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Old 05-02-2022, 04:31 PM
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Luckily we run those separate Innovative widebands on the cars anyway, so I can tell if I'm way out in left field on the tune at a glance.

So I probably won't bother trying different sensors in the Snipers until they give up the ghost.

Only other sensor I had a problem with, in both units, was the engine temp sensor reading about 10 degrees too high. We've talked about that before and it's pretty common in the Holley line to see this issue. Easy fix, I just ran up to O'Reillys and got a new sensor and that fixed that.

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  #42  
Old 05-02-2022, 04:38 PM
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My CTS shows hotter by 6-8 degrees than my mechanical gauge as well. I just don't worry about it. Maybe I'll replace it one day.

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Old 05-02-2022, 04:52 PM
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It's ohm's across the sensor. Through testing on my end as well as reading, it doesn't appear that most sensors are all together inaccurate across the board vs a mechanical gauge, but rather because of the ground path across the sensor, may show out from a mechanical gauge at certain temeratures.

My CTS is 10-15 degrees colder than my mechanical gauge from 130 degrees to 160 degrees. It's 10 degrees colder from 160-180 and is 2 degrees hotter at 190 where my engine runs.

in the FiTech and Sniper the CTS is used to calculate cylinder temp. I don't know the exact calculation, but I know it uses the coolant temperature and the intake air temp to guess at the cylinder temp. This informs its open loop data tables which are then modified by the closed loop oxygen sensor to adjust fueling.

As such a small discrepancy in the coolant sensor against a mechanical gauge is not typically a big deal. If it's 30 degrees off at operating temp, I'd change it. If it's 10 degrees off I wouldn't worry about it. The replacement sensor, even if it's a quality unit like an AC Delco may still read similarly.

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  #44  
Old 05-02-2022, 05:05 PM
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I forget what brand I ended up buying but it now follows the mechanical gauge to within a degree everywhere, and now also matches the manifold temps perfectly on a cold start day. I wanted the Sniper temp to be as accurate as possible because the plan always was to remove those mechanical gauges once the Sniper was dialed in and clean up the interior from all the accessory gauges.
(I still have the factory dash gauges in the Chevelle functioning though)

Before I made the coolant temp sensor change on the Sniper I was having cold start issues. Basically with that thing reading 10 degrees hotter at every point than what the engine actually was, it was causing me to change the cold start fuel tables in the wrong area and I could never get it "just right"

Wasn't till later when I realized the temp sensor was reading high and I wasn't making changes in the right area.

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Old 05-02-2022, 05:10 PM
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That makes some sense when you realize this is all percentage and ratio based. Hot on the cold start could definitely cause some fueling trouble that is hard to nail down. There's a big difference between 10 degrees too hot at 80 degrees and 10 degrees too hot at 180 degrees.

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Old 05-02-2022, 05:25 PM
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That makes some sense when you realize this is all percentage and ratio based. Hot on the cold start could definitely cause some fueling trouble that is hard to nail down. There's a big difference between 10 degrees too hot at 80 degrees and 10 degrees too hot at 180 degrees.
Yep, it was the cold start stuff it was screwing up, or I should say I was screwing up because the temp sensor was reading too high lol.

Once it got to a temp where it was learning it really didn't seem to have any problems that I noticed on the fuel tables. It just corrects itself and goes on it's way.

Just something of interest. We use the 8 injector units on both cars. Over the weekend we took dad's to the dragstrip and grabbed a data log. Even with an engine making 724hp those injectors have a ton of room. At WOT and 5800 rpm peak injector duty cycle was only 43% LOL And pulling 14% fuel. So I went in and pulled 10% out of the WOT area from 2000 to 6000 rpm and the car picked up a solid 1 mph on the next pass. I didn't even open the hood.

So many cool features on these things.

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Old 05-02-2022, 09:01 PM
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If I keep my foot on the pedal I can keep it running. I did find that I didn't plug 1 vacuum port. If I give it a little bit of throttle it will back fire once in a while. I cant stay in the garage to long because of the exhaust fumes.

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  #48  
Old 05-02-2022, 09:11 PM
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Uh Oh,

This is starting to sound more like we'll need to see a short data log and see what's going on. That's one of the benefits of these systems. Makes it much easier for people to diagnose and usually pin point an issue.

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Old 05-02-2022, 11:05 PM
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A generic fyi, not just related to Sniper, is the fuel pressure that it's "expecting" to see. If the expectation is vacuum referenced, and it's not, that's an automatic recipe for very rich conditions. Everywhere except WOT anyway. This could be due to a leaking vacuum line to the regulator, or just a vacuum leak in general. Hopefully some of those with direct experience with the Sniper can elaborate on this. I believe it can use the existing internal regulator or an external one. Maybe the OP can elaborate on his particular situation.

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  #50  
Old 05-03-2022, 01:07 PM
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Is Sniper controlling the timing?

If no, backfires through the throttle body are almost always vacuum leak related.
If yes, the backfire through the throttle body can be a vacuum leak or timing that isn't setup correctly (usually jumping terminals)

If the system is currently controlling timing, shut that off and run a distributor that is known good while you sort this out. If backfiring stops, you know there is a timing set up issue. If backfiring continues, start looking for vacuum leaks.

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  #51  
Old 05-04-2022, 04:23 PM
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I am using my msd box. the motor ran fine before a put the sniper on. I will look for a vacuum leak. I just need someone to help me.

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Old 05-04-2022, 04:51 PM
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Are you using the internal regulator, or an external?

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  #53  
Old 05-04-2022, 05:00 PM
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Internal.

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  #54  
Old 05-04-2022, 05:04 PM
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I just got off the phone with Ryan from Holley. We went over a few things and got it to idle but we for that the front left injector is not spraying fuel. So he sent me a call tag so I send it back and they are going to repair it under warranty.

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  #55  
Old 05-04-2022, 05:06 PM
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That should hopefully be handling the fuel pressure issue as intended. Give as many details as possible, and folks will help. There are some here with much more direct experience with Holley than me. Formula Jones is one, hopefully he'll check back in. The datalogging tool is a very good one for diagnostic purposes. If you can take one from key on, even if it only runs briefly it will provide clues.

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  #56  
Old 05-04-2022, 05:08 PM
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That's good news that you found a smoking gun. Frustrating for sure though...

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  #57  
Old 05-05-2022, 05:58 AM
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Yes it is. The for AFR was at 15.

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Old 05-05-2022, 08:34 AM
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Were you datalogging at the time? If the injector wasn't working you should be able to see that by the pulsewidth readings. Embrace the datalogging its really very helpful at figuring things out.

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  #59  
Old 05-05-2022, 03:46 PM
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Quote:
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Were you datalogging at the time? If the injector wasn't working you should be able to see that by the pulsewidth readings. Embrace the datalogging its really very helpful at figuring things out.

Does the Holley have the ability to feedback actual injector pulsewidth signal as a data log output, or is it assuming based on commanded by the ECU and triggering?

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Old 05-05-2022, 03:54 PM
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I honestly made an assumption that it would. That's a basic fundamental piece of the puzzle. But I don't own one of these units personally. My old FAST EZEFI would read duty cycle on the hand held. I figured surely Holley logs injector parameters.

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