Revving freely at last!

After an enormously frustrating time trying resolve why the engine wouldn't rev above 1600rpm - the problem is now sorted!

After testing just about everything I could test this weekend has proven to be a breakthrough one. Some suggestions from forum members on tipec helped chase the problem down to something to do with the throttle position sensor.

Along the way I tested the fuel pressure which turned out to be good, as did various other sensors.

Although multimeter tests on the TPS proved it was healthy, the same readings were not being translated through to the DME connector end of the wiring loom. I realised that much earlier in the project cycle I had to extend the length of the wiring for the TPS in order to fit the S2 intake and throttle body.

Pulling the loom out from under the intake I could check the wiring and it was clear that it was a little more elastic than it should've been - and sure enough the connectors had come adrift essentially isolating the TPS from the DME. Which I'm presuming prevented the ECU from switching from the idle map to open throttle mapping and limiting the rpm to 1600.

With a quick rebuild of the TPS wiring extension and checking with the multimeter all the way the issue was resolved and the engine now revs freely!

However, all the testing did reveal that injector #4 isn't working properly and will need replacing as my attempts to fix it have not been successful. Using a 9v battery wired up to the injector brought no response and it did not "tick" like the other three.

With that injector fixed the engine will run even better!

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Living with a Porsche 944

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