No power past 65 and horrible gas mileage

[procadman]

I know everything points toward a clogged catalytic converter but Meineke says it's ok.

'89 2.9 auto w/overdrive and posi-traction.
75k on bottom end. 10k on top end. <30k on tranny. 150k on most other peripherals.

Compression is around 110 (to spec).
New wires, plugs, cap, rotor.
New EEC.
New EEC and fuel pump relays.
Timing is correct.fuel pump and filter is about 2 years old.
Has same size tires I have always had on it since new: standard ones in front and 50 series in rear.

Exhaust past converter has been replaced once and needs it again.

It was never good on gas: about 250m to a tank. Now it's just over half that.

Around town it has plenty of pull. But, when you get to 65 or 70 it's like stepping in a hole. There is very little pedal left and it makes no difference to use it.

Yes, all signs point to a clogged exhaust, despite what Meineke says, but, my experience with a clogged converter, though similar, has always included an overheating engine when you keep pushing it.

My code reader emits a constant beep and may be faulty.

Any other ideas, guys?

 

[Surrey]

Have you tried the zip tie throttle cable mod?

 

[RonD]

Well fuel pump and fuel filter could cause the loss of power at higher RPMs, but wouldn't give you bad MPG, so I think they are off the table.

A cheap vacuum meter($20-$30) could tell you a lot.
Probably the best way to tell if you have exhaust limitations.
Visual inspection doesn't tell you much.
With engine at say 3,000rpm vacuum should be steady, when you snap the throttle plate closed the vacuum in the intake will increase greatly because pistons and valves are still pumping air out of the intake until rpm decreases.
If exhaust flow is limited the vacuum will not increase much because without the firing of the cylinder the exhaust pressure doesn't allow intake air to come in.

Sticky injectors could lower MPG, but probably not reduce power at higher RPMs.
Can of Seafoam in the tank is always good once a year, IMO.

TFI ignitions have their issues, weak spark could cause reduced MPG and poor high RPM power, but you would probably notice other faults, hesitations and missing now and then.


Yes, zip tie on the throttle cable on these rangers is a good idea, but this has nothing to do with MPG.

 

[procadman]

zip tie and vacuum.

Thanks, buys.

I have a vacuum gauge and will try that tomorrow.
I'm assuming I just replace any direct vacuum line.

I'm not familiar with the zip tie mod.

 

[RonD]

yes, any vacuum line on the intake

Good read here on what vacuum gauge can tell you about an engine:
http://www.gregsengine.com/using-a-vacuum-gauge.html


Ranger throttle cables are known to stretch over time.
So when you push the pedal to the floor you only get 7/8 throttle, not full throttle
Inside the cab on the top of the gas pedal bar you will see where the throttle cable attaches, pull gas pedal away from floor to see if it can come up more, usually it can and you will see the bare cable sticking out.
Put 1 or 2 zip ties around the bare cable, this will put the gas pedal back to new position.

 

[procadman]

Thanks,

Will try those ideas tomorrow.

 

[gw33gp]

Posting in a 4.0L forum for a 2.9L problem is not the best way to get solutions.

 

[procadman]

My bad.
Apparently I compounded another users mistake.
I originally did a search on "lack of power" and posted where I found results on a 2.9.
In the future I'll be more thorough.

 

[procadman]

(Ron,
I'm just a few hours from Gregs.
I'm east of Cincy.)

 

[procadman]

Okay, vacuum test showed the only issue was timing, though I had just set it to tdc without the bypass. It held a constant 16lb. I adjusted the timing to 17lb.
All other vacuum tests were negative.

Surprisingly, since it has set a lot over the years the throttle cable was stretched. I put one medium size wire tie to take up about 70% of the slack.

If any of this helped I will let you guys know.