Light Knocking-pinging noise at 17PSI

[Sik89supra]

Mods, Boss GT61 Turbo,2 1/2 IC Pipes, Aeromotive fuel pump(30PSI), walbro Pump with 12v mod, Lex AFM, RC 550's,Full 3 inch turbo back exhaust. I only run shell 93 Pump Gas.

Only when im under a heavy load around 15-17 PSI, i makes a light Knocking- or pinging noise, at first i thought it was the timing off, so i checked the timing and its at 10,Set as per TSRM, i just replaced the plugs with NGK's heat range 7 i think and gapped them to .30 Wires are new also NGK's. Im running low on ideas, any help and ideas would be great, Thanks guys. -Matt

 

[supradjza80]

Mods, Boss GT61 Turbo,2 1/2 IC Pipes, Aeromotive fuel pump(30PSI), walbro Pump with 12v mod, Lex AFM, RC 550's,Full 3 inch turbo back exhaust. I only run shell 93 Pump Gas.

Only when im under a heavy load around 15-17 PSI, i makes a light Knocking- or pinging noise, at first i thought it was the timing off, so i checked the timing and its at 10,Set as per TSRM, i just replaced the plugs with NGK's heat range 7 i think and gapped them to .30 Wires are new also NGK's. Im running low on ideas, any help and ideas would be great, Thanks guys. -Matt

I don't have first hand knowledge of this but I would guess with stock timing advance, the bigger turbo, and that much boost, you may be at the knock limit of the fuel you are using. Hopefully one of the tuning gurus jumps in.

 

[Kevin]

Are you getting any codes?
The pinging could be detonation.. causes could be running lean, or timing, or too much compression.
could be bad knock sensors or connectors. idk. pull your codes

 

[tekdeus]

Check your air fuel ratios, and tune for around 11.5, and keep it limited to 15psi on pump gas. What are you using for tuning? Be careful, knocking and detonation that is loud enough to hear can easily cause piston damage.

Also can check that your timing belt is aligned properly. A shop once had mine off by a tooth and this caused the base timing to be 20-25 degrees advanced.

 

[boostin300]

Gap your plugs to .26 just for fun.

Shouldn't your base fuel pressure be more than 30 for that much boost?

And yeah pushing 17lbs on pump is pushing it.

Get a AEM, full fuel sys and good tune for E85, youll never knock again. E85 is cheaper than 89 oct where I live.

 

[Mastapip]

No expert here either, but my thought was hitting the knock limit.

I think I've heard that the most you'd want to boost on 93 is 18psi.

 

[Sik89supra]

Checked Codes, Didnt get any codes. my a/f ratio as of right now is around 12.2 under wot. Ive got a maft pro in there right now but the only thing im using it for is boost control, i havnt done any tuning with it. Would it be ok to bump up the fuel pressure to 35-40, and retard the timing a lil, like 2 degree's from stock 10? The timing marks are good i set everything as per TSRM, I also did a compression test, and im running between 180-185 PSI of compression.

 

[Sik89supra]

Anyone???

 

[IJ.]

Either run better fuel or pull it back a couple of PSI it's doing damage.....

 

[rawmk3]

Either run better fuel or pull it back a couple of PSI it's doing damage.....

:werd:

Agreed, sounds like you are experiencing an octane knock. drop boost or get a higher octane fuel. I would personally dial back the boost. Its not the amount of boost pressure, its the volume of air being put into the engine.

 

[frontierguy25]

Do some tunning. You should be fine with 17psi on pump with that turbo. You didn't mention what sized injectors you have, that might be it right there. Anything over 17psi run race gas with 550's. I have the same setup as you for the most part, but I do a lot of tunning on my car. You need to tune that Maft Pro system and I bet you'll be ok.

Do you have the vac hooked up to the afpr?

 

[funky_monkey58]

I have ran around 20psi on pump before. I gap the plugs down to .24 and enrichen the fuel to 10.5 and back the timing by 2-3 degrees in boost and I think it would be decent.

Or just run better fuel 110 ftw!

 

[Sik89supra]

Yes i have RC 550cc injectors sorry about that, I had the vac line hooked up at one time, Had it set to 38psi vac line off, but when the vac line is on it would drop to like 20 psi and it would idle real lean and idle like crap, and under boost the afr would be down in the 8.9 thats a lil to rich for me so i just unhooked vac line and ran the fuel pressure at 40psi static and now the afr is around 11.6 at wot, i like that a lil better.i bumped the timing 2 degrees and that seemed to help a lil but it seems like the turbo is running hotter, and i dont have a EGT gauge so i but it back to stock just to be safe. Im planing on switching to aem standalone here soon, so ill just turn the boost down a lil. Thanks for all the help guys.