Project let's get my engine running as good as it can!

[ecgreen]

OK, new plugs it is

 

[ecgreen]

Cooper or platinum? Does it matter?

 

[Uncle Gump]

My rule is what comes in it from the factory is what goes back in... unless that number is superseded. Platinum plug are optional and last much longer.

 

[Uncle Gump]

Like I said originally... when the plugs come out to be changed... run a complete compression test. Follow the rules of compression testing and this will give you a baseline for overall mechanical health of your engine. When you're trying to make it the best it can be... you really need to start here.

 

[ecgreen]

Like I said originally... when the plugs come out to be changed... run a complete compression test. Follow the rules of compression testing and this will give you a baseline for overall mechanical health of your engine. When you're trying to make it the best it can be... you really need to start here.

Will do! This is definitely the kind of suggestion I am looking for.

 

[gaz]

I switched to 93, because it did reduce pining under load.

My truck is a manual, so maybe my idle is a bit high.

The idle for a manual should be 850.

If you are still experiencing surging or irregular throttle after changing the plugs I would look at the throttle body. Pop it off, thoroughly clean and inspect it and all associated sensors:

TPS
MAP
IAC

If you still haven't restored normal throttle look at your ignition module if you KNOW THAT YOUR BASE TIMING is spot on.

 

[ecgreen]

OK I re-did the timing and it runs the same, but I think I found a bigger issue. I did the compression test and I got values between 155 and 170 on cylinders 1-5. On # 6, however, I couldn't get it above 95. I assume this means doom lol. So where do I go from here?

 

[ecgreen]

Here is a pic of the plug from that cyl:

 

[Eddo Rogue]

Forget about cheapo plugs, my ranger didn't even like the NGK or Bosch plugs, Only autolite or motorcraft, double platinum. I am currently running the autolite double platinums, she loves em! Fords waste spark system eats up plugs. She hated the NGK iridiums.

If you wanna save a few bucks you do the double platinums only on the waste spark side, and regulars on the other.

as for the driveability issue, PJ made some good points...but when I had the issues you describe it was a bad MAF once time, a throttle body/tps the other time. May vary for you though, for I had already gone thru the stuff PJ mentioned...

Good luck and happy wrenching!

 

[Uncle Gump]

Just to ensure the compression test was fair...

All plugs out...

Throttle plate blocked wide open...

Battery charger on...

Test each cylinder with the same amount of compression strokes...

Sound right?

If so... you could put a squirt of oil or two into the bad cylinder... retest. In theory the oil would help seal the rings. Compression goes up... rings. Stays the same... valves.

I've found it better to do a leak down test. This will pinpoint where you are loosing compression.... valves or rings.

The other five seem good.... 10% highest to lowest is acceptable.

 

[ecgreen]

Yep, that's how I did it, minus the battery charger. Think the battery went down too far by cyl 6? I don't see how that could be, but what do I know?

Guess I gotta track down a leak tester

 

[ecgreen]

I will add that I did this with a warm engine, as per the Haynes manual. I just went out and tried it cold can couldn't get any compression readings. Whats up wiith that?

 

[Uncle Gump]

It should make compression cold... gauge stuck open maybe? adapter not screwed in tight?

The battery will degrade by the end of a compression test... how much I don't know. but it could affect compression.

 

[ecgreen]

ok let me screw with it. thanks for the help!

 

[gaz]

ecgreen:

The number 1 with a bullet cause of low compression is worn valve guides, improperly seated valve guide seals do not help.

Pop off your valve cover and inspect your valve guide seals. Unfortunately, to inspect your valve guides is a little more effort. The good news is I just had a complete valve job done on my new to me 4.0L and it was $247, including all replacement parts and new gaskets.

Valve job Labor $150
Replacement guides and guide seals $50
New head bolts $24
Head gasket set $26

There was a bunch pitting on my exhaust valves (another potential low compression causer), the valve seats needed to be recut but it was part of the job ..)