Hi guys, I have a problem whit my 03 STR, so like a 10 minutes after start and running it, start to make some preignition noises. Always super unleaded fuel. Thank u

 

Not any where close to enough information for even the most wild *** guess.

Take it to a shop.
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Pre-ignition is not related to fuel octane rating in any case.

 

Give us some more info, like when does it happen, full throttle,idle, mid range, cold, hot, etc. And how do you know it's pre ignition?

 

My car work better when the weather is cold, so my str running fine about 10 minutes, then begin to loss potency, making sounds "cascabelear" (spanish) like when the gas is in low octane (pre ignition), lower gas mileage. However is no overheated & no codes.
2 months ago had a burn head gasket, that was replaced tensioners & guides, no chains was replaced...

 

You mean detonation (pinging) not pre-ignition.

Do you have any codes or warning lights?

 

I asked about that a mechanic... (no jaguar certified) He said think the motor no have enough antifreeze, that need to purge it, I did but nothing change. I thinking about radiator fan problem, because the second speed is not working (I think so), I'm put the A/C on maximum and no change to second speed.
Thank You guys for u interest

 

the sound is like when the fuel is low in octane... the sound is in the engine.

 

no lights, no codes at moment, just restricted performance, rattling and loss of power when accelerate and run for long time on freeway (like 20-30 minutes), no restricted performance when driving in city, just rattling and loss of power

 

I recently change the aux intercooler pump... I'm not sure if it's working properly

 

?????

Do you have an OBDII code reader?

 

no, but I was to autozone and no codes

 

I got 2 codes from bad HO2 and intake air leak, they was replaced and fixed codes gone... no codes

 

Can u recommend a obdii to buy... I will