rough idle and engine light flashes

[d.GATOR.b]

I'm new here and not sure if I'm posting in the right spot or not. But I have an 89 ranger 2.9 with auto trans and it idle really rough and if I push the gas pedal all the way down (when in park) the engine light will go off for a second and then back on. It also sputters when I first take off from a stop.
Any help would be appreciated. Thanks!

 

[RustedRanger]

Welcome to TRS....first thing to do would be read the Tech section and find out how to check for codes then go from there. If you don't get some direction on what needs replaced you can spend a bunch of time and money fixing things that aren't broke.

 

[d.GATOR.b]

I don't have the stuff to check for codes and neither does any of my buddies or any local autopart stores. I have replaced the throttle position sensor, idle air control valve, and the o2 sensor and still nothing. I pulled the plugs to clean them (that also didn't work) and found that 4/6 had oil on them. I drove it today and found that under heavy acceleration the engine light goes off until the rpm's drop down under about 1200. When I first start it the rpm's go up to around 12-1500 like they always have then it drops to about 800 and that's when the engine light first comes on. And I did mess with the little throttle stop screw (I know, shame on me)

 

[RustedRanger]

You can use a test light to check codes...if you don't have a test light,make one out of a bulb and two wires. There is so many different things that could be causing your problem. Otherwise find a good shop that can do diagnostics.

 

[d.GATOR.b]

Ok so lets ignore the engine light. I'm sure some people have had these symptoms before and know what im talking about. Any ideas on what part may be bad? Fuel pump and filter were just replaced last summer.

 

[d.GATOR.b]

I'm kinda leaning towards the for being bad because when I remove the vacuum line to it and plug the line with my finger there is no change in the way it runs. And my oil smells like gas.

 

[RustedRanger]

You mean the FPR? I didn't understand what you wrote. So nothing changes when you remove the vacuum line from the FPR? If so it sounds bad....I got mine from rockauto.com and saved around $50 over the local parts stores,it arrived quickly also. No vacuum says to the FPR that the motor is at full throttle and raises the fuel pressure.

 

[d.GATOR.b]

Yes I meant FPR. The autocorrect changed it on my phone. Can you explain that last sentence again?

 

[adsm08]

First things first. A flashing CEL means a misfire. Especially when coupled with your crappy idle. Your FPR may still be at fault.

The FPR is vacuum operated. Vacuum is just pressure lower than atmospheric. When the throttle plate is closed there is high vacuum in the intake manifold and the FPR closes it's orifice to restrict the amount of fuel pressure in the rail. When low vacuum is applied (a high throttle position) a spring pushes the orifice open to allow more fuel into the rail at a higher pressure. If the diaphragm ruptures or the hose gets knocked off the FPR acts as if the engine is at wide open throttle and starts allowing lots of fuel in even if it isn't needed.

I would start with new plugs, wires, cap and rotor and FPR.

Run some seafoam through the system and change the oil ASAP. If it has gas in it it will be thinned out and your cylinder walls will be getting gas washed which is bad for compression.

 

[d.GATOR.b]

Ok thank you. I will replace these parts asap and see how that works

 

[RustedRanger]

Thanks for the additional details adsm08......Gator let us know what ya figure out.

 

[d.GATOR.b]

Ok so I put new plugs wires cap and rotor on and still the same. I will post a link to a video I just uploaded of the engine light

 

[d.GATOR.b]

here is the link
http://www.youtube.com/watch?v=ULxG0MbxuSY&feature=plcp

 

[1989LongbedGT]

I watched your video. It sounds like your having a fuel issue or the timing is severly off. How does it idle? Hard to tell in the video and on my shitty laptop speakers.

I would suggest putting a fuel pressure gauge on the shrader valve that is on the fuel rail. Its on the driver side just next to the intake manifold. Next is to get the truck warm, Let it idle for a bit so it warms up and check your base timing. Factory should be 10degrees BTDC. I think fuel pressure should be between 30 to 50 psi? Im not sure on the exact amount for these trucks. thats just a general pressure for most early efi and fuel injection systems.

Double check that you dont have your plug wires backwards. Firing the wrong cylinder at the wrong time can give you the same symptoms.

Also you mentioned you had oil on 4 of the 6 plugs. How much oil? This an indication of Blow By which is caused by worn piston rings or failed PCV system. Oil doesnt burn as efficient as fuel... lol.

As ADSM08 added about the FPR, i noticed it says hes a Ford Technician. I however am not one for ford but am a technician. Most times a FPR maintains the correct pressure in the rail regardless of throtle position, the ECM lengthens the injector pulse width to give you more fuel at WOT. Again that is a general statement not particularly to do with FORD. Each manufacture has their own unique and stupid way of doing the same thing.

Try to borrow some tools, or buy tools (having a old truck like this you should have most of your basic tools anyways). Or take it to a known good mechanic.

Throwing parts at a vehicle in attempt to fix it is no way to repair a vehicle and can get very costly.

Hope this helps! Heres a quick check list again.

Fuel Pressure (fuel pressure gauge on shrader valve)

Correct Plug wire Placement (go to tech section for firing order) Pass side is cyl 1,2,3 driver side is cyl 4,5,6. Start with 1 then go from there.

Base Timing (timing light)

Best of luck!

Matt

 

[d.GATOR.b]

All of the above have been done other than checking the timing. Fuel pressure stays around 32-35 psi at all times. And I should have started the video before I started the truck. When you first start it it runs fine for a minute then acts like the IAC valve quits working and that's when the engine light comes on and it stat,s to ac,t up. Around 2500rpm's and up it runs perfect again. I'm stumped.