Winter Strip Down and Rebuild (Done and Dusted)

[Mikie711]

Had the car MOT'd so while a Ricky's thought we would stick on his road and see what it was putting out. Being as his road has been around a while we had a real problem with tyre slip so ended up without a definitive figure as once it got up to 180-190 the needle started jumping about all over the place. Best we saw was 217bhp at 7500rpm. So, as this thing revs to like forever with the red line at 8200 will probably have to take it to Wallace's at some point to see what it puts out on theirs at least I'll get a graph to look at if nothing else.
Map still needs some work on it around idle, going to strip the TB's down and set them up again. Problem is that it idles fine but if you coast at about 2000rpm without touching the throttle pedal then dip the clutch it idles at 1700-2000 rpm, blip the throttle and it returns to normal. Thought at first it was a sticking throttle, which it had prior to Boyndie but that's been sorted so not really sure what's causing this to happen. If there are any Emerald experts then feel free to offer suggestions as I am all out of ideas at the moment.

[Shug]

It will be one of the map sites above idle holding onto the RPM - usually through timing. A little time fiddling the map when it does it methinks.

[Mikie711]

Ye, it's jumping to loads site 3 (1500rpm) which seems to be holding the revs up, stopping it dropping back to load site 2, but why is what I don't understand. How can it hold the revs up it should let it fall back. The only thing I could do is retard the timing for that site I suppose.

[Shug]

Yup - mine did it as well. Not 100% au fait with the technical reasoning, but having too much advance will cause it to rev. That's how it can stabilise the idle automatically with advance (although it's sh*t at it)

[Kev]

Mike hows the TC/LC working out?

[Mikie711]

2 of the wheel sensors lost there signal so wasn't able to use it last time out. Will be investigating the cause over the next couple of days and hopefully be able to use at least the LC at Fintray. Rest of the logger produced some good data which was quite interesting to look through especially as 2 different people were driving. Should me at least where I was losing all my time. Got hold of a pressure sensor for brake pressure to use up the last available channel.

[Victor Meldrew]

2 of the wheel sensors lost there signal so wasn't able to use it last time out. Will be investigating the cause over the next couple of days and hopefully be able to use at least the LC at Fintray. Rest of the logger produced some good data which was quite interesting to look through especially as 2 different people were driving. Should me at least where I was losing all my time. Got hold of a pressure sensor for brake pressure to use up the last available channel.

Glad I could be of service

[robin]

Ye, it's jumping to loads site 3 (1500rpm) which seems to be holding the revs up, stopping it dropping back to load site 2, but why is what I don't understand. How can it hold the revs up it should let it fall back. The only thing I could do is retard the timing for that site I suppose.

Is it load=3 or speed=1,500 RPM or both? It's a two-dimensional map. The load sites are on the vertical axis IIRC which is translated directly from the throttle angle. The horizontal axis is RPM.

So when you let off the throttle it should always be on load=1 (or maybe it starts from zero, top line anyway) and then the column will be the current engine speed.

If it's on load=3 when the throttle is closed, then there is a problem with the TPS, TPS wiring or TPS calibration.

Cheers,
Robin

[Mikie711]

You could well be right Robin, this occurred to me when reading through Dave Andrews set up instructions for TB's. Will try recalibrating the TPS and see what happens. BTW it's the speed site that is sticking, load shows zero.

[robin]

If you haven't already done so, you'll need to use a synchronometer (is it?) thingmy to balance airflow on all four cylinders first. This is very important - the emerald doesn't do cylinder-by-cylinder fuel trim for lambda control, so you may run dangerously lean on one cylinder whilst the other three are running rich - result is correct lambda and one very hot cylinder!! I seem to remember the target is either 6 kg/min air for the whole engine, or maybe for each cylinder ...

So, if load = 0 and speed = 3, cylinders are balanced and idle airflow is correct, and it still won't return to idle, then it's what shug says.

