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Brockoli · Posted: Fri Apr 13, 2007 10:52 am Post subject: No power to CSV or AAV

i am new to the board and have many questions. Any help will be greatly appreciated. I need to get this car running, ive looked at it in the drive way for way too long.

My '77 924 does not run yet. I have checked the injectors, they are spraying good. I have good spark, no air leaks that i could find. Havent checked my timing (Should this be done first or when all components are working properly). So i started to check the CSV.

Question 1: When I took it out of the manifold it had quite a bit of oil on the nozzle. Is this normal/bad?

With the cars key is in the on position( but not cranked over) I attached the CSV to the battery with wire. But it did not spray. So i checked the tech section and it said to check the resistance of the CSV. I used an ohms meter and bridged the two prongs on the CSV but a got a reading of zero.

So i pulled the CSV out of my '79 924 and checked it the same way, with the same end result.

Question 2: Did I check the resistance properly?

Question 3: If the reading is zero ohms does that mean it is broken? Or is this the correct amount of resistance (I think it is broken)?

While I was working on the '77 i checked the connection for the power to the CSV with a voltmeter. So i bridged the female recievers in the plug with the voltmeter and got a reading of 0V. I then checked the power to the AAV the same way, and got the same reading of zero volts.

I do not have a fuel pump relay, the fuse box is jumped the way the Hanyes manual described.

I am also not getting power to my fuel pump. I have to attach a 12V battery charger to the terminals and have to manually turn the pump on/off by plugging the battery charger to an outlet.

Question 4: If the fuse box is jumped for the fuel pump will i get power to my CSV+AAV? What are the other prongs on the fuel pump relay for?

Hopefully i explained everything enough.
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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)

leadfoot · Posted: Fri Apr 13, 2007 11:51 am Post subject:

1. Should be fairly clean apart from some light fuel/oil covering, the EGR recirculation will return a bit of this stuff over time and it will eventually settle in the manifold, 20 years of this happening will leave a bit of this crud around the tighter pockets in the manifold.
2. To test the CSV, Assume one side of the csv is the 12+ connection and the other side is the ground connection. Remove the electrical connector by pushing in the release bar and pull off the connector leaving the bare terminals of the csv showing.
Put your ohmeter red prong to the 12+ csv connector and the black prong to the other prong. If your reading is still 0 ohms then the csv is faulty.
3. IIRC the AAV gets power in the on setting with the key position, the CSV only gets grounded though when the car is cranked over. I think you can still test power by grounding the csv to another suitable point.
Leadfoot
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Brockoli · Posted: Fri Apr 13, 2007 12:13 pm Post subject:

That makes sense. CSV definetly fried. but why am i not getting power to my AAV+fuel pump?
_________________
'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)

Smoothie · Posted: Fri Apr 13, 2007 2:26 pm Post subject: Re: No power to CSV or AAV

Ozzie · Posted: Fri Apr 13, 2007 9:34 pm Post subject:

The CSV, AAV and fuel pump only get power when cranking or the engine is running unless you bypass the fuel pump relay with a jumper wire.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Brockoli · Posted: Sat Apr 14, 2007 11:22 am Post subject:

Smoothie - In the FAQ it says that it should be something like 5-10ohms. I also could not find it in the Haynes manual.

I am thinkin that there is a wiring problem somewhere. Do you have any suggestions on where wires may rub a lot of tend to break due to sharp bends in the wire. Any help would be great. I will probably go through everything but a place to start is nice.

Thanks everyone
_________________
'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)

Smoothie · Posted: Sat Apr 14, 2007 8:25 pm Post subject:

Look at Haynes pg. 252 - the CSV "N17" and TTS (thermo-time switch) "F26" are on current tracks 11-12 near the middle of the page. You can see there that the CSV grounds through the TTS, so a problem with the TTS or its' ground would cause the CSV to not operate. Above the TTS and CSV you see a connector "T7a". Pg. 251 shows connector T7a is a 7-pole (7-pin) connector in the engine compartment - "" indicates pin 3 of the connector. It also shows that items on current tracks 12, 15, 17 use connector T7a - on 15, 17 are the airflow sensor switch and WUR+AAV. Following the bk/re wire up above the TTS+CSV you see it meets a point labelled "C10" - that and everything horizontally across from it are pins on the back of the fuse-relay board. "C10" indicates pin 10 of connector C. Pg. 237 shows C is the white connector, 3rd from the right when looking at the back of the fuse-relay board. Check it, its' slot on the fuse-relay board, and the T7a connector for burnt/oxidized pins and broken wires.

To test the TTS, use a test light or voltmeter on the CSV wiring connector - you should get a reading when the engine is cold when you turn the ignition switch to start (the TTS has a built-in heater that limits its' operation to a maximum of roughly 10 seconds, so you have to be within that initial ~10 seconds + have the key held in the start position to get voltage to the CSV).
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Johann · Joined: 07 Aug 2016 Posts: 240 Location: Netherlands

Reviving an old thread...

Today I realised that my AAV was not closing when installed in the car. I knew it worked because it was tested in the K-jet guru's lab last week and he confirmed its functioning. I then tested the plug and I got no reading, 0V. That was very discouraging

Diagnosing electrics gives me the creeps and it not my strong suit. But since no one in my area understands these cars I have no choice other than figuring it out myself.

So of to Google I went. After some searching on this site, other 924 sources, and reading the Haynes manual I found the cause

Thanks to Smoothie's post I located T7a right behind the coil. It was chock full of dirt and grime and the two halves weren't fully clicked together. I cleaned it out with contact cleaner reinstalled the plug and Viola! I now have 12v going to the AAV and WUR.

One more problem solved