CIS Tuning: My Pressure Specs with modified WUR - Advice please!

[racer86]

Hi All,

My car is a '78SC but with a later, '81 Euro 204hp motor running air filter and headers (no cat or O2 sensor). WUR is an 089.

I've read lots on this forum about making your WUR adjustable and all the pressure specs so I did just that.






I've done the work and set the car up and my specs are as follows:

find the nearest bb&t bank

System pressure: 4.5 (spec 4.5 - 5.2)
Cold control pressure: 1.2 @11degsC
Warm control pressure 3.1 (spec 2.7 - 3.1)
Leak down 1.4 after 20mins

WUR is rebuilt and heater element is in spec and working.
AAR is fully functioning and tested.
New accumulator
New fuel pump
New fuel filter

Car starts and runs and drives well but is FLAT and down on power compared where it used to be (when it ran horribly cold but went like stink).

So, I'm after advice (have done a search but can't find anything solid) as to where I start and where to go after:

1. System pressure is on the bottom of spec @ 4,5 - Do I re-shim the control pressure regulator?

2. Do I adjust the WUR to lower warm control pressure thus enriching the mixture?

3. Am I in spec so fine adjust on the mixture screw?

Appreciate your thoughts and feedback before I make my next move.

Cheers Rob.

[Dmitry at Pelican Parts]

Hello - your photos didn't seem to upload.

[SkiVT]

Are your pressure specs with or without vacuum applied? Post a picture of your vacuum lines from wur. The vacuum contorls your afr with that wur and performance can suffer if not working corrrectly.

[racer86]

Hi,

Hopefully I've now sorted the images and you can seem my specs Vs the testing specs.

I've not measured with vacuum applied as I don't have a mittyvac or similar. I have checked (by putting a pipe on and sucking!) that the vac system in the WUR is working and it does influence (increase control pressure).

I'm just not sure if being on the lower limit for system pressure and the upper limit for warm control pressure is giving me an issue. If so, as I'm in spec can I tweak the mixture on the mixture screw or am I best re-shimming the system pressure control valve in the metering head?

Thanks again.

[al lkosmal]

Since your pressure measurements are within reason and the car is running well, i'd recommend measuring the A/F mix.

regards,
al

[boyt911sc]

Originally Posted by racer86

Hi,

Hopefully I've now sorted the images and you can seem my specs Vs the testing specs.

I've not measured with vacuum applied as I don't have a mittyvac or similar. I have checked (by putting a pipe on and sucking!) that the vac system in the WUR is working and it does influence (increase control pressure).

I'm just not sure if being on the lower limit for system pressure and the upper limit for warm control pressure is giving me an issue. If so, as I'm in spec can I tweak the mixture on the mixture screw or am I best re-shimming the system pressure control valve in the metering head?

Thanks again.

Unless you have an AFR meter installed, you do not know at this point if the WCP with vacuum is correct or not. Run the motor with the CIS gauge installed and record the WCP with vacuum. The enrichment capability of the diaphragm might not be on spec. Keep us posted.

Tony

[racer86]

WUR vac set up.



Thanks all.

Tony will run at the weekend and check back in. Thanks

[SkiVT]

Tony’s test will get you there. The vacuum line from the lower left side of the wur back to the throttle body typically runs through a TTV and a decel valve. Your picture doesnt quite show if those items are present or not. Only will matter if the test idicates a problem as it could then be the wur or something amiss in the path of the vacuum line.

[boyt911sc]

Originally Posted by racer86

WUR vac set up.



Thanks all.

Tony will run at the weekend and check back in. Thanks

Racer86,

Where does the vacuum line from the WUR connect to? Do you have a thermotime valve? Picture would be helpful. Thanks.

Tony

[scarceller]

The mod you made to the WUR I think only effects cold CC, correct? It basically relocates the bi-metal arm? If that's the case it has no effect on warm CC.

