Got it started after years but running very rich

[slimlavud]

Hi All
You may recall that I rescued an M100 from sitting outside for years. I took the fuel pump out and unseized it, cleaned out a lot of water from the tank, fitted a new filter sock on the pump and replacement filler neck from a very helpful forum member - thank you surfboardfiller - and tried to start the car with fresh fuel. I cranked it for a long time but nothing, the pump was running fine, staying on for a few seconds after stopped cranking etc. I checked it was pumping a decent pressure at the tank - yes - then checked the spark - very healthy but dry spark plugs. Then I checked and cleaned a lot of underbonnet electrical connections including some rather rotten wiring for the CAS. Still no joy.

I also cleaned the throttle body etc with carb cleaner, it was pretty clean anyway.

Then I undid the fuel pipe at the o/s (drivers side) end of the fuel rail (at the pressure regulator end of the fuel rail) and ran the fuel pump - lots of fuel but I clumsily broke off the plastic end of the MAP sensor filter/damper take-off on the o/s end of the common chamber/intake plenum. Then it started!

It seemed to run OK with the air leak through the fitting that I broke and if I removed the whole fitting (leaving a 12 mm hole) then it revved up and idled at about 2,500 rpm.

When I try to blow down the pipe that WAS attached to the common chamber/intake plenum (the one I broke off!), it seems to be blocked (pass no air blowing or sucking) - is that correct? I will repair this fitting now and refit it.

I ran it up to temperature, fans came in properly etc but it kept blowing black smoke from the exhaust even when fully warmed up, running very rich, and smelt very rich too.

I blocked off the hole completely but it ran just the same, smoothly but very rich.

I have checked it with the turbo pipe off and it is the same, the turbo spools up well and blows quite hard and does not have a lot of play in its shaft etc.

I don't think the water in the tank could have got to the injectors and thus consequent rust could be holding them open all the time - is that a possibility?

I would guess that perhaps a sensor thinks it is very cold and is telling the ECU/injection to richen the mixture a lot - does that make sense?

Any ideas please? I think the car is a series two - it H registered and is a turbo and the chassis number is SCC100ZT1MHD18166, engine number is 089876 if that helps? It does not have airconditioning.

[Simon_P]

The thing you broke is the MAP sensor take-off. The Manifold Absolute Pressure sensor tells the ECU the Manifold pressure.

The ECU uses pressure and temperature to calculate density, so it is seeing denser air and adding fuel accordingly, except under boost when it will be lean as the pressure is too low.

[slimlavud]

The thing you broke is the MAP sensor take-off. The Manifold Absolute Pressure sensor tells the ECU the Manifold pressure.

The ECU uses pressure and temperature to calculate density, so it is seeing denser air and adding fuel accordingly, except under boost when it will be lean as the pressure is too low.

Thank you Simon, I hope that fixing that fitting will fix it! I got confused as I was hours trying to get it started for the first in many years, it seemed that breaking that fitting made it run...! I presume I would not feel anything when I blew or sucked on the pipe that comes from that fitting then? No movement, free passage of air etc?

Thanks again, it all makes sense now I have got home and collected my thoughts!

[HJ2]

Just out of curiosity: When I measure the MAP sensor @ warmed up idle, what would the correct values be approximately?

[Simon_P]

From memory I think it is 0.23 to 0.26 on my car. There is probably a range in on of the manuals.

[Giniw]

I think it's more like .31-.32 bars, but I could be wrong since it's just from memory too (.34-.35 being already a bit high)

[Simon_P]

Yes my error
I've just looked through some scans for another car I had. Left to Idle from cold to warm when the thermostat opens the MAP reads 0.29-0.3 bar and the Barometric pressure reads exactly 1 bar - of course it varies with the weather

0.23-0.26 bar is minimum pressure under hard deceleration - I was testing the servo

[HJ2]

My Multimeter won't read 'bar' But i will dig out the Elanscan cable