My friends 91 Explorer XT has no power above 2000 rpms. He stuck a code reader on it and it came up with code 57 octane boost CKT fault NPS. Its a 4l 5 speed manual. The dealership says that have never seen one. They wont tell him what it means, only work on it. Any ideas on what might be wrong?

The VIN is 1FMCZZX5MUB01813. Its supposed to be rare because the only emission equipment it came with was cats, no smog pump. Also, a rocker arm rattles and does this have any connection?

thanks
wayne

 

Hi jff24gordn and welcome to FTE

When I noticed your nickname I wasn't going to reply but you asked nice so I guess I will

The code 57 is for the Octane Adjust Shorting Bar. It is a little connector that can be removed to retard the ignition timing by 5 degrees (I think). Typically it gets removed if a vehicle was pinging and no other cure was found. The connector that it plugs into is a small squarish one near the heater blower motor on the R/R of the engine compartment. It should have a dark green and a grey with red wire going to it. You should be able to buy a new plug or bar for it at your local Ford dealer. It is the same as the timing SPOUT connector on most Fords.
The code could also be caused by the wiring to the Octane Bar but I'd bet the bar is just missing.
Pinging and no power can be caused my a dirty MAF sensor.

The rocker arms and pushrods wear out on these engines as the pushrods dont turn so they just wear in one direction. It usually doesnt cause any problems in the way the vehicle wunds unless they are realllly bad.

if your dealership thinks a 4L, 5 spd with no air pump is rare I think it's time to find a different dealership. I dont recall seeing an Explorer with an air pump and have worked on quite a few with 5 speeds.
Let us know how you make out.

 

thanks for the reply Racerguy.

you can see what kind of dealership my friend has to deal with if they think a explorer with no smog pump is rare. I'll pass the info on to him and hopefully this will work.

 

there was some wiring missing on the fender where the bar is at. the bar being missing would seem like the problem.

is there a knock sensor on the engine, and where is it at?

 

also, is the octane bar the same as the one that is used in the rangers of the same era?

 

I dont believe there is a knock sensor on the engine.
The octane bar should be the same as on a 4.0L Ranger and it is also the same as the SPOUT connector on most Fords. The SPOUT connector is what you remove when checking the timing. It makes it so the PCM doesnt control the timing. All the Octane bar or SPOUT plug is is a little jumper to connect the 2 terminals in the connector.
You should be able to get a SPOUT at any Ford dealer or at an autowrecker. On most V8s it is near the distributor in the harness going to the ignition module. If it has a remote module like they did on a bit later trucks the SPOUT will be near the module which is usually on the left inner fender near the brake booster.

 

well, he got it runnin like a charm. he now has a good explorer that runs like a raped ape for all of $200 + $50 parts.
thanks racerguy

 

Sounds good
so what all did they do to it?

 

plugs, plug wires, and octane bar

 

Ok so now that your friend's truck is running better what are we going to have to do to convince you to get a Ford instead of a Dodge and to start cheering for someone other than #24?

 

as far as the 24, forget it, lost cause.

as for the truck. all of my friends are die hard ford fans. they will buy nothing that doesnt have a ford oval on it, except for a truck like mine. Ive got a 96 2500 4x4 5 speed with a Cummins turbo diesel. I tend to beat the hell out of my truck. I drag race it (2 wins, a 2nd place), pull big trailers (up to 20,000 pounds) and drive around everyday like I stole it and the cops are shooting at me. Ive got around 400hp and 800ft*lbs at the flywheel. And if something goes wrong, it can be fixed with out a degree in automotive computer engenering. Its nice having a truck where the computer has nothing to do with running the engine. I can take out the battery and alternator and run it with a zip tie and a pull start. Do that with a power stroke. In short, my truck aint on the cutting edge of technology, but I dont bleed from it either. And thats just fine with me.

 

Ok I guess if we cant change your mind about the #24 at least we
know you're smarter than to drive the brand of vehicle he drives

 

lol