We have a 1990 Ford Ranger 4-cylinder 5-speed bare bones with 84,000 miles. Truck runs smooth while the engine is cold but with noticeable spark knock. Once up to normal operating temperature, the engine idles rough, can detect spark knock under "light" acceleration, loses some power and there is static in the radio speakers.

Have run the codes - no errors. Fuel injectors have been replaced recently which did not help appreciably.

Anyone else run into this problem? How did you solve it.


Russ

 

Russ, I'm not sure which engine that you have. If it has a distributor, retard the timing in 2-3 degree increments until the pinging stops. If you have the DIS engine (no distributor), the timing is not adjustable, except for an "octane reduction plug" that is located on the passenger side wiring harness, next to the firewall. Just remove the plug. This will retard the timing slightly, hopefully enough to stop the pinging.


78 Bronco Ranger XLT, 351M, 4 speed, Trailer Special

 

Oh yeah, just re-read your post. If you have ignition noise thru the radio, look at the distributor cap and rotor, and the plug wires. I would replace the plug wires first.

78 Bronco Ranger XLT, 351M, 4 speed, Trailer Special

 

Our Ranger has the 2.3 L 4-cylinder engine with the EEC IV distributorless ignition. It has 8 sparkplugs with coil packs mounted on each side of the engine. There are no timing adjustments that can be made. I will look for the Octane Reduction Plug this evening and report back if it makes any difference. Should this engine idle smoothly?

 

RangerRuss, yes, this engine should idle and run very smoothly. I have one in a 92 Mustang. Check the coil pacs and the plug wiring very carefully. Since you have radio static, a plug wire may be broken or loose. The only timing adjustment on these engines is the octane plug. Let us know how it runs when you remove it. Good luck.

78 Bronco Ranger XLT, 351M, 4 speed, Trailer Special

 

I have been unsuccessful at locating the octane plug. I did however find a broken vacuum line. Repairing the leak went a long way toward a smoother idle. What does this octane plug look like??

Any help is appreciated.

 

Russ, I'm not 100% sure that you have one, if you can't find it easily. It is a 5/8" by 5/8" (approximately) gray plastic plug that is attached to the wiring harness. You have to release the plastic clip on the side to remove it. It should be found on the passenger side of the firewall, in the wiring harness. Good luck.

 

Found the octane plug. The spark knock has subsided some due to a fresh tank of gasoline which tells me that it must be time for a legislated reformulation of gasoline here in Calif. I unplugged the fuse for the ECM to let it reset itself. I will disconnect the octane plug over the weekend and report back.

The truck now seems to be lacking power at higher speeds - 60 mph plus. This began with fixing the vacuum leak. The "pinging" is much more noticeable when the engine is cold. Once it warms up it is not so noticeable any more. Does this make any sense???

Russ

 

Does this truck have an anti-knock sensor anywhere? If not, does some other sensor do double duty?

Any help is appreciated.

Russ

 

Russ
I have an 89 Ford Ranger w/ the same engine. I am not sure whether you have fixed your problem, but I have experienced the same problem with mine, and others. I don't think your ignition plug is a problem. The first thing I recommend doing is checking and changing your spark plug wires. I am willing to bet that is your problem. while you change the wires, look at your spark plugs, it may be time for a change. If you are up for recommendations, the Bosh Platinum +4 plugs work very well in these 4 cylinder motors. If that does not fix your problem, then post or write me at slammindeuce(No Email Addresses In Posts!); and I can lead you through some other things. I have done work on many of these Ford 2.3 engines and also perform many performance upgrades on them. I can help you with basically any of the Ranger related problems!!!