Idle speed causing rough running
Discussion
I've been learning to balance the throttle pots recently, and after a fair bit of patience, I'm really happy with how they are now set. The software shows the throttle bodies are now as closely matched as they ever have been.
After setting the idle speed to around 950rpm, I fitted the air box and realised that the idle speed had dropped with the reduced air flow.
Not being able to remove the bonnet by myself, my next opportunity was a 5 minute window a couple of days later just before a long journey. After quickly adjusting the idle to around 800rpm (whilst cold), resetting the adaptives and throttle, chucking the bonnet back on and setting off in bit of a hurry, I realised the engine had quite a vibration at the idle speed I set. Almost like I'd managed to set the perfect revs to cause the engine to resonate. Also, an AFR fault on the first 3 cylinders lights up immediately and adaptives are really high, again, just on the first 3 cylinders. The other 3 are fine.
Can adjusting the idle really cause such a change in fuelling? Especially such a difference between the two banks of cylinders. From everything I've read I thought you could set the idle to anything you like, as long as the adaptives and throttle are reset.
Whilst I'll have another another go with the syncrometer to make sure all is still balanced, the ecu readings for the throttle pots read really close. And with the air box off when I balanced the throttles, the idle was really good and no AFR faults lit up at all.
After setting the idle speed to around 950rpm, I fitted the air box and realised that the idle speed had dropped with the reduced air flow.
Not being able to remove the bonnet by myself, my next opportunity was a 5 minute window a couple of days later just before a long journey. After quickly adjusting the idle to around 800rpm (whilst cold), resetting the adaptives and throttle, chucking the bonnet back on and setting off in bit of a hurry, I realised the engine had quite a vibration at the idle speed I set. Almost like I'd managed to set the perfect revs to cause the engine to resonate. Also, an AFR fault on the first 3 cylinders lights up immediately and adaptives are really high, again, just on the first 3 cylinders. The other 3 are fine.
Can adjusting the idle really cause such a change in fuelling? Especially such a difference between the two banks of cylinders. From everything I've read I thought you could set the idle to anything you like, as long as the adaptives and throttle are reset.
Whilst I'll have another another go with the syncrometer to make sure all is still balanced, the ecu readings for the throttle pots read really close. And with the air box off when I balanced the throttles, the idle was really good and no AFR faults lit up at all.
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