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Stall on start, Fast idle 4.2 Rover v8


mad_pete

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So after breathing life into a 15 year old laptop with lubuntu and Tuner Studio (which works very well) I'd forgotting how confusing I find all the megasquirt settings

Setup

Rover v8 4.2 new injectors

LC1 wideband sensor

ZF4 auto

PWM idle valve (the recommended type)

Issues

Cranks for several seconds before firing - may be due to inactivity (not much use in last 3 years)

First start will run for 1 -2 seconds then stall, second start is fine although will try and stall under load for the first few minutes

Runnnig when warm - absolutely great (a vintage Nige tune :-) )

Idle - in drive against the torque convertor 900 rpm but in neutral 1200rpm and runs away a touch in drive on tickover could do with being a bit lower for creepy forwards on tickover

Stopping, grumbles on a little after key off

So I thought I would post up my settings in the hope the experts of megasquirt might be able to see some offending values while I dig out the manual ponder how complex squirting petrol in a tube an lighting is.

For some reason the photos are all uploading upside down, which is very annoying, I'll keep trying to fix that appologies

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Try extra cranking pulse width, if it gets worse at starting, then try less!

As for stall after starting, more warmup enrichment, and more after start enrichment.

Remember you only have one start per day, engine needs to be cold... Properly.

Will take a couple weeks to get right, but once done it is great :)

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  • 2 weeks later...

You turned the hex-key bypass screw in on the throttle body? You should easily get it down to around 600 rpm. Think they are 1/4" rather than 6mm, which just round it out!

With the idle valve disconnected, plenum connections bunged, fiddle with the duty cycle of the idle valve, while looking into the valve. Looking into one of the valve ports you will see a rotating shutter, as you change the duty cycle, this should move the shutter around. Adjust it until the shutter completely closes the valve -this is the duty cycle figure you need to know, and is your baseline to work everything else from, so is VERY important to get right :)

If you have that duty cycle going to the valve, and the engine is hot your idle should now be 900rpm... or 600, or whatever you set it with the hex-key bypass screw.

How are you going to use the valve? Warmup only or closed loop? Recently I have binned closed loop as too many variables to get right, like trying to balance a 12-legged stool, and just using warmup mode, which works very well.

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  • 2 weeks later...
  • 2 weeks later...

Ok, I have +12v but not the gorund, pull the loom apart and find where that's gone. I put the other connector to earth on the engine and the valve leaps open so that's good. Wonder if when it starts working the tuning will be out.

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With engine cold, remove idle valve with it plugged in, turn on ignition and play with cranking duty cycle and see if the valve moves.

If it doesn't then either the valve is dead or the wiring is guffed.

To test the valve, just put 12V across it, it should snap sharply in one direction, and be fully open.

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  • 4 weeks later...

thanks Fridge does seem to be those colours. So pulled the squirt plug apart I do have red/blue on a pin, follow it through and that connects to orange/trace black nearby. Check engine bay, do have orange trace black sealed off not doing anything. Check that to the red/blue pin, does have continuity. Great. Looking like epically not connected. So wire that to the solinoid. Plug it all back it. Put the key to ignition, fuel pump relay engages, good sign, get a tick tick tick sound from the bonnet, ignition off, still tick tick tick. Doesn't seem to be the idle valve but something on the top of the engine. Disconnect the idle valve ECU connection. Ticking stops. I don't understand. :-S

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I'm sure I have the Bosch valve. I'll post a picture. The valve has 12 v one side and the other wired through to the ecu. The only thing I can think of is if the orange wire is touching something else. I didn't think it mattered which was pos and neg on the valve. Unless the red blue connector is on the wrong ecu pin from my plug ?

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