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Old 03-13-2012, 08:13 PM
deere842 deere842 is offline
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Exclamation 2.9L Running rough, bad mileage, I'm stumped!

Hey guys,

I'm having a problem with my 1986 Ford Ranger 2.9L Manual trans, 207,000 Miles. i would really appreciate it if you guys can help me.

Heres the Deal...

When I start the truck up in the morning it idles high and when i go to drive it, it sputters and pops a little. When its completely warmed up it runs rich at times and has a very rough idle and the Rpms fluctuate between 600-1000 Rpms. I use to get 20 MPG now im lucky if I get 15... It runs great on the highway but at low rpms it runs like crap.

Heres all the things I have done:

Prior to all these problems I bought 6 new injectors and replaced the upper plenum gaskets and cleaned the hell out of everything. Ran like a brand new truck. Then less than 1000 Miles later....

New Parts:

Egr Valve, Fuel canister filter, engine coolant temp sensor, Pcv Valve, Air charge temp sensor, Map sensor, New Vacuum lines, New plugs, Wires, Distrubter cap, Rotor, Coil. O2 Sensor.

Things I have tried

Cleaning a spare AIC valve from a junkyard and installing (Not difference)

Swapping junkyard EGR control solenoid + Pressure feedback sensor

Tested the TPS and tested fine.

Tried 2 different computers.

40 psi at the rail with key on and 32 psi with engine running.

I took it by a mechanic today and he said to check and see if the timing chain could of stretched and to do a compression check, Ill do that tomorrow.
I hope I have provided enough information, if you have any questions please ask.

Thanks for all your help!
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Old 03-30-2012, 08:38 AM
Lead Head Lead Head is offline
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I'd try doing a "wiggle test". Basically grab bits of the harness and connectors while its running, and wiggle them and see if engine operation changes.

The next thing I'd try, is disconnecting the SPOUT (spark out, or spark control) connector. If you look just under the IAC valve, you should see a connect coming out of the harness with a plug in it. That plug is the SPOUT connector.
- Ian

1987 Ford Ranger XLT 4x4 2.9

Needs a lot of work, including some rot on the body, but shes getting there.
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Old 04-01-2012, 09:53 PM
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882tank 882tank is offline
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Sounds like possibly a massive vaccum leak. Did you replace both the upper and lower plenum gaskets? The lower intake needs to be retorqued after it is warmed up.
Torch Red 2005 Ranger Level II, 4.0, M5OD, 4.10 LS
Medium Fawn Metallic 1981 F100 Custom Shorty, 300, NP435, 3.08 LS 9"
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Originally Posted by WilleyJoe.62 View Post
This is my line in the sand, my stand against technology, hopefully the last truck I'll ever own.
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Old 06-10-2012, 06:58 PM
pcmenten pcmenten is offline
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I'll bet a 6-pack of road soda that your rockers are failing.
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Paul Menten
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Old 06-10-2012, 06:58 PM

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