Problems with lack of power

[reed b.]

Hello,
I will try to use the correct English and sentence structure as well as punctuation as has been requested of me. Please forgive me if I fail to do so at times.
I have a 1988 Ford Ranger XLT 4 WD that was given to me years ago in poor running condition. I had it running a couple of years ago however it was determined that the engine, a 2.9 liter, was in need of a rebuild. I was able to have that work done as well as a considerable amount of old parts replaced this year. I have the locally rebuilt engine installed however I have a significant lack of power when I attempt to drive it. It idles and revs up well when under no load. My scanner shows only a Code: 11 meaning the computer (EEC) is holding no DTC codes. I have timed the engine to 10 BTDC with the SPOUT connector removed and replaced. I have replaced the oxygen sensor, the IAC valve, and the ECT sensor. I have used two different but compatible (same id numbers) EEC s with no difference in the problem. I have accessed the rear of the catalytic convertors (CA) and can see through them to the tip of the O2 sensor. One thing that I do not understand is the lack of any MAF sensor or wiring for one on this vehicle. I have one throttle body valve with a TP sensor that tests within it's limits. There is no other piece attached to the air cleaner nor any signs for an attachment. The hose connecting the air cleaner box and the throttle body fits well and is of the correct length.
Any comments or ideas are welcome and appreciated. Thank you for your time. I hope that all are able to understand what I have written.

 

[rusty ol ranger]

The 2.9 doesnt have a MAF (mass air flow) sensor. Except for very late run (91/92) ones with cali emissions.

Yours should have a MAP (manifold absolute pressure) sensor.

How long ago was it rebuilt? What was the reason for thinking it needed rebuilt? The 2.9 is a pretty hearty engine.

Sounds like youve covered alot of bases...i would test fuel pressure and see what you come up with. Something as simple as a plugged filter can cause power loss.

 

[PetroleumJunkie412]

I'm always very leery of rebuilt engines... are you certain that they used a fresh camshaft, etc?

The rebuilt heads I had on mine for a year or so were rebuilt with used parts by the machine shop that sold them - absolute junk.

 

[RonD]

Use, get, a vacuum gauge, $20

Should see 18-21" of vacuum at idle, lower means there is either a timing or compression issue

Vacuum gauge is still one of the first tools out when I have power issues, tests here: https://www.gregsengine.com/using-a-vacuum-gauge.html

Doesn't matter what they add to the outside of a gasoline engine, its still just a self powered air pump, so best way to test a pump is with a pressure gauge

If vacuum is low then you will need to test compression in a few cylinders, 160psi is expected in a 9.0:1 compression ratio engine, especially if just rebuilt


+1 on the MAP sensor, you won't have a MAF sensor on a 2.9l Ranger
MAP sensor may be mounted on firewall, it will have 1 Vacuum hose running to the intake and a 3 wire connector
Check vacuum line to make sure its air tight and check connector for corrosion or frayed wires

MAP sensor IS the "engine load sensor" so can definitely effect power when driving

 

[reed b.]

Rsuty, I'm glad there is not MAF on the vehicle as I can't find a thing for one! I do have a MAP sensor which I am trying to find out how to test. I had the engine rebuilt by a local and very qualified automotive machine shop; I know the owner/machinist and he is well qualified with a long history of satisfied customers. He showed me the crack in one head that went through both seats even as well as the minute crack in a web of the water jacket that anyone else would have reused; however now both heads are new castings. The engine had overheated I believe and I knew there was a bad head gasket at the least. I am afraid that with listing all the other things I've done that i forgot to mention that I had also put a gauge on the fuel rail schrader valve and tested for pressure while idling as well as with raised rpms. It showed a consistent reading of 32-36 psi. I had also replaced the main fuel pump and filter prior to the rebuilding of the engine. I have done my best to test and replace whatever may be the cause of the problem prior to listing it on the forum. I do not want to waste anyone's time. And Thank You.

 

[reed b.]

