Did pressure test, feedback appreciated (Tony?)

[LIRS6]

Cold start - Car starts up fine although idle at start up is only around 1200 rpm after about 10 secs.
During course of warming up, when say coming to a stop and engaging clutch, rpm's will drop momentarily to about 300 rpm - almost stalling - then recovers to about 850 rpm. Once engine is warm, all is good - rpm's stay at about 900 rpm, with no near-stall issues.

Warm start - no issues.

The car :

'79 SC (USA)

Original 3.0 with WUR ending 045

74 degf

WUR ohms : 26.3

Test results :

System pressure: 4.9 bar

Cold pressure : 2.1 bar

WUR Power connected

30 secs : 2.2 bar

60 secs : 2.45 bar

90 secs : 2.7 bar

120 secs : 2.8 bar

150 secs : 2.95 bar

180 secs : 3.03 bar (3.03 - not 3.3)

210 secs : 3.1 bar

240 secs : 3.1 bar

270 secs : 3.13 bar

300 secs : 3.18 bar


Residual pressure :

1 min : 2.3 bar
5 mins: 1.8 bar
15 mins : 1.55 bar
30 mins : 1.4 bar
60 mins : 1.2 bar

Does the above suggest an out-of-tune WUR?

Thanks

Jason

[Bob Kontak]

I dug this out of an old post. The title of the pic is euro CIS. I see your's is a US model but I do not know if they had separate Euro and US WUR's both numbered 045. Kind of doubt it.

[LIRS6]

Thanks Bob.

So system pressure is good at 4.9
my cold pressure is on the low point but within spec. at 2.1
Leak test is good - 1.4 after 30 mins
Not sure about the warm test - what determines if vacuum is present? regardless it would appear to be below normal range.

Any thoughts?

Jason

[boyt911sc]

Jason,

Were the data you have for the control fuel pressures taken with the engine running or not? Make another test with just the FP running with a fully charged battery. Post the data and I might be able to interpret your test results. Thanks.

Tony.

[LIRS6]

Originally Posted by boyt911sc

Jason,

Were the data you have for the control fuel pressures taken with the engine running or not? Make another test with just the FP running with a fully charged battery. Post the data and I might be able to interpret your test results. Thanks.

Tony.

Hi Tony

Engine was not running - only the FP throughout the testing

Thanks

Jason

[boyt911sc]

Originally Posted by LIRS6

Hi Tony

Engine was not running - only the FP throughout the testing

Thanks

Jason

Jason,

Use the table posted by Bob K. There are two values you need to know, with and without vacuum applied. Use a hand-held vacuum gauge for the initial and final readings. Since I’ve been calibrating WUR-045’s this week, the values are still fresh in my mind.

No vacuum: 39~45 psi.
W/ vacuum: 46~52 psi.

Sorry, I use psi. unit for my calibration and testing for years and been a habit. I seem to remember psi. values than the bar unit (old habit). Keep us posted.

Tony

[LIRS6]

Originally Posted by boyt911sc

Jason,

Use the table posted by Bob K. There are two values you need to know, with and without vacuum applied. Use a hand-held vacuum gauge for the initial and final readings. Since I’ve been calibrating WUR-045’s this week, the values are still fresh in my mind.

No vacuum: 39~45 psi.
W/ vacuum: 46~52 psi.

Sorry, I use psi. unit for my calibration and testing for years and been a habit. I seem to remember psi. values than the bar unit (old habit). Keep us posted.

Tony

okay, here's where I demonstrate my ignorance ....

unfamiliar with vacuum gauges and how to use them ... how would I do so in this application? Any suggestions for a gauge?

If I have only the FP running (not the engine), is vacuum not being applied? How is vacuum applied? - by running the engine? a vacuum pump? If so, again how to use?

