I am in the process of upgrading my engine to put a trigger wheel on as I have a Nissan RB26 which have only got a cam angle sensor which pretends to output a crank signal.
Can someone tell me how the syvecs handles timing scatter when it has a seperate signal from the cam sensor and the crank sensor?
Does it just use the Cam sensor for injector timing and the crank sensor for spark timing and therefore coping which timing scatter?
Timing scatter
Re: Timing scatter
Hmmm.
Timing scatter doesn't really happen with an appropriate trigger setup (nothing like it does on the OEM CAS setup anyway), and I would highly recommend upgrading any RB26 to a crank based trigger. The "scatter" you may be used with the Nissan CAS unit is a function of the thing that determines the crank position being attached to the crank by something that is essentially elastic, and then there is float between the disc hub and cam drive (reduced by the o-ring on the CAS shaft).
I have made custom setups with just a crank trigger wheel (36-1) and you can leave the CAS in place to pick up the cam sensor info to give phase position (the CAS has 6 unique slots on one part for this purpose which can be used with the "manual cam checklist" so you don't need to fit a new cam tooth sensor). I also work some a few RB26 setups that use the ROSS Performance kit that use a 12 tooth crank wheel keyed by a single cam tooth.
Once setup the ECU only uses the cam sensor to detemine the phase of the engine, ALL timing is done from the crank position and this is generally the way all ECUs work. If you use a 36-1 or similar missing tooth wheel, the ECU can determine crank position just from the crank sensor, but in a 4 stroke engine TDC can be one of two positions in the whole cycle, which is where the CAM sensor comes in. It will run the engine with just the crank sensor in wasted spark mode and batch injection (Sync 360 in Syvecs terms) and then when it has established the phase of the engine, it will run the engine with full sequential ignition and fuel control (Sync 720 in Syvecs terms). Some trigger setups require the cam sensor to key the position of the crank (such as 12 evenly spaced teeth on the crank) and it's rechecked using the cam but still uses the crank teeth for all event timing.
Timing scatter doesn't really happen with an appropriate trigger setup (nothing like it does on the OEM CAS setup anyway), and I would highly recommend upgrading any RB26 to a crank based trigger. The "scatter" you may be used with the Nissan CAS unit is a function of the thing that determines the crank position being attached to the crank by something that is essentially elastic, and then there is float between the disc hub and cam drive (reduced by the o-ring on the CAS shaft).
I have made custom setups with just a crank trigger wheel (36-1) and you can leave the CAS in place to pick up the cam sensor info to give phase position (the CAS has 6 unique slots on one part for this purpose which can be used with the "manual cam checklist" so you don't need to fit a new cam tooth sensor). I also work some a few RB26 setups that use the ROSS Performance kit that use a 12 tooth crank wheel keyed by a single cam tooth.
Once setup the ECU only uses the cam sensor to detemine the phase of the engine, ALL timing is done from the crank position and this is generally the way all ECUs work. If you use a 36-1 or similar missing tooth wheel, the ECU can determine crank position just from the crank sensor, but in a 4 stroke engine TDC can be one of two positions in the whole cycle, which is where the CAM sensor comes in. It will run the engine with just the crank sensor in wasted spark mode and batch injection (Sync 360 in Syvecs terms) and then when it has established the phase of the engine, it will run the engine with full sequential ignition and fuel control (Sync 720 in Syvecs terms). Some trigger setups require the cam sensor to key the position of the crank (such as 12 evenly spaced teeth on the crank) and it's rechecked using the cam but still uses the crank teeth for all event timing.
Re: Timing scatter
Thanks for the response.
That makes a lot of sense, so the crank the preferred reference point and knowing the position of the piston for fueling and spark is all important. I suppose I wondered if the ECU would do something to compensation for the timing belt slack in some way.
Maybe pull some timing out.
That makes a lot of sense, so the crank the preferred reference point and knowing the position of the piston for fueling and spark is all important. I suppose I wondered if the ECU would do something to compensation for the timing belt slack in some way.
Maybe pull some timing out.
Re: Timing scatter
Scatter isn't just some delay, it bounces around all over the shop, as much as 6 degs in my experience!
-
tarmac terror
- Posts: 30
- Joined: Fri Apr 27, 2012 6:30 pm
Re: Timing scatter
Hi Mikey, I have gone for Andy's (of AMT) trigger kit to for my S8 install too. Its always struck me as odd why Nissan would choose to collect crank angle data from a cam-based sensor!!I mean, its not as if decent crank trigger setups were not available at that time.
A crank-based trigger with phase sensor will tighten things up nicely. The difference when comparing data plots of std CAS Vs crank-based trigger scatter are astounding!!!
Been keeping an eye on your build thread on GTROC...coming along nicely.
TT
A crank-based trigger with phase sensor will tighten things up nicely. The difference when comparing data plots of std CAS Vs crank-based trigger scatter are astounding!!!
Been keeping an eye on your build thread on GTROC...coming along nicely.
TT