I usually do not worry about cold start, I leave that for last.

I verify the warm pressures and then use a WideBandO2 gauge and set the mixture at idle so it's in the 13.4 to 13.8AFR range, the CIS cars seem to idle nice in the mid 13s AFR.

If you get the warm setup correct you can then use the mod you made to help dial in the cold start.

Often I see folks trying to fix cold start first, do not do this. I find that if you get the warm CC and mixture setup the cold start fixes it self or at least gets significantly better. Also, if the motor hunts at cold start you are likely to rich, if it sputters to lean.

[scarceller]

With fully warm motor and at idle, remove the vacuum line from the WUR and the CC must drop by about -0.5bar. For example if you are at 3.5bar at idle with vacuum connected and you remove the vacuum from the WUR the CC should go lower to around 3.0bar you need to verify this to be sure the vacuum line is working correctly on the WUR.

Basically, vacuum drops as load increases and at WOT you have nearly no vacuum and this in turn drops the CC and the mixture goes richer.

Hopefully that helps.

[racer86]

Hi Tony Vac routing is straight from WUR to throttle body as far as I can see

[SkiVT]

It looks like its below the plate so should produce vacuum. The pressure tests with running engine described by others will tell you if its all working as intended. The missing TTV helps with cold start but that doesnt seem to be an issue for you. When you start the engine, you should have immediate vacuum as no TTV so your pressure should be 1.8 or so as CCP and in the 3.4 to 3.8 range from the spec chart. Pull the hose as scarceller describes and whatch the pressure change.

[targa72e]

I have done some of this tuning, here was my process.
First: Make sure all 6 injectors are delivering he same amount of fuel. Use 6 cups to capture fuel and measure result in graduated cylineder . Tune/replace parts as needed (I was working with a 78 CIS fuel head which has adjustment for each injector on fuel head.

Adjust fuel pressure thru adjustable regulator: I used wide band to look a A/F ratios as I adjusted. Ended up adjusting control pressure to low end, tweeking mixture at fuel head for correct A/F. Goal was minimum resistance (control pressure) at fuel metering plate (by letting it open easy/farther) but making sure mixture was good.

Final tuning on dyno to get best A/F and ignition advance.

Remember all the factory settings are for compliant emissions not best power.

Dyno is important as butt dyno lies. Car that has good torque down low and flat torque curve will feel slower than can that has poor low end torque but steep slope to max power.

john

[racer86]

Hi All,

Firstly, sorry for the long delay in reply, I've not had a lot of time to work on the car. And now I've had a disaster....

I took the car for it's annual MOT and while I was there I used the CO meter to set the car up to 2.5% CO at Idle. It was reading 4.7% CO @ 3000rmp



Having set the car up it then started running badly and would cut out and not idle until it was warm. Then it would run fine but with a higher idle of 1200rpm. Even just stopping for petrol would see it start running badly again and hunting a lot.

Checked the plugs:



I did some more adjustments to the mixture but could not stop it hunting so I re-fitted the pressure gauges.

Cold Control Pressure: 2.4
Warm Control Pressure: 2.8

I figured while adjusting the WUR the pin had span and but the bi-metallic strip at an angle: I was right:



Despite the damage to the heater element it was fine. Phew. I've glued it and it's OK.

So I rebuilt the WUR again and tested it....

Cold Control Pressure: 0
Warm Control Pressure: 2.8

Yep, ZERO cold control pressure.

So I stripped it and rebuilt it again with a new seal in the diaphragm.

Cold Control Pressure: 0
Warm Control Pressure: 0

Yep, no pressure now. I check system pressure and it still shows 4.2 so the gauge works. when I turn it off the pressure comes up to 1.2. Bck on and it drops to ZERO



I bled the lines while the pump was running to prove there was fuel flowing
I blew out all the connections and filters when it was in bits and proved there was no blockages.

