Half bridge engine idle

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rameshr
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Half bridge engine idle

Post by rameshr »

Hi

Does anyone have a half bridge engine (231), that’s perfect on idle? Mine hunts when cold or even when hot. Have 9XX coils from rotary revs for a while :)

Aem intake, don’t want to waste time trying to fix if it’s normal.

Thanks


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Re: Half bridge engine idle

Post by 350matt »

I think if you employ someone like carl ryan (rotary revs) they can sort it
probably by raising it up to 1400rpm
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V8 Power
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Re: Half bridge engine idle

Post by V8 Power »

I had a full bridge and it had a steady idle. I believe half bridges idle normally as well.
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warpc0il
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Re: Half bridge engine idle

Post by warpc0il »

All our engines hunt a bit on idle, so I assume you mean that it's hunting more than other 8's, rather than just hunting more than a piston engine.

There are various dynamics that can impact the idle revs, even if everything is tuned correctly...
Idle Speed Control.jpg
The main impacts include the charge state of the battery and whether the a/c is running.

The load from the a/c compressor is managed by the PCM controlling the magnetic drive clutch.
However, this can get sticky or even seized, so it doesn't disengage when it should.

Is the idle more or less stable in gear with the clutch down, compared to in neutral?
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rameshr
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Re: Half bridge engine idle

Post by rameshr »

When the clutch is down no issues, sorry should have mentioned this


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M3 E92

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D969 Coils
BlackDiamond Disc + M1144 Pads
YellowSpeed Suspension
Dwell timers adjusted
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Re: Half bridge engine idle

Post by warpc0il »

In that case it could be a problem with the neutral switch on the gearbox or the associated wiring.

The PCM uses this and the clutch switch to know when the engine is in "no load" condition.

Sounds like the clutch switch is having the correct effect but the neutral switch isn't.
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rameshr
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Re: Half bridge engine idle

Post by rameshr »

Where is the neutral switch? Is this easy to replace get hold of?


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YellowSpeed Suspension
Dwell timers adjusted
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Re: Half bridge engine idle

Post by warpc0il »

A bit awkward to access
Neutral Switch.jpg
I've only known the switch itself to fail twice, and one of those it was still working, just leaking oil.

All the other times have been damage to the wiring.
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rameshr
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Re: Half bridge engine idle

Post by rameshr »

Will check wiring and see cheers


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Half-Bridge Engine
Lightened Fly + Clutch
Whiteline ARB's + Droplinks
Brake Upgrade 4 pot front
AEM Intake
D969 Coils
BlackDiamond Disc + M1144 Pads
YellowSpeed Suspension
Dwell timers adjusted
Short Shifter
Braided Brake + Clutch Lines
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Re: Half bridge engine idle

Post by Paul_13 »

I've got half Bridge on my engine. Idled fine at standard setting, but I raised mine to 1k at idle. Mainly to raise the oil pressure
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Re: Half bridge engine idle

Post by ChrisHolmes »

Bridgeported and lightened flywheel hunts when cold but settles to a smooth c1000rpm idle when warm.
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rameshr
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Re: Half bridge engine idle

Post by rameshr »

Tested this again it does settle down once warm, will def try and check cable to sensors though.


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Current
M3 E92

OLD Car
Half-Bridge Engine
Lightened Fly + Clutch
Whiteline ARB's + Droplinks
Brake Upgrade 4 pot front
AEM Intake
D969 Coils
BlackDiamond Disc + M1144 Pads
YellowSpeed Suspension
Dwell timers adjusted
Short Shifter
Braided Brake + Clutch Lines
rameshr
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Re: Half bridge engine idle

Post by rameshr »

Used my mazedit app to read codes, it shows issues with neutral switch/cabling. Will need to get it on ramp to check this out :)
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Current
M3 E92

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Half-Bridge Engine
Lightened Fly + Clutch
Whiteline ARB's + Droplinks
Brake Upgrade 4 pot front
AEM Intake
D969 Coils
BlackDiamond Disc + M1144 Pads
YellowSpeed Suspension
Dwell timers adjusted
Short Shifter
Braided Brake + Clutch Lines
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Re: Half bridge engine idle

Post by Paul_13 »

seems as though you have a problem which the section of loom which runs over the top of the engine to the gearbox.
Maybe clean up the earth which bolts onto the wiring harness tray /support bracket
rameshr
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Re: Half bridge engine idle

Post by rameshr »

Will give that a shot thanks..on the premise I find the look :)


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Current
M3 E92

OLD Car
Half-Bridge Engine
Lightened Fly + Clutch
Whiteline ARB's + Droplinks
Brake Upgrade 4 pot front
AEM Intake
D969 Coils
BlackDiamond Disc + M1144 Pads
YellowSpeed Suspension
Dwell timers adjusted
Short Shifter
Braided Brake + Clutch Lines
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warpc0il
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Re: Half bridge engine idle

Post by warpc0il »

I would be nice to have been right, and even better if it gets you sorted :D
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rameshr (Sat Jul 11, 2020 11:03 pm)
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