Flow

I sold my 300whp Vortech Supercharged Focus SVT and bought a Cobalt SS, for a daily, the focus was, well a handful.

I bought it very low on gas and everything ran fine. Even beating on it. On the way home I got gas in it and I noticed when it started back up and almost seemed like the IAC (if we have one) wasn't plugged in, trouble starting and RPMs bouncing hard. I right away thought eh, it probably needs a purge valve. It ran fine all night, other than a minor misfire at idle.

A couple days go by and I get on it and first is fine but when I hit second it almost feels like a coil is completely dead. It started doing this dead coil feeling every time boost goes above 5-10lbs with a little throttle. So I went to autozone and grabbed plugs, NGK 4644 gapped .030, and still nothing. When they ran the codes it came up 2 codes for random misfire, 1 code for purge valve flow rate high, and 2 codes for cat efficiency, I'm sorry but I don't remember the numbers.

I'm really leaning towards a dead coil being my problem but I'm pretty lost honestly.

Bought the car 5 days ago, 110k. On the car fax it says at 90k "spark plugs changed, engine checked" then states engine checked 3 more times in the next year which makes me think this problem might of been long term.

If anyone can please point a direction to look it would be greatly appreciated, I'm a huge Ford guy trying out Chevy and there's just some things I'm lost on.

P.S. I really like the car!!!

Sharkey

iTrader: (1)

generally when you have a dead coil it will set a misfire code for that specific cylinder. further, there is only one code for a random cylinder misfire (p0300), so if it had 2 codes for random misfire, id bet it had one thats cylinder specific and they told you the wrong thing (autozone morons). the codes for cat efficiency are what interest me, these cars are bad for plugging the stock cats up, and it causes a huge loss in power and high boost. stock these cars are only supposed to run around 12psi max, if your seeing 10psi with a little throttle, thats leading me to think its plugged. have you tried going full throttle on it, and if you have how much boost did it make?

another thing to consider, is the car stock? best way to tell is by the color of the injectors (green or black) and have a look at the blower pulley. if the pulley is pressed on its stock, if it has 4 blue bolts its a gm stage 2 or 3, if its anything else it should have a size on it. and does it have an aftermarket intake or exhaust?

Flow

Alright. The car appears to have a Injen intake, (new throttle body at 90k guessing oem replacement), GM stage 2 pulley, black injectors, header, 3" exhaust, it's definitely catless and if I had to guess it's the ZZP Longtube with 3" catless and their 3" exhaust. It also has the stealth heat exchanger. The car makes about 16-17psi.

Now it came up with two spark related codes before I changed the plugs, I'm hoping if I go in next time after a battery pull that there will only be 1 spark code and hopefully not the random code.

Keep in mind I'm completely new to these cars, while mechanically inclined and force induction knowledgeable I don't know the exact parts that are on the car. Bolt ons and tune is a good way to say it. Full exhaust, no doubt, it's stupid loud and raspy.

Sharkey

iTrader: (1)

ok well we can rule out plugged exhaust then. and the 2 codes for the cat would be because its not there.

hopefully it will spit a code for specificly what cylinder is is the issue. the ideal thing is to hook a scanner or hp tuners onto it and watch the data and see whats going on, but thats not always possible.

Flow

Got codes pulled, supercharger inlet pressure sensor. So I replaced that but I think I found the map sensor (identical looking?) and it's has a vacuum port on the bottom of it plugged into nothing, anyone know where that goes?

Sharkey

iTrader: (1)

thats the barometric pressure sensor, its supposed to be just hanging out there with nothing plugged into it. the s/c inlet pressure sensor is on the top of the blower, the map sensor is in the intake manifold near the snout of the blower, close to the #1 injector.

Flow

Well, purge valve was a good investment, definetly bad. Supercharged sensor was oilily so I replaced that too and it still misfires.

It has a minor misfire at idle, then a hard misfire at about 40% throttle or so, boost builds between 5-10lbs and dies out, starts missing hard.

I put a new battery cable on the car, ground cable was toast.

Codes were:
Cat
Cat
Purge
Purge
Random misfire
SCPS

63 Nova SS

iTrader: (3)

I haven't owned the supercharged version so I'm no help. Just wanted to say thanks for you doing some homework in what was done to the car, and figuring out what mods/boltons you have because most new guys don't have a clue what they have and want you to figure all that out for them. Welcome to Chevy world.

