Crate LS3 with ASA cam - idle high and revs hang
03-30-2018, 12:23 PM
#1
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Crate LS3 with ASA cam - idle high and revs hang Guys,
I have just fitted a crate LS3 into a Porsche 996. I swapped the stock 430hp cam for an ASA cam. I have used the GM wiring harness and ECU that is pre-tuned for the LS3 525 hp.
I am having issues - my tickover is 1000rpm, and the Revs hang when driving, i.e if you change gear at 3000rpm and push the clutch in and let off the gas the rpm takes ages to drop.
Lots of people have advised its a vacuum leak - I cannot find one. As the motor is new I am struggling, and thinking it may be the tune the ECU came with.
Any advice please?
Note: i'm good with mechanical stuff and fabrication, but struggling with this modern electronic tuning.
Mark from the UK.
I have just fitted a crate LS3 into a Porsche 996. I swapped the stock 430hp cam for an ASA cam. I have used the GM wiring harness and ECU that is pre-tuned for the LS3 525 hp.
I am having issues - my tickover is 1000rpm, and the Revs hang when driving, i.e if you change gear at 3000rpm and push the clutch in and let off the gas the rpm takes ages to drop.
Lots of people have advised its a vacuum leak - I cannot find one. As the motor is new I am struggling, and thinking it may be the tune the ECU came with.
Any advice please?
Note: i'm good with mechanical stuff and fabrication, but struggling with this modern electronic tuning.
Mark from the UK.
04-07-2018, 03:56 PM
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mark,
I'm assuming this has a cable throttle body fitted?
if so you need to be sure that at idle without touching the accelerator the throttle position reads 0%. you can verify this with any basic OBD2 handheld scanner/code reader.
if it says anything greater that 0.8% the car will never idle properly.
The ECU also needs a speed signal input to operate how most "mail order" tunes are set up
I'm assuming this has a cable throttle body fitted?
if so you need to be sure that at idle without touching the accelerator the throttle position reads 0%. you can verify this with any basic OBD2 handheld scanner/code reader.
if it says anything greater that 0.8% the car will never idle properly.
The ECU also needs a speed signal input to operate how most "mail order" tunes are set up
04-07-2018, 04:15 PM
#4
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mark,
I'm assuming this has a cable throttle body fitted?
if so you need to be sure that at idle without touching the accelerator the throttle position reads 0%. you can verify this with any basic OBD2 handheld scanner/code reader.
if it says anything greater that 0.8% the car will never idle properly.
The ECU also needs a speed signal input to operate how most "mail order" tunes are set up
I'm assuming this has a cable throttle body fitted?
if so you need to be sure that at idle without touching the accelerator the throttle position reads 0%. you can verify this with any basic OBD2 handheld scanner/code reader.
if it says anything greater that 0.8% the car will never idle properly.
The ECU also needs a speed signal input to operate how most "mail order" tunes are set up
Andrew
04-10-2018, 02:35 PM
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The car is at a local Porsche independent dealer for a few bits and bobs and I have asked him to smoke test it so I can 100% eliminate that from my investigation.
HTH.
Mark.