I have a pinging on acceleration on my 91 Ranger 4.0. I am thinking maybe the crank sensor is defective and causing the timing to go crazy. I have already added Seafoam, went with a higher octane gas and I have good compression. Does anyone know what the procedure is for checking the crank sensor? Or anything else to check?

 

Here's the steps I would take:

1. Clean the MAF sensor. There is a small internal passage with a wire. That can sometimes get gunked up and / or generally dirty. Spray some carburetor cleaner up there to clean the wire.

2. If that doesn't do it, check for vacuum leaks.

3. Retorque the lower intake manifold bolts. If they come loose, you can get a vacuum leak which will cause pinging.

I dont think it's the crank sensor. Those usually dont cause too much trouble.

 

I replaced the crank sensor, retorqued the intake bolts, cleaned the maf sensor, and checked for vacuum leaks and there were none. Also checked the modulator on the trans. and there is no trans. fluid leaking by it into the vacuum hose that goes to the intake. I am lost and dont know what to do? Can anyone help?

 

How exactly did you use the Seafoam?

 

I added 1/3 pint Seafoam into the intake through the brake vac. booster hose while the eng. was running, then shut the eng.down for 5 minutes and then re-started and drove it about 10 miles. I also added a pint to my fuel in the gas tank, and added 1/2 pint to the oil. I followed the exact instructions on the can. The can did not say how long to leave the Seafoam in the oil? But I have been driving it with it in the oil.

 

I'd change the oil and get that stuff out of there...

Here's how I use Seafoam:

1. Warm up engine to operating temperature.
2. Locate the vacuum tee near the rear of the upper intake.
3. Attach vacuum hose to an unused port, plug hose.
4. Start engine
5. Unplug hose, stick in full can of seafoam.
6. Leave it there until engine dies, then remove and plug hose.
7. Wait 5 minutes.
8. Restart engine.
9. Unplug hose and suck up the seafoam from the can, removing hose when engine sounds like it's about to die. Let engine recover and repeat until 1/3 to 1/2 the can is gone. Yes, your neighbors will hate you...
10. Now go drive the engine and see if pinging is gone.

 

I dont understand step 9? Do you mean pour a full can in the hose on step five and then on step 9 put the hose in another can of Seafoam and let it be sucked out?
Just curious why you said to change my oil to get the Seafoam out?

 

No... You leave the can upright and let the engine vacuum suck the seafoam up the hose. Stick the hose right in the can, below the level of the liquid. It wont suck much up before it dies in step 5. In step 9 the process is the same but you periodically pull the hose above the level of the liquid so that the motor doesn't die during the process.

I try to avoid adding chemicals to my engine oil. It was engineered for best performance when it was made. You might be cleaning up some sludge, which is nice, but it wont make any difference with your pinging. That is, unless oil was getting past the rings due to stuck rings. If that's the case, you need to be using a different brand oil! You'd notice this though as blue smoke out the exhaust.

Something that does help if you're having stuck piston rings and / or sludge is diesel rated oil. It has more detergent / dispersant additive which helps keep things clean, and can also work miracles with stuck piston rings.

 

I will try it your way, Thanks

 

4.0L OHV Fords are notorious for carbon combustion chamber deposits which cause pinging preignition because there is NO knock sensor....Ford even put out a TSB on the problem in the mid '90s...can get a can of carbon remover from Ford dealer parts dept with the Ford name on it, never used the stuff, Ford TSB says whole can in thru TB or vacuum hose

if the Seafoam won't remove the extra hvy carbon deposits, use the old reliable water micro burst steam cleaning method....use 1/8" tube to suck up 1 qt of water thru hole in TB plate while engine runs at approx 2k rpm....small tube limits water intake rate to a fast mist....water injection has been used for 75 years in infernal combustion engines to clean deposits and increase horsepower....high octane tetra ethyl lead deposits required changing plugs every 20k miles up to the early 70s

England would have lost the Battle for Britain if it were not for water injection in their Rolyse Royce Merlin V12 engines in the Spitfire and Hurricanes.....the German Messersmidts and ****e Wolfe fighers would fly hundreds of miles and be all leaded up when they met the Brits....the Brits turned on their water injection, cleaned their engines and boosted the HP by 20%....guns guns guns and the *****' went down in flames

 

I did the Seafoam again through the vacuum port as described above with no change.
I still have a pinging on aceleration. I believe it may be a spark knock, I tried hooking up a timing light, but there is no clear path to aim the light at the timing mark. There is to much stuff in the way. Has anyone got any tips on checking timing on a 4.0?

 

I had a good reply typed up, but FTE ate it. Oh well.

You have to go forward with the timing light, just watch out for the fan. There is kind of a hole between all the stuff.

When you said you retorqued the intake bolts, you did retorque the LOWER intake bolts, right? These are the ones that go through the lower intake into the block. Those do come loose and is a common cause of pinging. Also check the throttle body to upper intake bolts. Basically anything that could be causing a vacuum leak after the throttle body.

Are you absolutely sure it's pinging? I had a leaky exhaust manifold gasket that I could've swore it was pinging. Only made the noise on acceleration...

 

The intake was torqued by the recommended procedure in the manual. I did have a couple loose ones at the time. All other bolts are tight. No vacuum leaks that I can find and the exh.manifold gaskets are new and the bolts were tightened to spec.
I was told also that there is a octane plug, kind of like a spout connector for the timing.
I was informed that if I remove the octane spout connector that the spark advance will be dropped about 3-4 degs. and could help diag.a spark knock , but I cannot find it. I found the spout connector for the timing, but cannot find the octane spout connector. Any idea where it might be?

 

When I did my exhaust manifold gaskets, one gasket didn't do it. I had to double up the gaskets, and extra-tighten the bolts!

I think that connector is back by the computer, but I'm not 100% certain.