Ref values, I will express warm pressure test in PSI :

WUR Power connected

30 secs : 2.2 bar / 31.9 psi
60 secs : 2.45 bar / 35.5 psi
90 secs : 2.7 bar / 39.2 psi
120 secs : 2.8 bar / 40.6 psi
150 secs : 2.95 bar / 42.9 psi
180 secs : 3.03 bar / 43.9 psi
210 secs : 3.1 bar / 44.97 psi
240 secs : 3.1 bar / 44.97 psi
270 secs : 3.13 bar / 45.5 psi
300 secs : 3.18 bar / 46.12 psi

thanks

jason

[T77911S]

you can buy a hand pump at HF or advance., they come as a brake bleed set. nice tool to have. you can also check other CIS components with it.

just post the CCP with and without vacuum and the WCP with and without vacuum.


RPM dropping like that is a too rich condition.
you also have a thermo time valve.
that should open up after about 20 seconds of engine running.

with no vac pump here is a way to test it.

with the engine warm and running remove the vacuum line to the WUR and see if it has vacuum on it.

if you buy the vac pump you can do this with engine off.
pull a vac on the TTV, turn key on and you should lose vac after about 20 sec.

pull a vac on the WUR and make sure it holds to test diaphragm.

not related, I would also pull a vac on the brake line to the booster. that hose can cause air leaks.

[LIRS6]

^^^ Much appreciated ^^^

Jason

[Bob Kontak]

Originally Posted by T77911S

you can buy a hand pump at HF or advance., they come as a brake bleed set. nice tool to have. you can also check other CIS components with it.

(+1 on T77's input)

Believe they are called Mityvac. It's not a "Harbor Freight" tool if you know what I mean. It is a decent quality assembly. Pretty much the only brand I see anywhere for sale. $40-ish these days unless you buy online.

As soon as I said it's the only brand, I see HF has cheaper ones. Spend the extra $15 and get the Mityvac. Mine is beat to hell and 15 years old. Still carrying the torch.

The scale is Hg on the mityvac. You can go to a conversion website and convert the factory scale to Hg.

https://www.harborfreight.com/mityvac-vacuum-pump-39522.html

[LIRS6]

So I bought a Mityvac, now I have no clue what to do with it.

Can someone hold my hand?

Thanks

Jason

[Alan L]

Looks like a guide is enclosed. It is slightly different to mine - but basically it should have a switching mechanism that allows it to pressurise, or evacuate the system. In your case you want the vacuum function. Your gauge should be a + and - gauge - above/below ambient pressure. You want to pull around 0.5-0.7 bar to replicate idle vac. This will fit on to your WUR at the port hooked up to the Throttle body port - once you find some appropriate plastic hose bits. The trigger handle does the pump +/- work.
Alan

[T77911S]

it only pulls a vacuum. wish I could find something small to pressurize, like my WUR for boost CP.
anyway, just play with it. connect it to the WUR and pull a vac and see if it holds.
you would be surprised, I use mine quite a bit.

[LIRS6]

Thanks.

So if I have this right, I am going to re-run the warm pressure test (power to the WUR) with vacuum to the WUR port and note pressure values every 30 secs upto say 5 mins?

Jason

[Bob Kontak]

Originally Posted by LIRS6

So I bought a Mityvac, now I have no clue what to do with it.

Open the package, put your wet finger over the snoot and pull the lever. You will feel a vacuum on your finger tip. Put a rubber hose on the snoot and the other end on the WUR where you pull the vacuum line off. Create the vacuum inside the WUR for testing. Observe if there is change in the warm control pressure with test vacuum applied AFTER you reach that max BAR setting of 3.18.

Your mityvac scale is in inHG (inches of mercury). You need to convert the factory specs in millimeters of mercury to inches of mercury.

350-450 mmHG is 13.8 - 17.7 inches of mercury. Pretty much high noon on your mityvac scale if you take it to 15 inHG.

Did you confirm vacuum at the line going into WUR as T77 suggested?

[LIRS6]

Originally Posted by Bob Kontak

Open the package, put your wet finger over the snoot and pull the lever. You will feel a vacuum on your finger tip.

