No power issue 1990 2.9lXLT...need advice

[Uncle Gump]

With vacuum gauge connected... check vacuum at idle. Then increase RPM to about 3000 RPM. Vacuum gauge with likely increase slightly from idle reading. Blipping the throttle will drop vacuum to zero... but should increase as RPM rises and is held steady. If it wont... restricted exhaust.

Plugs being clean/white... sounds a bit lean.

My 2.9L at idle...

It's north of 40 psi with no vacuum. If your gauge is accurate... lower pressure = leaner mixture. O2 sensor can compensate mixture to a point... but would likely set a code in extremes.

 

[Maggrett]

I noticed the tachometer started blipping erratically which is why I replaced the TFI module (had one laying around because I now know how flippant they are). I do sometimesnotice the amp gauge either low or high. It might be an electrical short. I was thinking of driving on the highway with the fuel pressure gauge on a longer hose so I could put it into the cab. Otherwise, I'm stumped.

 

[Maggrett]

With vacuum gauge connected... check vacuum at idle. Then increase RPM to about 3000 RPM. Vacuum gauge with likely increase slightly from idle reading. Blipping the throttle will drop vacuum to zero... but should increase as RPM rises and is held steady. If it wont... restricted exhaust.

Plugs being clean/white... sounds a bit lean.

My 2.9L at idle...

View attachment 103677
! I appreciate you. Tomorrow I will go back out and redo the vacuum test. My pressure definitelyis a bit off. Wondering if something else is causing it to dip further when I'm on the highway. Will do the checks and report back. Thanks!

 

[Maggrett]

Thanks for your time Uncle Gump. I appreciate you. Tomorrow I will go back out and redo the vacuum test. My pressure definitely is a bit off. Wondering if something else is causing it to dip further when I'm on the highway. Will do the checks and report back. Thanks!

 

[Maggrett]

 

[Maggrett]

Not sure if there is something I'm missing so I posted a video. Anyine notice evidence of exhaust restriction or the like?

 

[Maggrett]

I will say that my throttle cable was stretched pretty well. Taking up the slack improved tĥe situation a bit, but it still lacks uphill power.

 

[Uncle Gump]

Vacuum readings look ok... I have zero experience at higher altitude though.

 

[Maggrett]

Thanks Uncle Gump. I'm starting to think I just have a tired old engine. Drove 120 miles, without much power, buy solidly.

 

[Uncle Gump]

Ya know... they do get tired. A compression test would confirm.

Did you get all the slop out of the throttle cable?

 

[Maggrett]

Yep, throttle cable is taut. It still seems variable. Sometimes I had power on the highway without much effort and others it was excruciatingly slow with the throttle floored. I think I will pull my tank and see if there is crap on the sock.

 

[Angry Possum]

Definitely do a compression test. Post your findings here.

 

[Angry Possum]

PS- Make sure all your plugs are tight and the correct gap, or even the correct plugs. Is it the correct fuel filter, or could it have been put on backwards. Troubleshoot everything you replaced.....

 

[Maggrett]

PS- Make sure all your plugs are tight and the correct gap, or the correct plugs.

I just changed the plugs and same symptoms. I will do a compression test and post the results.

 

[Angry Possum]

I just changed the plugs and same symptoms. I will do a compression test ans post the results.

How about the filter? Do you have the right flow direction.