new mpi engine wont fire. please help
Turbo Mini Forums

what if the sump has fuel in it? does this effect the oil pressure?

Well the fuel will thin the oil out abit and probly have an effect on oil pressure.

I would replace the oil and fit a new filter just to be on the safe side.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

eeek, 5 pounds! thats very very low.

did you prime the oil pump and get oil pressure before trying to start the engine?? hope you havn't wiped the bearings out :(

Team Racing

Doesn't sound good

If something is worth doing, it's worth doing half of.

the pump and filter were primed.

i used a new gasket for the pump (without sealant). the bottom end bearings are new. used a new 'o' ring for the gearbox oil puckup.

i think its to do with the oil pressure relief valve on the front of the block, someone has fucked about with this before i got the engine by the looks.

will have a look later and let you all know how i get on.

if not, any idea what else could be the cause?

Edited by welshdan on 20th Nov, 2009.

personally I would not have tried starting the engine until I saw at least 20psi while cranking the engine over.

Team Racing

5psi is VERY low indeed.....

the standard oil pressure light doesn't come on until 7psi, which to be honest is too low already. most people change this for a 21lb switch, that gives you a bit more warning.....

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

got an oil pressure between 60-80 pounds.

only thing is that it only idles at 500rpm (it has always done this), note sure if cam change etc doesnt like this, as it sometimes cuts out if allowed to idle at 500.

other thing is the cooling fan is fucked, need to use it tonight so wired a switch in for now. will play around with sensor/relay when i get time.

engine itself seems to go well. will limit it to 3500 revs for a couple of weeks.

not got a power boost valve on yet, will leave it a week or 2 until things have bedded in, then fit it and get iut set up on the local rolling road.

the engine did miss a lot on 2 occasions, thought things were seizing, pulled over, restarted, everything was ok. not sure what that was all about.

just going to take it easy for now.

Phew! glad theres pressure now.

was it the relief valve then?

I always add an over ride switch for fans.

yea, relief valve. the spring was in the oil temp hole :S

the only thing now is that it keeps cutting out (revs drop below 500rpm at idle).

does the ecu have some element of control over the idle speed, or is the minimum idle speed adjusted on the throttle adjustment screw on the throttle body?

cheers

mpi idle is done by the iacv on the side of the inlet manifold.

If something is worth doing, it's worth doing half of.

what is iacv?

is there anything i can do to adjust the idle?

4-500 rpm is obviously too low.

the car has a new battery on it, also charges at 14volts, so think its the low idle that makes it cut out

also, i drove from s wales to bristol at 50-60 mph last night on a 3.2 final drive. the oil temp went up to around 80 degrees. will have to keep an eye on this, maybe look at an oil cooler with thermostat as i have got a feeling that oil temp will go higher when its driven properly and iin warmer weather.

its a little bleck think with 6? wires, looks like this,

You need to get this plugged into a diagnosic service tool to check everything is working as it should and also reset the IAC stepper motor. First check that its actualy connected and that it is not sticking. I have seen these valves damaged in such a way that while the motor 'clicks' as it is operated, the pintle doesn't move anywhere. You cant miss it its a big black valve thing with 5 wires and a connector fixed to the side of the inlet manifold. The picture above is just the motor and pintle, the valve body is not shown.

By the sounds of it the valve is fully closed and the only air getting into the engine is through the minimum throttle position. The idle should be ~850 rpm no less.

The actual reason that the valve is not working could be several things and the fact that you dont know that there is an idle control valve, might mean we are going to be here some time speculating what the problem is or is not. Get the ECU and controls checked out with the diagnostic.

You could try the mythical ECU reset that most seem to suggest, depress the throttle pedal 10 times with the ignition on, or turn the ignition key on and off 10 times, or turn the ignition on, depress the accelerator pedal 10 times, get out, run round the car once, get back in the car, turn the ignition off and back on again then depress the accelerator pedal a final 5 times.

At the very least remove the whole valve from the inlet manifold ( not just the motor from the valve body) watch the pintle as some one turns the ignition on and off. you should see the pintle drive fully closed and then open back up to a pre determined position in relation to engine temperature.

Edited by Sprocket on 21st Nov, 2009.

have noted the coments. i have a spare inlet manifold with sensors, may be worth changing and seeing if it helps. is the idle control the stepper motor, on the left of the inlet manifold as you look at it?

yep on the left as you look under the bonnet. just swap the iacv over to start with. it's what i did with my mpi

If something is worth doing, it's worth doing half of.