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Ever since I ran 1 tank of United Boost 98 in my car it has pinged and knocked like hell when running anything over 10 psi. Putting new Iridium plugs in stopped the knock at anything around 8 psi, but it still knocks like crazy on high boost when previously it was fine. When testing it out after putting in the new plugs I saw a knock level as high as 110 on my PFC hand controller when running about 12 psi!

Obviously I should have thought more about what I was doing when I filled up, but I feel that my fuel pump is probably on the way out too.

I will never run another car on anything with ethanol in it again, just not worth the risk if you have a modified car.

So far I have replaced plugs, next in line will be a new fuel pump. Does anyone think I should check anything else before I shell out for a new pump?

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It's been proven that if you tune your car specifically to run on boost 98 (10% eth) you will reap rewards. Your tune must have been near the limit ie timing to ping that bad straight away. It'll be all thru you're system, just run another brand thru it to clear it up. BP98 FTW :P

from all of my experiences with tuning and fuel etc

ive found occasionally a bad batch of fuel - all you need to do is back out the timing and then get rid of the dodgy fuel

once that is done you can either try other fuel or back to the same place

in the 4 years ive owned with an aggressive tune ive only seen one batch of crap fuel

i think he said he has finished with the boost98.

I would replace your fuel filter and pray it fixes the problem. if not your going to have to remove the injectors and get them cleaned.

once you have done that then you can look at changing the fuel pump. it shouldnt wreck the pump. maybe the fuel was dirty and it clogged the filter

Thanks for all the responses guys. I should add that I have run quite a few tanks of Mobil and BP 98 Octane through the car since the United debacle.

What confuses me is that the car runs great at 8 psi, yet runs like shit over 10 psi. So basically the only way to diagnose the problem is to systematically replace the components I guess. I don't know a lot about the tuning of the PFC, is it something that I can do myself, or do I need to go back to my tuner and blow another $150?

try new coils if you are sure the plugs are spot on and correct

my coils died - one day they are perfect, the next day the car detonates its ass off on high boost

dropping boost makes the problem go away

try new coils if you are sure the plugs are spot on and correct

my coils died - one day they are perfect, the next day the car detonates its ass off on high boost

dropping boost makes the problem go away

Haha, I was worried you were going to say that. Laughs aside, thanks to everyone who has contributed to this thread.

Do you (or anyone else) have any suggestions for what coils I should consider?

Go with Nissan stock ones, or after market like Splitfire etc?

Oh I might replace the fuel filter first and pray :)

it wont be the fuel filter - i fail to see how this is causing the problem you are experiecing

if the fuel filter was blocking fuel the car would be lacking fuel on full load

this would mean it would lean out which would skyrocket the exhaust gas temps, which would cause engine failure

given your engine still works it doesnt sound likely

go for splitfires - dont get stock ones you would be mad to do that

when my knock count went bad it turned out to be the fuel pump running out of puff, to make it worse the knob who sold me the car told me it had a bosch high pressure pump in there and it turned out to be stock, anyway wouldnt hurt to change fuel filter and pump!

i would start at the basics first. there is no reason why you need to replace expensive parts if you have not checked the simple things first.

dodgy fuel pump or blocked filter can cause high knock levels. even pull the filter out and blow through it. it must not be hard to blow through at all.

Before you go buying new coild, check out some of the DIY's on the subject. Sometimes tape around the coils, or even nail polish will work.

Have a quick search in the DIY section, you should find something useful.

Ever since I ran 1 tank of United Boost 98 in my car it has pinged and knocked like hell when running anything over 10 psi. Putting new Iridium plugs in stopped the knock at anything around 8 psi, but it still knocks like crazy on high boost when previously it was fine. When testing it out after putting in the new plugs I saw a knock level as high as 110 on my PFC hand controller when running about 12 psi!

Obviously I should have thought more about what I was doing when I filled up, but I feel that my fuel pump is probably on the way out too.

I will never run another car on anything with ethanol in it again, just not worth the risk if you have a modified car.

So far I have replaced plugs, next in line will be a new fuel pump. Does anyone think I should check anything else before I shell out for a new pump?

just a question, which United station did you get your fuel from?

and when?

Yeh, after looking at prices I think I might try some cheap fixes first. If they don't help then maybe I should take it to my mechanic and see what he reckons.

Thanks for all the tips guys, now where did I leave that nailpolish...

just a question, which United station did you get your fuel from?

and when?

I bought the fuel from the Mornington United on the corner of Mornington-Tyabb Rd and Racecourse Rd in early January.

And in response to me being keen to spend money on coils, I'm not really, I just don't know a lot about these kind of issues, so I thought that if that was definitely the answer then I may as well do it. But after reading further advice I will obviously try the cheaper options first.

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