Slight knock after CAI install...

[bricker82]

2004 Grand Prix GTP CompG 3.8 S/C
32800 miles

I put a K & N FIPK CAI on Wednesday and I noticed a slight knock under acceleration, but not when idle or in park. So today I put Autolite Double Platinum 605's in to help (1 stage colder), but it's still there.

I'll be honest, I'm not sure if it's knock or just the difference in sound from the CAI. There seems to be no power loss though.

The only mods I have on the car are the CAI and a 180 Tstat, so I didn't think I'd have to use colder plugs, but I tried it anyways. I also had a Gatorback S/C belt put on, what a difference in sound there!

I really didn't want to do anything else on the car yet, as it's still under warranty. Any suggestions? Do I need the car re-tuned? U-bend delete?

I appreciate any and all input.
Thank You,
Brick

[jeepgclwj]

Have you checked your oil level...Just curious. I havent done my FWI yet but I wouldnt think that allowing the car to get more cooler air would cause any kind of knock...



Keep us posted

[bricker82]

Oil level is good. Not low at all. I use Mobil1 5w30 and a Puralator PureONE filter for that. I'm going to change my oil today though, not over the mileage, but it has been 3 months.

I will let all of you know if it helps!

Thanks!

[bricker82]

OK, oil changed same as before Mobil1 5w30 with a Puralator PureONE filter. "Knock" is still there though. Here are some exact symptoms.

In Park, when revved between 1000 and 4000 RPM's no knock present, sounds great actually!

In Neutral, when revved same, same result, no knock.

In Drive, under acceleration between 1800 and 2500 RPM at any speed whether stopped or rolling, "knock" is present. Sounds like slight sputtering almost like the exhaust is loose, but then that noise would always be present if that was the case. When I accelerate hard ~3000 and up, no audible "knock", but the whistle is loud and may be masking it. When I accelerate low around 1500 no "knock" either.

I hope this helps a little.

Should I just schedule an appointment with the dealer to have it looked at? I really don't want to, but I want my car running smooth too!

Thank You all again!

[04GTP-WhatLAG?]

its just the injectors, don't worry this is normal... when you put on the open cone you can hear your injectors "clicking" under acceleration, there is absolutely nothing wrong and get used to the sound, there is no cure, well except for going back to the factory setup...

[bricker82]

I was beginning to wonder if it was normal!

I just couldn't believe that I would have a knock that caused no loss of horsepower and only occurred under very strict circumstances.

I take it you have the same sound from your GTP? I see you have quite a few more mods than me to include the (I assume) ubend delete and larger downpipe and cat. I would imagine that if anything would reduce knock that would be it!

I appreciate your advice man, thank you! I'm a little more at ease now!

[04GTP-WhatLAG?]

yeah don't worry about it, its very common in these cars... As well as jeep wranglers(my friend put an open cone CAI on his jeep and has the same problem)... the injectors are just really loud on these cars, like I said, the "clicking" is always there, but with the open cone you can hear it, if you went back stock you wouldn't be able to hear it anymore... and we don't have a ubend on the '04+s, but yeah I have scanned my car and have only slight KR at the shifts, nothing major... Also you won't be able to "hear" KR so this is definitely not that, I am about 99% sure its the injectors clicking... I have(and have had) the same 'clicking' ever since I put on my K&N aircharger, a year and half and a few more lbs. of boost later, its still running like a dream... and I see you went with the AE 077s, I was torn between those and the 192s, finally decided on the 192s...

[bricker82]

When I bought the car in 2006 it had the AE077's already on it. I am looking at changing them when I change the tires in the fall. I'm not sure what yet, but I will definately post if I change them! I like the chrome, but it is a pain to keep clean! Here is a pic of the aluminum billet accents I put under the hood.

[04GTP-WhatLAG?]

i'd stick with the 077s, they are some of the nicest looking wheels on the L32s...

my engine bay looks ghetto as hell, but I couldn't care less:









the insulation keeps the Mass Air Flow much cooler and gives a more accurate reading, so its functional, if I knew of something that looked better but served the same purpose, i would gladly get rid of it... Until then, its looks riced out under the hood...