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Posted by: Bill Meyer Mar 15 2012, 03:04 PM

My fresh 2056 is really running poor during break in, low power, slight miss maybe. One of the issues I've noticed is when using a laser temp gauge (pointed at the exhaust manifold, directly off the head) I've found #4 is running around 230 Degrees while all other cylinders are in the 330-360 range. I suppose it's more of a EGT temperature as I'm measuring the header, not the head, but regardless number 4 is out of whack and probably where some of my trouble is.

Pulling the #4 plug and it is noticibly wet, sort of oily too. I've got good spark there, swapped plugs too, checked wires.

Any ideas what to look for next?

Posted by: Vacca Rabite Mar 15 2012, 05:25 PM

#4 is not firing, or only firing intermittantly. You car probably feels like it has no power at all.

Carbs? If so, pull the idle jet and clean the circuit, then do the same for the mains. But it was always my idles that got crap in them.

Clean the spark plug. Fouled plug won't spark.

Check valves and the other stuff, but if it was a new build they should be fine.

Zach

Posted by: Racer Chris Mar 15 2012, 06:21 PM

QUOTE(Vacca Rabite @ Mar 15 2012, 06:25 PM)

Posted by: Bill Meyer Mar 15 2012, 08:27 PM

Thanks Chris, I do have an extra injector so I'll try that tomorrow. As for intake leak, do you mean on the runners with the large rubber connector? or is there another place they can leak?

QUOTE(Racer Chris @ Mar 15 2012, 07:21 PM)

QUOTE(Vacca Rabite @ Mar 15 2012, 06:25 PM)

#4 is not firing, or only firing intermittantly. You car probably feels like it has no power at all.

Carbs? If so, pull the idle jet and clean the circuit, then do the same for the mains. But it was always my idles that got crap in them.

Clean the spark plug. Fouled plug won't spark.

Check valves and the other stuff, but if it was a new build they should be fine.

Zach

OP says he has good spark.
Title says D-jet.

I can think of two things: Intake leak; bad injector

Posted by: aircooledtechguy Mar 15 2012, 09:05 PM

To check for an intake leak, get the engine idling. Then use a can of carb cleaner with the thin tube attached to the spray head. Spray around EVERY joint, seal and gasket in the entire system from the throttle body to the head where the manifold attaches. If the RPMs momentarily rise as you spray, you have a leak there. If you find a leak, don't stop thinking it's the only one, continue until the whole system has been checked.

Common areas are the plenum to runner seals, small injector seals, cracked vacuum hoses, etc.

Posted by: Prospectfarms Mar 17 2012, 09:23 PM

Last summer Cap'n K. posted a refinement to the "carb cleaner spray to find vac leak" procedure: check small areas at a time, get the straw very close, spray a little, and wait a few seconds before moving on. For years, I'd just fogged a portion of the engine hunting a leak. That sorta works, but this is much better.

Posted by: 76-914 Mar 17 2012, 09:48 PM

You don't have 3 & 4 inj leads crossed do you?

Posted by: Bill Meyer Mar 20 2012, 08:52 PM

Not sure, but wouldn't that cause both 3 and 4 to not fire at all?

QUOTE(76-914 @ Mar 17 2012, 10:48 PM)

Posted by: 76-914 Mar 20 2012, 09:07 PM

Nope, just makes it run like hell. Ask me how I know.

Posted by: brant Mar 20 2012, 09:12 PM

also the injector leads (broken wire on the plug in or harness)... or injector points can cause a dead cylinder.