I have a issue with my vent and blend doors opening and closing on accelleration. I have allready used the search button and checked all vacum lines for leaks holds vacum over night on gage in all dash settings and i have replaced the vacum check valve twice and still the issue is thier very annoying since going down the road in OD the 318 don't have enough ***** to pull the truck 70mph without downshifting ever so often on the straight aways. So if it don't have the power and it is being worked to death in OD i have latly been leaving the OD off and running it like a old 3 speed auto and only running 60mph everywere i go. This thing needs more power and should have more power than this. I have also noticed the cat is rattling if in gear idling for a while but it has never run hoter or started to wistle yet. This thing is absolutly gutless and i know it should have more power than this it is getting close to winter and I need this thing to run right to haul wood to customers. At this point i thing a Yugo could out pull my truck. Any help will be appriatated.

I have recently changed the plugs from Champion's to the NGK's due to having trouble due to the Champion's missfiring and sparking thrue the porcline. Since then the truck started getting better mileage (8mpg to 12.5mpg), running smoother, firing on all 8, has alittle more power. The cap is the heavy duty brass cap and is not burned up, wires are just stock replacement, Air filter is a K&N drop in, It has just had the plentum pan gasket replaced, and injectors power flushed.

 

My guess is the cat is clogged. That explains the loss of power. The cat should not be rattling at all, if it is, its time for replacement. I suggest the Magnaflow hi-flow ones.

Especially if the plenum gasket was just replaced, and the old one was confirmed busted, the cat is probably clogged from that.

 

+1. if the exhaust can't get out, it can't pull full vac.
and if its rattling, its shot.

 

I don't have the money right now for a cat and mine is the one that has dual pipes in and one out could i punch it out and do the O2 extention and my SES stay off?

 

Have you looked to see if you truck has 2 vacuum valves. There is one at the firewall on the passeengers side and one on the drivers side at the throttle body.

 

Nope just have one unless you are refering to the valve to the brake booster and that one was replaced too other than it thier is no other lines on drivers side intake or tb. The valve on my truck is not at the fire wall but at the intake with only a 90 degree elbow connecting it to the intake. I am going to run a back pressure test on my cat and see if it is pluged or just rattleing and yes is do agree the cat needs to be replaced due to it rattling but i don't think this is the real problum but just a issue the truck has. I will know very shortly thoe.

 

I agree that the cat is bad! And it needs to be replaced before troubleshooting the other prob. I assume when you did the vac check that you did it without the check valve in the mix ?

And BTW! You better check again, because there should be like three check valves.

 

The back pressure test only shows .75psi@idle and 1.2psi@WOT I also installed a test pipe and went for a test drive and there was absolutly no change in the way the truck run so the cat is NOT the issue but just annoying due to it rattling. I also looked in my cat while it was off to see if it could be temperaly pluging itself up due to the guts moving around and it looks good (can see thrue honey comb) and just looks like it came loose from casing like every cat I have had does. Cat temp is between 600-670 degrees (with-in spec). Still plan on getting it replaced but after no power and vac issues fixed first. The vacume issue i have took another look and only have 1 check valve in my system to the cab so i added a second one and still no change and yes I did the vacum test without the check valve and tested the new valve by itself so that nether could give false positive's.

 

Anymore idea's? i had somone today mention that the lobes on the cam could be getting worn off has anyone had this happen around 152,000?

 

I checked the timing chain today and it has just been replaced before I bought the truck it has less than 1.5 degrees of play. Any other idea's?