Papillon

The car hesitates on boost. I have done the following

Rebuilt to wasted spark
New phase and crank sensor with correct gap
Adjusted TPS
New mapsensor
New plugs
Took it to a mapper, all he found was that the mapsensor indicated 1,7bar of boost when in reality it was more like 0.7 when the hesitation came and there was nothing he could do in the map to get rid of it. He thought there might be a problem with the 5volt output.

Ive done a little measuring and this is the result so far
5volt = 4.96volt on ignition and idle

Water temp : direct on sensor = 3.75ohm.
On the ecu plug when connected to ecu = 1.77ohm.
On the plug with no ecu connected = 3.82ohm.
Ign = 2.38 volt and lowers when engine gets hotter.

Air temp : sensor = 3.44ohm.
On the ecu plug when connected to ecu = 1.70ohm.
On the plug with no ecu connected = 3.44ohm
Ign = 2.26 volt.

Is it normal for the ohm to change when these sensors are connected to the ecu? voltage seems normal.

Map sensor = 1,58volt on Ign (should be 2.2 according to my papers?) and 0.5volt on idle.

I havent tried measuring while boosting yet.

If there somehow is a momentarely problem with the 5volt output, what could cause it?
Trying to sort out if its an ecu or loom problem.

Any input is greatly appreciated.

William MK2 Cosworth

when you have the plug connected to the ecu, you're probably measuring the ecu resistance aswell.

i'd look at the map sensors wiring for a fault.

also have you tried a different map sensor?

sierrsteve1980

iTrader: (7)

Are you still running standard engine loom?

I had a very similiar problem when running the stanadard 2wd engine loom, i was gonna go wasted spark as i thought that would solve my issue. Lucky enough i changed the engine loom instead first as it saved me money in the long run as that was at fault.

Papillon

Its a brand new mapsensor.

Yes its std loom, ive been suspecting it but i would like to have morr confidence that its really the loom beford i get a new one. Did your rpms also drop atm of the hesitation? It can also cough on idle every now and then.

I plugged in a narrowband lambda and its shows its running rich when it get hot even though i had lambda 1 on my last MOT when the hesitation problem was still there, only adds to my confusion.

oldford

Map sensor signal of 1.58V suggest it's a 3-bar sensor.
What's the number of the map-sensor?

Papillon

Ah ofcourse, my papers must be reffering to the std one then.. Its a 3bar yes, thanks for ruling that out

Papillon

Btw, is the 0,5volt on idle correct for a 3bar map?

Turbosystems

iTrader: (5)

some useful data for you here
www.bigturbo.co.uk

Papillon

Update

I fitted a new loom, got better but not 100%, still hestitated a little but a lot less. I did find a dodgy connector to the ign amp in my old loom done by the previuos italian owner so i was pretty sure the ign amp had something to do with it.

Anyway i changed fuelfilter and then i moved my wspark coil, which i had mounted right next to the amps, and positioned it where the std coil normally sits. I noticed some interference coming from the coil when i measured the amps when it was next by the amps. And now it runs perfect what a difference the loom did aswell!