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Help needed, spare 012 AMM to test

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Old Dec 15th, 2018, 10:45   #11
Laird Scooby
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Originally Posted by T5Sweep View Post
It dies as soon as you let off the throttle, idles pretty lumpy too.
That sounds more like an air leak or an FPR failure to me. Usually an AMM/MAF failure the engine dies if you try to rev it. If you simply unplug the existing MAF and try revving it, you'll probably find it won't rev at all.

Check the carbon brush inside the dizzy cap, plugs, leads, vacuum hoses etc and don't forget the brake servo hose!
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Old Dec 17th, 2018, 15:17   #12
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Have you checked the throttle switch on the butterfly? It’s set to tell the ECU when the throttle is closed (well it triggers just before closed so the ECU has time to react). Just pull the connector off and check the continuity through the switch with and without it pressed.
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Old Jan 11th, 2019, 17:38   #13
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Have you checked the throttle switch on the butterfly? It’s set to tell the ECU when the throttle is closed (well it triggers just before closed so the ECU has time to react). Just pull the connector off and check the continuity through the switch with and without it pressed.
Didn't see this, I'll give it a go thank you!
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Old Jan 11th, 2019, 17:48   #14
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The maf isn't really used much in idle, its too slow to react. The ECU assumes a certain air flow, but does pay it some attention. Dirty throttle body can cause idle dips on start up while the idle valve adjusts to compensate. I think it remembers the position though, so reving should be ok after start up.

Sounds like a weak mixture caused by potentially:

1. Air leak post throttle body
2. non functioning dump valve (does this happen after acceleration/boost or reving parked up?)

Idle runs very lean in closed loop mode, so makes any air leak worse, if you disconnect the throttle switch it might stay running because it will be richer, but it just a bodge.

Last edited by TonyS9; Jan 11th, 2019 at 17:51.
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Old Jan 11th, 2019, 18:16   #15
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The maf isn't really used much in idle, its too slow to react. The ECU assumes a certain air flow, but does pay it some attention. Dirty throttle body can cause idle dips on start up while the idle valve adjusts to compensate. I think it remembers the position though, so reving should be ok after start up.

Sounds like a weak mixture caused by potentially:

1. Air leak post throttle body
2. non functioning dump valve (does this happen after acceleration/boost or reving parked up?)

Idle runs very lean in closed loop mode, so makes any air leak worse, if you disconnect the throttle switch it might stay running because it will be richer, but it just a bodge.
Post throttle body? Meaning a vacuum leak to/from the inlet manifold?

Both acceleration and when it's parked up.
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Old Jan 13th, 2019, 23:22   #16
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You can also get stalling issues when off throttle if the recirculating hose from turbo to manifold is damaged/split 👍

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Old Jan 28th, 2019, 15:41   #17
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You can also get stalling issues when off throttle if the recirculating hose from turbo to manifold is damaged/split 👍

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I have no recirculation valve as the little standard turbo has been replaced.
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