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Quote:
Originally Posted by mark houghton View Post
What's a vacuum driven WUR? Yeah, there's a "vacuum line" attached to it, but it has nothing to do with vacuum and everything to do with transmitting a boost signal to the WUR to enrichen during boost.
Am I missing some cool mod here or is it just my narrow minded 930 view of things?
This is a naturally aspirated motor, the WUR only senses vac. Your 930 WUR has a pressure (Boost) one side vac the other (off boost). Everything is cool with N.A. (vac only) WURs up to the point manifold pressure changes to positive.

I protect the WUR vac line with a check valve. This makes the WUR see Boost as the same as full throttle. Problem is the system runs out of additional fuel and goes lean over 5000rpm without supplemental fuel being added. I use a 7th injector with split second controller and program in additional fuel.

I experimented with 930 WURs (pressure/vac) and they did not work on my smaller motor. One may be the answer to this 3.0L conversion however N.A. conversions have been done for years and all that I know of have used supplemental fueling.

The delay problem sounds like an exhaust leak - (flange alignments/gaskets) or

A lazy wastegate - the W/G having a low pressure spring desired for low boost may not be strong enough to hold the valve seated against the exhaust pressure. Pulsation can blow it off the seat early. I would lock down the W/G (disconnect and run the adjustment screw in) and do a road test using the boost gage to see it this is an issue. Controlling to low manifold boost pressure is often more difficult than controlling to a high pressure.
Old 09-03-2011, 08:10 AM
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How can k do this test, I have dual tial msv wastegates. I too have thought about this and wondered if they opened early.
I don't think there is an exhaust leak but could be wrong.


I will try the vac advance first when I get back into town and then will try the rest.
Old 09-03-2011, 09:25 AM
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And there is a 930 wur on there
Old 09-03-2011, 09:27 AM
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Get a boost gauge and report back.
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Old 09-04-2011, 06:29 PM
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Quote:
Originally Posted by copbait73 View Post
This is a naturally aspirated motor, the WUR only senses vac. Your 930 WUR has a pressure (Boost) one side vac the other (off boost). Everything is cool with N.A. (vac only) WURs up to the point manifold pressure changes to positive.
Sorry, still confused. The original poster JCC911 was talking about a boosted motor...that is not nornally aspirated in my book. Plus, 930 WUR's have only a single hose connected to them. All it does is sense the boost signal to enrichen. Engine vacuum has no impact on the WUR to adjust fueling as far as I know...but then I don't know all is to be known!

Again, my narrow minded 930 view, not knowing squat about a NA 911.
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Old 09-04-2011, 08:08 PM
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Gauge is on it's way.
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Jeremy C.
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Old 09-04-2011, 08:37 PM
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Mark:
Jeremy's engine is much like mine. Was an N/A engine. Jeremy fitted a 930 intake setup. I went with the stock SC setup and an old BAE kit. I knew nothing of 930 hardware when I did mine, analagous to the narrow minded 930 view!

The 911 WUR has a single vacuum line. The 930 has a boost line. Principally, the same sort of action on the diaphram. I realized the 911 WUR was not worikng out well, so I went with a Brian Leask 930 WUR. The 911 internals are almost the same, but the 911 has a much highr static CR of either 8.5 or 9.5 to 1. And SC cams. Also, the 930 distributor has both vacuum and boost retard mechanisms, where the SC distributor is simply vacuum. My SC distributor is set up for 27 deg total advance, probably the same as Jeremy's. I have an MSD Boost Timing Master, which is coming out in favor of a J & S Safeguard unit.

Now, as with any engine, what the bottom line is is "how much charge can I pack into the cylinder just prior to combustion?" The turbo is certainly going to allow much more charge than an N/A engine. However, the many variables which go into the charge density are vastly different in both engines. Valve timing events and CR both effect dynamic CR. Exhaust system flow and and leakage will also effect the charge. And, turbo sizing aslo has a big effect. A good discussion of the small vs. large turbo is in Bell's book(I think it's Bell's), along with the Porsche vs ricer sizing from the factory.

That said, 3800 is awfully late. My old Rajay was making positive pressure at about 2400, and the full 6 PSI was in shortly after. My new Borg Warner is making boost almost the minute I get a load on it, and keeps pulling up past 6K RPM.

The two essential onboard diagnostics are the boost gauge, and the AFR meter. These two instruments will greatly aid in the troubleshooting. Jeremy, when you get the boost gauge, you will get a much better ide of what is going on. I have learned it is important to isolate one variable at a time when troubleshooting this. There is no such thing as "bolt on".

Pat
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Old 09-05-2011, 07:10 AM
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Thanks Pat.
OK Took the car for a beat run to check the AFRs and here is what I found.
First note was when I pulled the 02 bung plug, the face of it was black, am I too rich, I wondered?

I have set the timing to 28 advance at 4500 with the vac line off. (as suggested by Aaron at RW).

