DIY_EFI Digest Wednesday, November 17 1999 Volume 04 : Number 648 In this issue: Motronic 4.1 newbie--fixed it! Airflow and A/F Mix calcs See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 17 Nov 1999 15:15:57 +0200 From: Putter C Subject: Motronic 4.1 newbie--fixed it! - ---------------------------------------------------------------------- Date: Tue, 16 Nov 1999 10:57:22 EST From: "Derek Kaznoski" Subject: Motronic 4.1 newbie--fixed it! I disconnected the battery, but this didn't help. However, while inspecting the joints between the plenum and engine, I noticed a large 3mm gap at the first cylinder. I repositioned the rubber sleeve and the car is running and idling again. Needless to say I'm psyched! My little mishap with the injector connector which caused the backfire was ironically my saving grace: the backfire blew the sleeve far enough out of place that even an idiot like me could see the gap. After I repositioned it, I could no longer hear the hissing sound here. I'm concerned, however, with the fact that the sleeve is spanning a gap of about 2 to 2.5 cm and just barely covers it. It seems that the plenum chamber isn't close enough to the engine here. Any tips on how to adjust the positioning of the plenum here? The idle is still a tad low, but basically the same as when I purchased the car. I think it would be better if the plenum were properly positioned, but maybe not. It just seems that malpositioning here would cause subtle airflow changes which could adversely affect performance. Also, the AFM currently on the car is not the original. The previous owner replaced the original with a refurbished one, but then found that the original wasn't bad after all. I still have the original one. The refurbished one feels much stiffer than the original, though still has smooth operation. The original one has noticably less resistance in its flapper opening. Even after detensioning the spring by 3 notches in the refurbished one, it's still a lot tighter than the old one. Should I put this old one back on? Would this improve idle/performance? (I know there is a lot of debate over this) Thanks, Derek '90 Alfa Spider [CPutter] Congrats. As far as I know the Bosch units controlls the idle speed by means of a electronic by-pass valve. The speed is sensed from the engine and is then regulated to the specifically programmed value. In som of the bosch training manuals that I have seen they specifically state that the idle speed is not adjustable. (Maybe it is Hard-coded in the EPROM). Another thisg you can check is if the by-pass valve is actually in operation. Close down the by-pass hosse while the engine is ideling, if the speed drops, and then when it is openned the speed goes higher than normal, then the closed loop control is still in-tact. (On my astra i can close this hose by pressing it with my thumb an finger, I do not know your set-up). Cheers Carlo Putter Stellenbosch South Africa ------------------------------ Date: Wed, 17 Nov 1999 11:04:49 -0800 (PST) From: Bob Moon Subject: Airflow and A/F Mix calcs Howdy all! Does anybody happen to have the calculations for airflow requirements of an engine handy? I want to start compiling the lookup table for the injection on my bike, but I can't find the calcs anywhere. Did I just miss them in the archives? Thanks, Bob Moon __________________________________________________ Do You Yahoo!? Bid and sell for free at http://auctions.yahoo.com ------------------------------ End of DIY_EFI Digest V4 #648 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".