I cant figure it out

[stegomon]

YouTube link

i cant figure out why it doesnt like to run properly. I changed the iac and tps. The spark plugs, wires, dizzy cap and rotor button looks good. Any other ideas?

 

[franklin2]

Check your fuel pressure. Should be 35-45 psi. on the fuel rail when you rev it like that.

 

[Curious Hound]

Also check for codes, even if CEL isn't on. And clean the MAF.

 

[stegomon]

I don't think the 2.9 had a mass air flow

 

[Curious Hound]

I don't think the 2.9 had a mass air flow

Oh, yeah. We just talked about that in another thread, a few days ago. It depends on whether it's CARB compliant or not and maybe what year it was made.

 

[rusty ol ranger]

Check your fuel pressure first off.

Did you ever swap the PCM?

 

[stegomon]

Check your fuel pressure first off.

Did you ever swap the PCM?

No I didn't. I have been running the stock pcm for almost 15 years with no problems. The truck has been in the garage for about 4 years

 

[alwaysFlOoReD]

Mouse nest in filter box?

 

[rusty ol ranger]

Mouse nest in filter box?

Yes....check this.

 

[rusty ol ranger]

Nevermind....he had the intake hose off in the video

Sorry about bringing up the PCM i forgot it wasnt your thread about thenother one.

Id go for fuel pressure first

 

[stegomon]

Thank you all for your inputs

 

[89longbed]

Was this truck running fine before changing the things mentioned in your first post, or it hasn't run fine since before it was sitting for four years. Many more posibilities in the second situation. What year is the 2.9 from?

There supposely were 1990 2.9Ls that used a MAF, but others used a MAP sensor. See 'Ford Fuel Injection Book (.pdf)' in TRS '83-'11 tech pages.

 

[stegomon]

Every thing worked fine. Then one day it just didn't work properly. I have changed those things 1 at a time to see if it will work better. The truck is an 88. But I think the engine is from an 89

 

[89longbed]

What exactly is and isn’t it doing that you’re calling doesn’t like to run properly? (Edit: I now see the link to the YouTube video.) Are these things constant or intermittent? How old is the O2 sensor? That's not likely to be the problem, but it's commonly ignored for much too long. Is our ECM generation known to have the leaky capacitors?

After watching the video I thought about the MAP sensor. When you open the butterfly, manifold MAP is changing a lot and your ECM may not be getting that signal. I checked the EEC-IV book mentioned earlier (pg 78-79) and it says you can't test a MAP sensor with just a volt or ohm meter, so no suggestions there. Maybe check some other posts and see if the symptoms sound the same. I do recall people getting problems fixed by changing the MAP sensor.

From the book: CAUTION - Ford MAP and BP sensors measure frequency-the signal is digital pulses of reference voltage. That's different from pressure sensors in most other cars. You cannot measure frequency with a voltmeter. Do not test for resistance with an ohmmeter. You may damage the sensor.

 

[ryan445]

Definitely check the fuel pressure if you haven't already. My truck did kind of the same thing when it's ECM went but not as drastic. If you have a code reader it maybe able to help pin point the issue. If it's the ECM it could throw random codes that don't clear. For me it was always complaining about the EGR system stuck open when it wasn't and something about the sensor. When it went and I replaced both of those codes never showed again.