Hotwire 350se tick over issues

[Lemonentry]

After a refurb I've got my 3.9 hotwire engine now running timed at 8 degrees with new oils , ignition, leads plugs etc.

All is fine, except when started from cold with no throttle touch, just key turned, the engine starts and revs to 2000 revs, and then drops after 10 secs to 1000 revs, it then does this up and down the rev range business by itself for about 2 mins until it's warm and then it settles down to a tick over of 800 revs. A tiny bit of popping at the rear tail pipe, but clear air coming out so not rich.

Is this all correct, or have I got a sensor playing up in the choke stage?

Kev.

[Wedg1e]

Sounds like the idle stabilisation valve (servomotor) needs a clean. Black thing bolted to the rear of the plenum chamber.

[jmorgan]

Not much help but my hotwire does not pop and bang. When I clean the stepper, or check it, I use ptfe tape on the thread. Its a bit slack.

[mrzigazaga]

Lemonentry said:

After a refurb I've got my 3.9 hotwire engine now running timed at 8 degrees with new oils , ignition, leads plugs etc.

Hi Mate...I may be wrong but isn't the timing supposed to be around 4-6 degrees?...Although this probably wouldn't cause "Hunting".....Could it be an air leak?.....Ziga

[Jack Valiant]

mrzigazaga said:

Hi Mate...I may be wrong but isn't the timing supposed to be around 4-6 degrees?...Although this probably wouldn't cause "Hunting".....Could it be an air leak?.....Ziga

No 8 degrees is the normal start position Zig! Any thing from 14 to 18 at 2k rpm depending on the motor used. Most idling issues are usually down to to the stepper motor as mentioned. What ecu you running? Is it pre Cat but with Lambdas? If you have the 14CUX and a diagnostic port then put a EcuMate on it or a version of RoverGauge

Chris

[Lemonentry]

Hi guys. Just a note to say thanks for all your help. Yes it was the stepper gunked up. Anyway cleaned the engine balanced out at 1000 rpm cold, 800 hot, and smooth as you like at all temperatures.

I also found the air screw had been wound right out, so put that back to 2.5 turns as per manual and the popping stopped. Now the engine sounds super smooth in all stages.

As a note, 8 degrees def seems to suit it in the garage, 10 sounds too far forward and 4 is slightly smelly, so I feel once on the road if 8 at all pinks then I suspect 6 could be it, still got some work to do before the play day!

Kev

[ElvisWedgely]

On my 3.9 the stepper motor is completely disconnected. The pipe that connects the stepper motor to the plenum is removed and the holes blocked. It always starts first time but won't idle on the morning start until the temp gauge starts to move. That aside, the car goes like a rocket and doesn't miss a beat.

Tony. TCB.

[Lemonentry]

Ok understand but Is there any advantage to taking away the stepper other than its one less thing to go wrong?

[ElvisWedgely]

I actually bought the car with the stepper motor disconnected and my initial reaction was to have it reinstated. However, after using the car for a while I rather got used to it, and compared to the previous 3.9's I've owned it seems to be a lot more lively and more economic on the fuel. It's one less thing to go wrong and it's often been said that it's the cause of many running issues. Without the stepper it always starts first time and once warm runs very well indeed. The only drawback being the warm up time takes longer before the engine will idle.

Tony. TCB.