Builds Skreddy’s 70 Non-Resto (1 Viewer)

[fyton2v]

I was just thinking through the MPG expectations for my now nicely running motor. How is it that your speedometer shows the correct speed but your odometer is off by 7%? I know that the 33s I'm running throws my speed off by at least 10%. I presumed the odometer would just be sync'd correctly with whatever speed the truck thinks it's going. So you're saying the odometer could be missing a tooth or something and that could throw the whole thing off?

 

[Skreddy]

I was just thinking through the MPG expectations for my now nicely running motor. How is it that your speedometer shows the correct speed but your odometer is off by 7%? I know that the 33s I'm running throws my speed off by at least 10%. I presumed the odometer would just be sync'd correctly with whatever speed the truck thinks it's going. So you're saying the odometer could be missing a tooth or something and that could throw the whole thing off?

I’m assuming there is some wear on one of the gear interfaces somewhere causing the discrepancy. I too thought it’s weird, I was expecting the odometer being off more and the speedo matching the odometer.

 

[EmanC]

Followed my wife in her car, with a gps too to ensure accuracy. Looks like my speedo is spot on but the odometer is 7% off. Drove another 100 miles and topped off and got almost 9 mpg (with odo correction). Still seems wrong. I do see a lot of 10 ish afr so increased idle and cruise to 13 target. Now I’m getting surging at idle and afr will spike to 30-40 and usually die. Also can’t get a steady idle speed below 720 ish. Changed the settings to what they were and still the issues. At idle, looking down the sniper, seems like there is a lot of fuel being delivered. I may try a settings reset and see if anything is better. Otherwise I’m at a loss. Maybe bad O2 or tps or????

Can you run the Sniper in open loop mode? Usually, you can unplug the o2 sensor and drive it around and see what it feels like. This should lock the AFR to a fixed value. This can help diagnose a bad o2 sensor.

 

[Skreddy]

Can you run the Sniper in open loop mode? Usually, you can unplug the o2 sensor and drive it around and see what it feels like. This should lock the AFR to a fixed value.

Yes you can turn off closed loop.

 

[Skreddy]

I did a lot of reading last night on the small issues I’m having and have a plan. First, I am going to replace the exhaust flange gasket between manifold and downpipe because I think I may have not done this when I pulled the manifold to fix the exhaust leak? I know I bought one, I know I pulled the manifold off and I know there’s one on my bench with a receipt that matches a couple weeks ago……
Then, I’m going reset the sniper and run the wizard again. One thing I’m going to try is entering a smaller engine displacement. Read a lot about people thinking the sniper tune is rich to begin with and entering about 20% smaller displacement helps, especially on a stock, lower performance engine. I think the learn would get to the same point eventually, this may just speed it up. Part of this path is because yesterday while idling and driving and watching the fuel display, the sniper was almost always pulling fuel out of the tune; like 10-25% across the board except WOT. I can always change back to actual displacement, but I think I’m going to enter 200 cid and see what happens. Either way, at this point with my new idle lean spikes, something is corrupt and I think it’s best to start over, especially if there is a possible exhaust leak at the flange.

 

[Skreddy]

Initial impression is pretty good. Got the exhaust flange gasket changed, ran the setup wizard using 200 cid and 720 rpm. Fired right up and idled lumpy but not spitting fluid out the exhaust like it was: afr about 10.5! Temp hit 160 and immediately you could see the sniper tuning. AFR started jumping around between 10-15 but within a few seconds settled in between 12.5-13.5 and idle smoothed really well at 710-730. I let it idle about 10 minutes and the AFT band tightened up. Took it for a drive about 15 miles and instead of AFR between 10-maybe 13 it was very steady 12.5-13.5 with small deviations from there but really consistent and smooth. Looking at the CL%, can see the sniper was rarely adding or subtracting fuel from the tune. Hoping to get more time tomorrow to put some miles on if it’s not raining.

 

[fyton2v]

Good news!

 

[Chungas Revenge]

Well played….

