hoobby Posted June 6, 2020 Share Posted June 6, 2020 Analogue Resistance meter between pin 5 & 7 slowly & steadily open flap thought I would see the needle drop steadily down but keep get little increases through the whole sweep range VID_20200606_132216.mp4 car is starts first time every time and idles well fine to drive round town but on open road doesn't accelerate any where near as well as the 2.0s I had before.dirty sweeper plate?. Mot co2 check came out at 0.2 running lean? Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted June 6, 2020 Share Posted June 6, 2020 I bookmarked this a few days ago mate, guy spent a lot of time on L jetronic stuff, might help with testing &setup. http://alfa-wahnsinn.de/L-jetronic-america_gtv6.pdf 1 Quote Link to comment Share on other sites More sharing options...
hoobby Posted June 6, 2020 Author Share Posted June 6, 2020 Cheers jess think I'll carefully remove the cover and give it a clean up had it on a digital meter and its all over the place. 1 Quote Link to comment Share on other sites More sharing options...
hoobby Posted June 6, 2020 Author Share Posted June 6, 2020 TEA TIME Quote Link to comment Share on other sites More sharing options...
hoobby Posted June 6, 2020 Author Share Posted June 6, 2020 Well all cleaned and back together has made no difference to its behaviour Quote Link to comment Share on other sites More sharing options...
Snowy Posted June 6, 2020 Share Posted June 6, 2020 27 minutes ago, hoobby said: Well all cleaned and back together has made no difference to its behaviour They are almost impossible to test at home as you can check the wiper but not the combination of spring pressure v position of the wiper. The only way to do it at home is to check the wiper electrically then using a wide band lambda and check the fueling across the rev range. If it is out you can adjust the spring tension under the cover. If you still can't get it right it's time for a refurb, assuming everything else is ok. There just isn't any reliable way to test these with just a multimeter. 1 Quote Link to comment Share on other sites More sharing options...
Exclusive Opel Posted June 6, 2020 Share Posted June 6, 2020 Think the proper way to do it is to connect it up to 5 volts and measure the output voltage which will be linear in respect to the flap position. I may grab mine from the garage tomorrow and have a play. Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted June 7, 2020 Share Posted June 7, 2020 (edited) http://www.type17.ch/downloads/Injection/Bosch - L-Jet - Troubleshooting.pdf where to test with lamp and ohmmeter, might help especially if checking broken wires/terminals. Page 37 ish for wiring diagram for the pin outs of the afm. Attached picture seems to be correct output. but a great guide to testing the a 9v battery. http://www.clarks-garage.com/shop-manual/elect-22.htm Edited June 7, 2020 by Jessopia74 Attachment Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted June 7, 2020 Share Posted June 7, 2020 just out of curiosity what have you got the ignition timing set at ? depending on what petrol you are using it should be on the timing marks at idle or 5 degree retarded. this was the official reccomendation back in the day but modern petrol and condition of engine etc will mean this is only a rough guide. my 2.2 is actually set at standard timing marks but i have an adjustable screw on the vacuum canister to limit the advance rather than retarding the whole lot.this works great for me and definately better than full vacuum advance and idle retard.each car and engine will have its own happy settings 2 Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted June 7, 2020 Share Posted June 7, 2020 The engines are not set after tdc (retarded ignition). It is BTDC. Ignition wants to be as advanced as your engine can cope with without detonation. I believe it is 10Deg BTDC with unleaded. Just remember any setting static timing should be done with a true TDC marker and strobe gun for proper accuracy and vacuum hose taken off the disi. Just a further note on fuels- Old 4Star had sane RON as most SuperUNLEAD around 98. E85 will be closer to 102+ , so your static timing can be advanced more. Quote Link to comment Share on other sites More sharing options...
