Emerald warm up enrichment on 400SE

[Lesliehedley]

I have an Emerald ECU fitted to my 400SE. It has been rolling road tuned by Jules and he has as usual done a superb job. So the base map is perfect. Unfortunately, when Jules had the car there was no IACV fitted. I have since fitted an IACV and started tuning the warm up enrichment for it. I was happy with the figures I had for this. It starts easily and warms up nicely with what I thought were good AFR figures and idle. This was all done while stationery using data logs etc. But when I tried to drive it from cold, whenever I came off the throttle or pressed the clutch to change gear, the revs took a second or so to drop which was horrible to drive. I am guessing this is due to having too much fuel and the IACV too open which acts a bit like an open throttle. If anyone knows better please let me know.

I think the main problem is that searching the internet there is no data as to what the idle, AFR and IACV settings should be during warm up enrichment for a TVR 400SE. So the idle figures and AFR at different temperatures were a guess on my part.

Can anyone have a look at the figures I have used and advise where I have gone wrong and what I should be aiming for.

Temp:    -30    -20    -10      0     10      20      30      40      50      60      70      80

Idle:   1200   1200   1200   1200   1170    1140    1110    1080    1030     980     930     930

AFR:    12.8   12.9   13.0   13.1   13.2    13.3    13.4    13.5    13.6    13.7    13.8    13.8

[spitfire4v8]

Your original map will probably have the max 10 degrees ign compensation for coolant temps up to i think 40deg, this is to try and prop up the idle speed during the warmup period with no idle valve. You will probably also be running more hot idle airflow than would usually be the case in order to give a little extra airflow for cold starts. Both of these are probably adding to your issues.
You can't do much about the base idle airflow without skewing the whole base map at small throttle angles, but you could try reducing the ign compensation map at low temps.
I would put zeros into all the sites in the coolant temp ign compensation table and see if that improves the off-throttle rev hanging at low temps. if it does then try introducing a couple of degrees at a time back into that table until you get a good trade off of no revs hanging v the improvement in drivability you get when adding the cold temp ign advance back in ..

you will spend longer trimming the cold start fuel , afterstart fuel , and ign and iacv table than the whole of the rest of the mapping put together, and then some!

I spend a week on this on each car and that's with the benefit of 20 years experience.

[adam quantrill]

The other side of the coin: I still run the 4CU (albeit one with an enrichment pot) on the 400SX.
When I get it out of the garage it won't idle, I just let it stop while I shut the garage door.
But after 90 seconds running up the road, it idles fine, so I never bothered fixing this issue.
If I compromised and raised the idle then it would so be idling at 1100 when warm, which is my "MoT" setting, but uses up too much fuel really, I prefer it to be chugging nearer 850 personally.

[Belle427]

I found this a while ago based on RV8 tuning, may help a little.

[Lesliehedley]

Well, Jules has hit the mark again. I've altered the ignition temperature compensation table and the hanging revs have disappeared. Thanks Jules. Thanks also to Belle427 for the sample of AFR values for rover V8 engines. This showed I was trying to make the car idle with too little fuel at each temperature. So I added fuel until it seemed happy and it's much more stable. What would we do without the expertise on these forums?

[adam quantrill]

That's nice to know. Did you self-install your emerald setup? I was thinking of getting into an upgrade for the 4CU some time but was wondering how to do it and look fairly stock. Emerald is one possibility but there's "Speeduino" out there now which might be more up my street.

My lump has the extra complication of the Spintex on there :-)

Anyhow any pics of the installation or technical details would be interesting.

[Lesliehedley]

I did the wiring for the Emerald myself using their manual. It's fairly straightforward. I removed the air flow meter and replaced it with a straight pipe. To keep it simple I left the distributor in place and use it to distribute the spark but obviously the K3 controls the timing.At the time of my install the Emerald was the K3 model which didn't support the Marelli IACV so I didn't have an IACV fitted. I did try tuning it myself but after trying for quite a while (years) I decided to leave it to the experts and asked Jules to tune it. I recently found a way to drive the Marelli IACV from the K3 which is why I am now fitting and tuning the IACV as the last step of my installation.

[gmw9666]

Jools did a fantastic emerald install on my SEAC, was able to loose the AFM, dizzy, extra air valve…..all the old stuff gone woo hoo. Starts on button and super smooth idle……literally brilliant. Rest of the car is OE but wanted reliability and this has given it :-)

And even able to have a cheeky pops and bangs setting on the dash for a bit of extra errrrr noise lol

https://m.youtube.com/watch?v=OMr99Z63EOA

[Belle427]

Megasquirt is often overlooked but is a very good system, it gets a bad reputation from poor installs though.
Can be mostly self tuned on the road but final rolling road time to finalise is recommended.
I think Speeduino and Megasquirt are the same thing.

[adam quantrill]

No Megasquirt is a closed proprietary design, Speeduino is open-source, anyone can make their own hardware as wanted.