Can't anyone figure this mind bending issue out???????????

88 XLT Ranger · Feb 12, 2017

I am at the end of my rope :sad:

I hate making new threads but it seams the only way to get help. If you go through my "On Going Saga" thread you can see I spent $$$$$$$$$$ replacing parts with same results. Today I pulled number 3 plug carbon fouled I put a fresh plug in fired it up running rough a quick throttle jab pop sound I shut it off pulled the plug fuel fouled. I cleaned the plug and took and switched number 3 and number one on the Dist cap I fired it up running a bit rough let it run at 3k for a bit than shut it off. I pulled number 3 plug burning good and clean. I drove it that way no power pulled over put number 3 and 1 back on the Dist cap ran perfect good power. I drove to town up the 6 mile grade again popping bogging same shit

The Napa parts store guy said its a stuck valve now my question is if its a lifter or lifters not pumping do to cam bearing wear would this be the results? is there any way to adjust these rocker arms to make like a solid lifter cam? or is it time to give up and let it die be crushed and become a Toyota?

Spott · Feb 12, 2017

Have you done a compression test on all cylinders, as was suggested numerous times?

88 XLT Ranger · Feb 12, 2017

Spott said:
Have you done a compression test on all cylinders, as was suggested numerous times?

Thanks Spott for responding its very much appreciated. I did a compression test around 135psi is the figures I get. I also did a vacuum test on the engine that passed as well. What I don't understand is number 3 was black carbon fouled looking when I took and switched number 1 and number 3 on the cap number 3 looked good burning good no fuel or carbon fouled. When I put it back its getting carbon and fuel fouled again. I changed the injector in number 3 and 6 cylinders

When I fired it up this morning as it was running rough I could smell a lot of fuel vapor. Again I checked the FPR vacuum line no fuel in it or the smell of fuel in it

Spott · Feb 12, 2017

What are the compression figures for each cylinder?

adsm08 · Feb 12, 2017

Have you considered the possibility that you have a bad injector that is over-fueling the cylinder?

88 XLT Ranger · Feb 12, 2017

Spott said:
What are the compression figures for each cylinder?

I only did number 3 cylinder as all others are burning good no issues. Now number 6 the plug is a little dark looking but looks to be firing ok

Spott · Feb 12, 2017

To do a compression test, you must warm up the engine to operating temperature, take all the plugs out at once (do not lose track of which plug wire goes where), hold the throttle wide open, and test each cylinder for 5+ revolutions.

Each cylinder must be above a minimum value, and they all must be within 10% of each other.

For example: If the other 5 cylinders are 150-154 psi, then the fact that #3 is at 135 psi means it has compression problems, because that's more than 10% lower than the others.

Please report the values for all cylinders when tested properly.

88 XLT Ranger · Feb 12, 2017

adsm08 said:
Have you considered the possibility that you have a bad injector that is over-fueling the cylinder?

I did change number 3 and 6 injectors with Napa brand as I was told it could be a bad injector. No change same results when I switched number 1 and 3 on the dist cap number 3 plug looked the best it ever has. Once I put it back it went carbon fouled again. I did take that plug put in number three boot and grounded the plug case I see it firing a little spark

This thing pops bogs but once I floor it and it goes into low gear no popping or bogging it reves to 3500+ and gets going but once I let up it goes into high gear popping bogging

RonD · Feb 12, 2017

+1 ^^^

Except, IMO, you don't need to warm up the engine first unless there was an issue with cold compression test, you will get higher numbers with warm engine, but that is not what you are after here, you are testing for a valve or ring seal issue.
All spark plugs MUST be removed, or testing is invalid for info you are after.

After testing all 6 cylinders if #3, or other cylinder, is lower than the others then retest WET
Use a straw and dip it in a bottle of motor oil, put finger over the end and pull it out, put straw in spark plug hole of #3 and remove finger, should get about a teaspoon of oil in that cylinder.
Now repeat compression test
The oil will help seal the rings but not the valves
Compression WILL go up, but by how much will tell you if it is rings or valves that is causing the loss of compression

I know you want this problem to be a fuel issue, from the last thread, but fuel fouling does not mean it is getting too much fuel, it means it can't burn all the fuel it is getting.
And that can be from a misfire.
When a cylinder misfires all the unburned oxygen goes into the exhaust, O2 sees that as LEAN burn, so computer opens injectors longer to add more fuel.
And if #3 was having a hard time igniting previous amount of fuel then it will get even worst with more fuel.............................
So you get fuel fouled spark plug

Misfire could be from lower compression, fuel fouling is the result of that lower compression.

