CRAIGO

It's very cold over here in the UK at the moment so I've took the opportunity to try and dial in my cold crank PWs more accurately.

I thought I had it nailed at -3degC the other day and I tried again yesterday at -6 and it took me nearly 15mins to get it started.

I've attached a log of the poor cranking sessions at -6degC and todays good efforts at +2degC (this is as cold as we got today).
The problem is that -3degC and the car started with little fuss but at -6degC it was a bitch but these two values share the same cranking PW value?

The only thing I can think of after analysing the MLVs is that during cranking the PWs fluctuate from the correct PW value of around 10ms to some other higher value based on the fixed map value of 80kpa (VE cell value of 67). This either ends in the engine nearly catching and dying or after a few seconds of cranking I hear a hydro-locking sound before I attempt to crank again and it usually catches on the second go. Anything over +degC/hot re-starts and the car mostly starts first time, every time.

Another theory I have on it is that I have my cranking advance set to 16 and my spark map does show a fluctuation during cranking of this value and that of what resides on the spark map 13, 14, 16, 17 (idle region). So obviously during cranking, the spark is igniting over those 4 numbers and could be preventing a clean start at very cold temps? I may well set all the 500rpm spark cells to a solid 16 or 17 degrees and see if it helps.

The logs show it all, so I'd be grateful if any of the experts could have a look and shed any light on the situation.

Cheers,
Craig

Rouphis

I find that mine start better in the cold with less cranking advance. I'm at 8 right now. At 12 it would not start below 50F.

-Rouphis

Braineack

iTrader: (62)

what size injectors?

Scotty15

I have this exact same problem. And my car is basically stock (for now 1994). It also does the slow turn over thing sometimes. It sounds like it either has the timing too far advanced, or it's hydrolocking. Often times on the second turn of the key it will start fine. It only does this below about 50 degrees F.

I also backed off the cranking advance, and it seemed like it may have helped some. Sometimes it will start just fine. It almost seems like at times it doesn't read the CAS sensor correctly and gets initialized wrong. It has done this with the stock ignition, and with it's current Toyoda COP setup.

wayne_curr

iTrader: (8)

I get that hydrolocking thing too. Done it since installing my 550s.

Braineack

iTrader: (62)

just start with a really low pulse-width in that CLT temp range. then keep adding like .2 at a time until it starts perfectly.

Steve-A

I'm also in the UK and have been having issues with starting my megasquirted MK1 set-up.

Like you Craigo, I noticed that as soon at the car started to catch I the pulse widths jumped right up, and fluctuated lots. I was getting those hydro lock noises, and the car was nigh on impossible to start when around 0 C or lower.

I had a moment of inspiration when i was trying to get my general driving tune right. As I've got a mk1 1.6 the TPS is basically useless, so I'm running MAP based acceleration enrichment. When I looked at the table, the base map I'd started with had the AE adding anything upto 9ms of pulsewidth!

So under Accel/Deccel mode I turned off AE while the cars in ASE, and I seem to have stopped those hydro locking sounds. My cranking table was all over the place by this point, so I leaning it right out and started over, and so far I'm getting much more reliable starting. Once the engine catches the pulse widths are much more constant for the first few seconds and it stumbles less.

I also ended up etting my max AE to 2.5ms with my 305cc green top supra injectors which is giving me AFRs of 12ish for a split second if I punch the throttle quickly, much more like it!

So if you are using MAP based AE, maybe look at a datalogged start and see if its doing anything odd

kotomile

iTrader: (24)

What are y'all referring to when you say "hydrolocking"? I've always understood hydrolocking to be what happens when your Honda's cold-air-intake sucks up a puddle.

Braineack

iTrader: (62)

fill your cylinders full of gas and see what happens on the compression stroke.

CRAIGO

Sounds like Im not alone.

Im on stock 1.8 injectors (230cc). It does seem like a "sometimes it does it, sometimes it doesn't" problem. I just started it up and datalogged another start-up and the PWs at 10degC crank at 10ms (which is what I have it set too), the reason the PWs jump up during cranking are because the MS thinks the car has started and adds in the WUE and ASE values immediately after the crank light goes out which causes spikes in the PWs (~15ms) even though the engine hasn't caught properly yet!?

So it goes...

CRANK (10ms), WUE+ASE (~15ms), CRANK (10ms), WUE+ASE (~15ms), CRANK (10ms), WUE+ASE (~15ms), oh no I've filled the cylinders full of fuel, SPLUTTER, SPLUTTER, ENGINE SHAKES, CRANK (10ms), HYDROLOCK sound. User then decides to stop cranking before the engine implodes. Then I'll crank again some 2 seconds later and the engine fires right up on the first or second crank and shudders to idle within a second or two. Hardly OEM...

