MAP sensor theory

[Wobba]

Map sensor is there to report to the ECU the pressure in the inlet manifold right? In turn the ECU sends data to the ISCV on how to operate, right?

In theory, lets say u have a faulty MAP sensor that is telling the ECU there is too big a vacuum, it would have the ISCVopen full blast right?

If you take the hose of the inlet manifold > MAP sensor, block the inlet hole and leave the pipe open to atmosphere...if it was a working MAP sensor wouldn't it tell the ECU there was too much air and try to lower revs accordingly?

[stan]

ISCV doesnt come into it....that only controls the idle via a target rpm.

the map sensor gives an indication of load...ie. low vacuum=high load, high vacuum=low load.
load being the % of max power being produced, the ecu then relates this signal to a site on the correction map, and so a fuelling value is obtained (as determined when the engine is/was calibrated).

if you ad a faulty map sensor, or ose, it would give te ecu an incorrect signal for te engines actual operating condition, and so the engine wouldnt run right.

[Wobba]

ok thanks. I dont think its that then.

[105epwr]

it controls the ignition aswell..dont it?

[teabag]

it controls the ignition aswell..dont it?

isnt that crank position sensor?

[105epwr]

yes thats just the trigger point,but im sure for different loads etc it uses the map sensor,recent had a RR and we was getting different ign timing by unplugging the map sensor and i elongated the crank sensor bracket holes and moved it back to gain more ign advanced.BUT half of my loom is unplgged (injectors,tps,iscv and 5th inj)as i run carbs.

[teabag]

ahh i see

wouldnt is be easier to run a mappable ign. driver?

or an aftermarket ecu like megasquirt for example?

[stan]

yes, it does control ign, i was just using fuelling as an example.

what sort of max advance was yours running with the bike carbs mate?

I can supply/fit/map an ign only ecu...

[105epwr]

yes, it does control ign, i was just using fuelling as an example.

what sort of max advance was yours running with the bike carbs mate?

I can supply/fit/map an ign only ecu...

well it got confusing.b4 my RR prima said do away with the map sens.couple of long stories short we got more adv with the map sens plugged in.I dont no the actual ign timing but we found the peak advanced so then we had to bring the timing back abit so i told prima this and he said he ment to say disconnect the vacum pipe only-dont see this making a difference?
how much for the ign kit stan?cheers ricky

[stan]

the ecu is about 250-300...i'll check tommorow.

its an all round better solution than a half plugged in OE unit!