Lotus Elan and Lotus Elan Plus 2 Forums

Simon,

I'd love to buy an LM-2 but there seems be a lot of folks who have had trouble acquiring a solid, useable rpm signal. This circuit seems prone to noise. Some folks scale the input signal. It might be possible to filter the signal. Seems like a lot of potential trouble.

Did you have any problems with your setup?

Bill

Sorry Jim it is too easy for this stuff to lapse into jargon. However please ask as I will do my best to explain in simple language.

Bill, in other words, meant give me a purple graph showing what happens when your at idle and one when you do everything but idle.

The purple graph is made of lots of vertical lines. The longer the line the more often the carb was supplying that particular air fuel ratio. The ratios in question are on the horizontal scale of the graph and the mythical 12.5 means 12.5 parts air to 1 part fuel. Which gives maximum power (it's most effective if you say those last two words with a Jeremy Clarkson voice)

This purple graph shows the "frequency of occurrence" Bill is referring to.

bill308 wrote:Did you have any problems with your setup?

Yes, a huge amount. I only got back on with this project since I sorted the RPM reading issues. The problems stem from the very messy signal you get from the coil as soon as you have electronic ignition involved. Innovate did not do a very good job of their tach reading circuitry when it comes to the real world signal.

Then suddenly it was easy when I realised that the circuit that Speedy Cables sent me many years ago to convert my RVI to an RVC style unit also had a pulse output. This provides a clean signal and works perfectly. I believe Keith found that his electronic ignition unit had a similar "good" output and this is what he uses. I'm not sure that Speedy still use the same circuit otherwise you could implement it specifically just to drive the LM-2 also has a stable 5V supply on board which is perfect for the TPS.

The said board with badly soldered hook-up wire.
This circuit is now inside the tach

It was so satisfying when I got it all to work. It's like having an F1 car with the data streaming in! I'm now contemplating the Innovate 2 dimension G sensor to add to the fun!

Simon,

What are you using for a TPS?

I don't know why Innovate doesn't fix that rpm circuitry to be more user friendly.

Bill

I am using the (rather over-priced) weber unit:
http://www.webcon.co.uk/shop/shopexd.asp?id=9948
It comes with all the correct mounting brackets which makes life easy.
See pics much early in thread.

Simon,

I agree with James,interesting but a bit confusing.I could follow after reading a few more times.Thats for the explaination.As for a comparison,would it be worth testing against a fully maped ECU controlled car?

Paul

You mean a race

Paul,

I remember from your other thread that you did not have an O2 sensor as part of your system.
So you would need to have a bung welded to your exhaust.
You can see this in the pics early in the thread.

With this fitted it is easy to transplant the AFR part of the system from one car to another.
Since you have a ECU accessing other data should be fairly easy too, I'd imagine.

I have to warn you this stuff is addictive, you'd soon start tweaking your mapping and then there's no turning back!

SImon

Simon,

Not now but not to far in the future i would like a beter exhaust so was thinking TTR with o2 adaptor anyway.If its possible then use the same equipment,yes,your gear,and in the grounds off research(honestly) and come up with a comparison.If that happens to be near a track then so be it,,,

Im always up for helping out if I can.

Paul

Here's what Bill was asking about yesterday.
It demonstrates how you can select portions of the log and so exclude or include static idling (in this case) from the graphs.



This is a 45minute run from the 23rd when I had 45f9 and standard e-tubes fitted.
Top left you see I have selected only non-idle sections (I did this over the full 45 mins)
Bottom left I used the handy "Invert Selection" menu item and hence it is only static idle.
By static idle I mean: not moving with closed throttle e.g. waiting for the traffic lights!
(apologies for not positioning the timeline the same between top and bottom)

The graphs on the right show the spread of afr that occurs for these two situations.
Watch out! The scale on both axis has changed - I can't control this.
When you look at the whole thing both these graphs are summed together so all that idle stuff just increases the peak.

The graph rescales to the highest value and you can see the potential to draw an erroneous conclusion

So here is the same with the best result I have yet.


Perhaps you can start to see why my early conclusion is that Keith's hypojets work!

Hmmm, just discovered that you can do equation based filtering in Logworks.
It's just they called it "Search", oooh this is another day wasted...

pauljones915 wrote:Not now but not to far in the future i would like a beter exhaust so was thinking TTR with o2 adaptor anyway

Yep it is easier to fit the bung if there is a reason to take the exhaust off anyway.

It will constitute another thread but I am going up to these guys soon.
http://christullettexhausts.com/
The plan is to completely weld the exhaust system since I have had a love-hate (actually just hate) relationship with my Y-pipe for many years.
How will you ever get it off I hear you cry. (fnar fnar)
The plan is to have a couple of custom flanges inserted in the two down-pipes just after the 2:1 combiners.
Nivarna will be no more U-clamps/C-clamps and no more paste, more ground clearance and no more fumes!
Like I say I will start a new thread on this....

Simon

Simon,

Thanks for all of the info you have put into this interesting thread.

Now that you have tried the .020 and .022 Hypojets (which replace the Weber idle jets) has the idle and low RPM driveability of your car improved noticeably?

I started using .020 Hypojets late last year and my idle has improved. Mine are at the 3rd largest air hole opening (H203). Since I don't have an air fuel meter, I used Keith's instructions for setting up Hypojets without an AFM. The instructions are on his Yahoo Sidedraft Central Group in Message 4630. One point there is that the Hypojets can be damaged by overtightening, so he recommends just holding the screwdriver with the forefinger and thumb.

I also have a set of Keith's O3 emulsion tubes that I will try this weekend. Without an AFM, it will all be seat of the pants for me.

I would say the engine feels smoother and I no longer have as much crackle on the overrun.
However I already had a good state of tune with standard spec jetting.
There was nothing to complain about in the lower rpm and the AFR meter confirmed that it was about as good as it gets.
This was only achievable by following Keith's 2006 white paper. Before this I had lumpy idle, hesitation when moving off, stumbling between 2 and 3K, backfires, spitting!

So is what I am doing academic?

I think at low rpm I have got some fuel saving to be had since every time AFR goes below 12 I am throwing fuel away.
Besides I also reckon that an engine that is being fed the correct mixture is going to last longer.
I always have visions of rich mixtures washing the oil from the inside of the cylinders.

On the main jets (I might put them in and spin up the M1 this evening!) I definitely have some fuel savings to be made since stock jetting always goes to about 11 when cruising and there is no need for this! Controlling the AFR at wide throttles is going to make a big difference to performance.

If you have an AFR of 12.5 all the time you have maximum power all the time. Shimples

Simon,

Just an observation really, your figure of 12.5 to 1 AFR giving max power.ok I thankfully understand that.If you look at my post with dyno prints outs it shows an average 13 from 3500 to 6500 rpm, going by that if I were to richen the mixture would I get more power? To be honest I won't change the mixture as it may be better fuel economy at the moment and that's more important, oh and it's working too.

Paul

If you tune for anything greater than 12.5 on webers then you will get lots of unwanted lean crap.

You have an ECU and injection so AFR is more or less set at each point.
Looking at the weber graph can't see you would loose much HP at 13

As I say this gets dangerous since why not get 12.5 if you can - tweak tweak tweak