I'm at a complete loss. I have no more ideas or things I can check and change. I can pay to have it rebuilt but that will take weeks and be £300 and I'm not sure what they can do that I haven't.

HELP, I'm at t he end of my tether!

[boyt911sc]

Originally Posted by racer86

Hi All.............(editted)......................... ........................
..................


I'm at a complete loss. I have no more ideas or things I can check and change. I can pay to have it rebuilt but that will take weeks and be £300 and I'm not sure what they can do that I haven't.

HELP, I'm at t he end of my tether!

Racer86,

I was hoping you would be successful repairing your WUR-089 after all the time and effort you had put into the work. I am not a businessman and doing this to help fellow CIS owner to get their cars back on the road. I will pretend you are local (USA) and I will take care of the shipping cost.

Have you been aware of the loaner program I have for PP members? I have provided WUR’s and FD’s as far as NZ, AUS, Malaysia, and Europe over the years. Some of these countries charged exorbitant import duties that adds up to the total cost of imported parts.



We could over come some of these adversities and have the part at your doorsteps in a matter of days. Let me know if you are interested and PM me. Good luck.

Tony

[pmax]

Maybe the pin fell off.

Did you put a dab of grease on the end ?

[racer86]

Tony: Thanks for the kind offer I massively appreciate it, if I hadn't fixed the car I'd absolutely take you up!

Pmax: You reply got me thinking: "what if the bi-metallic strip was too high and consequently the diaphragm was closing the holes in the valve!" A bit of a eureca moment.

I adjusted the pin all the way in to get a reading the prove the theory: NOPE. Still ZERO.



I stripped the WUR down completely again including valve. I rebuilt just the valve and ran it on the car. My theory was I could isolate the problem component:



STILL ZERO.

This had me complete flummoxed and ready for a box of matches and a rag for the petrol tank.

I stripped the valve again, changed the O-ring, blasted everything through with carb cleaner, compressed air, shone a light through everything to prove it was clear and even blew it with my mouth (for that lovely petrol taste) to make sure even a low pressure would get through....it was CLEAN (though I was convinced it was before).

I set the pin to the original height from when I stripped it (so factory as I'm pretty sure it hadn't been opened) and carefully built the whole thing up.

There was now NOTHING that could be wrong with it so I just ran the car. it FIRED STRAIGHT UP! WAHOOO!

It's at this point it gets a murky as to what the cure was because I tapped the gauge and it came up...this might have been fluke though.

I adjusted the pressure straight away while it was cold through to hot and got the following results:

Cold running control pressure: 1.2
Warm running control pressure: 2.6 (bit outside factory @ 2.7-3.1)
With Vac/ a few revs: 3.4

Idle is a bit fast @ 1200rpm with the idle screw all the way in but the car runs fantastically. No hunting/ missing hot or cold starting issues. What a difference! If I was being hyper critical is does still feel a little on the flat side, but when you hoof it it easily smokes both rear wheels and revs cleanly to the limiter.

Plugs:



So, happy I've got a well-running car, I'll live with it and enjoy it for the summer and hopefully draw a line under the WUR misery. I've not been entirely convinced my my £70 eBay gauges all the way though this, but maybe there was a blockage either way I wanted to say a massive thank you for all the help and advice!

[pmax]

Originally Posted by racer86

Pmax: You reply got me thinking: "what if the bi-metallic strip was too high and consequently the diaphragm was closing the holes in the valve!" A bit of a eureca moment.

If I understand it correctly, and always subject to being wrong (Disclaimer for Raw and his kind !), the 0 pressure is due to the fuel pressure being drained to the tank, i.e .the diaphragm is wide open.

There was now NOTHING that could be wrong with it so I just ran the car. it FIRED STRAIGHT UP! WAHOOO!

Congrats ! These CIS systems fire up immediately when the fuel pressure is set to spec with no vacuum leaks.

[jasonlbh]

How do i get in touch with you about WURs?