VHPD Emerald Map help needed on starting

[F355GTS]

I've recently had an Emerald and Verniers installed by DVA on my 98 VHPD (KV6 TB's std cams and head) I'm waiting to get an RR session with Emerald but can't get one till they move so early next year

 

The map used is a variation on Nigel Marston's Map with a lightening of the fuel charge roughly in line with Jue Thompson's cold running.

 

Once warm the engine idles perfectly with supurb pickup however I've been struggling with starting and idling from cold. Early attempts seemed to suggest over fuelling with a strong smell of petrol and an inabiltiy to idle. I've opened the IACV to 100% and once started the car idles however it won't start without throttle applied, it does fire but won't run and then after two or three attempts stops firing which maybe down to flooding. I've also tried increasing the advance whilst cranking but that didn't help.

 

Jue's been very helpful with ideas but I thought I would open it up to see if there are any other ideas

 

I can e-mail a copy of the map to anybody if it helps

 

 

 

Mark

[Johnty Lyons]

Mark I don't think its the map the clue is in your own words " it won't start without throttle applied" I reckon its an IACV problem the inital stat up position of the IACV is wrong refer to the emerald manual the IACV needs to be fully shut, when setting this up otherwise it cant find its home position and without a home position it won't be able to set it's start position.

All your doing by applying throttle is opening the butterfly and letting air in which is what the iacv should do also if it dosn't start first kick you need to sw off and restart otherwise the start up mapping is passed and you need to rrset it. been there done that. *eek*

 

jj

N.I. L7C AO.

Membership No.3927.

[F355GTS]

Johnty

 

 

thanks for that I'll give it a try, Dave did set the IACV to home but I'll do it again just in case

 

Mark

[Julian Thompson]

Your MEMS opened the IACV physically further than the Emerald will even set to 100% but Dave was saying there was a software revision that would allow more opening.

 

This said mine is fine at 100% even though this is still less than the standard opening.

 

Have you tried weakening the mixture yet?

 

[F355GTS]

Jue

 

Johnty

 

I reset the IACV using the Emerald instructions, even taken it out to ensure it's open when the ECU says it is

 

I've tried everything I know for the last three hours and I can't get it to start even with throttle open now, I've gone back to the original map with no joy. Once or twice it fired but for the last two hours I havn't even got it to do that.

 

I've even put my Mems and Jue's Mems with approriate Immobilisers and it won't start even with those????

 

 

I've checked and the injectors are firing and there is a spark on all four plug leads

 

The plugs are black as the ace of and soaking so I've tried drying and warming them but it just seems to flood again whichever ECU I use. I'm giving it 1/2 hour with the plugs out to ensure the cylinders are dry and then will try starting it with the Mems first

 

Unless I can get it going tonight it looks like I won't be going to Goodwood tomorrow ☹️

 

Mark

 

Edited by - F355GTS on 17 Nov 2002 18:55:38

[F355GTS]

Update

 

still wouldn't start after 1/2 hour checked everything again still nothing, tried anotehr ECU (Mems) still nothing, cleaned the plugs with a wire brush started first time re-connected Emerald runs fine

 

 

still got to sort out the cold start problem of the first post so will play with it tomorrow

 

 

thanks for the help todate

 

Mark

[V7 SLR]

Karl gave me a ROM update to increase the opening of my IACV. It still needed a bit of throttle whilst cranking, but you could immediately let your foot off thereafter.

 

Which version of my map are you using? It might be best not to use 100% IACV opening because they have a tendency to stick at the extremes. I never found out why though... sold my IACV with the TBs last month.

 

Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours

 

[F355GTS]

Nigel

 

I think it's a DVA variation of version 2, I do now have 100% opening set so could back that off a bit. The software I'm using is v1.1 rev 5

 

I'm not overly worried if I have to give it a bit of throttle to start so will try it in the morning and see if it will idle, it's possible the IACV wasn't opening properly so will report back tomorrow

 

Mark

[V7 SLR]

I've had a rethink about what I said to you... by opening it 100% you will only suffer from it sticking open. Quite obviously this isn't what's happening or it'd just idle too fast. Doh - Nig..!!

 

What is more likely is that you are still not opening it enough. I hear what you say about software version, it's the same as mine, but what I am not clear is what version of firmware you or I have. I remember receiving the ROM updates independently to the software updates but I can't remember how you determine which version of the ROM you have. Perhaps it's in the HELP - DIAGNOSTICS menu option..??

