I love an expert when..........

[mark030358]

He says he does not carry the require bits and you find out three hours later. This happened to me today. Booked my car in last week for a rolloing road session to get the idle/progression fixed and I asked before hand did they have bits..... the answers was yes!

Well I pitched up today, he hooked up the sun unit told my my timing, plugs, leads etc were fine (well bugger me if i did not already know that!!) and he told me I was pushing out lots of hydrocarbons (offscale at 2000+) at a 4% CO level (he meant I was running rich, well bugger me again if i did not already know that too!!!) Anyway, step 1 was to fit his only set of idle jets size 58 (mine are 50) guess what............even more black smoke and hydrocarbons!!!!

Anyway after faffing around he said he could do nothing as he did not have any more bits............but if they were Webers than it would be ok as he has lots of that stuff (what !!!!!! but mine are f***ing dellortos as I told you!!!)

Then he told me I must have air leaks (but I'm running rich...........I said......am I mising something???) Guess what no air leaks (well bugger me thrice if i did not already know that too!!!)

DEcided to call it a day, the only good news is after 3+ hours I only paid for 1 hour at ?50+vat, o tell me what I already knew!!!!!!!!!!

The only advice he gave me was to get a large selection of idle jet holders (leaner ones for more air) and a selction of idle fuel jets and have a play...........doh why didn't I think of that.

Anyway, I'm looking for a favour from anyone out there who may be able to help. As idle jet holders cost about ?20 for 4 +vat and I will probably need four sets(ish) and jets are about ?12 for 4 +vat, does anyone want to lend me some to try? I will pay postage both ways and give you a cheque to ensure I return all of your stuff after I suss out what I need.

Also, as this guy tried to baffle me with science, HC and CO measurements, is there an expert who can describe the relationship and whats happening?

cheers Mark

ps contact me by mail and I'll tell you which rolling road not to use!

[john.p.clegg]

Your idle jets are 50 so you want smaller ones?
What about the jet holders?
John
Glossop
P.S. the rolling road is not manchester way is it?

[mark030358]

John,
Thanks for the reply. I am looking for idle air jet holders nos:-
7850.7
7850.6
7850.3
7850.1

idle fuel jets of size:-
40
45
58

obviously 4 of each size

thanks
Mark

ps not in manchester, but if you miss off the man, then its close to this old city.

[steveww]

%CO gives an insight in to the combustion process going on inside the engine. You want to aim for 5%CO which gives you 12.6 AFR (Air Fuel Ratio) this is the ideal for maximum power. 14.7 AFR or Lambda 1.0 is the best compromise for power / economy which is 0.1%CO

My Elan runs 12.9 to 13.8 AFR across the rev range. I have a wide band Lambda sensor to measure this.

To set up your carbs properly you really need at least a CO meter, buy one from Halfords or Ebay. A wideband Lambda probe and data logger is ideal but expensive. Depends where you are in the country as you are welcome to pop round and use mine.

You should do a search of the archives and read up on what Keith has posted on weber tuning. Yes I know you don't have webers but the pricipals are the same.

[v7slr]

I know someone selling the Innovate LC-1 wideband lambda controller and sensor for about ?130. Let me know if you want an intro.

These are new units. He has an arrangement with Innovate. I think he might have a similar arrangement with another WB lambda manf too.

[steveww]

Now you tell me My LC1 cost me a bit more than that.

[type26owner]

Ah, be careful here. The LC-1 is the cable version controller of the meter. There is no direct readout. It has it be feed into another data aquisition system as a another datastream.

My dream has been nearly answered with the soon to be introduced ST-12 from http://www.innovatemotorsports.com. Only I'll need one which runs off of 12vdc. I can see it now, I'll have to run a 110vac portable generator in the passenger foowell to make this unit mobile.

[v7slr]

The LC-1 can be fed into the XD-1 gauge (similar price) but really there's little point in a live readout of AFR. You plug it into your laptop and log the output there until you've enough data to make changes.

FOr those with the Zetec engine controlled by the Emerald ECU, the ECU will accept an analogue feed from the LC-1 and so allow you to log your AFR against your speed and load site. You can can, with patience, create an almost perfect map this way. A friend wrote a perl script which allows you to feed in your 3 readouts and it makes suggestions for injection map changes based on your target AFR for each speed/load site. Upon visiting Emerald for a RR session with his turbo Cosworth powered Westfield, Dave Walker (Emerald owner) found the map only needed changing to his preference for target AFR which was a decimal point of two out from my friend's original guess.

For those without the Emerald, you can log your output direct from the LC-1. Once you've actually set up the lambda, there's rarely a reason to double check it. I accept that carbs may wander from their original setting and so a double check with the laptop before each MoT might be advised, but I don't really see there being much point in a live readout on the dash.