Exclusive Opel Posted June 7, 2020 Share Posted June 7, 2020 Had a quick play. I measured just resistance and moved the flap and had the measurments jump up and down. I did think it may be logarithmic rather than linear but that wouldn't explain the resistance droping lower than the previous measurement. With linear, if you plotted it on a graph, resistance against pot rotation position, you should get a straight diagonal line. There is more going on inside than just a carbon track and the wiper. However, it can be checked easily with voltage and the output shouldl be linear. These are my results after a quick try. I used a digital multimeter. Pin numbers taken from the AFM. Pin 5 and 8 - 362 ohms I just used a 1.5v new AAA battery. All we're looking for is a smooth consistant output. I wouldn't advise using a rechargeable battery because of the high output current if something went tits up like a short! Connect battery to: +v at pin 5 0v at pin 8 Measure the output on pin 7. With the flap closed: 1.2v (looking at hobbys photo above, the wiper doesn't go right to the end of the track, hence why it's 1.2v instead of 1.5v) Flap fully open: 0.38v Moving the flap gave a smooth changing voltage level. No guarantee mine is a good one to begin with but was working ok. Think I have a spare I could compare it to. Just to cover my arse, obviously don't do this while it's still connected to the ECU! 1 2 Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted June 7, 2020 Share Posted June 7, 2020 30 minutes ago, Exclusive Opel said: Had a quick play. I measured just resistance and moved the flap and had the measurments jump up and down. I did think it may be logarithmic rather than linear but that wouldn't explain the resistance droping lower than the previous measurement. With linear, if you plotted it on a graph, resistance against pot rotation position, you should get a straight diagonal line. There is more going on inside than just a carbon track and the wiper. However, it can be checked easily with voltage and the output shouldl be linear. These are my results after a quick try. I used a digital multimeter. Pin numbers taken from the AFM. Pin 5 and 8 - 362 ohms I just used a 1.5v new AAA battery. All we're looking for is a smooth consistant output. I wouldn't advise using a rechargeable battery because of the high output current if something went tits up like a short! Connect battery to: +v at pin 5 0v at pin 8 Measure the output on pin 7. With the flap closed: 1.2v (looking at hobbys photo above, the wiper doesn't go right to the end of the track, hence why it's 1.2v instead of 1.5v) Flap fully open: 0.38v Moving the flap gave a smooth changing voltage level. No guarantee mine is a good one to begin with but was working ok. Think I have a spare I could compare it to. Just to cover my arse, obviously don't do this while it's still connected to the ECU! Yes, so long as you see the smooth transition it should be fine. Great test results though. Quote Link to comment Share on other sites More sharing options...
cam.in.head Posted June 7, 2020 Share Posted June 7, 2020 1 hour ago, Jessopia74 said: The engines are not set after tdc (retarded ignition). It is BTDC. Ignition wants to be as advanced as your engine can cope with without detonation. I believe it is 10Deg BTDC with unleaded. sorry if we misunderstand each other here. i didnt mention anything about tdc.or after tdc.i quoted the timing marks which are as you say 10deg btdc.(or 5 deg btdc on carb cars) neither of mine will run without detonation at these marks( normal unleaded)and originally needed about 5 degree of retardation .and they are totally standard engines. definately better with the vacuum can mod thou ! all engines are different and as you say he needs the most advanced as it will run on (up to std) this was just something i thought he might need to check as obviously if the timing was out there would be a loss of power. 2 Quote Link to comment Share on other sites More sharing options...
Jessopia74 Posted June 7, 2020 Share Posted June 7, 2020 26 minutes ago, cam.in.head said: sorry if we misunderstand each other here. i didnt mention anything about tdc.or after tdc.i quoted the timing marks which are as you say 10deg btdc.(or 5 deg btdc on carb cars) neither of mine will run without detonation at these marks( normal unleaded)and originally needed about 5 degree of retardation .and they are totally standard engines. definately better with the vacuum can mod thou ! all engines are different and as you say he needs the most advanced as it will run on (up to std) this was just something i thought he might need to check as obviously if the timing was out there would be a loss of power. Yes I read it the other way, but I see what you mean now.👍 1 Quote Link to comment Share on other sites More sharing options...
Exclusive Opel Posted June 7, 2020 Share Posted June 7, 2020 There is some good info here: https://www.k100-forum.com/t11055-bosch-air-flow-meter-restoration-summary 1 Quote Link to comment Share on other sites More sharing options...
hoobby Posted June 7, 2020 Author Share Posted June 7, 2020 (edited) Yet Again thanks guys some fantastic information there will need some small crimp connectors before I test the AFM I can't rig anything up I'm happy with don't want to fry it Will plug and play ignition and check fuel pressure also remembered one of my mantas (carb) in the past ran like this went through the list found nothing wrong took it to a garage turns out one of the cam lobes had worn down got another head from breakers had the choice of five (yes it was a while ago) stunning change. I would just like to add that cover I really don't think they wanted anyone in there a totally nerve racking experience getting it off especially as the bonding starts to give loud sharp plastic splitting sounds...oh crap...no its OK....oh crap...ect. Edited June 7, 2020 by hoobby Quote Link to comment Share on other sites More sharing options...
Snowy Posted June 7, 2020 Share Posted June 7, 2020 Just remember that all these measurements, whichever way you do it, are only testing the electrical side. The AFM has a flap that is moved by air, the flap is governed by the spring pressure under the cap. The flap position is used to calculate the fuelling based on the measured airflow. Hence why I said you need to check the ECU's interpretation of the flaps movement by using a wide band lambda sensor. It used to be a popular mod to these types of airflow meters to adjust the spring tension to get more fuel into the engine for any given movement. Springs do weaken with use and age and not always uniformly. So there is a bit more to testing these than checking the carbon track. Quote Link to comment Share on other sites More sharing options...
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