Custom Tuning

[Beej '86 325es]

I'll be blunt, I'm ignorant when it comes to tuning. I was planning on just doing the Turner cam kit with their software. However, the head I'm installing is using +1mm stainless valves, ti retainers, port/polish job, etc. Plus if the shop comes back and says that my pistons are unusable, I may go with a higher compression. I'm worried that the software that Turner provides will not run properly, especially since I have heard that their software is very conservative.

How difficult is it for a first-timer to do custom tuning?

What's my best option?
-reprogram ecu?
-piggy back system?
-standalone?

Thanks guys.

[matt]

You probably don't have the skills or equipment to reprogram your ECU yourself. If you do, that's the best option.

Piggybacks are a stupid hackjob way of doing things.

Standalone is a lot of money.

I would find an off the shelf chip from one of the tuner companies (AA and Jim Conforti/TMS are the big two) that's close to what you're running and go for it. The other good option would be to have a custom chip burned for your setup, but it's tricky to find someone who'll do that, and you need to dyno a few times to get it right and such.

[BimmerToad]

that's the big problem whenever going with any setup that deviates from the norm. If I was in your situation, break in the engine with a non-aggressive chip and run it for a bit, then try to find a shop that will burn you a custom, dyno tuned chip. It's pricy, but it will be much cheaper than the standalone options available.

[PeaveyBassist]

Piggybacks are a stupid hackjob way of doing things.

How is a piggyback a hackjob way of doing things? Is it the most ideal? No. But if you dont have the money or the skill to buy a standalone and tune it or have someone tune it then a piggyback is alright. I havent looked into it much but once you have a basic fuel map and a wideband o2 sensor it should be fairly easy to tune fuel on the street. Spark is a ALOT harder to tune and can be a lot more dangerous if you dont know what youre doing. Either get a custom tune to the ecu with the mods you have done, or standalone would be the best option though.

Will

[Beej '86 325es]

I am thinking that the Turner software will not be too far off. I suppose the ECU does adapt to how the engine runs. That's not a bad idea letting the engine break in with a conservative chip and going from there. I believe I have also read of Active Autowerke cutting custom chips and working with the customer, but I'll have to double check on that. Maybe that would be a good place to start. Whatever I do, I'll have to make a decision soon since my engine is being built right now.

[matt]

How is a piggyback a hackjob way of doing things? Is it the most ideal? No. But if you dont have the money or the skill to buy a standalone and tune it or have someone tune it then a piggyback is alright. I havent looked into it much but once you have a basic fuel map and a wideband o2 sensor it should be fairly easy to tune fuel on the street. Spark is a ALOT harder to tune and can be a lot more dangerous if you dont know what youre doing. Either get a custom tune to the ecu with the mods you have done, or standalone would be the best option though.

Will

No, a piggyback is alright under no circumstances.

An adjustable FPR can only shift the fueling curve up or down. On an ECU like the 413, it'll learn around that as well.

Building an interesting motor with odd cams or odd cam timing or other things that are "different from some other stock motor" only change the VE characteristics of the engine. the *shape* of that curve will be different. This is essentially what the engine will want to know. You will need a certain A/F ratio at certain load points in the RPM band. Likewise, you can run a certain amount of timing given certain amounts of load in the RPM band. The stock ECU for something like an M50B25 has a very pronounced dip in the ignition timing where the VE peaks. Move the VE peak to some RPM where the ignition isn't so retarded and you'll get knock. Hence the need for tuning that suits the specific engine.

One issue with a piggyback is that it attempts to trick the ECU. For minor corrections this may be *relatively acceptable*, but for larger changes it will do bad things. You throw giant injectors on a motor and try to pull the fuel back with a piggyback, you'll be messing with the MAF signal. Relatively low MAF signal even at WOT will mean you never hit the WOT tables. The engine may still think it's at part throttle, just assuming something is wrong with the TPS calibration. I assume you can see how this could lead to bad things. Ignition timing is also something that would need correction, but the piggyback "corrects" this by messing with the crank position sensor value. Go too far off with this, and its no longer sync'd with the cam position sensor signal... bad. These changes don't just mess with ignition timing though, it also will advance/retard injector pulse timing.... again, bad.

Tune the ECU for the engine, and tune it right. adjustable FPR, piggybacks, etc... when used as a "fix" like this are just a

do it right, or leave it stock.

What he said.

