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Sun Mar 03, 2024 1:55 pm

I am currently working on adapting a Sniper 2300 EFI for my 1600cc VW motor. The motor starts up and idles. I have the oil temp sensor in my sump and I have adjusted the coolant temp enrichment to 100% at 120*. With that adjustment after a few minutes of start up the system goes into the learn status easily. However my current problem is that the AFR is stuck at 35.6, which from my understanding, is a result of a lean mixture reading. I believe this is a result of O2 sensor placement. I have attached pictures for reference of my current 02 sensor placement as well as the exhaust I have. EFI is completely new to me and after reading posts on the samba about others doing this conversion I thought it would be good for me to post and get yalls help!

Sun Mar 03, 2024 2:59 pm

A couple comments on your setup.

You O2 sensor should be installed between the 9-3 o'clock position. Not in the 3-9 o'clock position.
Moisture can collect and damage the sensor in the currently installed position.
Also, you have installed the sensor in the body of the muffler.
Ideally it should be installed in the header collector(where the 4 exhaust pipes come together).
Again the sensor should be installed between the 9-3 o'clock position in the collector.

Your extreme lean condition is likely due to a air leak in the exhaust system, somewhere.
I recently had a leaking head and would get AFR readings in that range. I fixed the issue and the AFR readings are now under 14.7.

Sun Mar 03, 2024 8:12 pm

So basically put the sensor towards the top somewhere. Aiming downward, not upward. The moisture will shorten the life of the sensor.
Keep tuning and posting!

Mon Mar 04, 2024 8:42 pm

Hey 67,

Thanks for the heads up on the 02 sensor position. I will adjust and also check for an exhaust air leak.

I knew that the ideal location for the 02 sensor was in the header collector, but with my current exhaust it doesn't seem to have a collector. It looks like the four pipes from the heads all gather right at the center of the back of the muffler. Are you suggesting putting the 02 sensor there?

Holley says that the 02 sensor should be mounted at a point where it can read a good average of all the cylinders on one bank and you need 18" of exhaust pipe after the sensor, which has me at a lose for what proper placement on my exhaust is lol.

Wed Mar 06, 2024 9:01 am

The beetle situation is not ideal for the O2 but mine still works. The location should involve flow past the sensor, rather than the more stagnant mix taking place in the muffler body.

If your kit came with a Bosch sensor it will last better than a generic brand. My generic brand went bad in an afternoon, and online research was lots of similar experience so I went Bosch for the replacement and it has worked for about a year.

Let the O2 sensor warm up for a full minute after turning the key on, before you start the engine. The Bosch instructions in tiny little print suggested that starting the engine on a cold sensor can ruin the sensor.

Here is your picture with a yellow dot added where I would put the bung on your muffler, and the yellow arrow is to say tipped down to keep moisture condensation off the tip.

Here is a picture of where I put one on a stock muffler, as the least-worst location I could think of:

And here is a picture of where I put one on a header that has a bit of a merge to it:

Sun Jan 05, 2025 1:43 pm

I am picking the EFI project back up this winter and have moved the O2 sensor placement and position based on yall's recommendations, which I am extremely appreciative of. I also checked for exhaust leaks when remounting the exhaust and did not find any.

After moving the O2 sensor I decided to start from scratch on the EFI tuning and reprogrammed it. I have the fuel enrichment set to 100% at 120F and all other setting are stock based on the motor size and such.

Once the motor is started the AFR is moving around trying to keep it at the target of 12.2, but the problem I having now is that it is taking FOREVER for the oil temp sensor to read 120F. I want to say it took about 30 minutes of running the motor and doing a few laps around my neighborhood to get it into learn mode. The oil temp sensor is currently in the sump and I am thinking I may need to move it to the fuel pump cover in order to get a more accurate reading.

Additionally once I get the system into learn mode and do a few more laps around the neighborhood the motor begins to bog and loses power during acceleration. Ultimately the AFR pegs and stays at 35.6 and the motor continues to run as described.

I have attached pictures of the new O2 sensor placement and the oil temp sensor location. Let me know your thoughts! y'alls wisdom and experience is appreciated.

