911sc warm running issue

[twaldron]

[boyt911sc]

Originally Posted by twaldron

TW,

That is a TTS (thermotime switch). I was referring to TTV (thermotime valve) or commonly called thermo valve. The TTV is usually mounted by intake runner #3. It is a black plastic circular looking device with two (2) vacuum lines and electrical connection. One vacuum line from the decel valve and the other to the WUR. You are doing fine.

Tony

[twaldron]

Originally Posted by boyt911sc

TWaldron,

Once you start the FP, with the WUR plugged-in the WUR starts to heat up from CCP to WCP. Therefore, it would take hours to get back the WUR to CCP status unless you chilled it. Secondly, check your TTV (Thermotime valve). It looks like it is OPEN @ START. Test and confirm.

Tony

My daughter came to visit for a week, so I dropped all projects! Back at it now.

When you say OPEN, are you referring to it as an electric circuit, or the mechanical side as an air (vacuum) valve?

At 80°F ambient temp in my Texas garage, it is passing air. Tested by blowing through the hose. After putting it into the freezer, it tends to be more difficult to pass air, or not at all, but not necessarily 100% blocked.

Electronically, I am receiving 11.5v with the key ON, and the two connector leads on the device have continuity (closed) regardless of temp, but I don’t think temp alters that with this device? Correct me if I’m wrong there.

[boyt911sc]

Originally Posted by twaldron

My daughter came to visit for a week, so I dropped all projects! Back at it now.

When you say OPEN, are you referring to it as an electric circuit, or the mechanical side as an air (vacuum) valve?

At 80°F ambient temp in my Texas garage, it is passing air. Tested by blowing through the hose. After putting it into the freezer, it tends to be more difficult to pass air, or not at all, but not necessarily 100% blocked.

Electronically, I am receiving 11.5v with the key ON, and the two connector leads on the device have continuity (closed) regardless of temp, but I don’t think temp alters that with this device? Correct me if I’m wrong there.

Twaldron,

I have posted how to test a TTV. Do not use compressed air. You will get a flawed test result. Instead use vacuum plus 12-volts for your test. Once the FP starts to run, the WUR, AAR, and thermotime valve are all energized too. The thermotime valve is closed when cold and will open up after 20~25 seconds of heating.

Tony

[twaldron]

Originally Posted by boyt911sc

Twaldron,

I have posted how to test a TTV. Do not use compressed air. You will get a flawed test result. Instead use vacuum plus 12-volts for your test. Once the FP starts to run, the WUR, AAR, and thermotime valve are all energized too. The thermotime valve is closed when cold and will open up after 20~25 seconds of heating.

Tony

Ok. I don’t have your dungeon for testing but I have a kitchen table. Please critique my work.

I have the Mityvac pulling on the AAV/Throttle Body side. I have the TTV on ice down to 30°. The only way I can get it to hold vacuum is to plug the center port (WUR side), which is cheating. It is not holding vacuum when cold in this configuration.

I haven’t even tried to heat it with 12v since it’s open already.

[boyt911sc]

Twaldron,

At room temperature, the TTV should be closed. Meaning: There should be vacuum with a Mity Vac hand pump using the center nipple. And the vacuum reading should be stable and not leak at all. Some TTV exhibit slight vacuum leak and could still be useful. If you could not get a vacuum reading, you got a bad TTV.



Tony

[twaldron]

Originally Posted by boyt911sc

Twaldron,

At room temperature, the TTV should be closed. Meaning: There should be vacuum with a Mity Vac hand pump using the center nipple. And the vacuum reading should be stable and not leak at all. Some TTV exhibit slight vacuum leak and could still be useful. If you could not get a vacuum reading, you got a bad TTV.
Tony

With the TTV at ambient room temp in the house (75°f) I can hook the Mityvac up to either nipple individually and it will not build nor hold a vacuum. The only way to hold a vacuum is to plug the opposing port. I’ll get one on order from the Host and report the results!

[twaldron]

Originally Posted by boyt911sc

Twaldron,

At room temperature, the TTV should be closed. Meaning: There should be vacuum with a Mity Vac hand pump using the center nipple. And the vacuum reading should be stable and not leak at all. Some TTV exhibit slight vacuum leak and could still be useful. If you could not get a vacuum reading, you got a bad TTV.

Tony

So to understand….

The TTV is testing as bad (ie not closing). I’m replacing that for sure. How does that affect the stalling after 2+ minutes when the TTV should be completely out of the picture? Are you thinking it’s stuck partially open and is causing poor vacuum to the WUR? Is there a test I can do while waiting for the new TTV such as applying Mityvac vacuum to the side of the WUR to see if I can keep the car running on its own?

