Author Topic: Rattle/Detonation at WOT  (Read 771 times)

Offline paulpolo

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Rattle/Detonation at WOT
« on: February 13, 2017, 02:05:42 pm »
I've started getting a rattle at WOT, i've checked the timing and it hasn't moved, I swapped my CO Pot for my spare and all it did was make the idle smoother (set at 550 ohms), checked the plugs and they're a little black but not oily. Just wondering what I should be looking for? Knock sensor? Can it be tested?
I've just been driving it really gently and avoiding WOT for now.

Things i've done so far:
- Taken the plugs out to check the colour
- Checked the pins on the ECU plug from the throttle body for Idle and WOT switches
- Checked in the top boost pipe is all clear
- Tested for boost leaks by using BRV for a few seconds
- Battery is good and voltage is good when running

My spec is:
- 1308cc with wossners
- standard charger on german toothies (65mm) with chip to suit from PPP, cone filter
- PPP full exhaust
- BRV mod (using short spray of the wurth grease from here every 1500miles roughly)

Is it possible its the lambda? Or more likely a fuelling issue? I'm not really sure what to look for next
« Last Edit: March 01, 2017, 10:23:56 pm by paulpolo »

Offline GR40

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Re: Rattle at WOT
« Reply #1 on: February 14, 2017, 12:07:00 am »
Mine had a rattle at full throttle (apparently was detonation) cause one of my injectors was clogged and one cylinder was starving! Thankfully I caught it early and didn't blow the engine. Cleaned the injectors and now it is fixed.

Offline paulpolo

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Re: Rattle at WOT
« Reply #2 on: February 17, 2017, 11:08:18 am »
I had the injectors cleaned and tested when I rebuilt the engine but its a possibility one of them has since become blocked, i'll see if i can test them into some jars or something. Cheers

Offline paulpolo

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Re: Rattle at WOT
« Reply #3 on: March 01, 2017, 10:22:19 pm »
I've filled the whole tank with ron97 and I can no longer audibly hear any detonation, but i'm not sure what that means in terms of what could be wrong, if anyone has any ideas I would much appreciate them!

Offline Yoof

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Re: Rattle/Detonation at WOT
« Reply #4 on: March 02, 2017, 02:27:59 pm »
Do you usually run 95?

What's the timing set to?

Offline paulpolo

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Re: Rattle/Detonation at WOT
« Reply #5 on: March 02, 2017, 04:41:09 pm »
Yeah i've been using 95 and it was fine up until now.

Timing was set to 5deg BTDC but i'll check it again

Offline Yoof

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Re: Rattle/Detonation at WOT
« Reply #6 on: March 03, 2017, 07:42:21 am »
Use super unleaded (or retard the timing) - fuel quality varies throughout the year, and I'd not use Digifant's knock control as a safety net against this.

Shell v-power or Tesco 99 are what most people run

Offline GR40

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Re: Rattle/Detonation at WOT
« Reply #7 on: March 03, 2017, 11:29:42 am »
It could still be a blocked injector. The detonation stopping when you switch fuel only solidifies that its a fueling issue!

Offline paulpolo

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Re: Rattle/Detonation at WOT
« Reply #8 on: March 03, 2017, 12:32:10 pm »
Good points, I appreciate the input as I was/am a bit of a loss. I'll do some more checking over this weekend, ignition timing and sensor wiring to the ECU. I believe it has been cracking the ceramic of the plugs, at first I thought it was just manufacturing faults on the plugs/installation clumsiness but its happened a few times now so I think it was the detonation causing it.

Definitely running it on the better fuel for now.

May look for some second hand injectors I can send off to be refurbished, if anyone has got any let me know!

Offline Yoof

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Re: Rattle/Detonation at WOT
« Reply #9 on: March 04, 2017, 08:37:47 am »
Stock injectors? I've got a set you can have for beer money  :)

Offline paulpolo

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Re: Rattle/Detonation at WOT
« Reply #10 on: March 09, 2017, 12:01:16 pm »
PM'd you Yoof, cheers!