S52 OBDI chips - including large MAF + injector tunes

[matt]

I don't start too many threads to plug our products in here, but I have had a lot of PMs and posts about S52 software, so I wanted to let you guys know it's up on the site and ready to ship out. There are actually two guys on here running this software already... maybe they'll chime in and let us know how they like it? :mrgreen:

http://www.racersmarket.net/catalog/product_info.php?cPath=32&products_id=98

Turbo chips are on the site also:

http://www.racersmarket.net/catalog/product_info.php?products_id=130&osCsid=aac37be3116002edbf2c5264a5643e23

Thanks guys!

Almost forgot: The coupon code R3VSHIP is good for free USPS shipping on a chip (and almost anything you buy with it) in the lower 48 states.

[BimmerToad]

I'd like to hear any feed back on the NA S52 chip. My AA tuning is decent, at best :?

[static]

any dynos/comparos to similar offering from JimC? (Turner) that's what i have and i am lovin' it

[matt]

Comparing chips is hard. If you just swap them on the dyno and see what happens, the results are nearly meaningless. You need to run the car for a relatively long time with each chip to let the ECU adapt and then dyno each chip. This gets expensive if you're trying to do it all on the dyno. If you do the pulls on different days, the different conditions can throw the power off also. It's sort of a catch 22.

[lateapex31]

What exactly needs to adapt in the ECU? Kudos on the S52 software, you'll be hearing from me soon :-)

[vr4boy]

i purchased one of Matt's chips and installed it in my 90 e30m3 w/an s52 obd1 conversion last weekend.
i am very pleased with the performance-the engine runs way better now w/ the new chip/software- it brought out the "beast" hiding in that s52-pretty much could feel the difference with the butt dyno test:-)
prior to installing the chip-i was running the motor temporarily w/ a 413 red labelled ecu off a 93 325is(stock tune for a 2.5 engine w/ green top injectors) i guess with the miss-matched software between the 413 and the s52-it robbed the motor of performance and made it run rough-i noticed it being on the rich side.
performance is way up now and the term scolded dog comes to mind....

economy wise it helped too, as i notice some good gas mileage- i'm not getting that "running rich" feeling anymore(unburnt gas smell at the exhaust).

The Racer's Market(TRM) has a good product here and i give them a two thumbs up! (good product and good price).

on a side note,Matt's right about the ecu needing to "learn or adapt" ...after swapping in the chip,i noticed a dramatic performance improvement after about 50 miles of the learning stage....

next years plan is to drop in supercharger:-)

[etxxz]

i want ibdII software :(

[matt]

What exactly needs to adapt in the ECU? Kudos on the S52 software, you'll be hearing from me soon :-)

The fuel trims are set on the engine we use to tune the chip. Your engine may not have exactly the same intake track or exactly the same amount of gunk built up on your MAF or any number of other things. Your oxygen sensor will read the actual air fuel ratio under certain conditions and calculate an adjustment to the fuel settings in the chip for your specific motor. This is why it's so important to use an oxygen sensor.

[SchnellerVert]

The guy from SC with the 525iT with the swapped S52 just commented on your chip, said he was very happy with it compared to the TMS/Jim C chip.

[matt]

Just saw that over at the other place...

http://forums.bimmerforums.com/forum/showpost.php?p=11200976&postcount=98

[BimmerToad]

Comparing chips is hard. If you just swap them on the dyno and see what happens, the results are nearly meaningless. You need to run the car for a relatively long time with each chip to let the ECU adapt and then dyno each chip. This gets expensive if you're trying to do it all on the dyno. If you do the pulls on different days, the different conditions can throw the power off also. It's sort of a catch 22.

From my understanding, aren't adaptive fuel trims only involved with partial throttle performance, for the Bosch OBD1 system? WOT doesn't learn because the rate of change in the engine parameters is much quicker than the system can react to. Correct me if I'm wrong.

Now, I understand that comparing one chip to another is meaningless if the engines and dynos are different ...

[matt]

Fuel trims are calculated at part throttle and applied globally.

The ECU can read and react to all of its sensors very quickly even at max engine speed. There is a really simple reason for this, not hard to deduce. It has to do with AFR targets part throttle vs full throttle and how an oxygen sensor works.

[BimmerToad]

Fuel trims are calculated at part throttle and applied globally.

The ECU can read and react to all of its sensors very quickly even at max engine speed.

I understand that fuel trims would be applied globally, to account for a fowling fuel filter or changes in injector performance. Sensors are read at max engine speed, but not all sensors governing emissions at WOT.

AFR targets at WOT are determined by the tuner burning the chip, not some target AFR ratio. The OBD1 system we're talking about does not use the oxygen sensor under WOT.

Taken from a chapter about European engine control systems (Bosch) Hatch & King, Computerized Engine Controls, 2003

During wide-open throttle operation, the control unit commands a fixed enriched air/fuel mixture. To avoid fuel quantity miscalculations from airflow sensor fluctuations, at this speed the fuel quantity is calculated based on engine speed

I know future European emission regulations may call for closed loop WOT throttle systems, but our mid-90s OBD1 Bosch systems aren't that advanced. If they were, then there would be a much lower gain in power from aftermarket chips, since the WOT tune would have an ideal AFR for torque, and timing could probably be set a bit more aggressive.

There is a really simple reason for this, not hard to deduce...

Was that really necessary? Sorry man, but you're coming off like a total douche

[matt]

Was that really necessary? Sorry man, but you're coming off like a total douche

Well... sorry about that. I am trying to lead you toward the answer rather than just spitting it out.

AFR targets at WOT are determined by the tuner burning the chip, not some target AFR ratio.

I don't really understand what you're saying here. The person burning the chip (hopefully) decides what the target AFR is. At full throttle, that's rich of stoich 99 times out of 100.

Anyway, that quote doesn't exactly apply to the Bosch systems we use. There may be some systems that ignore the MAF because of resonances or other issues at WOT, but not ours. The MAF is NEVER disregarded.

Now, why it calculates the trims at part throttle. The AFR target everywhere between idle and 90% throttle is stoich. A narrowband O2 sensor reads very accurately only right at stoich. Basically, the ECU looks for stoich at part throttle, if it sees rich there, it decides that something is making the MAF read high or some other issue is going on... it removes fuel globally. Any issue that richens the mix at part throttle will apply at full throttle also. And the same thing applies to a lean mixture, but usually the cause of this is an intake leak. Same result, more fuel is added to idle/PT/WOT via a correction factor.

The OBD1 system we're talking about does not use the oxygen sensor under WOT.

That's sort of true, but doesn't tell the whole story. Hopefully, I made it clearer above.

[BimmerToad]

I don't really understand what you're saying here. The person burning the chip (hopefully) decides what the target AFR is. At full throttle, that's rich of stoich 99 times out of 100.

When you first mentioned target AFR, I thought you were implying there was a target AFR value of a WOT closed loop system. Now that I realize that you mentioned target AFR with respect to the chip tuner, so now we're on the same page. Sorry for the confusion.

Anyway, that quote doesn't exactly apply to the Bosch systems we use. There may be some systems that ignore the MAF because of resonances or other issues at WOT, but not ours. The MAF is NEVER disregarded.

My bad, totally forgot about the MAF.

Back to comparing chips, assuming a well functioning clean fuel system, would it take that long for the fuel trims to get a ball park figure prior to a dyno run? Sure the AFR might not be ideal, but it almost never is. Besides, there is more power to be had in the ignition tables of the chip than the fuel tables.