If there is a second issue, I’d like to get a jump on diagnosing it. Thank you for your help and time!

tw

[boyt911sc]

TW,

Have to you tested the WUR with just the FP running (engine off)? If so, what are your control fuel pressure values for CCP and WCP (both without vac). To get the WCP with vac., simply apply vacuum @ 16” Hg to the WUR.

Next test is to run the motor without the TTV. Disconnect the vacuum line going to the center of the TTV and plug the line. This vac line is coming from the decel valve. Start the engine with a stone cold WUR. Make sure the WUR is at ambient temperature. Keep us posted.

Tony

[SkiVT]

See if this video helps assuming the link works. The TTV stops holding off vacuum right at the end of the video. I then shut off the engine as I was only trying to get a video of the pressure increase. If pressure jumps immediately when you start the engine from stone cold, the TTV isn't doing its job. Two possible reasons: TTV is bad or you have the vacuum hoses routed incorrectly. The hose from the decel valve has to connect to the center nipple of the TTV. The outside nipple goes to the WUR as Tony has noted.


https://youtube.com/shorts/fRFIsQSs92M?feature=share

[twaldron]

Originally Posted by boyt911sc

TW,

Have to you tested the WUR with just the FP running (engine off)? If so, what are your control fuel pressure values for CCP and WCP (both without vac). To get the WCP with vac., simply apply vacuum @ 16” Hg to the WUR.

Next test is to run the motor without the TTV. Disconnect the vacuum line going to the center of the TTV and plug the line. This vac line is coming from the decel valve. Start the engine with a stone cold WUR. Make sure the WUR is at ambient temperature. Keep us posted.

Tony

Those pressure results are in my OP. But I’m getting confusing Warm results between just the 12v non running, and actually firing up the motor, which I haven’t sorted yet.

The center nipple TTV hose goes to the WUR vacuum port. If you look at pic above with the TTV on ice, the WUR hose is still connected. Is that incorrect?

[SkiVT]

[twaldron]

Well well. I’ve had this car since the mid 90s. This is interesting. Thank you sir!

[SkiVT]

I only know as I reversed my lines after some DIY work.......

[twaldron]

Originally Posted by boyt911sc

Next test is to run the motor without the TTV. Disconnect the vacuum line going to the center of the TTV and plug the line. This vac line is coming from the decel valve. Start the engine with a stone cold WUR. Make sure the WUR is at ambient temperature. Keep us posted.

Tony

Ok end result is the same. Motor stumbles and dies about 2 mins in, once warm.

However, the cold startup was quite a bit smoother. No hunting. Idled up to about 1800 and slowly came down to about 1k before starting its stumbling and death throes. I also don’t have to wait hours to do a restart.

I still need a new TTV but it’s not causing the death.

On a second startup, when it began stumbling, I tried to gradually stifle the air intake with a rag to see if it was getting too much (unmetered) air. No-Go there. Died anyway.

[twaldron]

Originally Posted by SkiVT

I only know as I reversed my lines after some DIY work.......

Thanks so much for that.

[twaldron]

Originally Posted by SkiVT

If pressure jumps immediately when you start the engine from stone cold, the TTV isn't doing its job. Two possible reasons: TTV is bad or you have the vacuum hoses routed incorrectly. The hose from the decel valve has to connect to the center nipple of the TTV. The outside nipple goes to the WUR as Tony has noted

Or both I think this maybe solves why my WCP was leaping from 2.9 without starting to 3.5 instantly when I started the motor.

[boyt911sc]

TW,

You need a good working WUR and TTV to solve your problem/s. I could test and evaluate your CIS components for FREE. Send them to me with a RSL (return shipping label) preferably a UPS. And I will have them shipped back to you after 2 days from receiving the package with test results. PM me if you are interested.

Contact SkiVt (Mike S.). He is a capable CIS troubleshooter and could give you assistance to overcome your problems like many in this forum. Thanks.

Tony

[twaldron]

Originally Posted by boyt911sc

TW,

You need a good working WUR and TTV to solve your problem/s. I could test and evaluate your CIS components for FREE. Send them to me with a RSL (return shipping label) preferably a UPS. And I will have them shipped back to you after 2 days from receiving the package with test results. PM me if you are interested.

Contact SkiVt (Mike S.). He is a capable CIS troubleshooter and could give you assistance to overcome your problems like many in this forum. Thanks.

Tony

I really appreciate that offer Tony. Knowing whether the WUR is good or not would be invaluable going forward. Sending PM.

[twaldron]

Tony has confirmed that the TTV wasn’t functioning so a new one is on order. Will report results in a week or so with new TTV plumbed correctly