Knock knock

[keymaster]

So I was floating along on the freeway today, and went to accelerate past another car. I was probably doing 60-65 in 6th gear, around 2500rpm, and I didn't hammer the throttle...I was actually pretty light on it. But, I got a bucking going in the car, a pretty serious vibration, and then my Dashhawk went off with a knock alert (knock greater than 6). I wasn't logging unfortunately, so all I know is that it happened. I've had this happen before I got the Dashhawk, in a similar situation, and I was able to replicate it once...it seems to take just the right combination of factors, and it's hard to duplicate. Having the car shake/rattle because of engine knock is a bit disconcerting!

So, is this something I should be taking the car in to be looked over? Is there a way to get rid of the problem? Or is it something we live with and work around?

 

[tunersteve]

I've mentioned this before, seeing part throttle 'knock' on your DH on the highway isn't a problem, it's merely ignition adjustment to optimize mileage. Unless you feel a loss of power or hear an audible pinging sound, it's nothing to worry about.

In your case, it's hard to say, but you may have got bad gas, or there might be a more serious problem. Are you running the AP at all? Also, what kind of temps were you dealing with (ambient, conditions, etc.) because that might explain it.

 

[keymaster]

No AP yet, it's still in the box. Only engine mods are the Denso ITV22s. It was probably around 80F, I'd been on the freeway maybe 10 minutes with maybe 10 minutes driving beforehand. The temp gauge looked normal. Oh, and I was running the AC. And, I usually fill up with premium at the Union76 (cheapest prices)...maybe I should look for somewhere else for gas, I've actually been meaning to look up what the best gas is.

And, yeah, I definitely felt it...people have complained about a stutter when driving, and I bet that this is exactly what they have been talking about. It didn't backfire, but it made a chuttering sound; I initially thought the traction control was doing something odd until the Dashhawk threw the alarm.

 

[keymaster]

So, anyone have any more advice about this? It's only happened a few times, on the freeway when accelerating in 6th around 60--65mph, so I can work around it for the moment (not a lot of freeway travel in my normal day). But, if there is a fix I would rather get that done than worry about knocking the engine apart one day.....

Thanks!

 

[tunersteve]

There's a TSB for hesitation under acceleration that they can check and do one of two things; reflash the PCM with a new firmware setup, or replace the CDFP. I don't know if that directly relates to it, but it might be worth a shot if you've got a warranty.

If you run the car un-tuned and in cold weather, you get some noticeable boost cut. Once I installed the AP, it went away.

Get yourself some good 93 (or 91 if that's all you got) gas (Shell, BP) and see if it comes back.

 

[KTsuchiya]

So I was floating along on the freeway today, and went to accelerate past another car. I was probably doing 60-65 in 6th gear, around 2500rpm, and I didn't hammer the throttle...I was actually pretty light on it. But, I got a bucking going in the car, a pretty serious vibration, and then my Dashhawk went off with a knock alert (knock greater than 6). I wasn't logging unfortunately, so all I know is that it happened. I've had this happen before I got the Dashhawk, in a similar situation, and I was able to replicate it once...it seems to take just the right combination of factors, and it's hard to duplicate. Having the car shake/rattle because of engine knock is a bit disconcerting!

So, is this something I should be taking the car in to be looked over? Is there a way to get rid of the problem? Or is it something we live with and work around?

I've had the same crap happen constantly in the past year since I got my SPD6. Funny thing is, after I switched the Engine Oil to Mobil 1 5w-30 Full Synthetic last month with a K&N HP-2009 filter (thnx Qwik6), the knock came less under high speed/throttle mashing. This s*** worked for me, but this definitely is NOT a fix. You can give it a try.

The knock usually happens anytime, regardless of speed, when i want to pass someone by mashing the pedal to speed up. I was idle in lane today and the smoke issue is damn apparent as well. Hate this crap but I will soon pay Mazda a visit in NC since I already have 33k miles on the car.