I would set fuelling to 0 and advance to 0 on all speed sites > 1,500 with load = 0; this is obviously correct as when the throttle is closed you want the engine to stop spinning.

You probably have that much set up already.

Now when the engine is slowing down you need to start the fuel/spark off again before you reach the idle speed cell, otherwise the engine speed will undershoot the target idle speed by too much and stall. So in the 1,500 RPM cell you need to have some fuelling and ignition advance; in the 1,000 RPM cell you need a little more of both; in the 500 RPM cell you need more fuelling than you think as the air speed is so low that a lot of fuel vapour condenses back to droplets and ends up entering the chamber as a liquid. BTW the liquid fuel then sticks to the walls and doesn't burn - other ECUs have a x-tau function to model this wall wetting; not so the emerald - never mind, your engine won't spend much of it's life idling anyway.

So if you put in too much fuel/advance in the 1,500 RPM cell the engine will generate too much power and won't decelerate further. Best to knock off the ignition advance and leave the fuelling - the more fuel vapour you can get in the system at this point, the better as this will give a smoother entry to idle. Typically advance less than 10 degrees won't keep the engine idling, so aim for 5-10 BTDC in the 1,500 site, nearer 10 BTDC in the 1,000 site and by the time you get to the 500 RPM site you probably want 10-15 BTDC. Of course you'll tick the box somewhere or other in the setup that says "control idle speed with ignition advance" or similar that allows the ECU to tweak the advance up/down cycle by cycle to control the idle speed; that means that actual advance will be set dynamically once the ECU is in idle mode, within a range of about +/- 20 degrees around the configured value IIRC.

For fuelling I would suggest you allow the engine to warm up, turn off closed loop and set the fuel right for correct lambda but do so slowly (i.e. leave it running for 10-15 seconds between adjustments). The closer you can get the idle fuelling to correct, the better the closed loop stuff will work when you turn it back on. I would do this with no load for each cell up to 2,000 RPM (by the time you reach 2,000 RPM you might be on load site 1 - doesn't matter). The point is to get the no-load fuelling correct to improve emissions and economy when driving normally (you do a lot of no-load driving in town!).

Cheers,
Robin

[Esprit]

Hey Mike,

Did you get all your oil cooler hose and fittings from Merlin? What Hose and fittings did you end up going for? (specifics) By the looks of it your fittings are the plated steel ones?

I've been hunting high and low to try and find hose and fittings that'll allow me to run alloy BSP, but they're like rocking horse poo. For some reason, BSP fittings only seem available in push-end (not collar-type) fittings (and possibly pre-swaged) and only in plated steel. I've found a crowd in America that seem to do them in Ally, and Demon Tweeks seem to offer a BSP alloy push-in fitting too, but these are the only ones I can seem to find!

Just interested to hear what you found as well.

George.

[Mikie711]

All my hose and fittings came from merlin. They were all steel push fits and the hose was Mocal Blue Aeroquip Push On Hose -8 (1/2")
Hose here and fittings here

[Esprit]

Cheers Mike

[Mikie711]

The final pieces of the puzzle are coming together............

After much scrimping and saving I finally manged to get my stick paws on one of these





So, this weekend I will be under the car again. Going to refit the quaiffe straight cut short box and this new manifold. For those in the know it has the right primary and secondary lengths and should free up a bunch of mid range torque that the big bore Janspeed doesn't. Not sure I will feel the difference guess time will tell but I am well impressed with the quality of the manifold. Very well made and it all just slips together. Internally the welds are as near as dammit flush seems a shame to hide it in the engine bay.
Once it's all back together a quick visit to Wallace's RR will be in order.

If your wondering why the short box was out of the car so soon after being fitted, it developed a weird noise which I thought was the diff bearings but turned out to be a problem with 3rd gear selector fork. It had started to weld itself to the groove in the gear. Some filing and emery treatment hopefully will have cured this problem at least enough for Boyndie next weekend.

[tut]

Bugger me thats luverly. Will it fit on mine.. lets try It next week.

tut