Winter Clean - Afm Setup Etc

[gtimon 0]

I'm going to do a Winter Clean and Retune.

 

By this I mean I'm going to clean all the breather and intake Hoses, Throttle body ports etc, SAD and allsorts. Then recheck the Timing and Mixture settings, but my Hanyes manual tells nothing about the AFM setup. I've done a search on the subject, but all I find is 'fitting other types etc'

 

How do you check, clean and set up the AFM as I think the previous owner has messed with it, because the spring box cover is taped on.

 

I've the info for the setup for the LE system of the throttle and switch settings using a vacuum gauge and meter, but nothing for AFM when setting the mixture etc.

[jim21070 2]

The AFM can be set up. I do it like this. I emphasise this is my way and this method may not meet with universal forum approval but it works for me.

 

Clean the AFM internally with carb cleaner and a toothbrush and get it sparkling. Ditto the TB, SAD and all the breather hoses, oil pot, lid, gauze etc. Ensure no air leaks anywhere on the inlet tract.

 

Replace sparkplugs, overhaul ignition system and ensure timing is pretty well spot-on.

 

Ensure the TB butterfly and TPS are correctly set up as per the joke book.

 

Set the idle mixture screw on the AFM to half-way.

 

Then, get an exhaust CO analyser (The Gunson one is OK but let it warm up for a good 20 minutes on its own battery)

 

Run your engine up to full working temperature and take a CO reading at normal idle (900rpm).

 

This is only valid if everything on the engine is tip-top, hence why I say above what to do first.

 

Now Rotate the cogged wheel in the AFM to bring the CO reading to a low point (aim for about 0.5%-0.8%) Bear in mind that if you use the Gunson CO meter it has a longish reaction time so adjust slowly and allow the CO reading to stabilise. You will find two low points, one "rich" one and one "weak" one.

 

Rev to 2500rpm and check the CO level again at 2500rpm. It should be very low (between 0.5 and 1%)

 

Idle again, reset the idle speed if need be and then put on all electrical loads (headlamps, driving lights, HRW, heater blower). See how far the idle drops. It will drop a little but should not drop by much. If it really drops and hunts with the heavy electrical load on, redo the CO setting but choose this time the other low point and try again.

 

You are looking for a nice even idle at 900 rpm with very low CO, an idle that does not wander (hunt) and one that changes little under heavy electrical load.

 

Snap the throttle open and ensure the engine picks up very cleanly with no hesitation. Check again the CO at 2500rpm and ensure it is very low still.

 

Job done. Reseal the AFM cover with a bit of automotive grade silicome RTV.

 

As I say, that is my method and it works for me. There is a danger that this method can cause a high rpm, foot flat to the floor lean-out so if you want to be really sure have this job done on a Rolling Road.

 

I find I need to redo this setup in late spring and early autumn to cope best with the seasons. Another side bebefit of this job is it improves economy no end!

[KRISKARRERA 2 1 Cars]

Snap the throttle open and ensure the engine picks up very cleanly with no hesitation.

So if you snap throttle open and there is hesitation what does that mean?

[jim21070 2]

So if you snap throttle open and there is hesitation what does that mean?

 

Thanks for being my critic and reviewer Kris I do need it...

 

Good point, in my book, if it does not rev cleanly when snapped open it means that the adjustments made are not right and you need to back-track and reset the idle CO again, perhaps choosing the other CO "low".

 

I also should also have said that it's a good idea to mark the original setting in the AFM and to not move the cogged wheel any more than about 7 "clicks" either side of the original spot. If you get in a muddle it is then easy to get back to a known starting point.

 

I should also have said that the adjustment method is only good for an AFM known to be tracking OK. It is a good idea to check the tracking of the AFM by using a 9V battery and a high quality analogue voltmeter to watch the smoothness of the voltage swing as the flap is opened and closed. I cannot recall for the life of me the pins the battery connects to and the pin the voltmeter goes to but I'll dig it out. If the voltage swing is "bumpy" or jerky, this shows a retrack is needed and this must be done before trying to set the idle CO.

 

I also stress again that setting up an AFM like this is only valid if it is known that everything else on the engine is in first-class order. It is the last adjustment to be done and should never be used to overcome another problem.

[gtimon 0]

Well i finally got round to do the winter clean, thanks for your tips.

 

I downloaded an article "205 GTI Basics - by Zoldalma" which discribes the AFM setup etc.

 

In this I think I found an error, where the drawing showing the pinout for the Jetronic is back to front. Unless where he states (pictures show the unit side) is looking from inside the spring box ??

 

Anyway I think I found one of my problems where I can't get a the CO within the 2%, where the best I can get is between 4 & 6 %.

 

The Ohms reading on pins 5 & 7 starts at 109ohms then as its suppose to rise smoothly to approx 1k. Mine is very wild, at some positions I can get 20k or more at approx a 1/3rd to 2/3rds travel, then at some point along it shows as should approx. 800ohms then drops to 200ohms then back up or total short (off the scale on a 200k setting on the digital meter). I've tried cleaning it with electrical electronic switch cleaner with no joy.

 

Can I replace the graduated scale card or do I have to replace the whole AFM assembly.

 

Help please

[gtimon 0]

I've just tried to reposition the PCB board, can't undo the screws.

 

But if I did bend the wiper arms, with what readings I've got, would this do any good.

Bending the wipers that is.??

 

Just tried bending the arms, still no good.

 

Where can I get a new pcb board, cause if I get a AFM from a scrappy I could still in the same boat.??

Edited February 10, 2007 by gtimon

[gtimon 0]

While searching the net for AFMs and PCB boards I came across that using an "Emerald ECU". You would not require the AFM, only the throttle position switch, but would need an 02 sensor.

 

Has anyone tried this ??

[welshpug 1,627]

yup! loads of people use emerald, the most famous I remember was one of richard burns's 205's IIRC, standard injection but with the AFM dispensed with which is what I think would be every 205 owner's dream (if they didnt want a turbo or throttle bodies that is )

[Martin@PRD 0]

Im sorry, but it may seam right, but you cant set the Afm by hand by means of a DIY single test exhaust analyser, simply doesnt work or everyone would do it,

 

The most important thing missing in all of this is engine load, reason for rolling roads as they simulate load by using a low gear (4th)

 

The plastic cog which you describe is to calibrate the Afm (1.6 and 1.9 are different) this will have an major effect on throttle response if incorrectly adjusted, luckily over the years I have worked out how to over come kangarooing etc, which was due to DIY's messing with something they dont understand or have the means to adjust

 

My advice is to clean all Breathers, sad, remove cold start device and wire brush it, check that all the pins on engine plugs havent been pushed out, earth points are clean and free from corrosion, give battery terminals a good clean and a general good service.

 

Its all ways a good thing to give a engine a health check by means of Rolling road and more importantly someone that knows what they are doing, I have never come a way from a rolling road with it the same Afm/ignition timing going in and I always Get any new car a tune or an existing one every year

[gtimon 0]

Is there any where you can get a new or remanufactured PCB board for the LE-2 Jetronic AFM No. 0 280 202 109.

 

Thanks

[Ricardo 0]

Did you check this out about AFM?

 

http://forum.205gtidrivers.com/index.php?s...6&hl=antics

 

This is also a very interesting read!

 

http://frwilk.com/944dme/afm.htm

 

Good luck!