 

Anyway, it was one of these ROM updates which allowed my IACV to open more. Ask Karl about it.

 

This is exactly the problem I had with mine until I could open the IACV further, but if you fix that and it still won't idle you ought to look at what Julian has done regarding fuelling when cold, and what PC has done with regards to idle stability. I believe he had managed to alter the settings for ignition stability control with very good results. As I no longer have an IACV I will be looking into this kind of set-up once I rebuild the engine.

 

Worcs L7 club joint AO.//Membership No. 4379//Azure Blue SLR No. 0077//Se7ens List Tours

 

[Julian Thompson]

Running the engine with ignition advance idle stabilisation produced an uneven idle quality. We had this turned ON initially when the mixture was too rich from cold and it helped to keep the motor running.

 

Once I had trimmed out the unnecessary fuel in the cold start maps I found that I could deactivate the stabilisation and get a much smoother and more stable idle whether cold or hot.

 

I can't remember if this function had any effect on the cold start. I'm pretty sure it didn't.

[F355GTS]

Well it's definitely air or a lack of it or too much fuel, At 8 degrees coolant temp the mapping is increaing the fueling by 107% is that too much? I presume it's a mixture of the RPM Coolant temp increase and the Coolent temp /% fuel increase.

 

If I pull the old (now unused) vacuum feed to the Mems Map sensor which allows more air in, the car starts easier and idles faster.

 

So it sounds like I need the IACV to open more, I'll check the ROM version in a minute and then speak to Karl

 

I presume I need to reduce Jues figures even more than he has to reduce the mixture

 

Mark

[Julian Thompson]

As I suspected.

 

With the IACV set to full you've got nowhere to go; and you don't need to have either, because you've proved it to yourself that it is too rich.

 

Just fire it up and from the live adjustments screen trim fuel out using key 2 (from memory) - I betcha it runs like a dream!

 

Then you've just got to write down the level of trim you end up using for each coolant temp step and transpose this into your correction tables.

 

Your nearly there now !

 

(But fine tuning will take a while!)

 

I fired mine up today for the first time in a month and it started within 3 seconds of hitting the button. I reversed out of the garage, got out of the car, shut the garage door and climbed back in. I then drove off into the sunset without so much as a hiccup ! AWESOME. (If you are reading that thinking "Whats so impressive about that? - then you haven't tried a standard 2002 SLR !)

[F355GTS]

Quote "Whats so impressive about that? - then you haven't tried a standard 2002 SLR ! ..........especially with a 1998 Mems

 

Jue

 

i've tried taking fuel out, after 2 or 3 it's OK but anymore and it virtually dies

 

 

 

Mark

 

Edited by - F355GTS on 18 Nov 2002 22:57:05

[Julian Thompson]

Oh.

 

Now I'm surprised - we are starting to need DVA......

 

but, at a guess then, the airspeed it very low and the mixture seems about right. Which to me means more ignition advance or as you suspected, more IACV.

 

I think a 30 second call to DVA or DW will sort this out!

 

 

[Peter Carmichael]

FWIW, I get decent running without the IACV and I see it as a distraction when trying to set up cold running and starting.

 

Injection systems usually like starting with very small throttle openings, so rather than 100% IACV open you probably need less.

 

The injection interpolates between the 0 and 1 load sites depending on where the idle stop position is relative to the throttle pot calibration. I have resorted to recalibrating every time I fiddle with the throttle stop this means that my load 0 site fuelling *is* the idle fuelling.

 

It is worth being really careful with the throttle body balancing before you attempt to get any of this finalised.

 

From overnight cold, you can get pretty close in one sequence. You know that the warm idle is OK; this means that the base map setting is correct. You should lock out the IACV at the setting it uses at warm idle and see how well you can survive without it.

 

Once the engine is started from cold, only the fuelling controls whether it idles or not. If it won't idle, then the temperature compensation is wrong. Get it started and trim the fuelling so that the engine stays alive try and do this within 15 seconds of starting. Work out what percentage of fuel trim was required to keep it running and apply that as a correction to the temperature compensation for the current coolant temperature . Do not adjust the base map setting.

 

Because you did this and shut down the engine within 15 seconds, the coolant will not have picked up much temperature. When you next go to start it, try dropping 10% of fuel out of the cranking enrichment and see if it starts better. Maybe it will be 5% or maybe it will need more fuel. If it starts on the button (which it should do) then you have the cranking correction right for that temperature.

