Quote:
Originally posted by bowlsby:
Nice work again Paul. You are assembling a great wealth of data on the D-Jet system
Curious about how this information might be used:
1. Evaluate an ECU for functionality - publish a docuemnt with input/output data.
2. Make a test bench for testing ECU's (need a special harness for a test bench?)
3. Add an idle mixture control knob to early ECU's without the knob?
4. Add part load/full load enrichment adjustability for turbos/bigger displacement upgrades?
What might you have in mind?
Jeff
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Thanks, Jeff. I mainly did it initially because I wanted to know what is going on in that skinny lunchbox. But obviously, there are things that you can do once you understand the operation of the ECU. To answer your questions:
1. Evaluate an ECU for functionality - publish a docuemnt with input/output data.
Actually, that's what Frank Kerfoot did with the ECU schematics. I'd like to do it with some additional data and waveform displays. I've got most of the equipment, but it might be a while before I get going on it.
2. Make a test bench for testing ECU's (need a special harness for a test bench?)
I'm working on this, albeit slowly. Jim Thoursen has already built a beast like this. I would have been a bit closer, except some ding-dong on Ebay decided to jack the price up to $40+ on the used injectors I was going to snag!
3. Add an idle mixture control knob to early ECU's without the knob?
It is probably fairly easy to do this. I haven't seen one of these ECU's yet to see exactly how.
4. Add part load/full load enrichment adjustability for turbos/bigger displacement upgrades?
Turbos are limited with the stock D-Jet system to about 5 to 7 psig of boost, due to the limitations of the MPS in handling positive manifold pressure. Within limits, retuning D-Jet for bigger displacement should be fairly simple, by readjusting the MPS, and if necessary, by boosting base fuel pressure up to as much as 35 psig. I don't think it's necessary to modify the ECU to handle larger displacement.
A couple of people have asked me about adding closed-loop control with an O2 sensor. I think it's do-able by adding circuitry to the the TS2 connection, but I don't see that it's at all necessary. Mixture control with D-Jet is more than adequate for good performance across all operating loads. The only reason you might want to have closed loop is if you decided for some reason to fit a 3-way cat converter to your car - which is unlikely.
A more interesting mod would be to adapt an idle stabilizer to the 914. I haven't looked into it but a lot of owners could benefit. Even when D-Jet is properly tuned idle stability is marginal.
Brad Anders