I have a 1988 Ford Ranger Supercab 4x4 with a 2.9L engine. The truck runs good more often than not, but every now and then it has a random stutter to it. It doesn't seem to make a difference whether it is wet or dry weather, whether it's at an idle or under load (as in up a hill) or decelarating downhill for that matter. It sometimes does it several times in one day, or it may go for a few days to maybe as much as a week and never act up at all.
The "stutter" itself feels to me almost as if it is running out of gas, but it blows black smoke so perhaps it is getting too much gas? Bad plug wires COULD make it feel like this, but to me it just seems more like a fuel problem. Since it has been having this problem, both fuel pumps (I think there is a return pump on the frame, but I could be wrong) and filters have been changed. The plugs and plug wires, cap, ignition rotor, etc have also been changed. I think that the tps has also been changed. Could a bad injector or fuel pressure regulator cause such erratic symptom? thanks for all your input.

Joe

 

If the FPR is leaking gas into its vacuum line or if you have a problem with the O2 or ECT sensor could be the cause. Pull the codes for the sensors and check the vacuum line for gas.

 

what is the ect sensor? Electronic controlled transmission? I have a 5 spd manual tranny....would that have an ect?

 

I did check the vaccuum line for gas and did not find any, I will try to get the codes tomorrow at work and see what they say. I didn't know that an 02 could cause that.

 

ECT is the coolant tempature sensor. The black smoke indicates a rich condition so thats why I thought O2.

 

I have a very similar problem with my '88 2.9L Ranger. I have had it to three diferent shops and nobody has been able to fix it. The symptoms are, loosing power and Black smoke out the exaust. This happens when the engine has been working hard (ie. pulling a load, climbing a grade). When this trouble starts the engine will cycle in and out of the smoking mode seemingly directly related to the RPMs. Below 2500 it runs fine, about 2700 the trouble starts and continues untill it drops below 2500 again. At that point the motor runs fine untill it reaches the 2700 mark and the cycle repeats. I have made a special effort of keeping the throttle steady during the cycling to make this observation. If I continue on with out stopping the problem gets worse to the point the engine won't run normally at all unless it has full throttle. At this point I can only continue driving by flooring the pedal untill I'm going to fast, then cost untill I must floor it again. If when the trouble first starts I stop and leave the engine off for about 8 minutes, I can start back up and every thing is fine. I have had the pressure regulator, the temp sensor to the computer and the ignition modual changed. you guys seem to know alot about this stuff, whatever suggestions you have are sure welcome.
Craig

 

Like Ken said, a very rich fuel condition will cause the black smoke. But also don't forget, an EGR valve opening up wide when it shouldn't will also cause the same symptom. One thing I always advise is to disconnect the vacuum line that goes to the EGR valve, and plug it up, so that you are now driving with NO EGR AT ALL. If the problem completely disappears, then some aspect of your EGR control is at fault. If the problem continues on with NO change, it is USUALLY reasonable to assume that the EGR has nothing to do with it.

 

that sounds like good advice amp17757, I think I will try that. The thing that is tripping me up is that my problem is so random....unlike you, craighead, my problem happens at any rpm and does not matter whether the engine is hot or cold or up a hill or coasting or at an idle....it just does it when it wants to.

 

I had the same symptoms as craighead had on a 87 Ranger 4x4 2.9. What we found out was the tps sensor was off just a wee bit. Slotted the holes and turned a little more and problem solved! Don't know if that helps but you might give it a try.

 

I feel really stupid asking this because I work on cars for a living, but I looked today and couldn't find the egr valve or even a place that an egr valve had once been! I just sold my 87 bronco II with the same engine (2.9L) and it seems like i remember it having an egr, but I can't remember exactly where. Is it possible that my truck does not have an egr valve or am I just looking in all the wrong places. It does have some kind of tube coming off of the exhaust going under the air filter box, but I am pretty sure that is just to warm up the incoming air. So, anyway, WHERE is my EGR valve???????

 

Bronco2guy, there were one or two model years that didn't have EGR, but I thought they were in the mid '90's. I would have thought that yours WOULD have had it, but I could be wrong. I myself am only just now becomming more familiar with all the Ranger engine variations. If it DOES have EGR, I think it is a unit that is somewhat well disguised, bolted to the intake manifold. On my old 2.8, it is at the front of the engine on the intake.

Anyone else know???

 

I have tried tadking the vacuum hose off the EGR ( if thats the regulator thing) at the suggestion of the last mechanic I worked with. The problem still persisted. What and where is the tps sensor? I am a real mechanic, just trying a different approach to solve my problem. should I take my truck back to the mechanic and ask him to adjust the tps sensor ?

 

typo! I am NOT a real mechanic!

 

well, my stuttering problem turned out to be the oxygen sensor. I crawled under my truck to find it and discovered that is had broken in two and the upper half was dangling from the plug above. Anyway, I decided that even if that didn't fix my problem it needed to be adressed so I replaced it with a bosch. It was a real ***** to get out of there though! I broke 3 ratchets trying to get it loose....and that was AFTER I pounded on it with an impact wrench for half an hour to no avail. Anyway, I never did locate the egr valve, and my check engine light still comes on periodically, but the O2 sensor fixed my MAIN problem. Good luck to the rest of ya!

Joe

 

My '92 Mazda 2200 developed the same stutter problem after I had the valves and bearings replaced. The garage where the work was done did me a "favor" by removing all the pollution control vacuum lines. I don't know if that was a factor.