O2 Sensor Placement?

[Tex2131]

Guys, I have the Blueprint 351/427 with a Holley Sniper EFI and four into four pipes. Instructions say to weld a bung into the exhaust after the four pipes collect into one and before the muffler. It's a wideband sensor and that would put it on the outside of the body (see attached photo). I don't particularly like that and worry about clearance with the body.

Any photos out there on how you have done it?

Thanks, Don

[Big Blocker]

This worked for me . . . beta test before some of the major vendors started making them.

Doc

screenshot

Actually this is second generation after I modded it to take band-clamps.

[CraigS]

I have welded the bung for two friends in the top rear pipe about 6 inches above the 4 bolt flange. Sampling just one cylinder seemed to work fine for them.

[RickP]

Guys, I have the Blueprint 351/427 with a Holley Sniper EFI and four into four pipes. Instructions say to weld a bung into the exhaust after the four pipes collect into one and before the muffler. It's a wideband sensor and that would put it on the outside of the body (see attached photo). I don't particularly like that and worry about clearance with the body.

Any photos out there on how you have done it?

Thanks, Don

Hi Tex2131 -

You have yourself in a bit of a pickle with the 4 into 4 header setup. Ask me how I know? Putting a sensor in the header itself won't work. You will never get your engine to run correctly. Again, ask me how I know?.

You will need to put the sensor in the side pipe right behind the collector but before the muffler. It's tricky but doable. Mock up is everything and placement is key as to not have interference with the body.

1. Temporarily mount the body.
2. Align your side pipes (I put mine in the passenger side pipe). I also used a couple of Breeze wedges. One to align the pipe with the body, and another to space the pipe further away from the body.
3. Mark the pipe for a good location (if your state requires heat shields, now is the time to consider their mounting location).
4. Remove pipe.
5. Drill, weld bung, replace pipe.

The other option is to swap headers for a 4 into to 1 and place the sensor in the header collector.

Here's a pic so you can get an idea of where mine is. And for me, I will be doing this process all over again as I am swapping my pipes for Gas-N's.

[phileas_fogg]

I place O2 sensor just like RickP.

Rick: How did you route the wires for the O2 sensor? Did you notch the body & use a grommet, or did you just let them wrap under the edge?


John

[RickP]

I place O2 sensor just like RickP.

Rick: How did you route the wires for the O2 sensor? Did you notch the body & use a grommet, or did you just let them wrap under the edge?


John

I ran the wires under the foot box and zip tied in an inconspicuous location in the engine compartment so the wire wouldn't hang below the 4" tube. I do have it on my "to do" list to better mount the wire but what I did gets me down the road for now.

[alv69]

this is where I put mine. drilled hole thru body and put large rubber grommet, this way sensor is towards top half of pipe and will not have problems with moisture.

[RickP]

Don -

However you choose to do it, you want to measure all four cylinder banks at the same time. I originally mounted mine in the header tube/last cylinder bank. I am running a FiTech and it's no different than the Holley Sniper when it comes to the software logic behind the sensor. If you opt to have the sensor read only one cylinder, you will be hand cuffing your system right from the get go. Here are just a few of the symptoms I realized before moving the sensor to the side pipe location.

1. The motor always ran rich. Like smell gas rich.
2. Starts were sketchy at best. I would have to put my foot into the pedal to just get it to turn over.
3. Blue smoke out the pipes.
4. In the event I could get it running, I would drive from gas station to gas station.
5. The TPS setting would never read zero.
6. The Step setting could never be adjusted to land in the 3-10 range. Even if it could, TPS needs to read zero first.
7. Bogging at any engine speed.

When I moved the sensor to the side pipe, it was like a whole different motor. All my problems went away on first start and I could tune the FiTech with ease.

[cwrandolph]

I have welded the bung for two friends in the top rear pipe about 6 inches above the 4 bolt flange. Sampling just one cylinder seemed to work fine for them.

X2 - this works great for me.

[Tex2131]

Don -

However you choose to do it, you want to measure all four cylinder banks at the same time. I originally mounted mine in the header tube/last cylinder bank. I am running a FiTech and it's no different than the Holley Sniper when it comes to the software logic behind the sensor. If you opt to have the sensor read only one cylinder, you will be hand cuffing your system right from the get go. Here are just a few of the symptoms I realized before moving the sensor to the side pipe location.

1. The motor always ran rich. Like smell gas rich.
2. Starts were sketchy at best. I would have to put my foot into the pedal to just get it to turn over.
3. Blue smoke out the pipes.
4. In the event I could get it running, I would drive from gas station to gas station.
5. The TPS setting would never read zero.
6. The Step setting could never be adjusted to land in the 3-10 range. Even if it could, TPS needs to read zero first.
7. Bogging at any engine speed.

When I moved the sensor to the side pipe, it was like a whole different motor. All my problems went away on first start and I could tune the FiTech with ease.

Rick, thanks for the history and picture. That's what makes,this forum so great, guys willing to share lessons learned that help us new guys prevent mistakes. Don.

