loss of power (1 Viewer)

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Mar 6, 2010
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Location
Montrose, CO
My 97 FZJ has a loss of power. Upon checking out multiple things I found the hose at the bottom of the egr modulator had came off and melted a hole in the modulator. I replaced the modulator and hose figuring that was the problem. It done the same thing again, except it didn't get a chance to melt the modulator. I replaced the VSV and pulled the EGR valve and checked it and found it was fine. I ran a vacuum check on the engine off of the manifold outlet to the power brake booster and found that I had 10in of vacuum at idle (with a steady needle) and that it would drop when I ran the the engine at a steady 2k rpm. Thinking this was a plugged cat problem I pulled both off and repeated the vacuum test without any change noted. Has anyone else ran into this? The vehicle has 260k miles with the head gasket being changed and the head rebuilt at 130K. I'm thinking it might be engine replacement time.
 
I had 10in of vacuum at idle (with a steady needle) and that it would drop when I ran the the engine at a steady 2k rpm

Where did you measure vacuum from? The '97 FSM specifies 18.6 in. Hg at idle.

Has anyone else ran into this?

Tons of people have had loss of power issues for various reasons.

The vehicle has 260k miles with the head gasket being changed and the head rebuilt at 130K. I'm thinking it might be engine replacement time

That would be a pretty crazy conclusion to jump to.

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I would start by addressing your low vacuum. Replace every single vacuum hose, clean the upper intake, and test the VSV under the upper intake. Replace the fuel filter while you're under there.
 
Vsv was changed when I found the hose off on the bottom of the EGR vacuum modulator. All hoses under the manifold were replaced with high temp silicone about 3 years ago. I took my vacuum reading on the top of the intake manifold where the power brake booster hose port is. I didn't bother looking up vacuum specs due to must naturally aspirated, non big cammed vehicles running between 16 to 22 inces on average. I also replaced the fuel filter about 6 months ago when I changed the fuel pump. It just goes flat when going uphill and will only Rev to about 3200rpm. I've owned the vehicle for 11 years and this is something I've never seen before. I live at 7100' put 315 tires on it and regeared it with 488s shortly after purchase.
 
Vsv was changed when I found the hose off on the bottom of the EGR vacuum modulator. All hoses under the manifold were replaced with high temp silicone about 3 years ago. I took my vacuum reading on the top of the intake manifold where the power brake booster hose port is. I didn't bother looking up vacuum specs due to must naturally aspirated, non big cammed vehicles running between 16 to 22 inces on average. I also replaced the fuel filter about 6 months ago when I changed the fuel pump. It just goes flat when going uphill and will only Rev to about 3200rpm. I've owned the vehicle for 11 years and this is something I've never seen before. I live at 7100' put 315 tires on it and regeared it with 488s shortly after purchase.
This is a lot of random information. Have you done a compression check? I would do this as well as a leak down test before I would even consider an engine replacement. Do these two things before you go any further in your diagnosis. I know those silicone hoses can cause issues, as well as I’ve seen many run silicone vacuum hoses on Toyotas and not seal properly as they weren’t metric hoses.

These engines don’t have much power, so when the engine falls flat going uphill at 3,200 RPM may be an indicator of other issues or normal. Usually clogged cats or EGR issues have a surging problem when air cannot move through the engine correctly.
 
All hoses under the manifold were replaced with high temp silicone about 3 years ago

That doesn't seem to be working out very well. Or you've got leaks elsewhere.

Did you verify that the passages through the upper intake are clear? When the EGR modulator blows out, it seems to allow carbon into the vacuum passages.
 

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