 

[Skreddy]

This sniper just keeps crapping the bed. 200 miles, 9 mpg and it’s back to surging and spiking afr to 25-30 at idle and stalling. Also, taking off from a stop is spiking to 30 ish AFR and I have to pedal the crap out of it to get going. Took a couple data logs to send to Holley and see if they see anything. It’s like it’s tuning itself so good, then deviates and starts tuning itself poorly.
Also called Tank Inc and sent them a video because my pump is getting super loud. Can hear it over road noise at 60 mph!
I did get my pressure fitting plumbed back in and can verify I’m getting 62 psi so that’s nice.

 

[Skreddy]

In 10 miles since that last post, it has gone from bad to worse. Cruising it’s fine and a steady afr. Everywhere else is undrivable. Dies coming to a stop, starting from a stop, idling, slowing down, speeding up. Calling Holley first thing to get some direction.

 

[85roktoy]

That’s a bummer. Hope you get it sorted out. I’m about to start ordering sniper parts

 

[Skreddy]

That’s a bummer. Hope you get it sorted out. I’m about to start ordering sniper parts

Still do it! When it’s running right it is so good! There has to be a reason for my issues; bad O2 sensor, bad ecu, wiring problem, leak somewhere. Just have to find it.

 

[1970 Problems]

Still do it! When it’s running right it is so good! There has to be a reason for my issues; bad O2 sensor, bad ecu, wiring problem, leak somewhere. Just have to find it.

Very odd that is works fine when driving but everything else is no good. I am sorta having a similar problem with mine. Once it’s running, it’s good, but when starting from a complete stop it putters and wants to die. I say this because we may possibly have a similar issue. Or maybe not. I leaned out my mixture screw and I may have fixed something.

This might be completely wrong, but with the idle solenoid on the OEM carbs, it is possible to run, only if you are giving it lots of gas. Or at least that’s what happened with mine. So if you are going down the road at 55, giving it gas, it might run better, as opposed to idling when the circuit is cutoff. Not sure if this same idea could even translate in any way to your fuel injection setup. Just a possible line of thinking.

 

[JDNs78FJ40]

That is a bummer. Mine seems to be running like a champ now that timing is dialed in. Happy to compare your settings in the ECU to mine to see if there are major differences ?

 

[Skreddy]

That is a bummer. Mine seems to be running like a champ now that timing is dialed in. Happy to compare your settings in the ECU to mine to see if there are major differences ?

I was just looking in my data logging and found 2 interesting items. 1. It is showing timing curve but I don’t have sniper controlled timing? 2. My MAP values are all 80 kpa and up, in all rpm ranges. This doesn’t seem right to me. Still fumbling around the software to understand how it works and what I’m looking at. Hopefully I’ll know more in the morning after a call to Holley.

 

[whitey45]

Make sure you have no vacuum leaks

 

[Skreddy]

Make sure you have no vacuum leaks

I have been feeling like this was a vacuum leak all along: poor mpg, high map readings, low AFR’s. Have 2 vacuum gauges hooked up: 1 to the 4wd vacuum port on intake and 1 to the sniper full manifold vacuum port. Both gauges read a steady 17” at 700 rpm idle. The Sniper MAP reading is 88 kpa. Something isn’t right.
Holley had me wipe the sniper programming and start fresh, same thing. It is now pulled, boxed up and off to Holley. They think there is 1 or more issues going on with the unit itself.

Side note: Tanks, Inc. agrees my pump is way too loud so a new one is incoming.

 

[pjohnson]

I was thinking O2 sensor issue, but I guess Holley thinks much worse.

 

[EWheeler]

I have been feeling like this was a vacuum leak all along: poor mpg, high map readings, low AFR’s. Have 2 vacuum gauges hooked up: 1 to the 4wd vacuum port on intake and 1 to the sniper full manifold vacuum port. Both gauges read a steady 17” at 700 rpm idle. The Sniper MAP reading is 88 kpa. Something isn’t right.
Holley had me wipe the sniper programming and start fresh, same thing. It is now pulled, boxed up and off to Holley. They think there is 1 or more issues going on with the unit itself.

Side note: Tanks, Inc. agrees my pump is way too loud so a new one is incoming.

Wow, bad parts all around. Bummer. I guess that gives you some time to tinker on rusty red.

 

[fyton2v]

It sounds incredibly frustrating. Keep at it. You'll fix it in the next round.

I'm sure I can search to find this answer, but it's on topic ... What's the draw to the Holly Sniper vs. an old school Aisin? Better, faster, more fuel efficient and cheaper?