Bad Knock

[Joe]

I have a 2000 GTP all stock but I have; U-Bend Delete, Gutted Air Box, Stock Tune with fan changes for 180* Stat, Autolite 605 gapped at .055".

Scanned it the other day and I am getting a LOT of knock. This is from a scan today(34 degrees Fahrenheit during scan) about a 40min drive. Histogram showing highest values.



What would cause this much knock? Before I would only get up to 2 or 4 and that was rarely. Car seems to drive fine, no misfires or anything.

Thanks,
Joe

[matt5112]

scans and bin plz.

[Tuner-Extraordinaire]

Probably the cold weather.

[blueguy]

Joe,

How's the condition of the motor/trans mounts?

If they are shot...and the motor moves enough...downpipe can come in contact with the sway bar under heavy acceleration...giving the knock sensors false readings.

As well, are you using 91+ octane?

[Joe]

I was thinking mounts, ordered some online but they looked fine when I actually jacked the car up and looked. Might have to get a friend and see if the engine moves when it is put in gear. And I only run 91/92/93 octane. Also cold weather should HELP knock if I'm not mistaken?

[Swiggles]

Its your STOCK tune. the stock tune will produce knock. my girls base model 06 sees up to 8* at times. Colder weather, denser air, will cause an increase in knock too, many who run a 3.4 in the summer will switch to a 3.6 in the winter to get rid of the knock.

you'll be able to tune that knock out since you appear to have a tuner.

[Joe]

Scan:
HPL
CVS

HPT File

[Fivefingerdeathpunch]

You still have the stock front manifold, its pretty restrictive

[Swiggles]

and we are still on winter blend gas right now so that can cause some knock.

[Joe]

You still have the stock front manifold, its pretty restrictive

Good point, I had the power log till it rusted out. Forgot about that, also had a 3" DP till that rusted out too, now just have the U-Bend delete. Thanks for all the help, I will be trying to tune it out in the next few weeks. Just shocked me when I saw how much knock it had, figured something was wrong.

Thanks again,
Joe

[blueguy]

And actually, winter causes MORE knock...colder, denser air...means moar booosteses.

Summer has less knock...crappier air as well, more humid...less boost.

[Joe]

Learn something every day. Just assumed the colder air would keep the temps down causing less knock.

[Tuner-Extraordinaire]

Sorely mistaken, guy.

[SlowNA06]

Clean your MAF?
How many miles are on your spark plugs? Those copper cores don't last forever, you know.

[Joe]

Should probably clean the MAF, been a while. And spark plugs were changed 2 weeks ago, usually change them twice a year.

[Joe]

Joe,

How's the condition of the motor/trans mounts?

If they are shot...and the motor moves enough...downpipe can come in contact with the sway bar under heavy acceleration...giving the knock sensors false readings.

As well, are you using 91+ octane?

Just an update, it was in fact the trans mount. Now the most knock I see is 3, should be able to tune that out next week.

Thanks a lot,
Joe