convert Motronic to MAP sensor

[siverson]

Hi,

Have an idea to bounce off you guys, but I'm not sure if it's a good one or would work.

Recall, I have a 3.6 liter engine in my 914 w/ Euro RS cams, headers, and lightweight flywheel. I was having trouble with the idle/drivability when using the Autothority MAF/chip, replaced it with the stock AFM/chip, and things work much better. Still have a "sometimes stall on deceleration" issue, but the car idles and drives -very- smoothly. It's actually really strange, the 914 pulls/vibrates a lot like my 2001 Audi (except much faster) (and louder).

But, in the interest of squeezing as much power out as possible, I had an idea. And the engineer in me is saying, now that it works ok, why not take it apart again. Actually with my current setup the stock MAF doesn't fit well in the engine bay, and was thinking of an idea on how to get rid of it.

The idea:

Richard Clewett (sp?) uses a Manifold Absolute Pressure (MAP) sensor and a real (not 3-position) Throttle Position Sensor (TPS) (http://www.clewett.com/products/sensor.htm) with his Tec3 kits.

I'm using the Intercept Link to adjust the fuel map for the cams/header. (can't find the real web site, but here is some info: http://www.gururacing.net/DigitalMAFupgrade.html) This device can use the stock AFM, MAF, or MAP sensor as input. It also can take advantage of a real TPS.

Why not use Richard Clewett's modified sensors on the stock 964 manifold and the Intercept Link to convert to a MAP sensor? The MAP sensor would fit -really- well in a 914 engine bay (i.e. it's very small, and you wouldn't need the bulky AFM or MAF).

- Is there an particular advantage of a stock Air Flow Meter (AFM), or Mass Air Flow sensor (MAF), or Manifold Absolute Pressure (MAP) sensor, or do they all do the same thing?

- Is a MAF preferred over a MAP, or visa-versa?

- Would this work?

Thanks for any tips!

-Steve

[TimT]

Heres a Link

Link

I think Clewett is selling standard GM TPS sensors. When I set up a TEC , Link, or Haltech system, one of the parameters you need to tell the ecu is the range the TPS travels through. Typically with no preload in the throttle linkage you zero it (reads 0 volts) then you open the throttle fully and set that voltage.Now you have told the ecu the range of voltage to expect from zero to full throttle.

I dont know much about using the mass air units with motronic and a chip, but with the aftermarket enginemanagement Ive had experience with TPS and MAP were the sensors that the ecu used to determine ignition timing, and injector dwell.

I thought I read somewhere abouta chip that overcame the idle problems on 3.6 with light flywheels.

[siverson]

Thanks for the link. This is the device in particular:

http://link-electro.co.nz/interceptlink.html

-Steve

[1fastredsc]

Map sensor setups are neat, it's like the closest to instant throttle response you can have without having something like carbs. But you have to tune it alot, because as the motor wears the fuel delivery requirements change. But for a track car i definitely think that they are worth it.

[beepbeep]

Alpha-N: Perfect (near instant) throttle-response, hard to tune (must be re-mapped after each change), crappy idle. Otherwise optimal. Cannot be used with turbo. Good for naturally aspirated track engine.

MAP: Almost perfect responce (especially in conjunction with TPS), har to tune (must be mapped for your engine), works with turbocharging, slightly hard to get idling smoothly. Automatically adjusts for altitude. Best overall for race/performance engine.

MAF (hotwire): Little lazier responce, TPS should be used too. Very adaptive and doesn't need to be re-mapped so often. It measures air-mass so idle can be really good. Automatically adjusts for altitude. Slightly less free-flowing beacuse of hot-wire device but good nevertheless. Best option for strong street engine.

AFM (barn-door): Pretty half-a**ed responce, cannot adjust for altitude, adapts pretty well to changed parameters, not good for power (barn-door is obstacle in the path). Cheap and thus used on many cars. Suboptimal.


All that being said, i wouldn't mess with Mo(to)ronic anymore in your case but yank it out and replace it with Haltech, SDS, Autronic or whatever is fully mappable and has direct ignition (throw out that dizzy too). The step is not so far att all.

P.S. Certain designs (SAAB Trionic 7) use both MAP and MAF, just to take care of idle.