I have a 1988 4x4 ranger with a 2.9L v6. The truck runs great when it is cold but as it warms up starts to miss like I lost a cylinder. If I put it to the floor it clears up and runs fine for a couple of seconds, then starts missing again. I have changed plugs, wires, and cap and rotor with no luck. I have noticed when it starts to miss I get all kinds of black smoke from the exhaust. Any suggestions.... this is killing my gas millage.

Thanx in advance... brad

 

Have you replace the PCV valve?

 

My 87 2.9 efi does the same thing. Ive changed o2 sencer, temp control sencer, ignition switch, fuel regulator, and had ijectors cleaned. nothing worked. someone told me to try a new map sencer. I,ll try that next and see if that works. If you find the solution please let me know, this is driving me crazy! hillbillyt

 

Sounds like a fuel pressure regulator. The tip was the black smoke. It may get worse and really become hard to drive. Do a fuel pressure check.

98 F250LD 4X4

 

Did you change a fuel pump recently? I experienced something similar on an 89 BII 2.9l shortly following an electric fuel pump change. Fuel pressure regulator went bad. See if your oil smells like gas. If so, get this taken care of quickly as the excess fuel in the cylinder leaking past the rings will dilute your oil and take out the engine bearings.

 

That's a good point. If gas is blowing by the rings, you will readily know it when you drain the oil. It will feel like gas and smell like gas. Fuel regulator or fuel pump can do this.

If you catch it in time, the inside of your motor will be really clean at least.

98 F250LD 4X4

 

I just changed the fuel pressure regulator and that wasn't it. I don't smell any gas in the oil either. I pulled the plugs and found that evey plug is black. I haven't changed the fuel pump. Could this be a problem with the fuel injectors or maybe the ignition module? This has really got me stumped! any suggestion would be greatly appreciated.

thanx again, brad

 

I don't think it's your injectors. Before you change any more parts I would complete a fuel system pressure check. I think, that a bad fuel pump can cause this. But seriously, you need to complete a pressure check on your fuel system that should help eliminate it.

 

What it might be is that if you have a throtle body fuel ingection system it is not set properly or there might be a problem with the computer set up. it might be giving it to much gas and that could be the problem

kyle

 

I am by no means a mechanic, so please forgive me if I am way off base here....

A few years ago I had a 92 Mustang GT that was experiencing similar problems as those listed above.... The thing run like crap, and it was like it was "missing". Anyway, to make a long story short, a friend of mine was a mechanic at a pretty large Ford dealership, and he spent over half a day trying to figure out what the problem was.... Turned out to be a very clogged catalytic converter. He got it covered under the emissions warrenty, and viola, problem solved.....

About a year later one of my uncles was telling me about some problems he had been having with his Ranger that were very similar to the problems I had with the Mustang..... He had taken the truck to his local, small town Ford dealership 2-3 times, and was still experiencing the same problems (no power/missing/spitting/sputtering). I told him what was wrong with my Mustang, and sure enough, a new converter solved his problem too....

I'm not certain what year model, or what motor my uncle's little Ranger had in it.... I'm certain it was a V-6, but the year model slips my mind....

Might be something to check out.

Good Luck!

Gene

 

Good news!!! I just changed my O2 sensor and the truck is running great. Thanks everyone for all the information. I hope this helps anyone that might have a similar problem. This site is a great help for all us backyard grease monkeys. Thanks again.

brad