Check


Put a rubber hose on the snoot and the other end on the WUR where you pull the vacuum line off. Create the vacuum inside the WUR for testing. Observe if there is change in the warm control pressure with test vacuum applied AFTER you reach that max BAR setting of 3.18.

So I am applying vacuum throughout the test, and just looking for it to get beyond 3.18?

Your mityvac scale is in inHG (inches of mercury). You need to convert the factory specs in millimeters of mercury to inches of mercury.

350-450 mmHG is 13.8 - 17.7 inches of mercury. Pretty much high noon on your mityvac scale if you take it to 15 inHG.

Great, thanks. 15 HG = .5 Bar, so that's what I'll aim for per Alan L

Did you confirm vacuum at the line going into WUR as T77 suggested?
Not yet - will do so to see if it holds.

Will report back in due course

Many thanks

Jason

[Bob Kontak]

The test of the vacuum line going in is an engine running test. More of is there vacuum when you are running. This is a little separate from the engine not running test for WCP.

Let's say you are cruising at 35, nice and steady. You will have plenty of vacuum in the intake because the throttle plate is open just a little. Your WCP should be above that 3.18 bar because the vacuum is sucking on the diaphragm in the WUR. Let's say 3.5 for discussion. More lean for emission purposes.

Push the pedal to the floor and you open the throttle plate allowing lots more air in reducing intake vacuum. Suction on the diaphragm goes away and WCP drops to the 3.18 bar number. More rich for performance. Let off the gas WCP leans out.

You need to know two things. Is vacuum with engine running getting to the WUR through the hose? If you have vacuum through the hose, does the WUR hold the vacuum? The latter is the static test with the mityvac. Former is engine running. Put your finger on the end of the hose and check.

Edit: To answer the question of pulling vacuum throughout the test it is not necessary. Warm control pressure is what you essentially achieve after cold control pressure has gone through it's warm up cycle.

[LIRS6]

Originally Posted by Bob Kontak

The test of the vacuum line going in is an engine running test. More of is there vacuum when you are running. This is a little separate from the engine not running test for WCP.

Let's say you are cruising at 35, nice and steady. You will have plenty of vacuum in the intake because the throttle plate is open just a little. Your WCP should be above that 3.18 bar because the vacuum is sucking on the diaphragm in the WUR. Let's say 3.5 for discussion. More lean for emission purposes.

Push the pedal to the floor and you open the throttle plate allowing lots more air in reducing intake vacuum. Suction on the diaphragm goes away and WCP drops to the 3.18 bar number. More rich for performance. Let off the gas WCP leans out.

You need to know two things. Is vacuum with engine running getting to the WUR through the hose? If you have vacuum through the hose, does the WUR hold the vacuum? The latter is the static test with the mityvac. Former is engine running. Put your finger on the end of the hose and check.

Edit: To answer the question of pulling vacuum throughout the test it is not necessary. Warm control pressure is what you essentially achieve after cold control pressure has gone through it's warm up cycle.

Ok Bob, thanks, so seems I am doing 3 things:

1) - checking if the WUR holds vacuum by applying suction to the WUR using the Mityvac, with about .5 bar, engine not running

2) - with engine running, check if there is any suction on the vacuum hose which leads into the WUR

3) - with engine running, do pressure test

Will report back

Many thanks

jason

[Bob Kontak]

Originally Posted by LIRS6

Will report back

+1

Pressure test with engine on and off just to see if there is a difference. Hit it with suction post warm up to check if pressure goes in the right direction and does not exceed the max WCP as stated in the graph.

Hoping all will be well.

I would not sweat the 0.08 WCP higher than spec w/o vacuum. However, if you want more gas under full throttle send the WUR to Tony and he can adjust. Doubt you would notice a difference.

[Alan L]

Originally Posted by T77911S

it only pulls a vacuum. wish I could find something small to pressurize, like my WUR for boost CP.
a.

This what I got - don't know what you call it. The end collar slides back/forward. Changes from Vac/pressure. You will see the gauge is central - records +/- vac/pressure.
Invaluable.
Alan