[Tex2131]

this is where I put mine. drilled hole thru body and put large rubber grommet, this way sensor is towards top half of pipe and will not have problems with moisture.

That looks great! I've been worried about the whole 9 to 3 o'clock thing to avoid condensation and you just went right thru the body. Thanks, Don

[phileas_fogg]

I ran the wires under the foot box and zip tied in an inconspicuous location in the engine compartment so the wire wouldn't hang below the 4" tube. I do have it on my "to do" list to better mount the wire but what I did gets me down the road for now.

Thanks much!

[dncharo]

I’ve been reading this with interest because I have the same issue. I am planning on getting new headers from gpheaders which make them with a double collector with the O2 bung already welded in. I ended up just selling my 4 into 4 headers. Have others used these?

[Papa]

I’ve been reading this with interest because I have the same issue. I am planning on getting new headers from gpheaders which make them with a double collector with the O2 bung already welded in. I ended up just selling my 4 into 4 headers. Have others used these?

I just received a set of GP Headers with the double collector. If you have a newer Blueprint engine, be aware that the plugs sit about 1/8" higher than "normal". My headers are going back to GP Headers for a modification to correct this issue and allow the plug wires to work.

[dncharo]

Hi Papa, thanks for that tip! I’ve been following your build thread and remember the saga with your headers that you went through. Sounds like that continues with the GP headers.... I hope they get them to fit! When they do, would you mind posting a picture to your build thread to show the modification? I think we are going with a Blueprint EFI engine also. But likely the 351/427.

[Papa]

Hi Papa, thanks for that tip! I’ve been following your build thread and remember the saga with your headers that you went through. Sounds like that continues with the GP headers.... I hope they get them to fit! When they do, would you mind posting a picture to your build thread to show the modification? I think we are going with a Blueprint EFI engine also. But likely the 351/427.

I'll be sure to update my build thread when I get past this issue -- getting very close now. For what it's worth, your Blueprint 351/427 will likely come with the very same heads that are on my 347. Several header manufacturers that service Factory Five are experiencing issues that were introduced by the Blueprint head design and are working hard to get new/updated products available to us builders with these new parts. I've had the unusual opportunity to have been asked to test fit products from three different manufacturers and I can say that they each have their own issues and merits and are working their own solutions based on their unique designs.

[cgundermann]

I'll be sure to update my build thread when I get past this issue -- getting very close now. For what it's worth, your Blueprint 351/427 will likely come with the very same heads that are on my 347. Several header manufacturers that service Factory Five are experiencing issues that were introduced by the Blueprint head design and are working hard to get new/updated products available to us builders with these new parts. I've had the unusual opportunity to have been asked to test fit products from three different manufacturers and I can say that they each have their own issues and merits and are working their own solutions based on their unique designs.

That’s cool you are a test bed, working out the best viable mounting location that is also aesthetically pleasing and fully functional is a trick. With my 347/Pro-M Racing ECU & J-pipes it works out perfect. BUT, with all the different motor, header & sidepipe configurations - it’s a total challenge to meet everyone’s needs...

Chris

[Tex2131]

I'll be sure to update my build thread when I get past this issue -- getting very close now. For what it's worth, your Blueprint 351/427 will likely come with the very same heads that are on my 347. Several header manufacturers that service Factory Five are experiencing issues that were introduced by the Blueprint head design and are working hard to get new/updated products available to us builders with these new parts. I've had the unusual opportunity to have been asked to test fit products from three different manufacturers and I can say that they each have their own issues and merits and are working their own solutions based on their unique designs.

Dave, funny you should mention fit issues. My headers are going back to FF because I can't get a spark plug socket to the sparkplug. I sent an email and photo to Johnny at Blueprint explaining the problem and he forwarded it to FF. The bottom line is that FF had shipped the wrong headers. Between Johnny and FF they had the problem resolved before I woke up the next day (God bless Eastern time zone) and replacement headers are on the way. Got to love that level of service.

[Papa]

Dave, funny you should mention fit issues. My headers are going back to FF because I can't get a spark plug socket to the sparkplug. I sent an email and photo to Johnny at Blueprint explaining the problem and he forwarded it to FF. The bottom line is that FF had shipped the wrong headers. Between Johnny and FF they had the problem resolved before I woke up the next day (God bless Eastern time zone) and replacement headers are on the way. Got to love that level of service.

That's good news! I was able to try a set of the updated Factory Five BBK supplied headers. They have the 2" bolt spacing (my Blueprint heads have both 2" and 3" bolt spacing), which put the bolt very close to the tubes, but they did fit. For anyone ordering headers from FF for their Blueprint engine with Part # HP9009 cylinder heads, be sure to let FFR know that and they will send you the correct header. There are two differences on these heads that are creating fitment issues for the header manufacturers. The first is the angle of the exhaust side of the head and the second is the spark plug location. The first issue creates either interference issues and/or an issue with the exit flange. The spark plug location on the heads is 1/8" higher than other designs, which has created a plug wire interference issue.

Sorry for hijacking your thread.