Hi,

Paulf is kindly making me up a MegaJolt box. The question is, do I go for a throttle position sensor or MAP system?

Its for an 1800 zetec on 130ps cams. Yamaha R1 carbs on a Bogg Brothers inlet manifold.

If MAP is the answer, then where should I tap into for my vacuum reading? In the manifold before the carbs or into the airbox after?

If I go for TPS, will the standard Yamaha pot be ok or will I have to make the standard zetec one fit?

Any advice would be really apreciated.

Thanks
Stuart

[Edited on 16/3/06 by wesley_uk2k]

Hi Stuart

Map gives a better indication of the load on the engine, but you need a good clean vac signal

If the carbs dont have a vac take off, you can drill the 4 runners. The 4 vacs will have to go to a common point then to the megajolt

If you dont get a clean vac it makes it harder to map as the Kpa reading will jump about

TPS is a lot easier, the Yamaha pot will probably be ok it depends on its ohm reading. I'm hoping to use one off an efi sierra which is about 5000 ohms

Adrian

[Edited on 16/3/06 by ady8077]

Thanks for a really clear reply. I think I'll take the risk and ask if the megajolt board can be soldered up for MAP. There are 2 pipes described as "Vacuum chamber air vent hoses" and hopefully I can get a good reading from them. If not then I'll try the manifold.

I've heard people talk about using a damper. Are they just referring to a box with some foam in to steady any pulses?

Thanks
Stuart

normally not even got foam in - just a small canister with an inlet and outlet. Some have use the little CO2 things you get for blowing up pushbike tyres.

quote:

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Originally posted by wesley_uk2k

I've heard people talk about using a damper. Are they just referring to a box with some foam in to steady any pulses?

Thanks
Stuart

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Road or track? If it's track or a high strung motor don't bother with the vacuum signal, you don't need it for spark.

You can get a fuel trap/pulse damper off the vacuum line on a Rover 214 it is fitted in the vac line between the throttlebody and the ECU.

Ive been wondering the same. Paul has told me that Map SHOULD be fine if you can get a good clean signal. ive not had it running yet so cant tell you for sure.

This is how ive taped the runners.

I will feed all 4 into a co2 bulb that I got from Paul (Thanks) and feed that to the Map sensor in the megajolt ecu.

I don't mean to sound stupid but why do most normal systems have a TPS and MAP or TPS and AMM/AFM.

If you can just run with one or the other.

TPS gives a better indication for acceleration enrichment on a fuel injected system than MAP or MAF, but cannot provide an accurate indication of airflow over the entire operating range of the engine (because most of the action happens within quite a small range of movement of the throttle).

There is also the question of redundancy on a production car, the system should be able "limp home" should one of the sensors fail.

The megajolt is ignition only and so just requires the map or tps sensor.
I think either will be fine for road use as long as a good vacuum signal is supplied as discussed.The yamaha TPS will work ok as anything in the range of 5 to 10 k ohm will do.
Paul.

quote:

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Originally posted by MikeRJ
TPS gives a better indication for acceleration enrichment on a fuel injected system than MAP or MAF, but cannot provide an accurate indication of airflow over the entire operating range of the engine (because most of the action happens within quite a small range of movement of the throttle).

There is also the question of redundancy on a production car, the system should be able "limp home" should one of the sensors fail.

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Thanks for all the posts. MAP it is please paulf

As a related question, is the MAP sensor affected by 'T'ing off to the fuel pressure regulator with the same vaccum line or is this normal practice?

Chris

As far as i can see its normal practice, im running a megajolt for ignition and also adding megasquirt for the fuel so will have 2 map sensors running from the throttle bodys .Im hoping to get it started next week so will find out then.
Paul.

quote:

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Originally posted by Chris_G
As a related question, is the MAP sensor affected by 'T'ing off to the fuel pressure regulator with the same vaccum line or is this normal practice?

Chris

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quote:

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Originally posted by Chris_G
As a related question, is the MAP sensor affected by 'T'ing off to the fuel pressure regulator with the same vaccum line or is this normal practice?

Chris

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