The engine knocks under acceleration with scan tool connected
Thread Starter
Pro
Joined: Mar 1999
Posts: 678
Likes: 0
From: Oslo, Norway
The engine knocks under acceleration with scan tool connected
Hi.
I have an 85 4+3 z-51 with light modified engine. more progressive cam and CR 9.5:1. larger intake but still the cast iron heads slightly ported.
I have the scan tool (Winaldl)connected and the engine knocks much when accelerating.
It s said that the tool have disengaged the ignition regulating for knocks.
If it is so is it normal that the engine should knock with little acceleration with the knock regulation og the ignition disengaged?
Do I have to adjust the ignition?
The engine does not knock with scan tool disconnected even under hard acceleration.
Would appreciate some comments please
I have an 85 4+3 z-51 with light modified engine. more progressive cam and CR 9.5:1. larger intake but still the cast iron heads slightly ported.
I have the scan tool (Winaldl)connected and the engine knocks much when accelerating.
It s said that the tool have disengaged the ignition regulating for knocks.
If it is so is it normal that the engine should knock with little acceleration with the knock regulation og the ignition disengaged?
Do I have to adjust the ignition?
The engine does not knock with scan tool disconnected even under hard acceleration.
Would appreciate some comments please
Burning Brakes
Joined: Apr 2004
Posts: 762
Likes: 2
From: Huntington ma
This is normal. Two things happen here: 1. There is timing advance added when the ECM is in Diagnostic mode. The Amount added is a setting that can be edited in the PROM program (I have Mine set to Zero..). 2: In diagnostic mode the ECM sees the knock sensor, but does NOT retard the timing advance based on the input. I Believe that this is a true statement - but have not been able to confirm it.
This is why there are warnings in place to NOT drive the vehicle when in diagnostic mode (with a scan tool connected and reading data) - no detonation control is functioning.
This is why there are warnings in place to NOT drive the vehicle when in diagnostic mode (with a scan tool connected and reading data) - no detonation control is functioning.
Thread Starter
Pro
Joined: Mar 1999
Posts: 678
Likes: 0
From: Oslo, Norway
hi. Thanks for the answer.
What I am interested in with my scanning tool is to see the BLM and INT value at different loads and especially when going near full throttle as there the ECM is not taking other than the TPS reading into account to give the duty cycle for the injectors. If I have a lean engine with full throttle thats not good either. It looks like my tuning is quite good now with a 128 +/- 4 on both BLM and INT. I was a little on the rich side at 112 before and after rinsing the MAF with MAF cleaner it all came to normal. The reason for this was most probably that I rinsed the K&N filter and reoiled it maybe too much so that there was too much oil vapour and the MAF burnoff could not cope with the oilresidue good enough.
Thanks again
What I am interested in with my scanning tool is to see the BLM and INT value at different loads and especially when going near full throttle as there the ECM is not taking other than the TPS reading into account to give the duty cycle for the injectors. If I have a lean engine with full throttle thats not good either. It looks like my tuning is quite good now with a 128 +/- 4 on both BLM and INT. I was a little on the rich side at 112 before and after rinsing the MAF with MAF cleaner it all came to normal. The reason for this was most probably that I rinsed the K&N filter and reoiled it maybe too much so that there was too much oil vapour and the MAF burnoff could not cope with the oilresidue good enough.
Thanks again