[Beej '86 325es]

Well, I called up Active Autowerke, and they can make a custom chip...for a price of course. But that's probably the route I'll go. Thanks for the input guys.

[matt]

How much?

[hugh jass]

Piggyback units like Unichips work great for custom tuning engine parameters. I know the owner of one of the best independent BMW and Porsche shops in Northern California and he has burned dozens and dozens of Unichips on some of the craziest turbo and NA BMWs and Porsches you've ever seen. Trust me, none of the finished products were 'hackjobs'. This is the route I am planning on going with my engine management when I finish my twincam swap.

[BimmerToad]

an AA 'custom' chip is far from ideal. I'm using one of their custom chips on my S52 cam'd M52, and their original chip ran too lean, and the fact that the chip didn't knock showed that the ignition mapping was far from aggressive.

Be sure to dyno the car after the AA chip and opt for AF ratios. If they're off, give the data to AA and have them modify the chip. If it's way off, they should do it for free.

After the 2nd chip, I've been happy with the performance, but I have yet to re-dyno the car.

[Beej '86 325es]

an AA 'custom' chip is far from ideal. I'm using one of their custom chips on my S52 cam'd M52, and their original chip ran too lean, and the fact that the chip didn't knock showed that the ignition mapping was far from aggressive.

Be sure to dyno the car after the AA chip and opt for AF ratios. If they're off, give the data to AA and have them modify the chip. If it's way off, they should do it for free.

After the 2nd chip, I've been happy with the performance, but I have yet to re-dyno the car.

That was pretty much my plan, it sounded like they'd recut one if it wasn't working properly. Is that all you checked when you had the custom chip cut...the A/F ratio? Is there anything else that I should monitor during a dyno run?

I imagine it won't be perfect on the first chip cut because of the extensive head mods. I may go with a more radical Schrick cam as well, since they are apparently available.

Matt, AA told me about $599.

[trent]

That was pretty much my plan, it sounded like they'd recut one if it wasn't working properly. Is that all you checked when you had the custom chip cut...the A/F ratio? Is there anything else that I should monitor during a dyno run?

I imagine it won't be perfect on the first chip cut because of the extensive head mods. I may go with a more radical Schrick cam as well, since they are apparently available.

Matt, AA told me about $599.

First off, a good dyno operator could probaby tune and burn you a chip for around a $1000. It is way too hard to have custom one off chips made by a company halfway across the US (not trying to slam anybody). It is best done in person in your area, real time on a dyno. I will be doing this on my engine.

I have a conforti chip for a stock M50 currently on my M52b28 with S50 cams, and the car fucking hauls ass. Your car will probably run fantastic on a stock chip.

Also, do yo have any pictures of your headwork? I would like to see how "extensive" your headwork was.

[ed94r]

Mark Dasilva (EAT chips/Mark D) can do it. He did a chip for a buddy of mine (a DSP hot shoe running a 93 325i M52 2.8 OBD1), so I know he has the ability to do late model OBD1 chips. He will probably require some kind of dyno pull to see what the AFR's are...So you may have to start with the stock software and go from there.

He is not easy to get-ahold-of, and sadly I don't have the contact # for him. You may have to go thru Ireland...but I would try to find him without the middle man. His price was very reasonable...

I personally used AA software for my S50. It was shaky at first, but after 2 edits, my AFR is Rock Solid...although I think the timing's a little hot, I get some ping down low in 3rd and 4th gear using 93.

Ed

[Kilomph]

You're going to have somebody burn you a custom chip who's hundreds of miles away? Are there really no local tuners? It took me 15 minutes to find a well qualified tuner "body motion" that's capable of reflashing my stock ECU on a dyno. I'll still get the JC chip so they have a good baseline mapping.

[BimmerToad]

That was pretty much my plan, it sounded like they'd recut one if it wasn't working properly. Is that all you checked when you had the custom chip cut...the A/F ratio? Is there anything else that I should monitor during a dyno run?

I wish there was a way to look at the ignition mapping tables, but short of having the chip code, I don't think this is possible (someone please correct me if I'm wrong).

I'm sure I'm missing a good 5-10 ft-lbs of torque throughout some parts of the rev range, but for the cost, it's an acceptable compromise. If I were to do some custom work to the engine, then a real custom chip would look more appealing.

Oh, and when you're talking to AA, don't settle for their BS about how your chip is perfect. Every engine is different and no chip is going to be perfect, but it should be close, especially if you're paying more for a 'custom' chip.