What I want is it to crank at the given PW value (10ms) and not apply WUE and ASE until the engine has caught properly, this is why my cranking PWs will NEVER be tuned, I've been through so many values now that I've probably gone past the sweet spot in .2ms intervals several times now. It's no good using this method to tune my PWs if ASE and WUE start getting involved the second I try and crank from cold.

Scotty15

I find it really hard to believe that the engine is actually hydrolocking. Wouldn't that take a shitload of fuel? Like more than can be delivered in a second?

Can anyone think of a good way to determine if this is fuel or ignition. To me it seems like for some reason the ignition advance is just arbitrarily too far advanced.

Maybe unplug the ignition and just see if it turns over normally?

richyvrlimited

iTrader: (1)

Only just had a chance to read this thiread mate, from what your describing/desire, maybe try increase the cranking rpm?!

Increase that and it won't go out of cranking mode till the revs are at the higher setpoint.

poobs

iTrader: (1)

Ok add me to the list. Mine does that locking thing on first start up. It sounds like too much advance but how what do I change to fix it ?

ScottFW

iTrader: (4)

My car also suffers from this but I'm unsure if I want to put in the effort to mess with it. Meh.
You can adjust the cranking advance under spark settings. I think stock-ish would be about 10*. The thing is, as soon as the motor catches and starts to stumble up to idle speed, once it gets above your specified cranking rpm (mine is 300, set under the "more cranking stuff" section) then ignition timing is going to switch to whatever you have in your spark table. A bunch of people run timing between 17* and 20* at idle, because that's what's in the MSPNP base map (at least for my 94) from which many of our maps are derived. So if your motor is stumbling up to a start with 10* advance during cranking, as soon as it stumbles over 300 rpm it's going to suddenly advance to ~17*. I think.

I already tried changing just the cranking advance (was 14*, made it 10*) and it didn't help startup. I'm debating if I care enough about cold starting to dick around with the timing in my idle cells, retuning those VEs, etc.

CRAIGO

Aha! So the cranking RPM value is a 'setpoint'? That makes a whole load of sense now given my plight with cold starting. I've just had another look at the log where it took me ages to start the engine at -6degC and indeed, cranking mode switches off every time the RPM value exceeds 300cc and WUE and ASE then kick in. I see a peak value of 500rpm in my logs during failed cranking attempts so this is all starting to make sense now. i.e. the engine should crank and catch solely on the cranking PW value, this should momentarily raise the engine RPM above a hypothetical value of say 450-500rpm and then WUE and ASE will prevent the engine stalling/falling below this RPM threshold.

Im looking forward to trying this tomorrow now. Cheers Rich.

Cranking advance/retard should be adjusted if cranking is slow IIRC so maybe I'll reduce that a little to help smooth my start-ups.

At least I now have a few things to go at.

POOBS - If you're using TunerStudio, go to Spark, Spark Settings and then Cranking Advance Angle.

wayne_curr

iTrader: (8)

I'm feeling the same as scott about not messing with it. My motor has never NOT started. Sometimes it just takes a little more effort to get it there.

However, I dont think this is related to cranking advance so we must have different issues. My car wont get more than 10rpms before it feels like it locks. Hell it doesn't even feel like 1 complete revolution.

CRAIGO

But surely you want the comfort of knowing it'll start first time, every time? (maybe not )
I already have to wait 30 seconds for the damn LC-1 to warm up, If it doesn't catch the first time, I then have to switch off ignition, turn it back on, wait for the sensor to re-warm for a further 5-10 seconds and then crank again. If it fails to crank after a few attempts then the LC-1 starts to throw it's heater warm-up error (4 flashes) and then I have to switch off ignition, wait for 30 seconds, switch it back on, wait for the sensor to warm up and then crank again!

Now you know why I'm so pissed with this cranking in cold weather problem as I could have walked to me destination in the time it takes to start the engine.

I'm going to get this shed running on the button if it kills me!

poobs

iTrader: (1)

Ok, mine is different - it starts fairly well but if it misses starting on the 3rd crank, if I back off the key or if ithappens to stall right after it starts I get that hard cranking thing. Then after a few secs it seems to run much better.

It is almost as if it did not like the after start stuff...

What do you guys think I should try.

Scotty15

After reading that so many other people have this problem, I just flat out cannot see how this can be anything other than an ignition advance issue. My stone stock injectors really can't supply enough fuel to lock the motor in a couple turns. I'd have to be pouring gas out of a bucket into the intake to do that.

I'm going to go out and unplug the ignition, try to turn it, and see what happens.

Could this be as simple as a weak battery? It is quite small and has little reserve for cold weather.

poobs

iTrader: (1)

That is a great idea !!! careful not to blow your coil

As a bit of reference - Yesterday I realized that my initial timing settings where off for some reason. I may have inadvertedly burnt in the base MSQ etc. This meant that I was running retarded.
Unless the start -up timing is not ruled by the spark table the hard cranking problem should have gotten worse when I corrected the timing settings but it did not.