OT: 3.0 V6 update

[Anonymous-0]

I did some more checking last night, but I ran out of time before I got to the compression test. Fuel pressure tested and held 50 psi with the key on motor not started. With the motor running it maintained 60 psi at all rpms. The pressure guage that I used has a bybass hose on it. I pushed in the bypass button and got a steady stream of fuel with the engine running. Didn't seem to be starving the engine for fuel at all while I was doing this so I think fuel flow is okay. I got a can of the MAF cleaner that Gerald J was talking about and tried that. It seems to be running smoother at an idle, but still feels like it is missing under a load. Maybe it is the MAF sensor?? If I can find time this weekend I still plan to run a compression check. I also think I will see about checking the catylitic converter as many have suggested. One thing that I forgot to mention in my first post is that the engine is hard to start after it has ran for a while. Generally I have to hold down on the gas pedal to get it to start. When it has been sitting overnight it will usually start without even touching the pedal (like it should). Thanks to all that provided the helpfull input!

 

[Jim in NC]

Isn't it the MAP sensor?

 

[dhermesc]

Mass Air Flow sensor - it's in the intake pipe between the air cleaner and the intake manifold.

I don't think a bad or dirty sensor explains the low manifold vaccuum.

 

[supergrumpy]

3.0 Vulcan in son's Taurus kept getting O2 sensor codes, after lots of detective work found mouse had chewed up air cleaner to make a nest, fibres from the filter contaminated the platinum wires on the MAS

no monitoring of MAS but it threw the mixture off enuf to generate O2 sensor codes

if you cleaned the 2 wires on the MAS and aren't getting O2 sensor codes, seems you should be looking elsewhere

 

[Allan in NE]

Dunno,

Sure sounds like a fuel pressure issue to me, but I'm getting old and can't 'member 'nothin' anymore.

Does that thing have a fuel regulator on it?

Allan

 

[Anonymous-0]

Many years ago, I had a Ford station wagon (V8 engine) that would start OK but when you pressed the pedal for power, it coughed, stumbled and had nothing. I eventually found that it had a double wall exhaust pipe and the inner pipe had collapsed. This created so much back pressure that the engine couldn't breathe. I think it also affected the vacuum readings. Just a thought.

 

[Anonymous-0]

Maybe a cracked intake manifold? Did it backfire and break the intake manifold before the problem arose?

 

[Anonymous-0]

No it has never backfired. Actually this is a problem that got progressivly worse over time. I started trouble shooting and working on it a while back, but I've been unable to fix it yet.