dynoiasi Posted January 31, 2021 Report Share Posted January 31, 2021 Hello, I'm trying to fix some really bad jerking until I break something in my transmission. This happens on very low loads and especially when there is very little throttle. Low loads with more throttle usually do not trigger it. I attach a log with a mark where the jerking can be seen. I'm a little lost because the fuel DC and ignition seem to be pretty flat. Also no vanos switching and idle control/fuel cut do not seem to interfere. Please advice, thank you very much! https://www.dropbox.com/s/1mbyr1yf3eqoiay/Log 2021-01-30 4%3B13%3B59 pm.llg?dl=0 Best regards, Florin Quote Link to comment Share on other sites More sharing options...
Adamw Posted January 31, 2021 Report Share Posted January 31, 2021 Id say not enough advance, I would normally have around 40-45deg in overrun and cruise regions like that. Add about another 20deg in that area and see if it helps. Quote Link to comment Share on other sites More sharing options...
dynoiasi Posted January 31, 2021 Author Report Share Posted January 31, 2021 Thanks, I'll give it a try and post back. Quote Link to comment Share on other sites More sharing options...
dynoiasi Posted February 27, 2021 Author Report Share Posted February 27, 2021 Unfortunately advancing the ignition more or less aggressively did not solve the problem. It seemed to improve it a bit and for a while I thought it fixed it but no luck. What I especially tried was making sure all cells around the problem spot have the same fuel and ignition and you will see that in my new logs and settings. I learned and feel exactly when the car will start the jerking but I just can't cure it. Last thing on my list to try is disable CLL. Although on the logs the CLL seems bottomed out at -20% so it should not oscillate, it is my final lead. Here are the links to my latest logs and software: https://www.dropbox.com/s/tsucoq77q26r8r6/jerking 3rd gear.llg?dl=0 https://www.dropbox.com/s/7v7u4ngi1b4bdh7/jerk downhill.llg?dl=0 https://www.dropbox.com/s/a2bm8j0jyfd70c2/harta2021.pclr?dl=0 The only strange thing I see in the traces is related to the idle status and idle position DC. In "jerk downill" log for example, at timestamp 19.819 the idle status oscillates through a few states including "Active" which I don't understand. The RPM, vehicle speed and TP are all above the idle loop activation threshold. Also, the Idle position DC varies quite a bit and is larger than the value set in the table. At the current ECT the Idle position should be 45 or lower but it oscillates slightly around 46 - 47. It seems like this might be a idle regulation problem after all, but I don't understand what is going on. Any help is greatly appreciated, the car runs otherwise pretty good but this drivability problem is starting to drive me crazy and possibly also ruin the clutch . Thank you so much! Best regards, Florin. Quote Link to comment Share on other sites More sharing options...
0x33 Posted February 28, 2021 Report Share Posted February 28, 2021 Couple of things I noticed: - You can upgrade to latest firmware - Your idle status is doing some weird stuff, looks like a bug to me. I haven't seen it before personally, so might be a question for link staff. These are the possible idle status you can have, yet your idle status displays numbers that change as you are driving. Here is a screenshot from a log on one of my maps. Now compare your idle status from your log Not sure if that will have an effect on this jerking issue, but very odd behaviour. The idle status changing rapidly is also not common, as seen in some places in your log. - Your fuel map is not very smooth here Having 20% change between two cells is not ideal. Add more resolution to both your RPM & MAP axis in these areas if you need more fine control. - I dont have a lot of experience with E36 engines, but 470 degrees injector timing seems a bit high for idle/cruise areas. Try a range of timing from 320-470 in these areas and see if you can optimize the fuel delivery, this should have an affect on your responsiveness of the engine. - I've had a few motors with high compression & big inlets etc that want the opposite to what Adam suggested. Rather than 40-45 degrees ignition timing, try to reduce the engine's torque in these problem areas so it dosent try to fight itself as you in low load area. Start with around 10 degrees timing and make any ignition changes gradual and smooth as you work your way above 2500rpm. Again on your map you have areas where timing is jumping 10 degrees between cells, which wont be helping. - I don't know what injectors you are using, but I've had some injectors that react inconsistently at low pulsewidth. You can try making a virtual output that activates under the conditions you can identify the jerking happens under, then use that virtual output to activate a 4D/5D fuel and/or ignition map that either adds fuel or timing to try and help relieve the issue. Jerking is typically from too much torque or not enough fuel, so try and Quote Link to comment Share on other sites More sharing options...
Adamw Posted February 28, 2021 Report Share Posted February 28, 2021 37 minutes ago, 0x33 said: Your idle status is doing some weird stuff, looks like a bug to me. It was a bug that was fixed sometime ago but it didnt actually affect the way anything works from memory. Above the speed lockout the idle status was displaying speed for some reason. Quote Link to comment Share on other sites More sharing options...
dynoiasi Posted April 18, 2021 Author Report Share Posted April 18, 2021 Turns out in my case the jerking was caused by too much advance, like 0x33 suggested. I reduced significantly the timing/torque and the jerking is finally gone. Now my car is really starting to drive well, I just have to fix the long cranking / stall after startup issue and it's all dialed in Thank you all for you help! Gsab 1 Quote Link to comment Share on other sites More sharing options...
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