Detonation on ~14 psi

[Nismo1182]

I have a 89 240 with a redtop. All the bolt ons: 3" downpipe, testpipe, exhaust, FMIC, Profec B. Anyway, car runs awsome at stock boost. When I double the boost to 14, its detonates. Timing was set perfect to 15* so then I backed it down to 10* and it still detotates. Plugs are Denso Iridiums.

Now the only problem I see is the ECU, I cant read the codes because the red light stays on constantly. Im thinking its a ecu related problem?

[robbbby]

Get a wideband and something simple to control fuel like a safc.

[NoStickers]

What is detonation like?

I noticed when I dynoed my car at 14.8 psi I was running somewhat lean if that helps any.

[Phax]

Are you running real gasoline? By real, I mean some brand name stuff and not mom and pop market gas? Around here, we have a gas station called Arco. You don't want to put Arco gas into your turbo car because their gas sucks.

What are your plugs gapped at?

What is your timing set to?

When you're running at 14 psi, do you notice if the engine is backing the timing off to compensate for knock?

[Nismo1182]

It has a tank of Chevron 93, timing it still set to 10*, plugs gapped to .32, engine pulls strong but you can hear it detonate up top in the rpms. All my other friends SR's dont do this at 15 psi. So something is definately wrong here. Im out of ideas.

I also forgot to mention, it has a Walbro 255 fuel pump.

[NoStickers]

What does detonation sound like??

[Nismo1182]

Take an empty 12oz soda can and put some metal bb's in it. Shake it and thats what it sounds like.

[Nismo1182]

Ok, so I tried another redtop ecu and it went away for a bit but its still there, just not as loud/strong as it was before.

[240dreams]

isnt timing supposed to be at 15 or 16 degrees?

[Nismo1182]

15* yes, I had backed it down because it was still detonating like crazy.

Now its back to 15* and stock boost.

[dj_lennon_franz]

try some GOOD gas...100 octane will help cure yer problem...my car detonates on 14 psi with 91 octane...put 100 in...no more BB noise (100 octane is GREAT stuff...and it smells good too)...also if its really hot outside...dont run 14 psi...ESPECIALLY if youre only runnin 93 octane