Bogs at launch 1st pass - then OK.

[RockinRobin]

My door car has a Sniper 4500. New engine. At the track, no matter how much you warm it up, run it down the return road several times, etc., it always bogs at the start line the 1st pass of the day. After that, it's okay. Does this sound like a vacuum leak that's sealing itself, or do you think it's a tuning issue? Do I need to turn off Learn mode for racing? Thanks!

[Danny Cabral]

Forum members will want to see your Global File and a datalog of this occurrence.

This is a copy & paste from one of my other posts:

Originally Posted by Danny Cabral For further assistance, post your Global File and a short datalog of this occurrence for us to analyze. Also, review the datalog and inform us of exactly where in the datalog (time/seconds) the problem occurs. Datalog & Global Files must be linked to a document hosting website. I use Dropbox.com. Files can also be "zipped" (compressed zipped folder) & attached directly to a forum post ("Upload Attachments"). Your Global File is in the "Documents", "Holley", "HEFI V5", "Global Files" folder (.hefi file). Your Datalogs are in the "Documents", "Holley", "HEFI V5", "Datalogs" folder (.V5.dl file). Someone will analyze/troubleshoot the problem & offer advice. Also, ensure all this is right: http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Steps #1-#6!) https://documents.holley.com/199r10751rev1.pdf (Holley EFI 553-108 3.5" TSLCD - Download GCF From ECU To SD Card, Page 31)

Overlay the datalog onto your Global File, and pay special attention to the center paragraph in blue print:

Originally Posted by Danny Cabral Quick Datalogger Information: Always provide data, not just symptoms. Is the AFR & ignition timing optimized? Overlay the datalog onto your Global File. Ensure the Target A/F Ratio table is properly programmed for your engine. Ensure the ECU is "Learning" (Learn Table LINK). Scroll through the datalog to the problem area. Then look exactly where this happens on the Base Fuel & Timing Tables. Scrutinize: RPM, MAP, MAT, TPS, CTS, IAC, Target AFR, AFR Left, CL Comp, Ignition Timing, Duty Cycle, Fuel Flow, Fuel Pressure & Battery. When the engine is tuned & running well, you should decrease the Closed Loop & Learned Compensation Limits % to lock in a good tune. Using the Holley EFI software (LINK), look at where the live cursor moves to during this occurrence, and manually tune that area of the Base Fuel Table (enrich or lean) & Base Timing Table (optimize ignition timing). I find the most helpful datalog function, is overlaying the datalog on your Global File. I'm in the habit of using the datalog Overlay feature every time I review a datalog. Click on "Datalog" (on the top Toolbar), "Activate Overlay", then "Open Data Log". You can literally "playback" a recorded event, and watch it as it happened on any screen. Minimize (shrink) the datalog window, and move it to the bottom of any Global File screen. Then click & scroll anywhere on the datalog, and watch it playback on your Global File (EFI software). http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions) https://forums.holley.com/showthread...s-amp-Datalogs (Datalog & System Log Information - Read "NOTES") https://www.youtube.com/watch?v=iqHOtDNiTNA&index=25&list=PL24C6FEA0BB99AF 17 (How To Record & Email A Datalog) https://www.youtube.com/watch?v=q7OZUXLRS1Q (How To Record A System Log & Diagnose A No-Start Condition) https://forums.holley.com/showthread...7531#post77531 (Closed Loop Datalog Tuning - Posts # 2, # 4 & # 6)

[a b c]

Most likely it's a tuning issue. The first thing I'd do is capture a datalog of the issue and one without the issue and compare the two.

[GPatrick]

What are you running for a thermostat? What's your normal/desired temperature at launch? Have you checked your coolant temperature sensor to make sure it's correct? Many Holley supplied coolant temperature sensors read incorrectly out of the box. On a fully cold engine turn on the ignition and before starting use then handheld to compare the CTS and MAT. If the CTS is reading 10° or more higher than the MAT then it needs to be replaced. A bad CTS can not only read high at low temperatures but also high or low at higher temperatures.

