Issue...

Hey all. I have a 93 Ranger 3.0l 2wd m5od. The problem starts after I have been driving for about 10-15 minutes. It starts bucking, but I don't loose acceleration at first. After about another 5 mins or so, the truck feels like it is going to stall, and acceleration is harder. It runs really rough, and when I'm going into first gear, almost stalls. Its making a puffing sound at the muffler (after all of this happens and it's idling). The truck has been well maintained. Recently tuned up (within 6 months). This problem came out of no where (truck was running perfectly fine before this), and there is no Check engine light. Any suggestions please!

Have you tried pulling the codes anyway? Here is a link to get you started:

http://www.corral.net/tech/maintenance/eecivtest-koeokoer.html#koeo

Have you tried pulling the codes anyway? Here is a link to get you started:

http://www.corral.net/tech/maintenance/eecivtest-koeokoer.html#koeo

I ran the KOEO test and got 111. I ran the KOER test and got respectively 116, 538, and 536. I had my parking brake down which would explain 536. I'm not sure why I got 116 (temp sensor seems to work fine), or 538. These codes seem not to relate at all to the problem.

Doesn't the brake pedal have to be actuated, on que, for the test?

Did you test the temp sensor? ... this is not the sensor that drives the temp gauge.

Doesn't the brake pedal have to be actuated, on que, for the test?

Did you test the temp sensor? ... this is not the sensor that drives the temp gauge.

I haven't actually tested the sensor, but I don't see how a coolant temp sensor would cause the truck to run this way. As for the brake, I am not sure what exactly the test looks for, all I know is that the parking brake was down (brake light on) and quite posibly the explaination for 536. As for the 538 code, I have no friggin clue what the hell that is lol. Here is a list of what exactly these codes mean:
116 (O,R) Engine Coolant (ECT) sensor out of range - ECT
538 (R) System did not receive "goose" test - TESTS
536 (O,R,M) Brake On Off open or shorted to ground - BOO

Again, I don't think any of this means anything. I am not getting a CEL when the truck is running.

I would be concerned about the temp sensor ... will affect the fuel rate and ignition timing.

What is a good way to test this?

You may find something in a Haynes or in the maintenance section of AutoZone.com

What is a good way to test this?

Here is a link to Autozone's maintenance section for the testing of the ECT on your vehicle. The chart that the article refers to is located at the link to the right of the page. It's the last item listed as "Specification Charts".

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0b/96/7c/0900823d800b967c.jsp

the coolant temp sensor is like the choke on a carburator!!! it tells the computor what temp the engine is at and controls how much fuel the motor gets!!! it's only $15 or $20 so it's good to replace it anyway. it might clear up some of your problems

The 536 means you did not press and release the brake pedal during the koer test. The 538 means you did not have a wide open throttle during the koer test.

From your descriptions of the problem, my first inclination would be a catalytic converter plugging up. Again this is just from your description.

Since it gave me the 116 code, I'll just replace the ECT anyway since its cheap. Perhaps that will clear it up. If not, I will then look to the cat.

Ok well, I replaced the ECT, and it seems to run better. It still occasionally starts running strange out of no where, but then goes back to running fine... I had an assistant rev the engine a couple of times (after I drove it for a while) to see if the cat was turning red, which it didn't. Just wondering where I should look to next.

Pull the codes again!

Turned out to be faulty ignition wires. The damn things were only like 6 months old, but under inspection at night, you could see them arc. They fell apart when I pulled them off... Don't buy COBRA parts, they are junk. I just ended up putting my old wires back on, and it runs like a champ. Thanks all for your help.