 

Run it up to the next 10 degree point of coolant temperature and try again. You will be sorted in no time.

 

FWIW, my Supersport on throttle bodies is rather more hungry for cranking correction than the big engine ever was. The Supersport is running ~82% correction at zero degrees while the big engine ran about 50%.

 

The big engine's settings were:

60 50 40 31 22 16 10 7 7 4 4 3 3 3

[F355GTS]

Brilliant, thanks Peter, spoke to Dave Andrews and Dave Walker today who both advised much the same, most of my problem appears to be too much cranking enrichment and/ or too much coolant adjustment, at 10 degrees I have about +107% on injection.

 

Also managed to get a RR session booked for 3rd December

 

Mark

[Bangers quotNquot Mas1697456953]

Mark

 

I had the very same problem. Make sure the injectors are the same as Nigels . The roller barrel I fitted to my VHPD came with a fuel rail and injectors. I loaded what we thought was a suitable map and suffered the same as you (larger injectors). Dave and Karl at Emerald are superb though, get Dave to check the cam timing whilst you're there, he's got all the kit!!! You won't believe the difference when it's done!!

Best of luck!

 

Andy Marks

vhpd7@btclick.com

[F355GTS]

Well after much adjustment to the cranking and cold start fueling (much in line with Jues Cold Start and PC's Cranking numbers) it started 2nd time from cold without throttle.

 

Having said that it would appear that some of my problems were/ are down to a shortage of battery power. The above success was with another fully charged battery connected plus the 7 battery freshly charged. I'm using a Red Top 30 and whilst it is excellent at cranking the engine it would appear to be at the expense of a quality spark. Time for a bigger battery me thinks!

 

Mark

[Julian Thompson]

Mark

 

Not convinced about the battery problem. The starter draws a lot of current for sure, and this will clearly reduce the voltage available to drive ancilliaries when you crank.

 

However, it is when current draw is at its highest that earth issues will be most prominent. Now, intrinsically, your battery doesn't know that there is a a starter and an ignition system. It can't just route power to the starter and leave out the coil pack......... but of course your coil pack and your starter are connected to that battery by different means; ie different wires, different connectors, switch circuits and earths.

 

I would advise the following tests using a voltmeter.

 

1) Check the battery voltage when cranking right accross the battery terminals.

 

2) Now do the same test but use the engine block as your earth point.

 

Check your figures - they need to be pretty even otherwise you have a cack engine earth.

 

Assuming the above test indicated similar results (which bearing in mind that you state the engine turns over well I would expect).....

 

3) Check the voltage at the +ve side of the coil against the BATTERY negative when cranking.

 

This should be pretty much the same too.

 

If these three readings are in the region of 12V and you have synergy in the 3 values (clearly there will be differences because of physical issues)......

 

THEN you have an ignition fault somewhere because it is the -VE side of the coil that is switched to create the spark. Note that this could mean anything - ECU earth or power supply, ignition amp, coil itself - anything. But not the battery or associated wiring.

 

Hope this might help a bit?

 

[Peter Carmichael]

Experience with Red Top batteries suggests that in colder conditions and at anything other than fully conditioned form, the voltage can drop so low that the ECU switches off and therefore the sparks stop.

[Julian Thompson]

But your engine would stop cranking - or at least you'd hear it struggle.........

 

[Fred]

The ecu as peter indicates needs a minimum amount of power from the battery to enable it to function. if the battery is low the starter as it turns the engine over will starve the ecu of the

minimum power it needs.witch is 11+volts to establish it's settings.

[F355GTS]

Current position is that the last two times the car has started first time from cold using it's own battery, the battery is now being permanently 'conditioned' so was fully charged.

 

Mark

[Julian Thompson]

Voltage will only drop markedly if the current flow is excessive.

 

For goodness sake forget all this "starving of power" business. The electricity can't choose where it will and won't go ! You could have a duff starter that draws 200 sqillion amps and would dim the national grid, but the bloody voltage should be equal on the starter and the ECU, and if it isn't you have a wiring issue.

 

Quite simply you only need about 170A cold cranking to fire a std compression VHPD with a properly designed earth return and appropriate voltage.

 

If your battery voltage is low because it is out of condition then of course your amps will leap upwards too, which will compound the problem even worse.

 

Whacking a truck battery on it to mask the problem is not necessary or desirable.