IXLR8

Why, are they not calibrated? Please explain.

Or are you making relative measurements.

NineMeister

The most fundamental job often overlooked is to balance the throttles first. Each bank of three throttles will have a master that has the throttle stop and two slaves which adjust from the master. Using an airflow meter to measure the flow, first disconnect the throttle linkages and sync the left & right master throttles. Then sync the left slaves, then right slaves, then double check they are all perfect. Once you're happy and the hot idle speed is about right, reset the TPS in the software to zero. Now reconnect the linkages and get someone to open the throttle with the pedal & hold the engine at 1500rpm, then adjust the left & right linkages to give the same airflow on the master throttles. Now you're ready to tune the idle.

Let's assume you are aiming for 1000rpm. One common mistake is trying to get the engine to run too lean, so first set the ignition timing to 7 degrees advance at 1000, 1250 & 1500rpm in the main table and 15 degrees advance at 750rpm. Now tune the main fuel table numbers at the same 4 points (750,1000,1250,1500) to a similar number until the engine runs happy. Now adjust the two throttle stops equally until the engine idles at 1000rpm, tweeking all 4 fuel points as required. Check the sync again once there. You can now reduce the ignition timing at the 1250 & 1500rpm point to 0-3 degrees (as required)
at which point the idle should be stable. Final job is to trim the fuel, it will probably need the same number from 1000 to 1500 with a larger number at 750rpm.

Now you're ready for cold start tuning:

Ideally (assuming you are using Motec or similar) you set up a tables for ignition correction on a load vs cylinder head temperature table and add 5-7 degrees of ignition timing at 0% throttle when the engine is cold. Finally set up the fuel CHT correction table to add up to 60% more fuel at 0C ramping down to zero at 100C and all should be good to go......

camlob

Dynos read differently mainly due to atmospheric conditions. Temp, altittude etc have a very big impact on dyno nos. Also fuel quality has a big impact. Later model BMWs retard timing due to fuel quality. Over here there was a E60 M5 which registered something like 340rwhp bec of that. Of course there are other reasons which Colin and the others could further explain.

NineMeister

All dynos are calibrated and in truth fairly accurate to their own calibration, however due to a variety of factors rarely do differing dynos agree with each other - a fact that causes more debates than is worth discussing again here. The good news is that 99% of dynos are very repeatable, so the rule is to pick one dyno and use it as the basis to make relative measurements, thus avoiding potential measurement errors.

For the record, the 9m dyno is a Bosch FLA203 updated with a Dynostar electronic & software package. I measure rear wheel HP and rolling losses which the software then recalculates to engine power and corrects the result to DIN standards using correction factors from the built in weather station. To avoid power variations due to engine intake temperatures I always locate the air temperature sensor next to the car door rather than the engine bay.

Jean

Camlob,

I don't mean to be picky, but one needs to compare max. HP/Ltr but at the same RPM level. The 997s get their max power at 8k+ rpms. Thats why efficiency (or BMEP if you will) is best measured at peak torque to compare two engines, and that is also why it is the benchmark used by people in the know to keep dynos truthful. Porsche engineers have internal guidelines (dating back to the 60s I believe) that they can never produce a new generation engine without improving its BMEP over the previous one, HP or torque alone is not an acceptable outcome for them.

My point was that in 3 generations and about 10 years, Porsche engineers with sizeable budgets were able to improve BMEP by only 12%, (BMEP 997: 187, BMEP 993: 167) and had to go watercooled, develop state of the art electronics, 4V per cylinder, custom and carefully designed cams, huge intake and exhaust improvements and especially higher compression. Certainly adding a Motec to an otherwise almost stock engine cannot increase peak torque numbers by any measure.. This is where dynos sometimes fail.

I am a big fan of Motec and personally considering buying one for my '74 twin turbo, twin-plug converted engine, however not because I expect more HP or torque, but for practical reasons given that my car is in the Middle East and I like its flexibility for an engine that is so custom.

BTW I disagree that Motronic is not up to the task or slow (993GT2s used it), it works perfectly with these engines and has all the safety guards required.

camlob

I would have kept my motronic if it was capable of handling the ITBs. But I was told Steve W. that it cannot handle that task. Probably worked for the GT2 back then but if Porsche could get their hands on a ecu with better processing speed, I think they would. Again, I am only saying this because the motronic couldnt handle my build. If I stuck with a cam, LWF and a SW chip, then maybe I wouldnt have changed it.

I think a motec on a 964 will be very beneficial by removing the restricted MAF. Must be hot now in the Middle East!

Macca

Hi Colin,

Thanks for your information. Much appreciated. I have now made changes to my files for "docking" with the cars ECU in early November.

I do have the ability to programme P and D values but I cant find the LINK version of "I" (Integral) values. I have an Antistall Gain table, Aircon Step Table and a Start up Step table along with a Base Position table (Solenoid % DC) and Idle Rpm table so perhaps its one of those?