Sun Jan 05, 2025 3:09 pm

Just brainstorming here, but...

The Holley Sniper temp sensor is not an oil temp sensor, it's a water temp sensor, which you already know. The water temp rises much faster than the oil temp in a watercooled car.

My researching this topic led me to think the placement of the Sniper temp sensor should be in the rear breast tin, facing down, on the drivers side, half way between the belt and the heater tube from the fan shroud, so it picks up the temp from the hot air flowing out of the driver's side cylinders. Imagine the spot where a stock early beetle stove pipe to the air cleaner picks up hot air for the winter. This will be a much faster rise in temps than oil.

I have had this same Sniper kit sitting on a shelf for over a year now, to go on a 1776 build that has been on my engine stand languishing. I will follow your lead if you sort this out.

How do you have the gas feed and return lines sorted out?

Sun Jan 05, 2025 3:39 pm

I cut a t-shaped slit in the little tin piece behind the cylinders and folded the corners out out to make a little opening to blow air directly on where the sensor tip would be. Maybe you can find that modification in the pictures here, I don't have a paint pen on my phone. I don't think this modification is necessary, I just did it.

Sun Jan 05, 2025 3:46 pm

If you zoom in on this picture, you can see a water temp sensor in place down there behind the distributor vacuum tube. The brown wire to the base of the sensor is a ground to the case.

Sun Jan 05, 2025 3:49 pm

These pictures obviously do not have the Sniper kit in them. They are from some mock up activity for a location to mount the water temp sensor in our aircooled application.

Sun Jan 05, 2025 4:20 pm

[quote="Buggeee"]Just brainstorming here, but...

The Holley Sniper temp sensor is not an oil temp sensor, it's a water temp sensor, which you already know. The water temp rises much faster than the oil temp in a watercooled car.

My researching this topic led me to think the placement of the Sniper temp sensor should be in the rear breast tin, facing down, on the drivers side, half way between the belt and the heater tube from the fan shroud, so it picks up the temp from the hot air flowing out of the driver's side cylinders. Imagine the spot where a stock early beetle stove pipe to the air cleaner picks up hot air for the winter. This will be a much faster rise in temps than oil.

I have had this same Sniper kit sitting on a shelf for over a year now, to go on a 1776 build that has been on my engine stand languishing. I will follow your lead if you sort this out.

How do you have the gas feed and return lines sorted out?

Hey Buggeee,

The specs on the Holley temp sensor #54-120 that come in the kit show it will read temps between -40f to 275F. I know that coolant temp rises faster than oil temp, but to me the sensor should still accurately read the temp of the oil in the motor. I could be wrong, but others I have talked to have used this sensor and either put it in the sump or fuel pump cover. I know for a fact that my motor oil temp at operating temp is well above 120F so I am trying to figure out why the sensor is reading so low. I was speculating that it is either location or the sensor itself needs to be swapped out. I have read up on getting temp readings from tin, but only seen mixed reviews and the two guys I have talked to that have working motors with this system are both using coolant temp sensors. Not saying that reading the temp off tin can't work. I just haven't encountered anyone doing that with a Holley EFI.

To answer your fuel question I am running a Holley Diecast In-Tank Retrofit Fuel Module W/Return 12-168.
Since the return line is low pressure I am using the original gas line in the body of the beetle that runs through the tunnel for the return.
For the out I ran a fuel line from the pump in the tank and feed it through an opening I had in the trunk behind the spare tire, ran it through a hole I drilled into the cab and along the tunnel inside the beetle, under the rear seat and out a hole I drilled in the firewall of the engine bay. I haven't dressed the line yet, since the project isn't complete, but here are some pictures to give you ideas.

Sun Jan 05, 2025 6:59 pm

Thank you for sharing the tank part from Holley. Great access point and no bung welding. :)

The air coming off the cylinders gets above 120 faster than the oil, letting the computer leave the warm up loop earlier. The engine is ready to leave the warm up loop before the oil gets that hot. So using the air better mimics the rise in the antifreeze seen in the engines Holley built the program for. So it's the air coming off the cylinders beneath the tin that the sensor reads.

