free hit
counters
Frequency valve readings and help - Fuel System/Carbs - The Lotus Forums Jump to content
tf308

Frequency valve readings and help

Recommended Posts

I made a connector that taps into my frequency valve to see what my car is doing. Car is sitting in a garage where the cold start up temp is 75F.

If I disconnect my O2 sensor I get a frequency reading that bounces very tightly around 50% on the frequency valve (this is engine stone cold)

If I let the car heat up the value "hovers" between 46 and 52%.

Shouldn't the frequency be around 75% at cold start up? 65% at operating temp?

O2 sensor has a blade terminal AND a Bosch 2 pin terminal. I checked continuity to the ecu on the terminals which seemed fine. (Checked here because it says ECU will do 50% if there is an unhooked O2 sensor). Any ideas?

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.

Hi Tim,

 

What car do you have? I think your posting in the wrong section.

 

Brian

 

Good call Brian. We can leave it here as Tim's car fits the forum his post is in. :)


All we know is that when they stop making this, we will be properly, properly sad.Jeremy Clarkson on the Esprit.

Opinions are like armpits. Everyone has them, some just stink more than others.

Share this post


Link to post
Share on other sites

Your duty cycle should be lower when cold, and get higher as the car & O2 sensor get to temperature. Higher duty cycle means that the lower chamber pressure is bled and mixture is richer while lower duty cycles will build up pressure in the lower chamber, pushing the diaphram up and closer to the "out" port, leaning the mixture.


Something I learned about cars or planes, it all works until it doesn't anymore...sometime there is no way around it!

Share this post


Link to post
Share on other sites

What afffects the duty cycle? I'm trying to understand why mine is 50% instead of 65%.

Is there a bad connection at the ecu? Problem w O2 sensor? Did some previous owner replace the ecu w an incorrect one?

Im going to assume that the ability for the esprit to adjust fuel ends at this valve,therefore, I would like this to function properly.

The resistance is 2.3 ohms so the valve is within spec.

Share this post


Link to post
Share on other sites

50% is typical in closed loop.

65% you get only when pin No.7 of the ECU is grounded, which happens at boost under acceleration and/or when TPS is NC over 30 degrees.

Please read carefully section LF of Service Notes.

Share this post


Link to post
Share on other sites

Thanks Mr D. I must have read something incorrectly.

I am taking the plunge now into learning CIS on this car. I made the frequency valve tester and bought a cIS pressure testing kit.

I can't help but wonder what the FrankenCIS Wur would be like now. One day I want to be like Mr D!

Share this post


Link to post
Share on other sites

Tim,

The most important is to have fun with these cars and keep them running. Stir-up the curiosity of the crowd!

What you need first is a properly sorted car. By-standers wont know how much power are you wringing out of the engine and how did you do it.

I'm publishing descriptions of many changes/improvements to show others what's possible, (well, not only WHAT, but also HOW TO !). To inspire and energize the owners crowd. Repairs are boooo-ring. "Prototyping" is sexxxy!

Tinkering with an older car equipped with an ancient technology (CIS), has been fun for me.  It can be compared to mastering some (ancient) Kung-Fu style. Sure..., it's old, but you can cripple your opponent equally effectively.  LOL.

Even if I had S4s, I would start modifying it immediately, too.

Edited by MrDangerUS

Share this post


Link to post
Share on other sites

So I found my first problem.  The low temperature switch is open.  Engine is at 24C and it should be closed.  I grounded the signal and boom.....75% frequency rating.

Which brings me to the next question....what is the best replacement switch?  Did the Steves or S4 have a different sensor.   The slide on blade terminals are terrible to begin with.  Anyone have a replacement for this sensor? Cross reference?

 

my goal is to make sure everything is as it should be.....then I really like the frankencis.  Can anyone help with a base tune here?  (We can start a new thread, but I figured that I would ask)

 

Share this post


Link to post
Share on other sites

I too am learning the Bosh CIS. What is the original symptom that made you start testing your frequency valve? I believe it is controlled by the ECU and uses inputs from the Lambda sensor along throttle position switch.

 

Where did you get your CIS testing kit and can you show a pic of the valve tester you made? I need the same!

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...