The Link PC software has a tuition mode which advises on the base parameters to set the P and D tables to along with Anti Stall when starting out in closed loop so I have set those to the recommended base values also and will resume tuning from there using your recommend values for deadband, rpm etc

I have a TP% lockout (set at 0.8% - may be too low?) and have configured to read from the DI1 - digital input (speed) which provides a further lockout at below 10km ph (revert to closed loop idle). The RPM lockout value is a value added to target RPM value for given head temp which triggers reversion to closed loop mode so your 1500 rpm recommendation addresses that.

Do I need to set up the new ISV when I plug it in or can I just plug it in and use the Solenoid %DC table to tune it from there? Currently with the old ISV looking at my table the 1000 rpm range is achieved at about 35%. To achieve 920-930 rpm Id guess it will be around 30%. 0 Celcius starts at 53%. Does that sound realistic?

I have min clamp at 20% and max clamp at 70%.

I cant find where the alpha N tables you mention hook into the closed loop parameters. Are these simply the general and specific fueling and ignition related tables? The car has MAP and runs without lambda (it is used for setting up the engine only). I don't think that's relevant.

I guess Im curious as to if the car needs any dyno work at all for me to start using closed loop idle settings or if I can just work through this myself...?

Thanks in advance. You have been really helpful :-)

Cheers

Jean

There must be a misunderstanding of Steve's comments, of course Motronic can deal with ITBs!! Finding a tuner who knows how to tune Motronic is what is difficult, but they are around!! ITBs is much simpler than my 3.8 engine which was converted to twin plug, has no MAF and has the complexity of boost added to it, further, it still keeps knock sensing and runs a 993 Motronic ECU.

It also gives you more flexibility to run different fuels without risks to your engine.

Not to divert from my original comments, you cannot increase peak torque by any measurable amount by swapping ECUs.. You can improve response somewhat by changing timing tables and AFRs, but then you are compromising reliability or longevity.

I do like Motec for custom builds, but not due to performance improvement reasons.

camlob

Really? I double checked with Richard Clewett and he told me too that the stock motronic couldnt handle it. Believe me, if I could cut costs by not installing an aftermarket ecu I would have done it.

All the ITB builds in the engine rebuilding forum in Pelican used aftermarket ecu's. Well if I am wrong, at least I am with a crowd! LOL....

Jean

Camlob, I understand that this is what is being said and it is a perception that is out there, however Richard Clewett does not program Motronic, nor do 99% of tuners in the forums. They are out there, one needs to do research. I gave a live example in my car, which is a speed density converted engine, no MAF.

Motec is definitely more flexible for race cars that need quick changes, and you can have a number of different programs, sensors, etc.. at the tip of your fingers.

I am not debating Motec vs Motronic, I think both are great in their own way. I was more interested in the data shown as a decision-making tool.

camlob

Understood. BTW I like your car in the profile pic!

Jean

Thanks

NineMeister

The factory 993 Cup & RSRs often run Motronic in Alpha-N mode without a MAF sensor. The reason I choose Motec over Motronic is simply due to the availability of professional, reliable mapping tools with direct access to the ecu programme.

As for knock control, sure it's a safeguard, but let's not forget that Porsche built 76,500 3.2 Carrera's between 1984 to 1989 and fitted them all with an engine running Motronic without knock control. We have probably rebuilt 100 of these engines and I am yet to see one with detonation damage to a piston......

In respect of the results we see from the 9m Motec conversion of a 964/993, it's up to the individual to decide the worth of any upgrade they consider based on more than one single factor. For instance, I had one customer with a 964 C4 convert his road car to Motec purely on the grounds that I could get the car to idle perfectly with his lightweight flywheel. However, anyone in doubt as to the benefit is welcome to drop in to 9m, see the before/after results of every conversion we have done on our dyno then drive my car to sample the results for themselves. Furthermore, I'm that confident about the result we would achieve that I'm also prepared to offer a no-gain-no-pay guarantee to anyone who has a conversion who is not happy and return their car back to standard for nothing. Can't say fairer than that, can I?

Michael S.

Colin,

Is it possible to do an "out-of-the-box" Motec install kit? It would have to include an adapter harness, and probably slightly conservative programming. But, I would think for a given engine (98 3.6l varioram) you ought to be able to package a "kit". Maybe a dumb idea, but for those of us who don't live in England or anywhere near a competent tuner, it would be a welcome option.

Just thinking out loud, really...

NineMeister

No, Integral is a separate function.
The Base Position table is the key function which should allow you to set the normal open aperture of the valve which is Motec is around 48% duty. The proportional control will increase or decrease this number to achieve the Idle RPM target.
The start up Step table is a way of increasing the duty cycle when the engine is cold; Aircon & antistall are obvious & usually are an instantaneous % increase of the valve when activated.
Set the lockout to 2%.
The RPM lockout sounds like the idle speed vs CHT table.

Plug the new valve in & reset the frequency to 90Hz. If the Link has an output test function, with the valve in your hand look through it whilst changing the frequency and note the % number of full open and full closed. Use this as the start for low & high clamp. Then fit the valve & set the normal position at where it needs to be for 1000rpm.

I recommend that you work out how to set this up yourself, simply because unless your tuner has another 10 cars to convert he will not be willing to invest the hours required to work it all out....