I agree with abc above about tuning, but tuning can be ineffective if any of the sensors are not providing accurate data.

If you don't have a datalog currently, upload the Config File that's currently in Sniper memory so we can see what the system is trying to do.

[RockinRobin]

I don't run a thermostat. I can control temp in the staging lanes with my radiator fan. It seems to do best when I leave the line at 145-150°F water temperature. Runs a slower pass if I go higher. Maybe unrelated. I have ordered a new temperature sensor. Going to try to get to TNT before next race and datalog and upload it. Thanks!

[GPatrick]

The default Sniper setups have a 160°F setting to initiate Learning, so you may not be Learning at all with your staging strategy. The values can be adjusted and the amount of extra compensation can be altered if your normal operating range is 140°F, for example. We'll know more when we see your Config File. Some of the more experience drag racers on the forum will have better recommendations. A thermostat suitable for your application and Sniper fan controls may make it easier to maintain your desired temperature allowing you to focus on other conditions.

[Danny Cabral]

https://forums.holley.com/showthread...289#post233289 (Related Forum Thread)

[RockinRobin]

GPatrick: Thanks! It's gonna be a "NO" on the thermostat. I have a motor plate running straight to the top hose, no place to put one. This is a dedicated racing application.

[GPatrick]

Understand regarding the thermostat, but the fan controls may be of some help in the future.

[Danny Cabral]

Closed Loop & Learning happens at all RPM, provided the Closed Loop/Learn Parameters are programmed as such.
The Coolant Temperature Enrichment % & A/F Ratio Offset tables must be at 100% & zero to enter Learn mode.
You'll need to reconfigure these tables if you're running the engine colder than what the base calibration specifies.
https://forums.holley.com/showthread...289#post233289 (Related Forum Thread)

[RockinRobin]

Understand regarding the thermostat, but the fan controls may be of some help in the future.

I doubt it. Once the air temperature reaches about 85°F, I cannot hold the water temperature steady with the fan. I have no problem switching the fan on & off manually. I like to have it off when going down the track, then turn it back on when I'm slowing down. I may have too small or too large of a coolant restrictor in the water path. I may have to experiment with different size restrictors. It's never com back to the trailer higher than 190°F, so I'm not concerned.

[RockinRobin]

UPDATE: Got the temperature sensor from Rock Auto and installed it. Went to the track for TNT. Transferred Learning To Base before startup. Never had the bog issue, but 1st pass was the best pass. Made three passes, as the night went on and temperatures dropped slightly the car slowed down a littler rather than picking up. Strange, but the bog at launch is gone. Only thing I varied was CTS at launch, tried 150°F, 160°F, 145°F. BTW, I noticed that Learn is set to turn on at 150°F (I must've changed it) and Learn % is at 40 in all cells.

[GPatrick]

Download your Config File from the Sniper now that it contains your latest information. If your CTS enrichment isn't set properly for the temperatures you're running it may be running richer than you expect/need as the temperatures drop. We can see that in your Config File and make suggestions if appropriate.

[RockinRobin]

I have the Config File and a datalog in a zipped file. I cannot find the control called "Upload Attachments" as suggested in Danny's message.
EDIT: OK, I found it.

[a b c]

Your lean on the jump. Based on vacuum at idle, I don't see any reason to idle that high. My guess is 1100 or 1200 hundred would be fine and allow you to clean up your jump. The base fuel map is a mess near idle. At the least, apply the Learn Table and hit the Smooth button in the bottom 2/3 of the table.

Although the idle is not the major issue, looks like you need to lower the AE Blanking numbers and go test, it may also take adding fuel on that same diagonal line during the jump. The AE is not being invoked on the jump. Do you feel like you're pressing the throttle at a very quick rate that would normally squirt fuel from the AP on a carburetor? The datalog shows you're pressing fast enough that you should be using Acceleration Enrichment.