After looking thru E Bay, and not seeing much of a price difference, I got to ask. When doing an EFI swap, could a person run a wide band 02 full time? I'm NOT talking about the WB setups for tuning, as I already have a TT-1 from Dynamic EFI. I'm using a #16197427 PCM in my swap, and have read there's a way to tie a WB into the PCM on B16. I don't know all the details on this, just figured for roughly the same money I might gain some flexability. Thoughts? Thanks, Al

Simply because you can run closed loop to any A/F ratio, not just stoic. You can tune it open loop, but the closed loop will always compensate.

Thanks Doug. As this is all new to me, could you break this down a little more? I guess I really don't understand what your explaining to me, sorry, I'm still in the info gathering stage ( starting to understand most of the parts/theroy, but still lacking ). Thank you, Al

The reason that the Bosch O2 sensor is so inexpensive is that it was used in OEM applications. I believe the 1.8L turbo VW and Audi engines use Bosch sensor "fulltime." I've owned a Holley/FJO wideband with an NTK sensor since 2003. It was used to tune my Commander 950 setup as well as to provide the O2 signal for closed loop operation. My GTO now has an L92 setup with an OEM computer, but the wideband is still hooked up full-time as a monitoring device. It came in handy when I was on a road trip two summers ago. My fuel gauge said 1/2 tank, but I saw my fuel pressure going down and my wideband start reading progressively leaner. Gee....I must have run out of gas. :-)

Andrew

There is no need for full closed loop control once tables are properly tuned. If you have WB02 capabilities you should also have good datlogging capabilities. If you use AFR and get the tables dialed in they are not going to change provided the ECU has solid logic using speed density rather than MAF. There are some systems where you can run closed loop as opposed to actually tuning the tables, but why?? In this situation the ECU is always hunting where if the tables are tuned it knows what to do....

However, having a WB02 gauge on the dash is never a bad idea so you can keep an eye on things. Innovative Technologies has a nice gauge setup for a little over $200.

There is no need for full closed loop control once tables are properly tuned.....

I respectfully disagree. Closed loop operation makes for better drivability under a wide variety of altitude and weather conditions.

Andrew

I respectfully disagree. Closed loop operation makes for better drivability under a wide variety of altitude and weather conditions.

Andrew

Not going to hurt anything for sure, but.....

Speed density adjusts fueling for temperature and density variations and will adjust fuel accordingly. If the tables are properly tuned using WB02, AFR will not vary much at all with weather and/or altitude changes. Of course if tables are rough, then closed loop will correct this.

Been driving for over a year without closed loop, just tuned the fuel map with my wideband. Worked fine but was unhappy with my fuel economy. Yesterday I set my closed loop to now adjust for 16 a/f above 1400rpm and under 10% throttle. Seems to keep the a/f more steady at cruise, fills any minor holes in my map or any other anomalies. I have temp sensor heatsoak issues and sometimes that throws my a/fs off despite my fuel map being pretty good. Car sure feels sluggish at 16 a/f but apears to get better fuel economy. When throttle position passes 10% it just goes by the table and the car wakes up, burning lots of fuel in the process :p

I recommend closed loop but only if the settings are right. My megasquirt by default wanted to run closed loop on anything under 55% throttle, which would have been disasterous since I can hit boost in way less throttle than that with my 90mm TB. So just make sure its not gonna try and lean you out on hard acceleration.

Been driving for over a year without closed loop, just tuned the fuel map with my wideband. Worked fine but was unhappy with my fuel economy. Yesterday I set my closed loop to now adjust for 16 a/f above 1400rpm and under 10% throttle. Seems to keep the a/f more steady at cruise, fills any minor holes in my map or any other anomalies. I have temp sensor heatsoak issues and sometimes that throws my a/fs off despite my fuel map being pretty good. Car sure feels sluggish at 16 a/f but apears to get better fuel economy. When throttle position passes 10% it just goes by the table and the car wakes up, burning lots of fuel in the process :p

I recommend closed loop but only if the settings are right. My megasquirt by default wanted to run closed loop on anything under 55% throttle, which would have been disasterous since I can hit boost in way less throttle than that with my 90mm TB. So just make sure its not gonna try and lean you out on hard acceleration.

VW and Audis run closed loop under boost. Then again they probably have a room full of engineers putting in thousands of hours on idle...Get your tables right. LOL

Andrew

VW and Audis run closed loop under boost. Then again they probably have a room full of engineers putting in thousands of hours on idle...Get your tables right. LOL

Andrew

You guys don't seem to understand the differences in levels of ECU's you are talking about. A VW ECU is a far cry from anything you can buy to bolt on your hotrod. Most of the algorithms used in aftermarket stuff is hacked code from some other application. An oem on the otherhand has to ability to perfect the HUGE undertaking of live retuning based on lambda changes. The ECU's we are talking about here are like comparing ferarri to ford....both cars, but a few differences.

For aftermarket ECU's, stick with proper tuning and used closed loop cruise only if you like. I believe ms closed loop is shooting for a target, but should have drop out parameters for tps change not just absoluted position, tunable delay time for closed loop start, some kind of watchdog for MAP to drop closed loop, as well as other safety parameters. Now, if it doesn't....use it to tune only.

Since you guys are running full closed loop you should probably explain your technique for setting up the lambda reference table. It would also be interesting to discuss tps table correlation with the lambda table and prioritization. How are you tuning this?

It would be a great discussion and one you should be able to lead if you are tuning an engine using full time lambda table aka auto tuning.

I know alot about EFI tuning and this is not a tuning procedure I have been through since it is very complex, but I would love to see an in depth discussion.

