Problems with lack of power

[reed b.]

RonD I did a compression test and five were at 155-165 with #1 at only 135 psi. Also ran my scanner again and came up with another code 11. It isn't 'fun' and I'm not certain I got the readings for the MAP sensor with the engine running correct or not. With the + lead of the DVM on the middle wire and the - to ground I was getting variable reading all lower than about 100 hz. I took a couple of videos that I will attempt to attach. ( I did utube video uploads- here are the links; I think !

.... and with the vacuum gauge attached-

 

[reed b.]

Thats.... Thats not good.

Any chance you can post a video to youtube of it running and link it here?

 

[reed b.]

I had a problem like develop suddenly. Engine felt like it had 40 HP.
It turned out to be broken gasket (old and brittle) between the lower and upper intake. I doubt that the same gasket is your problem with a new rebuild but it may be vacuum leak.

Jerry- Thanks. I've already gone all over the intake manifold and all vacuum hoses and connections with a can of brakekleen with no signs of a leak.

 

[reed b.]

"PJ"- I did my best and the results are shown below.

 

[reed b.]

fixt

'Sheep herder'- And here I've had four border collie mixes in the past almost 40 years!

 

[reed b.]

If i were a gambling man, i'd wager your cam timing is a tooth or two off. Have you been able to check compression?

Kunar- I finally did do a compression test. Results were #1- 135 psi and all the rest at 155-165 psi.

 

[RonD]

155-165psi is expected with an engine running 9.0:1 compression ratio(at sea level), #1 at 135 is low but not a real concern and not the reason for a lack of power
General rule of thumb is compression ratio X 18 = expected PSI
9 X 18 = 162psi

But yours is higher than expected at 4,000ft elevation
The "18" multiplier is: 15 = air pressure at sea level and 3 = mechanical compression of the 15

Vacuum at 13-14" is low
If possible disconnect SPOUT and hook up timing light
See if you can get vacuum to go higher by adjusting base spark timing, or just see if its higher with computer's Load Advance disconnected(SPOUT)
If could be a computer load advance issue causing the lower vacuum and lack of power

 

[JerryC]

I'd do a leak down test next. It may just be a be leaky valve.

BTW, how do the power brakes work? I'm curious about the low vacuum's effect on the brakes and possibly if the brake booster is a vacuum leak

 

[gaz]

Reed,

I just listened to your 2 clips. That is A LOT of valve noise for a freshly rebuilt 2.9L. If you are certain that your engine is 100% correct in respect to cam/crank, I would do 2 things:

1) after completely warmed up, turn it off, disconnect the spout and advance the timing until the value stops increasing and just flutters before begining to lower in value. This is the process to get maximum vacuum.

2) Then with your engine at normal operating temperature, I would perform a rocker arm adjustment!

 

[reed b.]

I'd do a leak down test next. It may just be a be leaky valve.

BTW, how do the power brakes work? I'm curious about the low vacuum's effect on the brakes and possibly if the brake booster is a vacuum leak

Jerry- Thanks, but a leak down setup I don't have. And I really haven't been able to get going well enough to test the brake efficiency. I was also concerned, so put on a new grommet, adaptor with check valve, and new hose. I have also sprayed 'brakekleen' around all intake surfaces and vacuum line sites with no effect. I have to say I hoped it was something like that though.

 

[reed b.]

Reed,

I just listened to your 2 clips. That is A LOT of valve noise for a freshly rebuilt 2.9L. If you are certain that your engine is 100% correct in respect to cam/crank, I would do 2 things:

1) after completely warmed up, turn it off, disconnect the spout and advance the timing until the value stops increasing and just flutters before begining to lower in value. This is the process to get maximum vacuum.

2) Then with your engine at normal operating temperature, I would perform a rocker arm adjustment!

gaz- I would assume that since the engine has only been 'broken in' for a couple of 30 minute runs that most values I'm getting should improve; I haven't changed over from the break in oil yet! I put in a new MAP sensor and 'things' improved a little but not enough to solve the problem. I took it out on the street and the same issue persists. I will be working on it again today and will try out your suggestion. I am certainly hoping that something shows up soon! Again, my thanks to all.

 

[RonD]

As Gaz said, if your Rockers aren't adjusted correctly, noisy, then you would get good compression numbers but LOW power

 

[JerryC]

Jerry- Thanks, but a leak down setup I don't have. And I really haven't been able to get going well enough to test the brake efficiency. I was also concerned, so put on a new grommet, adaptor with check valve, and new hose. I have also sprayed 'brakekleen' around all intake surfaces and vacuum line sites with no effect. I have to say I hoped it was something like that though.

The diaphragm in the booster might be leaking, block the hose and look at the vacuum gauge.

 

[reed b.]

Jerry. The plastic adapter that goes from the vacuum hose into the rubber grommet has a check valve in it so it can't 'bleed' in that direction. I also crimped it down with no change in the vacuum reading.

 

[Dirtman]

Have you considered smoking a cigar?