2 step & pressure switch

littlemanjoe · 07-16-2023, 03:06 PM

Has anyone ever had an issue with your 2 step not turning off clean during the launch?

I have developed a studder during the launch.

It shows the O2's going rich almost like it's a ignition thing.

Willyracer · 07-16-2023, 06:29 PM

I assume you have a data recorder in the car. We bring the
12v signal from the pressure switch / 2 step into a digital input
Then you can see the 12 v drop and rpm increase. Our O2 sensor goes
rich on the hit also.I assumed it has to do with the vacuum secondary
in the carb
David

SDT1DYI · 07-17-2023, 10:46 AM

Quote:

Originally Posted by littlemanjoe

Has anyone ever had an issue with your 2 step not turning off clean during the launch?

I have developed a studder during the launch.

It shows the O2's going rich almost like it's a ignition thing.

Yes, a bad Pressure switch can cause this. I would change it out .

Steve Teeter. Stk/SS 620

littlemanjoe · 07-17-2023, 11:21 AM

David, I do have a Racepak. I will order the 12 volt event sensor.

Steve, good point. I will change it out while I'm at it.

Thanks,
Mike

Plyguy63 · 07-17-2023, 03:42 PM

Quote:

Originally Posted by littlemanjoe

David, I do have a Racepak. I will order the 12 volt event sensor.

Steve, good point. I will change it out while I'm at it.

Thanks,
Mike

Some pressure switches have buna type o-rings or wetted parts. Buna rubber is not compatible with brake fluid. EPDM rubber is compatible with brake fluid. Virtually all brake o-rings, seals, etc are edpm rubber. Not sure as to what extent that has with the switch, but I know one person who had a switch go bad and his had buna rubber parts.

B Parker · 07-19-2023, 06:29 PM

I get your using brake pressure switch but are you using one in conjunction with a button on the brake pedal. If you are that's the first thing I would get rid of.

Coleydog · 07-24-2023, 10:04 AM

What is the switch to buy?

SDT1DYI · 08-03-2023, 08:52 PM

Call Folk Race Cars. They sell what's called the Ultimate Brake Pressure Switch. Easy to adjust to different brake PSI requirements. Two wires.
( Has three but the black wire is not used). 150.00?.

Steve Teeter Stk/SS 620

littlemanjoe · 08-04-2023, 11:23 PM

What brake fluid are you using with these switches?
Thanks,
Mike

Eman · 08-04-2023, 11:37 PM

I'll have to dig up the part # but I just use a 2 wire brake pressure switch that has pipe threads. Listing is probably for and old Ford car.
Just found my spare switch, it's an S194 from Carquest.

07-16-2023, 03:06 PM	#1
littlemanjoe Member Join Date: Feb 2018 Location: West Layfayette Posts: 125 Likes: 195 Liked 75 Times in 28 Posts	2 step & pressure switch Has anyone ever had an issue with your 2 step not turning off clean during the launch? I have developed a studder during the launch. It shows the O2's going rich almost like it's a ignition thing.

07-16-2023, 06:29 PM	#2
Willyracer Junior Member Join Date: Feb 2019 Posts: 88 Likes: 8 Liked 57 Times in 24 Posts	Re: 2 step & pressure switch I assume you have a data recorder in the car. We bring the 12v signal from the pressure switch / 2 step into a digital input Then you can see the 12 v drop and rpm increase. Our O2 sensor goes rich on the hit also.I assumed it has to do with the vacuum secondary in the carb David

07-17-2023, 11:21 AM	#4
littlemanjoe Member Join Date: Feb 2018 Location: West Layfayette Posts: 125 Likes: 195 Liked 75 Times in 28 Posts	Re: 2 step & pressure switch David, I do have a Racepak. I will order the 12 volt event sensor. Steve, good point. I will change it out while I'm at it. Thanks, Mike

07-19-2023, 06:29 PM	#6
B Parker Senior Member Join Date: Sep 2009 Posts: 847 Likes: 953 Liked 2,334 Times in 463 Posts	Re: 2 step & pressure switch I get your using brake pressure switch but are you using one in conjunction with a button on the brake pedal. If you are that's the first thing I would get rid of.

07-24-2023, 10:04 AM	#7
Coleydog Senior Member Join Date: Jul 2014 Posts: 569 Likes: 36 Liked 50 Times in 35 Posts	Re: 2 step & pressure switch What is the switch to buy?

08-03-2023, 08:52 PM	#8
SDT1DYI Member Join Date: Nov 2016 Location: Indianola Washington Posts: 396 Likes: 0 Liked 450 Times in 145 Posts	Re: 2 step & pressure switch Call Folk Race Cars. They sell what's called the Ultimate Brake Pressure Switch. Easy to adjust to different brake PSI requirements. Two wires. ( Has three but the black wire is not used). 150.00?. Steve Teeter Stk/SS 620

08-04-2023, 11:23 PM	#9
littlemanjoe Member Join Date: Feb 2018 Location: West Layfayette Posts: 125 Likes: 195 Liked 75 Times in 28 Posts	Re: 2 step & pressure switch What brake fluid are you using with these switches? Thanks, Mike

08-04-2023, 11:37 PM	#10
Eman Member Join Date: May 2014 Location: E TN Posts: 463 Likes: 16 Liked 125 Times in 71 Posts	Re: 2 step & pressure switch I'll have to dig up the part # but I just use a 2 wire brake pressure switch that has pipe threads. Listing is probably for and old Ford car. Just found my spare switch, it's an S194 from Carquest. Last edited by Eman; 08-07-2023 at 11:16 AM.

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