here, but I just had the EXACT conditions in my 2003. I determined through much research, a lot of it in this forum, that it was probably the cat converter. (I have a CA. legal van. Don't know if that matters) I decided to spring for the CA. legal cat without paying for professional diagnostic because my research indicated that the cats in these vehicles are notorius for failing. I put the new factory cat in right as the van was becoming completely undriveable. Total mechanical restoration! The van drives like it was brand new at 100,000 miles on odometer!!
 
#15 ·
I, too, just diagnosed and repaired this problem. Van idled fine, but lost power under load, ie I couldn't get up a hill doing more than 35mph. SES light on, DTC P0101, MAF sensor.

Air filter was very dirty, might be what caused the inevitable issue. Cleaned the MAF, no difference. Figured its either fuel delivery or clogged cats. So I unscrewed the O2 sensors between the cat and the manifolds and took it for a drive, and it ran like a rocket ship. Then I put the o2 sensors back in and unscrewed the cats from the exhaust to make sure its the cats and not the muffler. Problems came right back. cut out the cats and replaced it with a temporary pipe until my bolt on cats come in the mail this week.
 
#16 ·
jimmyjam said:
I, too, just diagnosed and repaired this problem. Van idled fine, but lost power under load, ie I couldn't get up a hill doing more than 35mph. SES light on, DTC P0101, MAF sensor.

Air filter was very dirty, might be what caused the inevitable issue. Cleaned the MAF, no difference. Figured its either fuel delivery or clogged cats. So I unscrewed the O2 sensors between the cat and the manifolds and took it for a drive, and it ran like a rocket ship. Then I put the o2 sensors back in and unscrewed the cats from the exhaust to make sure its the cats and not the muffler. Problems came right back. cut out the cats and replaced it with a temporary pipe until my bolt on cats come in the mail this week.
Jimmy may I ask how many miles you had on your van when the cat failed? Also when you replaced the cats, did you replace the O2 sensors also? Thanks a lot, Jim
 
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