Vac Advance Disconnected
Idle was ~1100 12.0
Fourth gear cruising 2600 13.7
5th Gear 2200 13.7
Pedal to the floor, AFRs slowly drop till boost
WOT 10.0-10.6 on boost

Advance Connected
RPMs immediately increased, so I turned down the idle.
Idle ~1050 11.5
4th gear 2600 13.6
3rd gear 3200 14.0
WOT in boost drops to 10.0-10.6

I did not notice any significant difference with the line connected or not. Boost is still late.
AFRs never went past 15, unless I would accelerate then quickly push in the clucth then would briefly see 15.2-15.7.

No idea why the boost doesnt seem to come on til well past 3000.

Will update when the gauge is in.
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-2008 550i M-Sport
Old 09-05-2011, 08:18 AM
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Quote:
Originally Posted by patkeefe View Post
Mark:

The two essential onboard diagnostics are the boost gauge, and the AFR meter. These two instruments will greatly aid in the troubleshooting. Jeremy, when you get the boost gauge, you will get a much better ide of what is going on. I have learned it is important to isolate one variable at a time when troubleshooting this. There is no such thing as "bolt on".

Pat
This is completely true.

Without correct tools , it is impossible to make correct diagnosis and to have correct conclusion.

As it is impossible to keep an eye on it while driving , I would even add a datalloger with these 2 gauges in order to make records for correct analysis and comparison.

That beeing said, when the turbo start to spool, a too low ignition advance combined with too much fuel can lead near to engine stalling.
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Old 09-05-2011, 08:21 AM
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Quote:
Originally Posted by jcc911 View Post


WOT 10.0-10.6 on boost
This is too much fuel !

It should not be lower than 11.8 (even more if flow matched injectors)
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Old 09-05-2011, 08:33 AM
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Jeremy, do you have a 930 WUR? If so, the 930 guys can let you know what the fueling characteristics of it are. If you have an SC WUR, ditch it, as it will never work right. Sounds like you have a 930 WUR.

Thierry, I had an IA modded SC head, which ran pig rich at the track, so at WOT I was seeing <10 AFR's at times. I agree that high 11's is good. I have found that my WUR was VERY ambient air sensitive. I don't think this is a big problem on the street, but it was always fussy at the track. I now run stock late model SC fuel head, whichh is a bit lean, but I can tweak the lean to a manageable level with the WUR.

I put in a control pressure gauge. Invaluable!

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Old 09-05-2011, 09:03 AM
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the best thing to do is have somebody ride along with you and take video of the gauges. That is your home made datalogging. You might be surprised how far off you are.
Old 09-05-2011, 09:09 AM
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..Just a quick note to ensure nobody has overlooked the obvious - but, when you're car starts, the AFR would be around 10.0-10.8 (with the 'autochoke').

Give it a minute or two and the AFR at idle should be around 13.5->14.0
Old 09-05-2011, 10:55 AM
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My wife was data logging as I drove.
Yes it is a 930 Wur.
So if the 10s is too rich on boost how do I adjust? If I adjust the hex screw i am worried about being too lean.

So I should lean it out to the upper 13s idle?
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Last edited by jcc911; 09-05-2011 at 12:49 PM..
Old 09-05-2011, 12:45 PM
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Quote:
Originally Posted by jcc911 View Post
My wife was data logging as I drove.
Yes it is a 930 Wur.
So if the 10s is too rich on boost how do I adjust? If I adjust the hex screw i am worried about being too lean.

So I should lean it out to the upper 13s idle?
On C2T and on 930 with lambda regulation, the AFR at idle and low load is regulated near 14.2 -14.5 ( average).....not saying it provides the best feeling &behaviour at idle but it works.

13 at idle is correct. (especially with stock cams or close)

That being said, not sure it will correct the fat mid under boost but that's easy to check.

Have you check your "on boost" timing on FW with light gun and a pressure adapter ?
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Old 09-05-2011, 01:16 PM
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No, How I check on boost timing?
Thanks
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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport
Old 09-05-2011, 02:32 PM
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Just removed the LM2 sensor, do you think I am running a little rich?

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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport
Old 09-06-2011, 03:36 PM
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Wow that sensor is almost as big as the transmission... sorry for the abnormally large photo
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Jeremy C.
Why's he calling me meat? I'm the one driving a Porsche. (Bull Durham)
----Nothing is far away in this car!----
-1978 911 SC TURBO, Minerva Blue Targa 965 update.
-2008 550i M-Sport
Old 09-06-2011, 03:38 PM
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it is running rich "overall". But that doesn't mean it's rich when at WOT, thats why an A/F meter with datalogging is crucial
Old 09-06-2011, 04:02 PM
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boost check

Quote:
Originally Posted by jcc911 View Post
No, How I check on boost timing?
Thanks
Jeremy:
I am assuming you are speaking of boost enrichment onset. If you have an SC ignition distributor, you can't change anything other than static timing. You need to get a pressurization device, like a mighty-vac. I have a mighty vac with a vacuum and pressure gauge setup. you pump some positive pressure into your wur, and watch to see what the control pressure does. Of course, you need to have a CIS pressure tester on the system concurrently. At least that's how I check mine. So, whatever WUR you have, there will be a spec for when it starts boost enrichment at what pressure. I start enrichment at 4 PSI, I believe.

Maybe one of the 930 guys will chime in here. I have a Leask WUR, and it has adjustability the stock ones don't have.
Pat
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Old 09-06-2011, 05:20 PM
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