Look what i got into the mail. WUR guy was not going too much into the things he found. He basically said that he configured my wur according to the "053" instead of the 063 when doing the complete refurbishment in januari (i send the page i shared here also with him) and that he now re-configured it to a "063".
After i asked him what that had to do with the WUR not warming up/getting to the required warm control pressure he replied that he also replaced the bimetallic strip even though it seemed to be functioning. So not sure what he found, only one thing i can do i: install and try another pressure test. Good news it only cost me sending it to the guy by mail. I am bit busy but probably Saturday i will know more...I will keep you posted.

 

Hi Arie,
normally the guy should at least have test the WUR before jumping to conclusions....It is good to do a complete refurbishment, but to measure is to know.
May I ask you how much the refurbishment did cost the first time ?
Hopefully your WUR is now OK because it is a really important component on the KJET system
Keep me posted.

I currently struggle with other issues that I cannot comprehend. See my recent post idle/throttle issue

 

@wopfe Fingers crossed the reading check out ok.

@GerritD Have seen your other thread. Might be time to go back to basics and go through the system one step at a time?

 

You're right @Chopperharris. I need to check the following :
- System pressure (should be within the range 5.2 - 5.8 bar)
- System Pressure relieve valve (should be free and not stuck)
- fuel flow should be at least 1130cc/30sec (with 1 pump) and at least 11V when operating the pump with engine not running
- Fuel Distributor (plunger should move freely)
- metering plate (should be straight, move freely and rest position not too high)
- vacuum (no loss of vacuum)

Important remark : any idea why the engine doesn't stumble anymore when changing the timing (more advance ) by turning ignition distributor clockwise ?
Timing was originally set to 15° before TDC @ idle with vacuum hose detached (specs are between 14° - 18°) . CO was set to 2 % (specs are between 1.5 - 2.5)
So giving more then 18° is not really correct but it helps my engine to run smoother...perhaps because rpms @ idle will rise when doing this and as I said before once I pass the 1500rpms, engine stops stumbling

 

What model / engine is yours?

 

M28.12

 

Agree! I paid 200 euro for it, so thats including checking it again Will report back when i find the time to hook it up...

 

Good luck my friend. ...hopefully your problems are all gone and the road to let the beast out is all yours :-)

 

Alright, so i did a test today.

System pressure:
Temperature outside: 13 Celcius / 56 Fahrenheit

• Systempressure = 74 psi / 5.1 bar (that is low according the figures from the Porsche manual, but ok according to the classic928 manual (that says 65-75psi).

These figures are the pressure leaks after x minutes. I think it is performing good, but of course is should check with a warm engine later.

• 10 minutes = 60 psi
• 20 minutes = 54 psi
• 30 minutes = 50 psi

Cold control pressure:
Temperature outside: 13 Celcius / 56 Fahrenheit
Cold controle pressure = 16 psi (1.1 bar) (that is low according to the manual, if you look at the figure underneathit should be about 19 psi or 1.3 bar (I did not apply vacuum):

Warm control (without engine running):
Temperature outside: 13 Celcius / 56 Fahrenheit
Warm controle pressure = 28 psi (1.9 bar) (after waiting for 15 minutes, should be (40,5 - 46,5 psi or 2.8 bar - 3.2 psi).

Warm control (with engine running):
Temperature outside: 13 Celcius / 56 Fahrenheit
Warm control after about 20 minutes: 40,5 psi

I also made a video of starting the car and letting it up warm up. Some highlights:
- Its start right up after not being started for about a month.
- It idles at around 900-1000rpm when cold.
- The pressure at "45seconds" is about 16psi and it starts to get higher.
- At 5 minutes mark i rev the engine, the pressure goes up to about 30 psi.
- At 8 minutes 50 sec, the engine start to fluctuating the revs, like its not properly set (to lean maybe).
- At 11 minutes 45 sec the fluctuating stops.
- At 12.40 i rev the car again fluctuating starts again. Untill the end you see the pressure still rising to the final 40,5 psi.
- I added an extra video what happens when the engine is "flucteating", just because i never saw that before. I did not yet tune anything just let it warm up.

My first conclusion: way better then last time, when it would shut out when warming up. Smells less too, still not completely happy with the measured numbers, looks on both cold and warm a little low. Very curious what you think!

 

That cold idle seems low to me. Mine is about 1,200-1,400 rpm and gradually drops to 800 rpm as it warms up and the AAV closes down.

 

Ok Arie that's a lot of data to handle, but :

1. first of all the rise of cold control pressure to warm control pressure goes much too slow. It should have risen from 1.1 bar to 3.4 bar within 5 minutes.
2. your warm control pressure is also too low and should be around 3.4 bar with vacuum with engine running @ idle (2.8 bar without vacuum and with engine not running). That could explain the fluctuating idle. I am not convinced about the good functioning of your WUR
3. your cold control pressure of 1.1 is OK. That explains why your cold start is good.
4. as for your System Pressure, it is too low. It should be at least 5.2 bar. Fix this one and I am almost sure that your control pressure warm will be good. Also verify flow from fuel pump, it should be 1120cc/30sec
THE FLOW, TOGETHER WITH SYSTEM PRESSURE ARE THE FIRST ONES TO CHECK.

 

@GerritD I agree! Will check my fuel delivery first. I hope today, will report back later...

 

Alright did the fuel test, did not like the procedure but managed to have a good and clear test...(i have one fuelpump btw): 1280 cc per 30 seconds. So thats fine. so conclusion after this weekend:
- System pressure is on the low side, several people mentioned that it is not a problem (including the manual from 928classic) = 74psi/5.1bar
- The amount of fuel delivered is fine for one pump (1280 cc per 30 seconds).
- WUR looks like it is not within spec. Both cold and warm pressures are too low.
Thinking about my options:
- Send my WUR guy an email with my results, very curious what he will come back with.
- ​​@GerritD i think you had a guy in Belgium that has experience in refurbishing WUR's right? I think i will send it to him for a second opinion.
- Try another wur that is known to work within specs.
I really hoped to drive this weekend Again had progress so i am fine

Cheers,

Arie

 

Hello Arie,
that's already good news about the flow. How did you measure your flow?

As for my WUR, it was overhauled by Allan who regularly is also active on the forum.
It is a French guy . Just give him a call : https://m.facebook.com/pg/la.cliniqu...jection/about/

This week I will also do some test with my car as for fuel and vacuum

 

I did it as pragmatic as i could
- Disconnected the return line from where the steel pipe connects to the flex hose. Put on an old garden hose,
- I measured exact 1120 mm in a box with water.
- I put another box next to it.
- Asked my girlfriend to jumper the fuelpump, waited for a few seconds to let the fuel started gushing out in the first box and then put in in the measured box for exactly 30 seconds.
- It was clearly above the measured 1120 line but made another stripe at the height of the fuel and then tested exactly how much fuel it was.

Easy actually only messing with that fuelline/airepump assembly i dont like, always the danger of braking something in there