Over the last year or so, I've posted multiple times here and there, questions regarding my issues of what appears to be engine knock on my 87 Ranger 2.3L/Automatic 2WD Ranger.

This truck has been totally restored & rebuilt from soup to nuts, and just about each and every item, part, mechanical and electrical have been replaced, yet this knock still occurs.

This is the odd part, which each and every mechanich I interface with gives a look of "I dunno", and I never seem to get this problem solved.

The major issue that is of concern and bafflement is that the 'knock' ONLY OCCURS AFTER WARM UP, NEVER when cold, NEVER. I can drive the truck for 10-15 minutes, and as soon as the engine reaches normal operating temperature, the knock begins. THe knock ONLY is at from a dead stop while accelerating, and after the inital take off, it disappears. I can sit in neutral or park or in gear with foot on brake, and increase in RPM duplicates the knock. When cold, never, only after warmed up.

It seems to be engine related, but I also had a mechanic say it MIGHT be the transmission??

Remember, EVERYTHING has been replaced or rebuilt, oil pump, sensors (ALL), electrical (ALL), mechanical (ALL), tranny service with new torque converter, everything short of a major bottom end rebuild.

The truck has 122,000 miles, it's been there from day one, (I got it with 88k miles), and actuall, some days it's not even there. As of late (the last 6-12 months), it's there each and every day, only after warming up.

The truck runs like a top, idles perfect, accellerates flawlessly, minimal oil consuption, 99.99999% perfect, but the knock drives me nuts!

Can anybody have some insight of previous knowledge regarding this annoyance?

 

Please forgive the length of this reply. The colder the engine, the more gradually the explosion occurs, almost as if using a higher octane. As the engine heats up, explosions occur more rapidly, increasing the tendency to ping. Of course, anyone reading this must keep in mind that if there is a knock sensor, it will "compensate", thus pinging might be the same, or even WORSE, when the engine is cold, then diminish as it warms up. I think that you (BobFlowers) either have no knock sensor, or if you do have one, it is not functioning. So, when the engine is cold, pinging will be supressed, and nothing will "compensate". As it warms up, pinging will begin to occur, since again nothing is "compensating". One thing that immediately comes to mind is a sort of vacuum advance malfunction. This gets tricky with Fords, because the ignition module & computer completely control ignition timing electronically. However, they DO SENSE MANIFOLD VACUUM, in order to advance timimg correctly at part throttle. In an older vehicle, with a vacuum advance unit, it is easy to hook up the wrong vacuum line to the unit, giving it vacuum ALL THE TIME, including idle, rather than just at part throttle. I have not research my engine enough to know where the sensor is located, but I'm thinking that your computer and/or ignition module are keeping the timing advanced all the way from idle, which is why it would ping while accelerating. But then, as engine revs increase, the need for advancement increases, thus pinging will subside. I don't know the system intimately enough to give you fine details. But if you have a friend that knows the system fairly well, he might be able to help you track it down. Maybe if you put a timing light on the crank pulley, and observe where it is at idle, then observe as engine revs & load change (since it is an automatic, you can have someone apply load while e-brake is solidly locked). Do you have a timing light??

 

Not to take away from what was said above, because it may be the solution to your problem, but I had the same problem that you described on my 92 2.3 5 speed Ranger. After much head scratching and checking I learned that I was getting lean spark knock. To correct the problem I installed larger injector's and an adjustable fuel pressure regulator and upped the pressure 41/2 pound's. Believe it or not it corrected the knock problem and I gained some performance and milage. I should also say that I drive mainly on interstate highway's.

 

Good point big1. I forgot to consider that. If in fact you're correct, BobFlowers might be able to silence the ping (at least temporarily) by cleaning the injection & fuel systems real good.

 

The injectors are new/replaced (OEM). If you are suggesting I replace with different ones, please let me know which ones.

Fuel Pressure regulator, new (OEM), if you say I should replace with an adjustable one, please let me know which one, etc., where to get, etc.

Knock sensor, brand new, made no difference.

I appreciate the replies, keep 'em coming.

 

Timing is right on (10 degrees BTDC) at idle, with spout disconnected. Connected, it moves (I forget where to).

Under load, it advances, as required.

New ECU also.

The more replies/info I get, the more I can hit my mechanic with....

Thanks

 

OK, I tried a few more things. I replaced the fuel pressure regulator with an adjustable one (AFPR), set it to 43lbs., truck ran like a new one for 30 miles, came back from shopping, was back to square one. Knocking is still there, previously (usually) at part throttle (knocking), now, all the time. Also replaced the 2 'relays or solenoids' that are on the passenger side fenderwell that have vacuum and electrical connections to them, (and I found a broken vacuum hose that I replaced), still no difference.

Bottom line is: I'm ready in the next month to do another cross country, and I want to feel confident that the truck is 100%, so I want a new motor, most preferable an non-rebuilt, but a new factory fresh crate motor (considering all the $$ I put in), and cannot seem to locate one.

Other than that, if I decided to sell as is (99% restored), if I could get say $4,000, I'd sell and buy a new truck, maybe. Recently on eBay, I saw a '88 SuperCab XLT 2WD go for $4150, with nothing like my condition, so it might be possible. In any event, should I dump more $$ in a new motor, or get a new truck, I'm tied of this unresolvable problem?

In the event that most suggest replacement, who, where, how much As I'm considering driving cross country, I can stop by, have the 'primo place' do the work, and move on.

Thanks

 

Just something to think about..........I realize that "EVERYTHING has been replaced or rebuilt, oil pump, sensors (ALL), electrical (ALL), mechanical (ALL)". However, new parts are known to be bad too so don't rule them out.

 

If so, then as a process of elimination, what part would be the 1st choice to check/replace?

 

I have kind of the same problem with my '92 explorer with the 4.0L. Mine only knocks at idle under load when the engine is fully warmed up. Dont notice it driving around. I figured it was piston slap, as mine has 185,000 on it. My reasoning was this: when the engine is cold, so is the oil, and relatively thick. This will form a thicker layer so that the piston is better cusioned and does not knock. When it gets warmer and the oil gets thinner, you hear it knock. I dont know if you have new pistons in the rebuild, so this may not apply to you. Just a thought. You might want to try thicker oil, such as 10w40.

 

Wished I could help ya Bob, but I'm not familiar with the 2.3. I was only saying, from experience, that I've installed brand new/rebuilt parts and they were defective, so don't rule it out. Wished I could bring more to the table.