1990 2.9 Ranger Intermittent miss

[cougar190]

Hello folks! I've searched and didn't find this problem,sorry if I missed it. I have a 1990 Ranger with a 2.9ltr. and a 5spd. The motor was a recent replacement, motor was used so I don't know it's history (promised to be good). When it's started (cold) it runs great! May run great for 10 to 15 miles maybe more. Then after a while it will start to miss (badly to me) then after a few miles it may smooth back out and run great or it may not and continue to run bad till it cools some, not back to stone cold just after sitting a Short while. Sometimes it will run great my whole trip, 50 miles or more, but most of the time after 10 to 15 miles it will start missing but like I said sometimes it will straighten out while going down the road and run great! I've replaced these items plugs,wires,rotor button,cap,and the little box bolted to the side of the dist. No (sorry) I haven't coded it yet. Any other help would be appreciated! Thanks, ...cougar...

 

[DisturbedMXer8]

Maybe a bad temp sensor? If the sensor was bad and didn't tell the computer when the truck was warm, it could be causing it to stay in open loop and run really rich once it warms up, which could be causing the misfire. I'd definitely take a look at it to start with, as it sounds like it's a temperature problem to me.

 

[cougar190]

Hmm

Hey Disturbed, Would that be the same temp sensor as operates the Temp gauge on the dash or another one? The reason I ask is because the one on the dash seems to be functioning properly. I hate this new electronic ,computerized crap! I'm 48 and old school, give me a set of points and a carb. and I can do wonders, but this new stuff with all the electronics and sensors and computer commities making all the decisions for the motor is for the birds. Just my 2 cents worth, I know improved is better (yeah Right) 1

 

[DisturbedMXer8]

There should actually be two Coolant temp sensors, one for the dash and one for the computer. So even if your dash gauge is working perfectly fine, the other one could be giving your computer false readings. I know someone actually posted pictures of the two sensors somewhere on here, take a look around and see if you can find em.

Also, I know what you mean kinda. I grew up with two-stroke motorcycles, so I'm used to carbs, not all these EFI and EI systems. I've actually only been learning about this stuff for about a year now. I'm only 19 though, so I've still got a lot more to learn (meaning I could totally be wrong about your Temp Sensor, it's just what seems plausible to me =P).

 

[cougar190]

Hey Disturbed I'll look around . Like you said there ought to be something here somewhere! Thanks for the input . ...cougar...

 

[DisturbedMXer8]

Not a problem man, I hope you figure it out. I also hope I didn't steer ya in the wrong direction. I know how much it sucks to have problems you don't know how to fix =|.

 

[MrGoop]

2.9 with same problem??? from Mr Goop

Hello folks! I've searched and didn't find this problem,sorry if I missed it. I have a 1990 Ranger with a 2.9ltr. and a 5spd. The motor was a recent replacement, motor was used so I don't know it's history (promised to be good). When it's started (cold) it runs great! May run great for 10 to 15 miles maybe more. Then after a while it will start to miss (badly to me) then after a few miles it may smooth back out and run great or it may not and continue to run bad till it cools some, not back to stone cold just after sitting a Short while. Sometimes it will run great my whole trip, 50 miles or more, but most of the time after 10 to 15 miles it will start missing but like I said sometimes it will straighten out while going down the road and run great! I've replaced these items plugs,wires,rotor button,cap,and the little box bolted to the side of the dist. No (sorry) I haven't coded it yet. Any other help would be appreciated! Thanks, ...cougar...

I have a 2.9 that I can drive for about 20 miles at 55 mph and it will start to misfire on one cylinder ( well it feels like one cylinder to me ). If I drive it a little harder say 65 mph it will start missing sooner. Question is did you ever find out what was wrong with yours and how did you correct it??

Thanks; MrGoop

 

[kbold]

miss fire/ hesitation

i got the same thing going on, iv pulled codes and gone over it all, changed the tps,iac valve, MAP sensor, air temp charge sensor(passenger side of fuel injection), plugs, new fuel lines,fuel filter, fuel pumps, 2 in-tank pumps to be exact... still will start and run really good sometimes and the other times itll sit and miss really bad and cough and shutter blowing black smoke out the exhaust. smells like sulfury bad gas almost but has no bad gas in it. when problem starts if im going down the road and go WOT it gos away and picks up that cylinder/cylinders that are missing. any ideas would be great.. forgot to mention FPR has no fuel in vacuum line and all vacuum hoses have been replaced. along with a MSD ignition coil(50,000volts).

 

[cougar190]

I was told by a friend that I had a weak injector and I could test the injectors with an OHM meter. He said to measure them cold and once it's warm measure them again and that would show me the weak/bad one. I said screw it and just hammer on it when it starts messing up and go on down the road, Gotta Love a Ford !!! ...cougar...

 

[freedom5]

There should actually be two Coolant temp sensors, one for the dash and one for the computer. So even if your dash gauge is working perfectly fine, the other one could be giving your computer false readings. I know someone actually posted pictures of the two sensors somewhere on here, take a look around and see if you can find em.

Also, I know what you mean kinda. I grew up with two-stroke motorcycles, so I'm used to carbs, not all these EFI and EI systems. I've actually only been learning about this stuff for about a year now. I'm only 19 though, so I've still got a lot more to learn (meaning I could totally be wrong about your Temp Sensor, it's just what seems plausible to me =P).

The engine coolant sensor has two wires and should be on the pax side. I had to take the thermostat housing off to be able to get a wrench on it. Also - have you replaced the O-2 sensor? that could also cause the problem.

freedom5

 

[Spitfire1975]

just for giggles....

Block of the throttle body with your hand and see if the engine dies. Listen for a whistle, hiss or any other weird noise that would locate a lower manifold leak.

It should just die if you have no vacuum leaks.

Watch your fingers carefully near the fan and alternator.