Turbo A 7m wont run with map sensor vac line connected

[Wildsupra]

I have wired a turbo a 7M motor into another car and for some reason the car will only run with the vac line to the map sensor unplugged, the motor came out of a running car so VERY unlikely to be a problem with the map sensor.

It will start and idle for about 5 seconds with map sensor line on but dies everytime after that 5 seconds, but as i say will continue to run if vac line is left off.

Any ideas wot could be going on with the wiring?

Cheers
Matty

[Cuts]

sure the map sensor is wired in correctly?

[Wildsupra]

wouldnt have thought the map sensor wiring would have changed?? i havent really touched engine loom as such...
and plug on map sensor is connected the whole time just the vac line that gets conncted/disconnected that affects it.

[fixeruperer]

stick some fuel gauges on it, and see if fuel is getting cut when it dies.
so are you using the map from the car the new engine came from ?

[pandaah]

yeh sounds like a fuel related issue to me too...

[fixeruperer]

you can determine if its the ecu holding back the fuel or if something is switching the pump off.

[amichie]

IS it the MAP sensor on the side of the ecu?

[Wildsupra]

Na the map sensor is in the engine bay.

It does sound like fuel but im not convinced its the pump, maybe more injectors or just leaning out too far to run.
Cos it seems too chug a fair bit of smoke when vac line too map is disconnected (as if it thinks its reading 0 vac and pressure but throttle is closed so should be ready big vacuum and hence running much leaner than it obviously is.
Everything ran fine in the original car too and all the same parts have been used. Onyl really the dash type wiring that has been changed on the loom.

[midnight_purple_GA70]

probably seems kinda too obvious to be overlooked but is the idle control motor working correctly? or is the throttle slightly open? maybe when you are creating the vaccuum leak its allowing enough air in to keep the car running... try plugging the map sensor vac line back in and giving it another vaccuum leak elsewhere and see if it runs this time

[Wildsupra]

idle speed motor is working fine, have checked that and did wot you said anyway, no amount of throtttle will keep it running once map sensor line is connected, also it wont run without the electrical plug on map sensor plugged in either but i assume thats possibly normal.

[wilbo666]

Might be worth checking the voltage coming out of the map sensor... and also the +5V going to it...



Cheers
Wilbo

[stradlater]

yes, I'd be pointing the finger at the map sensor not doing it's job. That's what it looks like to me..

IE - Connected it gives a WAY wrong signal and the AFR's get so far off the charts it stalls.

then, disconnected, it gives out something roughly in the right range (or atleast enough to have an AFR that runs) and then the added air from the vac line supplements the additional fuel.

[WA_TRD_83]

*bumpo*
more help needed before Matty shoots himself in the head gasket!!

[Adsport]

has the map sensor got earth? sounds like its working backwards

[CrUZida]

You need to check what it making the motor stall.

Too much fuel?
Fuel injectors cutting?
Fuel pressure dropping?
Spark stopping?

Until this is known, we may as well just be pissing in the wind.