That said, the XD-1 is a lovely little unit. Very colourful if a little distracting when driving.

[type26owner]

Yeah, but you're assuming everyone is comfortable doing the analysis using Logworks only. Additionally, the real problem it requires installing a TPS onto the Webers otherwise the analysis is seriously hampered without knowing and correlating that parameter. If you just watch the mixture with the readout it makes that part of it a lot simplier since your brain controlling the throttle is the TPS.

BTW, the TPS parts are available from Weber. Guessing it cost me close to $150. You have to build your own 5vdc power supply though.

Finally someone to talk about Logworks stuff with.

[v7slr]

Gosh yes. I'd forgotten about the TPS requirement.

I've got to be honest... I don't like Logworks. Since getting the Emerald on my Caterham's K engine, I've been lucky to have benefitted from the wealth of knowledge on the Se7ens list, and the UK based Se7eners. The Emerald has been THE choice of replacement ECU for most K'sters and it's not hard to fathom why when you see the data logging facility.

I admit to being a complete idiot when it comes to carbs. Injection based systems are so easy to the guy brought up on computers. Carbs require a deeper understanding of what's going on I guess. Using the LC-1, the Emerald and this analysis perl script it takes the guesswork out of it. In fact it takes any human interpretation out of it altogether. This is why it appeals to those who are relatively new to car tuning (me).

I genuinely think the LC-1 can be worthwhile for carb-based cars. Bill, the chap who sells the LC-1s, has a wealth of knowledge about carbs and is more than willing to show people how such a tool can be used for the diagnosis of such. It's hard to argue with his results.

Is a TPS really that expensive? Crikey, for a plastic film pot, that's a lot. I bought a stereo ALPS pot for a hifi application and it was less than half that. I'm genuinely surprised they're that much but I suppose it's a supply/demand thing? Could you not rip one off a scrap car?

[steveww]

I must admit that I do not like logworks so much either. At the moment I just have the logging of the AFR.

I found a nice quiet flat bit of road about 4 - 5 miles long. I did a number of acceleration runs and a number of steady state runs at different rpm. Then to the laptop and look at the data. I had already set up the carbs with a CO meter. I am happy with the current set up as the mixture is between 12.8 and 13.8 across the rev range, different loads etc.

I could not be so certain of the set up with out the wide band lambda meter. The cost of the unit is well worth it as it has saved me a couple of hours on a dyno not to mention burnt pistons and valves from running too lean. The only pain was the actual mounting of the lambda probe. The tail pipe mount from innovative is no good for the small dia pipe on the elan. I used a 12" length of 38mm silicon hose with the probe mounted in the wall of the pipe at one end. This bit of pipe was then attached to the end of the exhaust secured with a jubilee clip.

[type26owner]

Steve,
The main shortcoming of the AFM is it only displays the average AFR. If one or more cylinder(s) is off by a lot you'll not know without doing an analysis with LogWorks. Though just logging the AFR is of minimal usefullness. At the very minimum one should be logging the AFR, rpms and throttle position (TPS).

The new version of the software promises 3D mapping. I've not downloaded it yet to get familiar with the particulars yet but soon. They're ironing out all the bugs at the moment.

There is a way to look at just the one parameter AFR and see the individual datapoints as a bell curve distribution. Load up the logfile and use VIEW, STATISTICS, LAMBDA. That gives you the Gaussian distribution of datapoints over time. The time you can preselect with the SELECT_TOOL. You want a nice, tight grouping.

[type26owner]

To really see the AFR on each cylinder the O2 sensor needs to be mounted as close to each exhaust port at the head as possible. Guess I'm going to buy another S2 exhaust manifold afterall and somehow weld in bungs or thread holes through the cast iron. The iron is glass hard at the collector flange and maybe is like that everywhere. Might have to EDM the damn holes in that case. Only in that way do you see the individual exhaust stream from a particular cylinder. Otherwise with a single bung in the collector it's a trial and error process changing the jetting and looking for the datapoint bell curve slope standard measure FWHM (full width half maximum) to minimize. That would be tediuos procedure having to do that at least 8 times but possible.

[steveww]

I am well aware of the "averaging" effect of using just one probe to measure four cylinders. However with any complex system like this you should not rely on just one measurement tool. You should collect evidence from as many sources as possible and examine it all as a whole. Thus I use my CO meter, lamdba probe, checking plug colour, venier etc......

I agree an ideal set up would be one probe in the header for each cylinder. If I was racing and after the perfect tune and my budget allowed this is the route I would go. However I am just after a good state of tune for mainly road use. At the moment I feel confident that this is what I have achieved.