I'm always very leery of rebuilt engines... are you certain that they used a fresh camshaft, etc?

The rebuilt heads I had on mine for a year or so were rebuilt with used parts by the machine shop that sold them - absolute junk.

 

[reed b.]

PetJunkie, I am also very leery of a 'rebuilt' engine and that is the reason I had my local shop do all the work. We only have one automotive machine shop still going here in the small town I live in. But Marv has been doing this work for a good fifty years now and he's well respected for his work. As I said in my response to Rusty, Marv even showed me a crack in the web of a water jacket location that I had difficulty in even seeing. It was not in a critical location, however he did not feel it was worth using that head at all. It was a just under $2000 rebuild in the end. And Thank You as well.

 

[RonD]

Try timing at 12deg BTDC and test that the timing jumps to 20+ BTDC when SPOUT is plugged back in
SPOUT is the "vacuum advance" for this electronic ignition system, so its the "engine load" spark advance
SPOUT signal comes from the computer, computer uses TPS and MAP to calculate "load" spark advance

Distributors TFI module does RPM advance, so engine can REV fine in driveway, RPM advance, but lack power on the road when you need "load" spark advance as well

 

[reed b.]

Use, get, a vacuum gauge, $20

Should see 18-21" of vacuum at idle, lower means there is either a timing or compression issue

Vacuum gauge is still one of the first tools out when I have power issues, tests here: https://www.gregsengine.com/using-a-vacuum-gauge.html

Doesn't matter what they add to the outside of a gasoline engine, its still just a self powered air pump, so best way to test a pump is with a pressure gauge

If vacuum is low then you will need to test compression in a few cylinders, 160psi is expected in a 9.0:1 compression ratio engine, especially if just rebuilt


+1 on the MAP sensor, you won't have a MAF sensor on a 2.9l Ranger
MAP sensor may be mounted on firewall, it will have 1 Vacuum hose running to the intake and a 3 wire connector
Check vacuum line to make sure its air tight and check connector for corrosion or frayed wires

MAP sensor IS the "engine load sensor" so can definitely effect power when driving

 

[reed b.]

Ron, I have an old Sun pressure/vacuum gauge I was going to use however I haven't found where it is yet ! I have assumed that the OBD1 scan would have shown an issue with the MAP sensor if there was one. Am I relying on scan information too much? And I agree that a vacuum gauge is one of the better diagnostic tools around. I had my own shop back in the eighties and it was a very useful tool. I will look some more or else go and get a new one (even though I won't find one as good as the old Sun one these days!) Thank you

 

[reed b.]

All- I forgot to mention that I have also replaced the distributor assembly with a rebuilt one with new TFI and 'innards'...

 

[lvwill]

Is the tfi on the new distributor the same color as the old one?
I bought a rebuilt distributor for my 92 2.9 and it came with a black tfi.
It ran like crap. Should be the grey one.

 

[RonD]

No, on the OBD1, or OBD2, that's not what they do

They basically just have a circuit tester on each sensor that tells if its hooked up, and then will have a "range" for that sensor, if its out of range then it will set a code or if its disconnected/broken it will set a code

Computer has no idea if engine is running poorly or running well
Fuel pump could die, no code
Head gasket blows, no code
Timing is off, no code
Lifter ticks, no code
Rod knocks, no code

Pattern is, if there is "No Code" then its a mechanical issue

But that being said, No Code may mean a computer issue, lol, brain damaged computers often won't set any codes
So just as a test unplug TPS and start engine, should get CEL and a TPS code right away, a sanity test

 

[reed b.]

Is the tfi on the new distributor the same color as the old one?
I bought a rebuilt distributor for my 92 2.9 and it came with a black tfi.
It ran like crap. Should be the grey one.

 

[reed b.]

lvwill..... Actually, the old distributor has a black unit on it; the new one has a gray unit on it. As far as I understand it, one may be for lower altitudes and one for higher altitudes.. I think I am at 4,000' which is between the two types.