Metal Guru

You have to PRESSURIZE the wur to read the boost enrichment. Buy a Mityvac pressure/vacuum pump model MV8510.
Then buy a manual please.

Metal Guru

Hmmm, when my car was running too rich it ran like ****. The OP's values are, IMO, a significant deviation from factory spec and need to be addressed.
Running out-of-spec rich is as dangerous as running lean and has three problems; (1) fuel economy is lousy (2) performance is lousy (3) good possibility you're diluting the oil and possibly washing oil from the cylinder bores.
I'm in favor of fixing problems when I find them; especially when they could cost me a lot of money down the road.
Still, we need an answer also on un-metered air entering the intake. A lack of idle speed adjustability is sure-fire way to diagnose it.
I had to troubleshoot this very issue. Couldn't adjust the idle speed. The other thing that comes up with this kind of problem is the following: when the engine is running at low load, it's pulling a vacuum and sucking un-metered air in through the breach and leaning the mixture. Under boost, it pushing air out through the same breach and running rich. I could never hit my afr targets and the car didn't run very good.
Had an Indie (independant) wrench smoke the intake. No joy. That didn't rule out a cracked injector block as they are notorious for deteriorating. Eventually I replaced them all with new and port matched them to steal a little extra torque from the factory. If the OP has a cracked injector block, cranking harder on it has the potential of making it worse.

fritz k.

We are not far apart at all, the WUR should be within specification and deviations up or down are not good. But I drive my car with slightly higher boost pressure and there fits more to rich tending mixture with lambda 0.85 -0.9 very well.

I was referring to the problems of the colleague from UK and I still don't think they are caused by the WUR. But anyway, he should it get fixed and maybe i'm wrong.

You'll find not only cracks in the intake flanges, but the studs in the cylinder head are coming loose. If this is the case, the car will not run even with a top WUR.

911 2

it drives fine, just the first few mins of idle
looking at my pressures what exactly is happening, when the cold pressure value drops below spec is it causing a rich idle thus the low/stalling idle.
to do the intake studs does the engine have to be removed
I have emailed Barry, I was thinking of a bigger turbo later so was looking at the adjustable wur, currently there is a 1 bar spring, if I stay with just this then should i stay with stock wur

Metal Guru

The upper value of the boost tolerance band that Porsche quoted was a tiny bit above .9 bar. I ran strictly stock cold, warm and boost control pressures when my engine was stock and I was right in the afr box, so IMO deviation from those values really isn't necessary.
I've actually never heard of anyone on Rennlist have broken head studs but that's admittedly a small sample size. It was definitely a big problem on 911SCs and 930's. If you have one chances are you will feel it and hear it.

Metal Guru

Please confirm that you can adjust your idle so we can eliminate un-metered air as an issue.
I think you are too rich at cold start-up, which is causing your issue, as well as across the board.

911 2

Thanks, I will have a look after i have put the intercooler back on and started her up.

fritz k.

This is also my experience but I was talking about the studs in the cylinder head not those in the crankcase. And they don't break but they loosen which leads to the loose nuts on the intake manifold.

Metal Guru

Intake studs. Got it.

911 2

I have rebuilt the wur and checked the fuel pressures before starting and my control cold pressure is still lower than what is should be according to the manual, the remaining pressures are still the same well may have increased by a psi form before the build

System pressure 92psi was 91 psi before rebuild

Cold control pressure 22psi, goes to 25 psi when pump switched off, this is at 12.7c when infra red thermometer pointed at the WUR, manual states, at this temp, the cold control pressure should be 36psi, so 14psi down.
Before the rebuild, cold control pressure was 34 psi at 27.5c, should have been around 47psi, roughly 13psi down

So the control pressure is down

Control pressure with the heater activated in the WUR is 58psi, same as before the rebuild, manual states it should be 65psi, so still 7 psi down

Control pressure drop within 10mins was 29psi and, manual min drop is 23psi
Control pressure drop after 20 mins was 25psi and manual min drop is 20psi
I think this has improved

Any idea please what is causing the control pressures, cold and warm, to be lower than what the manual states and the effects this will have on the running of the car, how can i increase the control pressure so it is in spec

Scott Dunavant

I have not followed all your posts.
There's a spring pressure plate in the fuel accumulator, I'm not sure how that regulates pressures back there?
I cut mine open after mine was not running for 22 years.
Did you have your fuel head rebuilt?

911 2

accumulator is new, it had failed, symptoms car would not start at all.
Rebuilt the WUR, the systme pressures and cold start pressure is in spec, the warm control pressure is approx 6 psi below spec, not sure if this should be measured with just the heater activated in the WUR or whether I need to get the car upto temp as the WUR also is influenced by engine heat soak.
Car ran well apart from the occasional stalling, when coming to a stop, this would happen when the car was warm, I would have to wait approx 30 secs after which it would fire straight up, driving through the rev ramge and boost was fine
Havent had the FD rebuilt but will be next

Scott Dunavant

Take a look at all the functions of the EZ 69 and the control units under the driver’s seat.
So many functions. I opened mine up and saw some corrosion and moisture shorts.
I replaced one of the units.
Not the EZ 69. I got lucky.