Funky Coil?

[MDJEEPER]

I am still trying to run down a lack of power issue with my engine. Following the advice of the forum, thus far I have replaced the most basic stuff first...plugs, wires, distributor cap, rotor. However, I have not yet replaced the coil. What are the symptoms of a bad coil?

So far, the work I have done has had little effect on the top-end power of the engine...PLUS if anything, it has made the knocking/pinging under load worse. I just can't figure out why!!??

...And no, I have not yet checked the timing...that's next on the list but I've got to get a working timing light.

Oh, and one more brand new symptom to add...while I was out taking it for a test drive today, it seemed like it wanted to stall a few times...just for a spilt second like the key had been turned off and back on again. This did not occur under load, but just cruising along holding about 40 mph...

 

[Old Dog]

So far, the work I have done has had little effect on the top-end power of the engine...PLUS if anything, it has made the knocking/pinging under load worse. I just can't figure out why!!??

...And no, I have not yet checked the timing...that's next on the list but I've got to get a working timing light.

Please get a timing light. Predetonation (knocking, pinging) causes some real bad things to hapen, like holes burned in pistons.

 

[MDJEEPER]

Please get a timing light. Predetonation (knocking, pinging) causes some real bad things to hapen, like holes burned in pistons.

Definitely do not want that!!! However, seeing as how it's been at least 20 years since I've even played with timing lights (and then, always under supervision!), can you give me some pointers on how to do it correctly? Heck, I am not even positive (though I think I know) what the distributor hold down bolt looks like!

 

[Sasquach]

I would recomend you get yourself a good manual. I have both a Chilton and an Ebay reprint of the factory 3 book service manual that I really like, the reprint was $80+- but have paid for themselves many times over.
You will get all the additional help you can ask for here but at least try to help yourself too!
Checking the timming is easy enough, light lead to #1 plug wire, clean off your timming marks so you can read them-maybe even highlight the numbers/marks with a sharpie, disconnect vacumm to dist., make sure everything clear of the fan, fire up and point the light at the marks and read at idle, supposed to use a tach. but I never bother. I think my 78 is 5 degrees BTDC. Twist the dist. to change reading.

 

[IOPort51]

The instructions are on the box.

Definitely do not want that!!! However, seeing as how it's been at least 20 years since I've even played with timing lights (and then, always under supervision!), can you give me some pointers on how to do it correctly? Heck, I am not even positive (though I think I know) what the distributor hold down bolt looks like!

 

[MDJEEPER]

Since I am having knock/pinging problems, what would you recommend for a correct timing setting at idle? By the manual it's supposed to be 9 degrees +-2 @1600 RPM. The manual also states that if you are going to do it at idle, the setting should be approximately 1 degree more than that specified.

 

[Sasquach]

Since I am having knock/pinging problems, what would you recommend for a correct timing setting at idle? By the manual it's supposed to be 9 degrees +-2 @1600 RPM. The manual also states that if you are going to do it at idle, the setting should be approximately 1 degree more than that specified.

Go with the manual, I said idle cuse mine after looking at the specs is 8 dgrees at 750rpm, vacumm advance disconnected

 

[Old Dog]

I said idle cuse mine after looking at the specs is 8 dgrees at 750rpm, vacumm advance disconnected

X2.
That's what I'm seeing also. I have never heard or seem anything saying to set the timing at 1600 rpm, it's always at idle. (700-750 rpm)

 

[LongHorn]

Since I am having knock/pinging problems, what would you recommend for a correct timing setting at idle? By the manual it's supposed to be 9 degrees +-2 @1600 RPM. The manual also states that if you are going to do it at idle, the setting should be approximately 1 degree more than that specified.

Don't forget to disconnect the vacuum advance line before setting your timing.
Did you ever get a chance to do a compression test?
If your rings or valves are leaking it's tough to make much power.

 

[MDJEEPER]

Don't forget to disconnect the vacuum advance line before setting your timing.
Did you ever get a chance to do a compression test?
If your rings or valves are leaking it's tough to make much power.

The compression test is on the short list of things to try. Doggone work keeps getting in the way of quality Jeep time!!

 

[Old Dog]

X2.
That's what I'm seeing also. I have never heard or seem anything saying to set the timing at 1600 rpm, it's always at idle. (700-750 rpm)

My bad I see your 86 does say 9* at 1600. This is from the FSM.

 

[Sasquach]

This is from the Autozone site......


1986 Jeep CJ7 AMC 258 i6 / 4.2l 2BL 6cyl





To find the correct specification, we need additional information about your 1986 Jeep CJ7 AMC 258 i6 / 4.2l 2BL 6cyl .
Please select one of the following:

• With automatic transmission
• With manual transmission

Ignition Timing

8 Degrees
Application:
With manual Transmission

Note :
Before top dead center
*Set at warm idle speed (700 RPM)
*Distributor vacuum hose disconnected & plugged
*Transmission in neutral (parking brake engaged)
*All accessories off




My Chiltons book...9BTDC on non high altitude models and 16BTDC on the high ones, can't find RPM setting other than correct idle speed at 700

 

[MDJEEPER]

Thanks guys!!

Unfortunately, things are getting more complicated with the various vacuum issues I've discovered. (See the thread on mysterious vacuum lines). So, I'm not even sure I can adjust the timing given the current situation...or can I??

I'd sure like to at least get rid of the knocking/pinging...

 

[Sasquach]

Thanks guys!!

Unfortunately, things are getting more complicated with the various vacuum issues I've discovered. (See the thread on mysterious vacuum lines). So, I'm not even sure I can adjust the timing given the current situation...or can I??

I'd sure like to at least get rid of the knocking/pinging...

Yes you can adjust the timming, you disconnect your vacumm supply to your distributor anyway when checking/setting.
The worst that could then happen is you have so many vacumm leaks that your distributor never gets enough vacumm to advance and that will just make it run like a dog(sorry old dog) and not cause pinging.

 

[nitor]

My bad I see your 86 does say 9* at 1600. This is from the FSM.

I believe I'd go with the FSM before I'd trust Autozone's website. To much generic.