Sniper seem to run rich

[Chris Wingardh]

Blueprint 347 with Holly sniper. have done many.... proably too many....starts and just idle to show off the sound. I am now at the go-kart stage and when i put it in gear it wants to stall, il drive a hundred yards give a little punch and engine will stall. A lot of exhaust smell.... I am thinking it is running too rich. Also now does not start imidiately as it did in the beginning. I just installed NEW identical plugs and verified the gap.

Whats everyones thoughts? before i call Holly.

Chris

[Blessidsoul12]

What gen is the sniper? I had almost exact same problem, my sniper was very old generation. Unable to fix, neither was Holley. Just got new sniper. Problem solved.

[Chris Wingardh]

What gen is the sniper? I had almost exact same problem, my sniper was very old generation. Unable to fix, neither was Holley. Just got new sniper. Problem solved.

Well, that is unfortuante. So you had to buy one or Holly replaced it?

[john42]

I just got a new Sniper II on my 347. One thing we had to tune correctly was the return to idle settings. At first it would die every time I came to a stop. We had to fiddle with the RPM above idle to catch it and the timing settings of settling down back to the desired idle speed. It's taken a bit to get it right and I'm now about 400 miles in on my new motor and 99% of the time it returns to idle perfectly now. About 1% of the time it will almost die, but catches itself, so I think I'm very close. It also does seem a tad rich, and soon as the weather warms up and I can drive it more. I've also made a dyno appointment with people far better at this then I am!

[Papa]

Where is your O2 sensor? My Sniper (replaced with Inglese MPFI) was very sensitive to fresh air near the sensor. Running without the full exhaust caused lots of problems. Also, the fuel enrichment settings will dump a ton of fuel into the engine until the coolant is above 160 degrees. Be sure your CTS is on the engine side of the thermostat. It's also very important to go through the setup wizard with accurate selections and verifying all the sensor values. Have you verified the fuel pressure? The built-in regulators on the Snipers are known to fail.

[Pat Landymore]

Chris:

Do you have the little Holley handheld unit connected? Suggest you go to it and pull up the indicated exhaust O2 level while the engine is idling.

If it’s reading super rich (10 or 11 to 1) then all the advice given above will help you.

If it is reading lean at idle (say sound 13.5 or higher, or no indication ) it could be via multiple short starts and stops you’ve inadvertently fouled up the O2 sensor. I did that on a previous turbo LS powered Foxbody Mustang build with a Holley HP system and had to purchase a new sensor.

Everything returned to normal after replacement.

Just a thought…

Pat

[Chris Wingardh]

Thank you gentlemen, I will proceed as adviced here, over the next few days. I will post my findings.

[CaptB]

Check the pressure, mine was at 90psi with 2 regulators fighting it out. A call to Holley and I pulled out the internal regulator in the Sniper. BAM! 60 psi.

[Chris Wingardh]

So.... I confirmed and saved all the correct setting on the handheld, 8 cyl, mild cam, coil. Then while cranking today nothing but a1 short fire tyhen nothing. AFR while cranking showed 34.5 in red.

I will call Holley in the morning....

[Papa]

So.... I confirmed and saved all the correct setting on the handheld, 8 cyl, mild cam, coil. Then while cranking today nothing but a1 short fire tyhen nothing. AFR while cranking showed 34.5 in red.

I will call Holley in the morning....

That is likely a bad O2 sensor.

Dave

[weendoggy]

IF, you do have a failed O2 and you've been trying to run the engine a lot, you've already corrupted your base tune, so, you'll need to investigate that part when you start over. One way to check if the O2 is bad is, if (keyword) you have a good base tune and you don't drive/run the engine much when first encountering the issue, put the tune in OPEN loop and the engine should run well enough to get you sorted out until you replace it. So many things can cause your symptoms and this is just a slice of what it could be.

Also, during cranking the O2 will not read actual due to the fact it hasn't warmed up yet, so seeing anything above "normal" isn't uncommon.

[Chris Wingardh]

Thanks, I will do that. Heve a new O2 from Holley comming... just in case.

[FF33rod]

Thanks, I will do that. Heve a new O2 from Holley comming... just in case.

FYI, you don't need to go to Holley for the sensor. A few mfgs make them including Bosch. What you're looking for is 4.9 Lambda wide band sensor, 5 wire.. like this:
https://www.amazon.ca/dp/B0863P6YLQ?...roduct_details

[Chris Wingardh]

WOW! 100 buck's cheaper and will be here tomorrow. Thank you sir.

[Pat Landymore]

Hi Chris!

So did a new O2 get your truck running correctly?

Also, did you go with the lower cost option suggested by FF33rod?

If so am thinking to pick one up from there as a spare for my current project.

Thanks!
Pat

[Chris Wingardh]

Sorry for the late reply. It has been quite embarising........ I was out of gas!! Everything is fine. Sometimes stupidity just cant be overcome!

[Pat Landymore]

Don’t ever be embarrassed Chris!

There are so many factors involved when a fellow is building a hot rod…some are familiar and some brand new…that at times the little things can get caught up in the 100 different other things a guy is thinking about and get lost in the fray.

Really pleased for you that your fix was simple and low $$.

Don’t ever ask me to offer a list of my ‘forced learnings’. It would be very long…..Ha 🤣

Best Regards!

[Chris Wingardh]

Thanks Pat, I know so so many things. Happy it was cheap. Cheers

[Shakey]

Chris,

I figured I would chime in here as well. I have a Sniper Stealth TBI system with Terminator X and it runs super rich. So rich to the point that after about 7 or 8 starts and 25 miles on the odometer it carbon fouled all my spark plugs and the engine would not event start. After changing the spark plugs it fired right up. I will say that some of the carbon fouling came from me not running the engine for a long time at operating temp. I would basically just get the engine up to temp, do some idle tuning on the handheld and then shut it off. Keep an eye on your spark plugs if you start having issues again. For my tuning, I started at reducing the fuel Prime shot and after start enrichment. There are a lot of forums on the internet that discuss this. Hope this helps.

V/r

Shakey

[Chris Wingardh]

Chris,

I figured I would chime in here as well. I have a Sniper Stealth TBI system with Terminator X and it runs super rich. So rich to the point that after about 7 or 8 starts and 25 miles on the odometer it carbon fouled all my spark plugs and the engine would not event start. After changing the spark plugs it fired right up. I will say that some of the carbon fouling came from me not running the engine for a long time at operating temp. I would basically just get the engine up to temp, do some idle tuning on the handheld and then shut it off. Keep an eye on your spark plugs if you start having issues again. For my tuning, I started at reducing the fuel Prime shot and after start enrichment. There are a lot of forums on the internet that discuss this. Hope this helps.

V/r

Shakey

Thank you Sir, I will dig in to it in a little while.