So recently I got a new starter for my 4AGE and now it starts really well. Too well in fact...it fires up so fast that there isn't much time for oil pressure to build up, and I get a half-second of bottom end noise on each start, like when people don't prime an engine after an oil change but not as bad. I want to add a cranking delay. It's a long story but adding proper analog oil pressure control to my Megasquirt 3 would be a big expensive job (engine packaging), so that can't work. This engine has an aftermarket oil cooler so it will take longer to build pressure than stock. I already have the Skip Pulses setting maxed out. What does Priming Pulse Delay do, exactly, could that do the job? The other option I was thinking of was hooking up oil pressure control to some kind of virtual input that would just act as a delay timer (maybe based on engine rotations)?
Put the MS3 on a separate manual switch that will allow you to crank and build oil pressure before you fire up the MS3/ignition?
Plus there's a little security built-in.
Separate starter button from ignition is SOP on large high compression engines with huge cams. They might have 20-30 degrees of "base" timing (assming that it isn't just locked to begin with) and it is easy to break the nose off of the starter if it tries to rotate the engine backwards. So the procedure is, you hit the starter button, let the engine spin up, and THEN hit the ignition.
This is why those "race switch panels" are set up the way they are, with separate switches for starter, ignition, and fuel pump. And ignition is usually the one right next to the starter button.
Does your Rolla have an idiot light or a pressure gauge? I forget which one the '92 had. If it's a gauge, replace the sender with a switch (cheap on amazon, etc.) like the idiot light senders have. Wire that to a relay pair to drive an idiot light and the fuel pump. That way the fuel pump won't come on until there's oil pressure. You could do the same with the coil +12v, actually. I'll scan my schematic if you're interested in persuing that.
Cadillac use to have a oil pressure switch that disabled the ignition until it saw enough oil pressure. It was a common failure. I purchased several of them back in the late 80s as no start cars. Look up a 83 Fleetwood brougham. It had it. You cold plumb that in and hook your ignition power to it and put a relay to it and put that to the fuel pump as you don’t want the cylinders filling with fuel as the pressure builds
Don't worry about it. If its crank bearing noise, and not timing chain noise, it will spontaneously disassemble itself shortly, no matter how long you crank it. And if it doesn't come apart, you are paying too much attention to small noises.
Or, add an accusump.
You are also using a Toyota oil filter, right? They have a proper anti-drainback valve for that motor.
Can you just wire in an accusump with a solenoid controlled release valve that fires on ignition on?
Turn key to on, wait 3 seconds (or whatever it takes), then crank?
You could use the cranking taper curve. This is typically used to sweep the pulse to make starting a bit easier, but you can set it to remain at zero pulse width for a short time to make starting harder, instead.
This car has an idiot light, and was also available with an idiot gauge (like the one on an NB Miata). I had the option of installing either one but chose the light because I thought it would be better at getting my attention and I know it reacts faster (a blink of an idiot light is equivalent to just a slight twitch of an idiot gauge). I'd thought about wiring it to only fire when the idiot light goes out, but that's probably overkill and would make the engine take too long to start. With the old starter that would mean a good 20+ seconds of cranking.
I am using a Toyota-brand Blacktop extended filter.
An accusump is way more money and complexity than this problem calls for, I think.
I hope I'm paying too much attention to small noises. I'll keep a close eye on it and get my oil pressure checked with an external gauge if there are any more new sounds. The engine has recently survived a track day and an autocross immediately before getting the new starter. I really can't afford to wreck another bottom end.
So I'll look into using the cranking taper curve settings. I just want to force it to crank for a second or two before firing up, right now it starts almost instantly, and with the thermo-mechanical cold idle-up system built into the throttle body, it immediately jumps up to 1500rpm when it starts at this cranking speed. With the old starter, it sputtered around 1krpm for a few seconds first.
If you've got an idle control valve on it, I'd be tempted to ditch the mechanical high idle thingy and let the MS3 control the cold high idle and how much of a kick it gets when it starts. Having it not snap the revs up as much when it catches might be enough to solve the issue.
I'd also put a real oil pressure gauge on it and see how fast the pressure comes up on cranking or when it starts. Does this engine have solid or hydraulic lifters?
This engine has solid lifters. I do want to switch to an electronic idle air control valve (which I don't have yet, and will be necessary for running ITBs in the future), and switch to an ECU-controlled oil pressure warning/shutdown system, but like I said, putting an analog oil pressure sensor on this engine is difficult.
To explain the long story, the oil pressure sensor is stuffed in a little cranny under the PS pump bracket which is barely big enough for the (relatively tiny) idiot light sensor, and the "access hole" is offset so much that the wire can barely make it out of there. So to fit a bigger (or at the very least, longer) analog sensor, I'd have to heavily clearance this bracket and hope it doesn't break, or make a custom one. Or get rid of it entirely and switch to EHPS, which would be nice. Running a remote sensor attached with a pressure line could be an option too, although that adds a fair bit of mess under the hood.
GameboyRMH said:
An accusump is way more money and complexity than this problem calls for, I think.
Yeah, sorry about that.. I was overthinking the problem. If there isn't a way to do it inside the MS3, I'd probably just wire up a timer relay. This is the first hit on the google:
https://www.amazon.com/Timer-Delay-Relay-Hours-Cycling/dp/B00PD65UGA
For $23, you can just have power to the ECU delayed 3 seconds (or whatever) before allowing the ECU to light up?
OK so here's a graph I've set up:
It moves fuel from 0% to 100% at 20 ignition events, which should be 10 rotations on a regular-fire I4. Does this look good? I'll have time to test it tonight. I'll move the "cliff" to tune the cranking time.
A simple on/off switch on the ignition does the job. Crank without ignition until you see the oil pressure gauge twitch then tunr the ignition on and fire it. Simpler, cheaper and easier than screwing around with pressure switches etc.
GameboyRMH said:
I do want to switch to an electronic idle air control valve (which I don't have yet, and will be necessary for running ITBs in the future),
Its not needed, IMO. I never had idle issues with mine, unless it was very, very cold, ITB's tend to idle a bit higher by their nature and that negates the need for idle controllers.
The cranking taper curve setting did the job, I ended up moving the cliff point from 19-20 to something like 7-8, which gives it a good two seconds of cranking, no more worrying noises on startup. I'll probably end up reducing it further.
I like that you are withholding fuel instead spark to prevent engine firing. Seems like a better way to do it.
