hey guys have a little problem with my lnf. before i shift at higher rpm (around 6k) i notice my balt hesitates and bulks in that rpm range (prob 5k-6k) I've replaced the plugs and gapped them and it still does it. do you think it could be my coils? compression is 160 on all 4

 

Are you monitoring the misfires per cylinder? Would like to know if it's happening on just one.

This will help us help you.

 

i have no way to monitor the missfires just looking for what could cause it really. i have the car stored for winter atm but this has been in the back of my head for a while now lol. i do know that in second gear i can spin the tires to redline and it will not have any of the symptoms

 

Well we don't really have a starting point for you.

So i would suggest getting a way to log it. Otherwise this is useless. Hate to throw parts at something without knowledge.

 

My car does the same thing, but it bucks real bad between 2-3k rpms and hesitates under load and misfires like crazy on acceleration and deceleration . Its getting worse, but still no damn check engine light. It idles terrible, and the boost gauge is all over the place. Im ready to blow it up, lol.

Replaced
1. Battery
2. Purge solenoid
3. Vent solenoid
4. Coils
5. Cam phasers
6. Spark plugs
7. New gmpp clutch
8. Hpfp
Mine sounds different too, and def loss of power.

 

Have you checked the lash adjusters? My problem is in the high rpm range other than that the car runs very smooth

 

HMM, it was a thought about the rockers/lash adjusters, but I thought I would hear that in the valve cover if they were broken.

 

Have any of you checked your maf or map sensors.

 

Wouldn't a check engine light come on if either one was bad???

 

Most of the time yes, they could also have a ton of oil on them.

 

Well my maf on the intake has been cleaned, and the map sensor on the lower chargepipe was cleaned as well, still didnt fix the rough idle or bad driving conditions.

 

my MAF was dirty i cleaned it up and it fixed the backfiring issue i had but not the other problems. map sensors are good

 

my filter is old on my short ram intake, but it would cause these problems and jumpy boost gauge...

 

Possible valve gunk on both cars. Check the condition of your valves and clean with walnut blast if required.

 

is there a how to on that?

 

found it lol https://www.cobaltss.net/forums/how-...emoval-304188/

 

Quicksilver beat me to it. Check for excessive build up on the valves. After you clean it, invest in a catch can.

 

seen on a few post around here that theres no point to get a catch can. whats your input on this?

 

on the SS/TC it's a very good idea. It's really the only way to prevent carbon build up. The kit from Powell is the only good one to get. It's expensive though.

Personally I'm not getting it because the cost of cleaning isn't that much. Can do walnut blasting every couple years. It's not for the faint of heart though.

 

im gonna pull of my intake manifold and do the walnut blast and see if that works lol

 

It was enough of a pain to do that I don't want to have to do it again in the near future. Hence why I have the Powell kit.

 

Scope your valves first so you don't have to take the whole manifold off it it's not the problem.

 

how much is powells? valves don't gum up with his system?

 

$350 roughly. Apparently it does collect oil but I'm not sure if we have seen long term results have we?

 

You are probably right about saving hassle and just getting it.

After a certain mileage I'm not sure if we have seen a "clean" set of valves. I'm at 72k and I don't notice tons of misfires, but I do get a couple on start up on the scanner as well as can be felt in the seat.

I may get a borescope becuase my dad has a non turboed 2.4L GM Direct Injected engine at 65k. Would love to see it.