924Board.org

[Gatornapper]

Chuck -

When I first got the 931 running, once warmed up, it ran like new. I drove it a couple hours - suburbs, country, no problems. Just wouldn't run till I started it multiple times.

High pressure problem did not develop until I blew out the valve stoppage.

If return were blocked, I don't think it would have run so well before I put pressure to the WUR.

Agree?

GN

[Fifty50Plus]

Sounds right but what are the pressures you get cold and hot? It should be higher pressure cold and then drop as the engine warms up and the WUR is working correctly. If the pressure never changes then I think that your fuel distributor is set for what the engine likes as a warm pressure but not rich enough for a cold start.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car

[Gatornapper]

Chuck -

Car now starts & runs fine cold - but overheats when hot. I'm guessing it's staying way too rich and not leaning out after warming up. My pressures were above 70 psi from the start and stayed there when the engine warmed up.

How the engine runs so well cold with pressure that high is beyond my understanding.

May I respectfully question your statement "higher pressure cold then drop as engine warms up"?

This is from the original factory Shop Manual:



It shows cold control pressure at 50 deg F to be 12 - 20psi, and at 95 deg. F to be 44 to 49 psi. And says Warm Control Pressure is 52 +/- 2.8 psi, engine off.


I have just rebuilt & cleaned the WUR and hope to get it in the car tomorrow.

[Fifty50Plus]

Rich engines don't run hot, lean mixtures cause temps to rise.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car

[Gatornapper]

Chuck -

Absolutely, no question. Didn't make sense to me.

On the other hand, a control pressure of 70psi would indeed lean it out and cause it to overheat.......max it is ever supposed to be is 52.......

GN

[Gatornapper]

More than 4 hours today trying to get WUR bolts in - finally got both in and boost line connected but only finger tightened the bottom one.

Just can't get my 1 1/2" 5mm x 1/4" socket allen wrench in the bottom bolt to tighten it. No room with the heater valve between the WUR and the firewall. Fingers all banged up from trying & arthritis in fingers going off the chart. Keep dropping it, spending time fishing it out.

I think connecting the fuel lines won't be that bad once I get the allen in that bottom bolt - top one will be easy.

Any tricks or suggestions for aligning the allen and getting it in the bottom bolt?
Extremely frustrating.........I know I got it in once to take the bolt out - just not able to do it again. Yes, pushing the valve away as much as possible.......

GN
_________________
'87 944 S, looks & runs like new - sold my sweet 931; '76 914 2.0 mostly restored; 2011 Porsche Cayman S in Meteor Grey, 3.4L, Softronics ECU tune 355+hp , PDK w/Sport Chrono. Got this thing for Porsche's.......

[peterld]

I feel your pain Gator, and there is no easy way.

Fortunately I haven't had that problem since 1998 when I had a small ali plate welded to the top of the inlet manifold (runner #1), then drilled and tapped two holes for new mounting for the WUR. Of course two new fuel lines had to be fabbed.

All well and good if originality is not paramount.
_________________
80/81 932/8 ROW

[Fifty50Plus]

Gator,
I fully sympathize with the digit trauma. Try loosely putting in the top bolt so that the WUR is at least in the proper up/down plane and will swing left and right to locate the bottom hole.

whoops, just reread your post and you have the top done but just can't tighten the bottom.
I sacrificed several 5 mm allen wrenches before I got the right length between the 1/4 drive socket and the bottom bolt. Very tight working space.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car

[Gatornapper]

Chuck and others -

WE DID IT! Here's what I came up with: I made a jig out of 1/4 plywood to, with a lot of force, push the heater valve as far out of the way as possible. The notch in it to slip over the coil mounting bolt so that it held the jig in place is in the center of the bright light and hard to see.

I took my 1/2" breaker bar, put an extension on it and used it to block the other hose on the passenger side of the car and push it out of the way as well.

THEN I could access the lower bolt AND get a mirror under it to see what I was doing.

VOILA! WUR mounted, bolts tightened! Many cramped muscles ratcheting the 1/4" rachet, but we got it done.

Next miracle - after much prayer - was to put the fuel bolts that go in the banjo fittings without dropping the inner washer that goes between the banjo and the WUR. SUCCESS!

Here's a pic of my jig if anyone wants to copy it - makes the impossible possible......you can see the 1/2" breaker bar on the left. A "U" notch is in the bottom to go around the heater valve pipe, and the upper notch that slipped over the coil bolt to hold it all in place.....I'll post a pic of the jig by itself later:

[Gatornapper]

I debated whether to check the CIS pressures at 3:30pm today, or to do it tomorrow. At first I thought tomorrow, but then temps are dropping a lot tonight so I went ahead - and am really glad I did.

All pressures within specs! Engine started instantly and purrrred from the first rev. At first, pressure was about 25psi. As the engine warmed, I watched the pressure very slowly rise, and stop right about 52 psi where it stabilized. I ran it long enough to see that it did not overheat.

That, of course, necessitated a good test drive!

Took the car out for 47 min. drive putting it through the paces on the twisty country roads where I live. Used all the gears. Used turbo plenty, but not too much. Engine temp stayed right around the 40% mark the whole time, and the engine is running GREAT!

After 17 years - SHE'S BACK! And I am one happy 931 owner.

One more question on the subject: there seems to be differing opinion of testing CIS pressures with engine OFF, and engine running. I think the factory manual says to test with engine OFF.

What does the 924board Brain Trust think?

GN
_________________
'87 944 S, looks & runs like new - sold my sweet 931; '76 914 2.0 mostly restored; 2011 Porsche Cayman S in Meteor Grey, 3.4L, Softronics ECU tune 355+hp , PDK w/Sport Chrono. Got this thing for Porsche's.......

[Gatornapper]

Just want to thank all of you guys for putting up with me & all my questions. Been years since I've worked on FI, and have never touched CIS before.

Down the road I want to be able to dial in the boost and put in a boost gauge, but plenty of other stuff to do before then.

Koni Sport shocks go in front first, new rotors up front. Then lotsa little details.

I'm sure I'll be testing everyone's patience again in the future.

GN
_________________
'87 944 S, looks & runs like new - sold my sweet 931; '76 914 2.0 mostly restored; 2011 Porsche Cayman S in Meteor Grey, 3.4L, Softronics ECU tune 355+hp , PDK w/Sport Chrono. Got this thing for Porsche's.......

[peterld]

Yea! How sweet.
_________________
80/81 932/8 ROW

[Gatornapper]

INDEED!!!

[Gatornapper]

As I noted in the two different CIS pressure charts, there is a significant difference in the pressures in the NA CIS and the 931 CIS. I'm sure most of you already knew this. Me? I'm still very much in "931 SCHOOL"!

But until I mapped out the different pressures on the chart for the NA 924, I didn't know how different they were.

So I took the NA chart (in black) and marked in red what the pressures are for the 931. Here you can see visually how big the differences are. Hopefully this might help someone in the future avoid setting their pressures for the NA engine in a 931:

GN


_________________
'87 944 S, looks & runs like new - sold my sweet 931; '76 914 2.0 mostly restored; 2011 Porsche Cayman S in Meteor Grey, 3.4L, Softronics ECU tune 355+hp , PDK w/Sport Chrono. Got this thing for Porsche's.......

[924RACR]

Awesome, well done.

Persistence is the only way to make these cars work properly.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype