Holley Sniper 2GC to 2F Install using Mosley Motors adapter

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Augustiron said:
Likely head gasket, but what about valve lash on 1&2?

If somehow the valve lash is extremely tight, and the valves aren't closing, you're not getting real numbers.

Valve lash, then compression test.

Looking at your screen name, don't worry the 2f valve adjustment is much easier than a desmo Ducati
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Further lash measurement forthcoming, I had to take a break!

Ha! For sure, good catch!
 
I blew mine between 5/6 coming off the trail in Chattanooga at dusk, but thought it was my AFI EFI system acting up. It had been in limp mode all weekend but suddenly got worse.

Ended up driving it the 6 hours home on four cyclinders but didnā€™t know til I did a compression after I got back

Put on a fresh HG and it was good as new. Drove it to CA & back after that.
 
FJ60Cam said:
I blew mine between 5/6 coming off the trail in Chattanooga at dusk, but thought it was my AFI EFI system acting up. It had been in limp mode all weekend but suddenly got worse.

Ended up driving it the 6 hours home on four cyclinders but didnā€™t know til I did a compression after I got back

Put on a fresh HG and it was good as new. Drove it to CA & back after that.
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I finally had the time and some experienced help to pull the head to investigate further.

I am pretty confident this is where all the compression was lost between 1 and 2!

Thanks everyone for the direction, tidying up a couple of more things and going back together!

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charliemeyer007 said:
Your coolant passages look plugged
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Yeah, there were some downstream effects or causes, a copy of bolt holes caught some water on the driverā€™s side and we had to do some cleaning on the coolant passages and the holes for the head bolts.

Went back with an OEM gasket, this one appeared to be a Fel-Pro or something similar from the aftermarket. Removing an old Vintage Air System I never used and a few other things, hope to back together soon and enjoying the 40 for late Summer and this Fall!
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Update, after moths of stop starts on this project with a new headgasket, valve adjustment, etc. the truck starts, sounds great, but after a few minutes it goes South, the Sniper display shows me this, backfires and barely runs.

I have reset the wizard, but still the same outcome.

 
 
One other guess would be fuel pressure dropping off -- if that's drops, injector pulse would deliver less fuel, ergo running lean. Just something easy to peep. A plugged fuel filter would give you pressure for a bit before starting to starve, for example.

That does assume the O2 sensor is good to have correct AFR reading - does the exhaust smell rich? (If the O2 is reading leaner than actual, then the sniper would in theory throw extra fuel to compensate)
 
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wngrog said:
Air Fuel Ratio is out of whack. Have you tried a new O2? Is the exhaust open?
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New O2 sensor and the exhaust is fully installed, new remtech gasket etc.

Seems good until it gets to temperature and goes to bad , quickly.

Let it cool down starts back, drives well and repeats again after it reaches ~170* or so.
 
If you get a chance to replicate - there should be a "fuel tuning" type dashboard, I think it should have Target AFR as well as AFR. Target AFR would show what it's gunning for, vs what it's getting - would just confirm that it's not some odd fuel-map-gone-rogue with a coolant temp offset or something.

Ie, is it asking for 14, and getting 21...or is it asking for 21 and getting 21.
 
zerotreedelta said:
One other guess would be fuel pressure dropping off -- if that's drops, injector pulse would deliver less fuel, ergo running lean. Just something easy to peep. . . .
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This. I don't run the Sniper, but I have a similar system. The external, in-line Bosch pump fails from time to time and leans-out the mixture. (I keep a spare pump in the vehicle)
 
Iā€™ve read a lot on the critical nature of fuel pressureā€¦ as a result I run a full-time fuel pressure gauge at the connection port to the throttle body of the carb. Itā€™s reasonably accurate at 58psi. Not sure that will help you but it eliminates a possible error
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wngrog said:
I would run a datalog and upload it to the Holley forum. Fastest way to get a tech to read it
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Thanks all for the help, I have exhausted all my skill and the local resources (and my patience) I think itā€™s time for a fresh set of eyes!

I will be in touch, I think it is time for this one to head South to MS or to the classifieds!


knuckle47 said:
Iā€™ve read a lot on the critical nature of fuel pressureā€¦ as a result I run a full-time fuel pressure gauge at the connection port to the throttle body of the carb. Itā€™s reasonably accurate at 58psi. Not sure that will help you but it eliminates a possible error.
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I have the same and the gauge is handy Fuel pressure is steady at 57-58, but I should check it after it warms up and acts up. To this point I have been in the driverā€™s seat trying to get it to a safe wide spot to cool off, I suppose it could loose pressure at temperature for some reason.
 
You can see if fuel is an issue with the Duty Cycle% on the handheld. Too high (over 85-90%) is an indicator that the injectors arenā€™t getting enough fuel.

I prefer the ā€œsensorsā€ multi screen as it shows alot more info.
 
I skimmed the replies but didnā€™t see it mentioned. Did you open the throttle blade to get the IAC down yet?

Thatā€™s the first step always. After re-running the Wizard to disinfect the tune from before. Do that too if not

Also switch to the screen mentioned that shows duty cycle.

We can get to the bottom quick if we follow the flow chart

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