MAF clamping

[Abbaso]

Hi guys as many of you know I was having problems with supercharger clutch disengaging at WOT.
I've clamped it with a 4.7 V 1W zener diode. It seems to have cured the problem also feel the car is a bit smoother but with less power. I will be getting it on a rolling road today if all goes as plan to check AFR's.
If AFR is not up to scratch will be trying a 5.0 V zener.

Just thought I would put it up here for those having the same problem. Pins 3 Brown wire and pin 4 brown striped yellow is where you place the zener with reverse biased as forward biased will clamp it to 0.8V. Meaning the side with the black ring (-) on it will go to the striped wire and the (+) will go to brown.

[John Jones Jr.]

Great news Abbas that you are making progress. Looking forward to hearing the results from the RR. I've replied to your PM. Don't forget to post the results.

[Abbaso]

Managed to get car to RR for AFR's. With Zener diode connected at WOT afr was 14.0 too lean. Zener diode removed afr was 10.8 too rich. So removing 4 bar FPR till I get kompressor pulley machined. Looking at installing a uni chip to clamp MAF and fuel it better. Gonna have to live with the S/C disengaging till then.

[Abbaso]

Anybody know what the max boost with turbo on M111K motor using stock ecu and helping fuelling with piggyback?

[KrumB]

Hi Abbaso,
I have not seen or heard of one.....

[Abbaso]

Here's a non kompressor turbo charged 202 by a company called Alpine Developments. It's running the stock ECU with extra fueling being taken care of by a 5th injector.(Look closer at the TB) It's a TDO 4 charger. Car was done about 13 years ago. It's currently in the process of being restored (engine not running well. Miss fire's)

[KrumB]

What power figures did it had at the time?

[Abbaso]

What power figures did it had at the time?

No idea spoke to the tuner they first gonna try and get it running as it's set up now. Failing that they will go aftermarket ECU. Will update once I know more.

[piko]

Hi!

I really don't believe that clamping the sensor is the best idea to prevent maxing it at 5v.
I've had some experience with Volvo Bosch ECU m4.3/4.4 and maxing the MAF sensor.
If you want to have more flow through the sensor without it maxing out you just increase the area of flow through the sensor (bigger MAF housing). That results in the sensor reading for example 10% LESS flow if the area is 10% BIGGER. At last to compensate for the decreased sensor reading you can increase the injector size by 10% and your A/F ration is spot on where it should be. So in effect if the sensor was previously reading a max of 5V it now reads a max of 4.5V with the A/F ratio spot on.
The only issue now becomes the ignition timing. You now read 10% less engine load so you effectively get more timing advance at any time. Optimally you would need an ECU remap to up the ignition or even the fuel if you decide to use factory injectors.
This is the only proper way to prevent maxing out the MAF. Clamping it is just a band-aid, because there's the ECU has no way of controlling fuel properly if it reads a static value when actual fuel demand is increasing.

Jan

[Abbaso]

Hi!

I really don't believe that clamping the sensor is the best idea to prevent maxing it at 5v.
I've had some experience with Volvo Bosch ECU m4.3/4.4 and maxing the MAF sensor.
If you want to have more flow through the sensor without it maxing out you just increase the area of flow through the sensor (bigger MAF housing). That results in the sensor reading for example 10% LESS flow if the area is 10% BIGGER. At last to compensate for the decreased sensor reading you can increase the injector size by 10% and your A/F ration is spot on where it should be. So in effect if the sensor was previously reading a max of 5V it now reads a max of 4.5V with the A/F ratio spot on.
The only issue now becomes the ignition timing. You now read 10% less engine load so you effectively get less timing advance at any time. Optimally you would need an ECU remap to up the ignition or even the fuel if you decide to use factory injectors.
This is the only proper way to prevent maxing out the MAF. Clamping it is just a band-aid, because there's the ECU has no way of controlling fuel properly if it reads a static value when actual fuel demand is increasing.

Jan

Hi you're right on that. I though about it and decided on a piggyback system that clamps the maf aswell as control over fuel and timing.

[piko]

Hi you're right on that. I though about it and decided on a piggyback system that clamps the maf aswell as control over fuel and timing.

Yes a piggyback will do the same essentially, but just by manipulating the MAF output signal. The only problem using piggybacks is setting it up properly so you don't have problems with the ECU compensating through short and long-term fuel trim.
This is theoretical given the fact all ME ECU's should work similar, but I don't have any experience with piggybacks myself.
My idea to set it up properly would be to temporarily take out and unplug the O2 sensor to force the ECU to run open loop mode (strait of the fixed fuel map with no O2 compensation). Then having the engine run at idle or low cruising watch the a/f ration with a wideband and adjust the fuel constant so the a/f ratio is steady at 14.7 where the ECU wants it to be when it adjusts with the O2 sensor connected.
This way the fuel trim compensation will be minimal like factory.
This is how I adjusted the fuel maps for bigger injectors on my Volvo, but using an open-source software to modify the maps and flash it.