I think I got this idea from red-e motorsports work on the Holley Sniper 1100. He's got lots of info and YouTube videos as well. Here is a link to his website, which you may already know about.

https://www.red-emotorsports.com/fuel-injection/

This a motivating discussion!

Sun Jan 05, 2025 7:14 pm

On the pegged AFR reading, could it be the O2 sensor? If the sensor is malfunctioning, the signal will push the program in the wrong direction. Its encouraging to hear that it runs around the block anyway.

For mine, I got a Holley to Webber Progressive adapter plate, to get it onto a typical Webber Progressive manifold.

Sun Jan 05, 2025 7:28 pm

Since the high pressure hose is passing through the sheet metal in the front and the back, can you put it through some cable pass throughs to protect it from getting cut with vibration? Like check out these on Amazon, or something like a bulkhead connector.

https://www.amazon.com/Joinfworld-Waterproof-Conne...&psc=1

:bug_red:

Mon Jan 06, 2025 7:50 pm

The Dub Shop offers a modified coolant temp sensor that attaches to the #3cyl head tin screw. I used this sensor with good results on a past Baja Bug build.

https://thedubshop.com/modified-coolant-temp-sensor/

Presently I'm assembling parts to put a Sniper 2300 EFI on my Super convertible. I plan on using this sensor to manage the "coolant" temp.

Mon Jan 06, 2025 8:04 pm

I plan on using an inline fuel pump using an EMPI -6an adaptor that threads on the stock fuel tank bung.

For return, I will be using Earl's Weld-less fuel return fitting.

I'm gonna try and snake aluminum fuel & return lines through the tunnel following the factory path.

Tue Jan 07, 2025 6:21 am

OPs original pix show full flow oil lines. Why not take oil temps at the Oil Filter mount? At least you'd have an active oil temp location and not a stagnant location like in the sump..

Tue Jan 07, 2025 4:18 pm

Buggeee wrote: Thank you for sharing the tank part from Holley. Great access point and no bung welding. :)

The air coming off the cylinders gets above 120 faster than the oil, letting the computer leave the warm up loop earlier. The engine is ready to leave the warm up loop before the oil gets that hot. So using the air better mimics the rise in the antifreeze seen in the engines Holley built the program for. So it's the air coming off the cylinders beneath the tin that the sensor reads.

I think I got this idea from red-e motorsports work on the Holley Sniper 1100. He's got lots of info and YouTube videos as well. Here is a link to his website, which you may already know about.

https://www.red-emotorsports.com/fuel-injection/

This a motivating discussion!

Hey Buggeee,

Thanks for sharing the info on red-emotorsports. I haven't seen their stuff so this will be good to look at. I will try getting a temp reading from this location and report back.

Tue Jan 07, 2025 4:22 pm

Buggeee wrote: On the pegged AFR reading, could it be the O2 sensor? If the sensor is malfunctioning, the signal will push the program in the wrong direction. Its encouraging to hear that it runs around the block anyway.

For mine, I got a Holley to Webber Progressive adapter plate, to get it onto a typical Webber Progressive manifold.

I think I could be dealing with a bad O2 sensor. I originally had it in the incorrect position and earlier replies to this topic some guys called out that it could be bad. I want to start with getting a solid temp sensor reading and getting the system in learn mode within a few minutes of start up to begin with just to rule that out. If I continue to have issues after moving the temp sensor I will swap out the O2 sensor.

Tue Jan 07, 2025 4:24 pm

Buggeee wrote: Since the high pressure hose is passing through the sheet metal in the front and the back, can you put it through some cable pass throughs to protect it from getting cut with vibration? Like check out these on Amazon, or something like a bulkhead connector.

https://www.amazon.com/Joinfworld-Waterproof-Conne...&psc=1

:bug_red:

Yes those pass throughs would work. I have some rubber grommets as well as fuel like clamps that I am going to use to dress the fuel line if I can ever get the system running properly. I also have rubber plugs for the holes in case I end up taking the EFI out and reverting back to carbs.