You guys don't seem to understand the differences in levels of ECU's you are talking about. A VW ECU is a far cry from anything you can buy to bolt on your hotrod. Most of the algorithms used in aftermarket stuff is hacked code from some other application. An oem on the otherhand has to ability to perfect the HUGE undertaking of live retuning based on lambda changes. The ECU's we are talking about here are like comparing ferarri to ford....both cars, but a few differences.

For aftermarket ECU's, stick with proper tuning and used closed loop cruise only if you like. I believe ms closed loop is shooting for a target, but should have drop out parameters for tps change not just absoluted position, tunable delay time for closed loop start, some kind of watchdog for MAP to drop closed loop, as well as other safety parameters. Now, if it doesn't....use it to tune only.

Since you guys are running full closed loop you should probably explain your technique for setting up the lambda reference table. It would also be interesting to discuss tps table correlation with the lambda table and prioritization. How are you tuning this?

It would be a great discussion and one you should be able to lead if you are tuning an engine using full time lambda table aka auto tuning.

I know alot about EFI tuning and this is not a tuning procedure I have been through since it is very complex, but I would love to see an in depth discussion.

Very valid points, whatever your name is.

Andrew

Very valid points, whatever your name is.

Andrew


Chris....

I run the most basic version of megasquirt, very limited features and options. The later versions have A/F tables so you can have closed loop all the time but mine has only one target, I use it to maximize cruise a/f for fuel economy. I tuned my car on the street with datalogs, maybe if I had money I would do a dyno session and tune that way. Unfortunately I have to stick with street tuning, so no doubt my fuel map and ignition timing isn't perfect but it works well so I'm not gonna complain.

I run the most basic version of megasquirt, very limited features and options. The later versions have A/F tables so you can have closed loop all the time but mine has only one target, I use it to maximize cruise a/f for fuel economy. I tuned my car on the street with datalogs, maybe if I had money I would do a dyno session and tune that way. Unfortunately I have to stick with street tuning, so no doubt my fuel map and ignition timing isn't perfect but it works well so I'm not gonna complain.

Totally understand. I ran a diy variant that is a whole other story, but I tuned on the street. The engine was turbocharged so it was slow go getting it right. However, once I got the WB calibrated I was able to use datalogs only to tune once it was rough tuned enough to go down the road. It is pretty cool to tune your engine at the kitchen table!

Kitchen table, pshaw! Real coolness is tuning in real time as you drive :yes:

So part of what is cool about MegaSquirt is you can write it to auto-tune if you want. I can see a setup where you allow it to auto-tune for a few thousand miles and then lock it down.

What I would find interesting is how to optimize the ignition map. The fuel map is not that bad in that, with a wide band O2, you have pretty direct feedback and instrumentation. Ignition is not quite so closed loop. Sure you can do knock sensors, but that is not really the critical parameter. Really need some kind of fast pressure sensor that could be read in synch with engine operation. Given that it would be a simple software function to move the peak to the right spot.

Yea ignition timing is strange, there is no common answer, every engine is different. I've tried to ask for help and never get any so I really just hope for the best.

This company has dataloggers and sensors built into spark plugs to take combustion pressure, allows you to see where the peak pressure is for serious ignition timing feeback.

http://www.tfxengine.com/SuperchargedEngineData.html

They list no prices but I'm assuming it's not cheap. You need a crank sensor too so it can feedback the pressure in relation to the degrees. I've read you want peak pressure usually around 14degrees after TDC. If I had money i'd look into it of course if I had money I could just go rent a dyno for a day too. :p

Kitchen table, pshaw! Real coolness is tuning in real time as you drive :yes:

So part of what is cool about MegaSquirt is you can write it to auto-tune if you want. I can see a setup where you allow it to auto-tune for a few thousand miles and then lock it down.

What I would find interesting is how to optimize the ignition map. The fuel map is not that bad in that, with a wide band O2, you have pretty direct feedback and instrumentation. Ignition is not quite so closed loop. Sure you can do knock sensors, but that is not really the critical parameter. Really need some kind of fast pressure sensor that could be read in synch with engine operation. Given that it would be a simple software function to move the peak to the right spot.

Well, I was tuning a 9 second truck so driving was the main priority.....dilly dallying with the laptop was not a real option. I just mashed the go pedal for a few seconds, watched guages, and then went back home and sifted through data.

Also, using knock only is not an absolute way to tune timing. Running at the edge of knock ALL the time how you tune timing. Cylinder pressure at low throttle/low RPM is not going to produce knock easily, but that does not mean you just rachet timing up untill it does. EGT is actually one of the most useful parameters for tuning timing once you get AFR dialed in. You have to have a fast reacting sensor, but very good information when tuning timing. It gives you a good idea how much energy you are using and how much is going out the load pipes.

Yea ignition timing is strange, there is no common answer, every engine is different. I've tried to ask for help and never get any so I really just hope for the best.

This company has dataloggers and sensors built into spark plugs to take combustion pressure, allows you to see where the peak pressure is for serious ignition timing feeback.

http://www.tfxengine.com/SuperchargedEngineData.html

They list no prices but I'm assuming it's not cheap. You need a crank sensor too so it can feedback the pressure in relation to the degrees. I've read you want peak pressure usually around 14degrees after TDC. If I had money i'd look into it of course if I had money I could just go rent a dyno for a day too. :p
That is very cool stuff, thanks for posting that. :hurray:

stuff like this is how they run those NASCAR engines so close to the ragged edge for a couple hours at a time. You just can't do that without the detailed knowledge of combustion processes, you'll get burnt by detonation. this equipment has been in use by top teams for some time now, a big part of the reason why the gap between the haves and the have-nots keeps getting wider.