924Board.org

[Brockoli]

Got the original engine back into the '80 for the remainder of the season. But its not running great. At part throttle cruising it is surging quite a bit. I installed a wide band O2 sensor so the wiring harness that goes onto the original O2 sensor is unplugged. Here is a list of new parts:

NEW:
CSV
AAV
WUR
TTS
fuel pump
fuel filter
air filter
spark plugs NGK
plug wires
cap and rotor

I have also installed a euro distributor and set the timing to 10deg BTDC with vacuum lines disconnected (and plugged while setting the timing).

I have set my idle AFR to 14.7 and during part throttle crusing it surges and AFR goes as high as 15-16. So I increased my idle mixture to 13.8-14.0 and it surges less but still isnt right.

I adjusted the micro switches on the TB so that the first one "clicks" once you give it a very small amount of throttle and the second one "clicks" once the second butterfly valve opens. During WOT I get an AFR of 12ish and the car pulls good.

I have checked for air leaks, bad grounds on the battery, loose ignition wires.

Here are my questions:

1) Whats the proper AFR for a Lambda system? At idle? Part throttle cruising? WOT? I can find general settings but does anyone know what this system runs stock?

2) Could the euro distributor be causing the problem?

3) Is this caused by not having the lambda sensor plugged in and therefore the frequency valve isnt doing its job to change enrichment?

Need some help as I have an auto-x saturday....tick tock....and its coming up fast
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'80 924 M471,Wideband O2, Full coilover susp,23/19 sways,Bilstiens,KLA Strut Brace,Roll Bar,Test Pipe,BBS RS, Willwood BBK

25% of a '87 944 Chumpcar http://straightpipe.ca/forums/showthread.php?t=2454

'79 924 Sebring Edition(Sitting)

[Brockoli]

put a different rotor in and I realized that the coolant line at the back of the head with the vacuum and electrical switches (close to the WUR) didnt have the electrical switch. With the engine swaps I must have switched this coolant line to one with only the vacuum switch (2 vacuum lines going to some switch like thing on the coolant line). I checked the electrical switch and decided to jump it with a small wire. Car runs much better.

ANyone have any clue what this electrical switch on the coolant line does?
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'80 924 M471,Wideband O2, Full coilover susp,23/19 sways,Bilstiens,KLA Strut Brace,Roll Bar,Test Pipe,BBS RS, Willwood BBK

25% of a '87 944 Chumpcar http://straightpipe.ca/forums/showthread.php?t=2454

'79 924 Sebring Edition(Sitting)

[Ozzie]

There is a thermo switch for the supplementary start valve on some models.
the valve is on the dissy and drops control pressure to richen the mix.
design was to purge fuel lines to assist hot start.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance