[Terry335]

Hi gang, I'm pretty sharp when it comes to tuning but somewhat of a n00b with regard to electrical engineering. I could use an experts help.

Terry Tuner v1.0 has control of boost, but now I need to retard timing. My first idea was just to use a simple op-amp, relay, and resistor to crank up the IAT temperature when boost is over 8psi. This works, but has limitations and side effects. Mainly, it doesn't pull enough timing for our needs.

So, I'm working on a more advanced concept. Offsetting the CPS signal.

I've located the following frequency to analog IC which I want to use to "listen" to engine rpm:

http://www.national.com/pf/LM/LM2917.html

This will be the trigger for controlling the boost curve with regard to RPM, triggering o2 enrichment in the midrange, and offsetting the CPS (once I figure out how to do it). As an aside, I'm starting to think I should learn about simple programmable chips rather than messing with op-amps and reference voltages.

So my big question for you EE's is how can I offset the CPS sensor signal? I haven't scoped the signal yet and don't know much about the sensor specifically, but want to get an understanding of the basics involved.


Thanks,

T

[schneid4323]

I thought Terry Tunner was a one man crew

[Terry335]

Originally Posted by schneid4323

I thought Terry Tunner was a one man crew

Nah its open source/forum development.

[Terry335]

I guess all the good EE's drive Corvettes??

[e.n335]

Originally Posted by Terry335

I guess all the good EE's drive Corvettes??

Terry you should build something that doesn't exist. 335i car-pc is already reserved, my project

[zenmaster]

Originally Posted by eugen.niederreiter

Terry you should build something that doesn't exist. 335i car-pc is already reserved, my project

Do you have the car-pc using the i-drive display?

[e.n335]

Originally Posted by zenmaster

Do you have the car-pc using the i-drive display?

It's a project, nothing finished. I need to see if the i-drive display's resolution fits the requirements. In principle it can be used.

[Terry335]

Originally Posted by eugen.niederreiter

Terry you should build something that doesn't exist. 335i car-pc is already reserved, my project

This is just for boost/timing control. Tell me what you know!

I think I'd need the DtoA converter, some circuit that does the shift, and then a AtoD converter.

[scalbert]

First, how much timing are you wanting to pull and why do you feel it is nessesary?

I was thinking the opposite in that you may want to add a degree or two. I was thinking about decreasing the percieved IAT readings to gain a little timing as well as enrich the mixture.

And the connectors are getting closer...

[Terry335]

Originally Posted by scalbert

First, how much timing are you wanting to pull and why do you feel it is nessesary?

I was thinking the opposite in that you may want to add a degree or two. I was thinking about decreasing the percieved IAT readings to gain a little timing as well as enrich the mixture.

And the connectors are getting closer...

Bad idea to put timing in, we need to take it out to avoid knock under the higher boost level!

If you increase the IAT reading it will decrease timing slightly and increase boost slightly (per the ECU logic). The IAT doesn't have any impact on the fuel mixture from what I can tell.

The biggest problem I have right now is the midrange. To add 2psi at up top I wind up adding 3psi down low, and down low the AF settings are pretty lean and the timing is more aggressive. It becomes risky adding more than 2psi up top.

The RPM IC above will let me adjust the boost curve so I'm only adding boost up top, where the factory AF ratio and timing is more reasonable. If we run stock boost up to 4500rpm and +3-4psi over 4500rpm, I think we'd be OK with only pulling 1-2 degrees of timing via the IAT (need to scan and verify, try at your own risk). That arrangement would probably put down similar peak dyno numbers to the procede. You’d lose out on the midrange boost but it would also be much more street tire friendly.

That lead to the idea of actually reducing timing through the CPS, which may or may not be easy. Waiting for good EE help on that. If we could pull out say 4 degrees in the midrange we could run a lot more boost down low.

[scalbert]

Originally Posted by Terry335

Bad idea to put timing in, we need to take it out to avoid knock under the higher boost level!

If you increase the IAT reading it will decrease timing slightly and increase boost slightly (per the ECU logic). The IAT doesn't have any impact on the fuel mixture from what I can tell.

The biggest problem I have right now is the midrange. To add 2psi at up top I wind up adding 3psi down low, and down low the AF settings are pretty lean and the timing is more aggressive. It becomes risky adding more than 2psi up top.

I would think a little timing would be fine on good fuel. Since the car can run on 91 octane, it should be able to handle a modest boost increase and a degree or two timing.

However, it is just speculation on both of our part as we cannot see the knock activity or KR.

On the IAT, I suspect it does play a big part in the load determination since this is a speed density system. The lack of a MAF means that it is working solely on absolute pressure and the other piece to determining air density; temperature.

[scalbert]

Why not modify the O2 signals as well? Of wait, by the time you have finished modifying the MAP, CPK and O2 signal you now have a PROcede.

[Terry335]

Originally Posted by scalbert

I would think a little timing would be fine on good fuel. Since the car can run on 91 octane, it should be able to handle a modest boost increase and a degree or two timing.

However, it is just speculation on both of our part as we cannot see the knock activity or KR.

On the IAT, I suspect it does play a big part in the load determination since this is a speed density system. The lack of a MAF means that it is working solely on absolute pressure and the other piece to determining air density; temperature.

Yep, the map reading and temperature is used for boost. I've found about .1psi per 10 degrees on the IAT.

Until I see the KR I can't say for sure how much timing we need to take out or if it can take more timing, but I strongly believe we need to take out timing.

The O2 sensors are easy enough to adjust, you just add or remove a little resistance to knock the current up or down. It's something to play with after we figure out timing.

[RiXst3r]

Originally Posted by scalbert

Why not modify the O2 signals as well? Of wait, by the time you have finished modifying the MAP, CPK and O2 signal you now have a PROcede.

Something to be noted is that the PROcede/Xede approach is very over developed for what the actual need is(lots of software, and many inputs/outputs are not needed, and all the extra stuff for compatibility with other cars). Its practically a full on computer. An interceptor with components created only for a 335 with specific hard wired logic, and zero extras would be significantly cheaper. More like a turbo tuner, but with a few more wires.

The terry tuner might have a market after all

[scalbert]

Originally Posted by RiXst3r

An interceptor with components created only for a 335 with specific hard wired logic, and zero extras would be significantly cheaper. More like a turbo tuner, but with a few more wires.

And a factory ECU harness adapter so that it is truly PnP.