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YOUR RESEARCHFuel gauge/level after cluster swap
Leading reported evidence
Check fuel filler neck and the relay clicks
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Performed · outcome unconfirmed · Original poster
I've checked the fuel filler neck and the relay clicks when I put my finger in.
Leading evidence: 'Check fuel filler neck and the relay clicks' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check /try, i'd love' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Run low again pretty quickly and only took 8.26 gallons
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Performed · outcome unconfirmed · Original poster
Level ran low again pretty quickly and only took 8.26 gallons to fill up.
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Performed · outcome unconfirmed · Original poster
Base on my OBC, I've done 107.3 miles and averaging 17.3 mpg, so that means I've used approximately 6.2 gallons.
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Suggestion · Original poster
If anyone has any other ideas to check/try, I'd love to hear them.
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Suggestion · Original poster
running fuel level low, disconnecting battery, then filling worked like a champ.
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The LOW FUEL light came on so naturally I assumed the fuel tank was empty. Didn't take much fuel at all to fill up but I figured the tank was a bit confused from the cluster swap and would sort itself out.
Level ran low again pretty quickly and only took 8.26 gallons to fill up. OK, weird but maybe it just needed a reset of sorts. And now after 90 miles, the gauge is down to 2/4. So clearly something isn't right. I drove it per the onboard monitor readiness reset sequence twice so been driving pretty easy. On board computer is saying 16.8 mpg which I have no way to verify so means nothing at the moment.
Part of the manual transmission swap was having to put a manual cluster in. The "new" cluster is from a 996.2 C4. My car is a C4S so the only difference should be a slightly smaller gas tank in the C4S, thus a small percentage of error over the range. Only thing done to the replacement cluster is a mileage correction by a shop recommended on here.
Car gets its annual state inspection tomorrow so I'll ask if they have any insight. There are no CEL's, no stored/pending codes, and my scanner shows that all of the on board monitor readiness tests have completed.
I've checked the fuel filler neck and the relay clicks when I put my finger in. The fuel tank in my e30 has a saddle tank over the driveshaft with a crossover tube, does the AWD tank in our 996's have one as well? Maybe that's clogged? .
Cluster is coded to US but I may try the ROW setting to see if it changes anything. I'll also fill the car up and pop the fuel tank cover off to visually inspect the level. And again when the fuel light comes on. If anyone has any other ideas to check/try, I'd love to hear them.
I'd like to put this car into the daily rotation but kinda want to sort this quirk out. Cheers!
The C4s/Turbo use a gas tank that has two huge pods that stick down and back from the main tank and hold about 1/2 the total fuel. There are two jet pumps, one in each pod, that suck the fuel out of the pods and dump it into the main fuel pump. The fuel lever sensor can only read fuel level in the main tank. Below about 1/2 tank the gauge reading is an estimate (guess) based on fuel consumption.
I believe the C4 is the same as the C4S? They share the same front end components.
I recall there was a fuel gauge reset procedure in the turbo service manual. I just looked for it and I can't find it. Perhaps I am not remembering correctly. I seem to remember that it was something like run the tank down very low, less than 1/2, preferably much less than 1/2. Disconnect the battery to clear the calibration in the cluster. Refuel to full.
Cheers for that bit of information, helped broaden my search results AND sounds an awful lot like the procedure below since 28L equals 7.4 gallons - 44% full.
Base on my OBC, I've done 107.3 miles and averaging 17.3 mpg, so that means I've used approximately 6.2 gallons. So based on those calcs, if I drive ~57 more miles, I should be awfully close to the 28L mark.
Soo......I'll break out my PIWIS, perform the fuel tank recalibration step, and report back.
Calibrating fuel level sensor system
Note:
Calibration is necessary after replacement of the fuel tank, fuel level sensor or instrument cluster.
The fuel level sensor system need not be calibrated if the battery was disconnected or a plug connection on the instrument cluster or fuel level sensor was removed. The values remain stored in the instrument cluster.
A range on remaining fuel of less than 15 km is not displayed in the instrument cluster.
1. Disconnect the battery and cover terminal or battery.2. Remove cap over the fuel level sensor system.3. Remove fuel level sensor.4. Using a fuel extractor, completely drain the fuel tank through the fuel level sensor opening.5.
Make sure that the two recesses on the left and right−hand sides of the tank are emptied completely.
6. Reinstall the fuel level sensor and, with "ignition off", fill the tank with
28 liters
of fuel.7. Perform tank calibration with the Porsche System Tester 2:
Select vehicle type (911 Carrera)
Select control modules
Select instrument cluster
Select menu item "Tank calibration"
Confirm calibration
8. The fuel level sensor system has now been calibrated.
No. I did some fancy math based on the average mpg, trip odometer and a smidge of wishful thinking. Seem like I'll be getting around 350 from this tank. I'm DD'ing the car to verify.
Cheers, hope you got through your tank and recalibrated. Any news on this reset? I tried it and end up with 100 to 140 miles reserve when the empty light comes on. Is that what it should be? Maybe that's more than I need...
