mattbred said:
I'm curious to know why the engineers decided to make the renix take a few seconds to start? Surely it wasn't accidental. Could it be that they wanted to cycle the engine a few times to get the oil everywhere, before firing up? Being an electronically controlled engine system, youd think it could start up almost instantly as the later years did.
I was also wondering what exactly it turns off. Fuel, or spark? I'm thinking fuel. I notice that if you crank for a few seconds, turn the key completley off, then restart it, it'll start up instantly. It got me thinking, is there some way to trick the system into starting up instantly? Some sort of fake signal. Would be nice.
I've heard (probably apocryphal - but you never know with AMC...) that the reason for RENIX to "spin up" before it starts is for oil circulation on startup.
I do know that the reason it does have to "spin up" has to do with it wanting two signals:
1) Valid 300rpm from the crankshaft position sensor (Mandatory)
2) Valid SYNC signal from the distributor (Optional)
It can and do start without the SYNC signal (I've tried,) but it
will not start without the CPS signal. If you unplug the dizzy and try to start, you'll think that the timing chain has slipped a cog - that's because the ECU is "guessing" where the #1 cylinder comes up to fire. Once it has its guess, it can work without the SYNC signal - but performance does suffer somewhat.
However, until it sees 300rpm from the crankshaft position sensor, fuel AND ignition are both cut off. It
will not fire fuel injectors or the ignition coil until it gets 300rpm.
To improve starting times, improve the mains (that seems to be the consensus.) I've put in 1AWG mains cables, and crank times are reduced (because the 1AWG will get a larger current supply to the starter motor.) I have heard reports from the field that indicate the same things.
Also, it can help to provide an additional ground from the battery to the chassis - the ECU grounds through the chassis, which grounds through the engine block, and
then to the battery. Just something else to think about...