so last week i finally got my 2.8" pulley installed along with 50lb injector and a tune from cobalt addiction. the guys there were really cool and were nice enough to let me watch them work on my car too. but they are pretty hard to get in touch with.

BUT. after my tune i got a cel which is apparently a lean code. yikes... and today i was doing a couple of rounds in gears to see if i got any knock. so far, other than surges that come and go quickly, i got 2-4 degrees of knock in 3rd gear from going wot at buttom end. it appears that the lower rpm i go WOT the more knock i get.

hhmm idk guys. i smell disaster... inputs are appreciated.

 

puttin a lot of stress/load on the engine will cause it to get KR..


just like if you floor it from 30mph in 5th gear

 

if you load the car down down(high gear, low RPM) you'll get knock but what your describing is far worse then that.

sounds like another intense tune.......argggg

sounds like another tune i'll have to go through an fix on the local guys......

 

yeah i have no clue what im gonna do. i cant tune myself and i dont believe CA will retune for free... atleast im not getting alot of knock at wot from top of gears.

 

Talk to BCP (06BlackG85SS). He knows these cars inside and out and does great tuning.

 

just hit me up man, I got a few people comng down for tunes over the next few weekends (and I live right out of the city, 40 miles closer than C/A). And I know for a fact that they do not run a lot of timing on the cars and they are setup to run pretty damn rich. (I know cause they all came off my car as base tunes) I can dial in the car for you if you want, but I need to make sure you at least have a wideband in the car, and please tell me you don't since that's one of the single most important things to have when modding and F/I car.
but don't be going WOT in 3rd gear at 2000 rpm's any car will get KR under those conditions, thats just way too much load on the motor. have to do pulls from 3k up in each gear to really get a good idea of what its doin.

 

So engine load can cause knock? I never thought about that.

 

mine doesn't

then again, i tune for the wierd conditions and funky driving styles.

 

How much normally occurs with high engine load?

 

aaah btw so you're they guy with the 50lb injectors.... that explains it, and lean code doesn't really mean you're running lean, just means under cruising your fuel trims are in the positive range. I have a feeling I know what the issue is, what fuel pressure are those 50lb injectors rated at?

personally my car gets maybe .3 degree KR at high load and up to 2 depending on what gear I WOT in. But normally I only get about .3 btwn shifts and thats it

 

haha yeah that would be me. i think im the only kid who dared to try out the 50lbs, i mean the car runs and feels great.and i do have a aem wideband its all hooked up i just need to get the o2 welded in and connected. but other than a lean code and yeah i would have imagined that in lower rpms at high engine loads it would create knock, i just didnt know wether it was normal or not. i got the worst knock in 3rd gear from 2k to 5kish at about 4-5degrees kr.

yeah before i got my tune they didnt ask me anything about the injectors, he said all he needed to do was change some variables.

but heres some info on them.
impedance: high
Resistance: 12omega
opening Ms: 1.660
closing Ms: 0.970
nozzle style: ball and seat
spray angle: 22.4 degrees
50 lbs. at 43.5 psi[cobaltperformanceparts]

id really appreciate you helping me out though and any input you have.

 

Your knock sounds completely normal. You HAVE to be in the right RPM's in the right gear before you can go WOT. It sucks, but if you really want a fast car with a lot of timing, that is what you will sacrifice.

Definitely get the Lean condition taken care of, because that will kill your engine if you push it hard.

50's are slightly tricky injectors to tune up, so I can understand the Lean Code. I too own a set oc Cobalt Performance Parts injectors. They sit in a nice box on the shelf. Tried them for a while, but they are a pile of crap in our cars. Shame too, because they are the perfect size for our cars. There just isn't something right about them.

 

problem is there rated 50psi at 43.5 psi and our cars run a 56psi static fuel pressure... so they are actually 56.73 lb/hr which through the tune off it setup for 50lb/hr. Pretty simple fix though, just have to adjust the flow rate vs KPA table.

 

hm i wonder what my IDC is.

 

I'd say up around 92% or so depending on how rich you're setup up top