Reddit reviews Bosch Fuel Injection and Engine Management: How to Understand, Service and Modify

i personally wouldn't tune for knock, the power should be a bell curve so as you hone in on the best settings power should rise then fall after maximum power is reached, then start to drop off before it knocks.

so that is what i'd tune for. at worst knock tuning would be a disaster on some engines, and on others you're likely loosing power . at the dyno i've often seen people say tune to knock then back off a whatever a good number/% they've heard is.

you have to know a lot of about the math of specific engine you're tuning for to do proper calcs to get you base maps that are close, so since not all that is available, VE being the most useful, it often does become iterative and you just get a feel for it.

dynos aren't that complex, they just measure torque. the manual for them usually has the operation procedure in them, or the rep shows you. but basically you just do a pull on it while it measures rpm/tq and AFR then it plots an HP/TQ graph usually with some compensation for loss, or which conversion factor to use, SAE etc (where a lot of the online battles take place on dyno figures)

i prefer dynapak's myself, mostly since theyre a lot safer and i don't walk over the roller when concentrating on the laptop, and i've felt they're more controllable/repeatable but YMMV

https://www.dynomitedynamometer.com/dyno-dynamometer-article.htm has a good overview of the different styles.

these are some of the books i have

https://www.amazon.com/gp/product/0837603005

https://www.amazon.com/gp/product/0470057572

https://www.amazon.com/gp/product/0837611083 (general motronic overview)

https://www.amazon.com/Bosch-Automotive-Handbook-Robert-GmbH/dp/0837617324

https://www.amazon.com/gp/product/0837615410

https://www.amazon.com/gp/product/1932494421 good starter book

https://www.amazon.com/gp/product/0760315825

https://www.amazon.com/Auto-Math-Handbook-HP1554-Calculations (updated ver)

So the research that I was able to find this has Bosch k-jetronic fuel injection. This is entirely mechanical fuel injection and is complicated. I've got an l-jetronic (early electric Bosch fuel injection) and this book is the best I've found for understanding archaic Bosch fuel injection systems.

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My experience is that these systems are extremely sensitive to air leaks and their failure modes are not particularly intuitive. So it may not be a fuel system issue specifically as anything in the air intake system could be a problem too. I would replace the injector/air intake seals just to be safe as the closer the air leak is to the valves the worse the effect is on the system.

You beautiful fool you. Here's a link to the guide for the Bosch fuel injection system. You might want to get that on order now as you'll need it because that D-Jetronic injection system is an unmitigated nightmare if when it goes wrong. Take it from a man that tuned a K-Jetronic on a Brooklands Capri on the drive. Perhaps you could start saving too?

I have this book. It's pretty good:
https://www.amazon.com/dp/0837603005/ref=cm_sw_r_cp_api_5YS2xbFC5K3T1

This looks like a great thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=21015

This has all the pages from the Clymer manual:
http://www.vwtype3.org/literature/clymer/service/Clymer.1972.07.pdf

The thing about working on older Bosch systems is this: unless you find a true expert, that worked in a VW / Mercedes dealer in the 70's, nobody can fix it but you. You must take the time to understand the system, and troubleshoot properly. It's actually a really simply open loop EFI system (no o2), with a basic computer and barn door AFM. (Not MAF).

Also, it will only run right with a vacuum advance distributor, so if someone put a pertronix electronic ignition on there (as many do), get rid of that and go back to vacuum advance.