Detonatios when shifting /97 tahoe 5.7

[arkaze]

Hi to all!

i have a 1997 tahoe 5.7 2 doors with some engine modifications (cold intake, headers, throtle body spacer, magnaflow mufflers, and lately presents a problem when shfting and when i maintain a rpm range, for example:

if i speedup smootly between 1st and 2nd gear detonates, same as 2nd and 3rd gear

if i select the 1st gear manually and accelerate up to 2500 rmp and keep it into this rpm range (or keep other rpm range) detonates like "PARRRRA PA PA PPA PA"

if i push full throtle speedup with no detonations

this problem could be caused by some sensor?

i replaced O2 sensors, tps sensors, spark plugs, spark plugs wires (msd), distributor cap and rotor, and no changes.

i've noticed an increase in fuel consumption and check light is off. When i check whith a fail code scanner its everything ok

Please helpme about and sorry for my english

Thanks from Chile !!!
ArKaZe

 

[retorq]

Obligatory "get rid of the throttle body spacer they do nothing on dry manifolds" comment.

Get yourself a realtime scanner and see if it's really picking up knocks. It's possible it's something else, valve float, header leak, tranny noise.

What grade/octane rating gas do you run in Chile?

 

[ccapehartusarmyINF.(ret)]

detonation is almost always going to be cause by low octane gas wich i thought was going to be a stretch untill i read Chile
chile uses 93 95 97 octane by the RON standerd wich differs from the AKI standerd we use so 93 octane in chile is more like our 85 octane and thats even if there ratings are accurate

 

[arkaze]

Obligatory "get rid of the throttle body spacer they do nothing on dry manifolds" comment.

Get yourself a realtime scanner and see if it's really picking up knocks. It's possible it's something else, valve float, header leak, tranny noise.

What grade/octane rating gas do you run in Chile?

Thanks, i'll test uninstalling the spacer

detonation is almost always going to be cause by low octane gas wich i thought was going to be a stretch untill i read Chile
chile uses 93 95 97 octane by the RON standerd wich differs from the AKI standerd we use so 93 octane in chile is more like our 85 octane and thats even if there ratings are accurate

as you say those are the kind of gasoline we use. i've test using 97 and no changes.


could the knock sensor be faulty?, its all covered by oil and dust

Thanks!

 

[SunlitComet]

Arkaze, do you have access to a scanner that can read knock retard, knock activity and ignition advance?

 

[arkaze]

Arkaze, do you have access to a scanner that can read knock retard, knock activity and ignition advance?

ask a person who scanned my truck, i don't know if this scanner have that option

thanks!