88 XLT Ranger · Feb 12, 2017

RonD said:
+1 ^^^

Except, IMO, you don't need to warm up the engine first unless there was an issue with cold compression test, you will get higher numbers with warm engine, but that is not what you are after here, you are testing for a valve or ring seal issue.
All spark plugs MUST be removed, or testing is invalid for info you are after.

After testing all 6 cylinders if #3, or other cylinder, is lower than the others then retest WET
Use a straw and dip it in a bottle of motor oil, put finger over the end and pull it out, put straw in spark plug hole of #3 and remove finger, should get about a teaspoon of oil in that cylinder.
Now repeat compression test
The oil will help seal the rings but not the valves
Compression WILL go up, but by how much will tell you if it is rings or valves that is causing the loss of compression

I know you want this problem to be a fuel issue, from the last thread, but fuel fouling does not mean it is getting too much fuel, it means it can't burn all the fuel it is getting.
And that can be from a misfire.
When a cylinder misfires all the unburned oxygen goes into the exhaust, O2 sees that as LEAN burn, so computer opens injectors longer to add more fuel.
And if #3 was having a hard time igniting previous amount of fuel then it will get even worst with more fuel.............................
So you get fuel fouled spark plug

Misfire could be from lower compression, fuel fouling is the result of that lower compression.

Thanks Ron & Spott

I will do a compression test on each cylinder cold and post the results here. Thanks for the info on testing now I can do the test the right way. I need to get a remote starter switch to hit the button to turn the engine over. I don't think turning it over with the key and running back to check the pressure is a good idea

Mark_88 · Feb 13, 2017

I'm still checking in on this to see where it goes and if you find a fix.

It is way beyond my knowledge level at this point for a few reasons so I'm not going to try adding any more suggestions...you covered everything I could think of and hopefully that didn't result in wasted resources (read $$$$).

With a distributor providing spark it just doesn't seem logical to me that it would skip 4 or even 5 cylinders and only provide weak spark on number 3 (or 3 and 6)...it just defies my understanding of how it works...unless as RonD suggested there is a weird wobble in the shaft that allows it to somehow miss those pegs in the cap...

Anyway...keep your hopes up and I'm persevere and I'm sure this will be figured out... :icon_thumby:

Being in the Urgent Help section may have gotten you more answers but obviously not the right ones...

RonD · Feb 13, 2017

You should use key to crank engine for compression test, and hold gas pedal to the floor while cranking.
It is a good idea

Must used screw in compression gauge, not "hold in place" gauge

I had a Chevy motor with distributor wobble, caused intermittent misfire on one cylinder, but never seen it before or after so very unlikely cause

AndyB. · Feb 13, 2017

It might be worthwhile to get a spark tester you can see with the engine running, and compare the spark between cylinders.

https://www.amazon.com/Lisle-20610-Inline-Spark-Tester/dp/B0002STSC6

One of the reason motorcraft distributor caps are more expensive than aftermarket is because of how they are manufactured. On motorcraft caps, after the lugs are molded into the cap, they're then cut so the points are all the same distance from center. I believe aftermarket caps have the lugs molded in, and that is the end of the manufacturing process.

Mark_88 · Feb 13, 2017

RonD said:
I had a Chevy motor with distributor wobble, caused intermittent misfire on one cylinder, but never seen it before or after so very unlikely cause

I can believe that and it was something that I considered once a bunch of other possibles got eliminated...I wasn't being contrary...I'd never ran into it with my distributors or heard of it happening to anyone.

Seeing it as being inconsistent and sporadic made that a lower possibility and that's why we started pursuing other possibles...

I liked the logic of it being a sort of backflow due to the engine tilt angle and that the cylinders were at the bottom of the angle...that seemed like the best and weirdest possible answer...

RonD · Feb 13, 2017

Occam's Razor is the best method for most problem solving

Simplest answer, with the fewest assumptions, is usually the right answer

New spark plug works for a bit then starts missing
Clean it and it works for a bit and starts missing
Looks blackish and fuel fouled

Is the cylinder running Rich or is the compression low?

Compression test is black and white, while possible, it is very unlikely to get intermittent compression issue(3.0l recessed exhaust valve seats, lol).
For me that's always the first stop because once tested it either IS the problem or IS NOT the problem, no wasted time or money on things that won't help

Can't anyone figure this mind bending issue out???????????

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