Flow

From one Supercharged car to the next.

I'm not bad around motors and would be much better suited if I had no just bought my first Chevy 5 days ago or so. I was really trying not to post but I'm pretty stumped.

Tomorrow I plan on cleaning the MAF, and trying to get the MAP sensor out. Every bolt on this car is stripped or broken. Literally every coil cover bolt is snapped in the cover, every coil pack bolt. Barometer sensor, injector cover bolts are screwed, oh it's a mess. However, all the wiring looks really clean and none looks damaged so far.

Sharkey

iTrader: (1)

how is the supercharger coolant level? reason i ask is i cant see anything in it. way back i had the intercooler core seals leak and fill my intake manifold with coolant. when this happened the car drove fine till it got enough airflow through the manifold and it would pick the coolant up and it would get into the cylinders causing a huge misfire/stumbling. sometimes id get coolant smoke out the exhaust, sometimes not.

Flow

OKay I will check that out tomorrow, I see myself possibly pulling this car apart tomorrow. Hmm. I was planning on pulling injectors at minimum, throttle body and more.

Flow

The code reader is directing me to injector, but my guess is that a clogged injector would be all the time not intermittent. I can see some of the wiring under the injector cover and it looks like there's electrical tape wrapped around it and the wires look messy. I'll have to check that too. I should of taken a deeper look at the car but the test drive it drove great.

Flow

Also my car seems to be making much more boost than normal, even though it's the stock boost gauge. I believe it has the 3.1" pulley on it. It's also considerably quicker than stock.

izcain

iTrader: (5)

Electrical tape is normal for the factory harness.


Cat efficiency codes are normal for no cat although it says a lot about the tuning since normally you would turn these codes off when tuning the car.


Random cylinder misfire is just a byproduct of the problem.

Quick down and dirty was to test the coils that may be easier for you would be to pull codes when it spits the misfire code. Find out which cylinder and go to that cylinder and swap the coil with the next one over. If the problem fallows to that companion cylinder then you can feel confident its the coil.


I second Sharkey and wonder how much coolant is in s/c heat exchanger. Also if the exchanger pump is even working.




P.S. Love that color. I looked for a long time for that color or the blue and could never find it close enough to me.

Flow

I wouldn't think it had the factory harness unless someone spliced into it to add aftermarket injectors. Then that could be my problem if one of those spliced wires is coming loose.

I'm going to have a dirty tear down with her today, girlfriend is coming with to help.

Sharkey

iTrader: (1)

if you have a bad connection with an injector it would set a code for injector circuit open/short, and the problem wouldnt be so specific on when it happens.

Flow

Well I tore her all apart. You're right the coolant tank for he heat exchanger was dead empty. No coolant in the manifold I could see, I cleaned everything, injectors were filthy, all the sensors are dirty. Haven't driven it yet but idle still has a misfire.

Flow

Had quite the day with her.

Girl cleaned up the injectors, rail, pressure regulator, pulse dampener, re-did all the wiring harnesses that were assessable; such as, injector harness, pressure sensor harnesses, MAF harness, and map harness.

I got the blower off and inspected everything. Everything was very oily, actually a pool of oil in the intake elbow. Throttle body was clean as I expected as it is new. Gaskets all looked good, map sensor gasket didn't look good though.

Now, my misfire is considerably lighter, even when it (Cobalt owner word coming here) machine gun misfires in boost, but I still can't make any power. Mind you, I've made about 25 pulls in this car before this issue occurred. I can daily it fine but I want to make it whine again already.

Thanks for the help guys! It has been a lot of help. It was really fun pulling the car apart today and getting to really learn the car. They're really easy to work on!

Flow

Also are the stock coil packs no name?

No I maybe thinking too hard here, but there is 1 ACDelco and 3 no names. So my thought is the 3 are cheapskis and causing a misfire for whatever reason and since three are randomly misfiring it's throwing a "random" misfire code.

I don't know if I think that because I'm leaning towards a coilpack being bad or I'm thinking to hard.

izcain

iTrader: (5)

Did you reseal the laminova cores?

Find any other leaks in the heat exchanger setup? Verified the pump working?

Just curious since you said it was dry.

Flow

It's bone dry. Everything is dry like it was purposely drained honestly.

izcain

iTrader: (5)

Not good! So you filled it?

Flow

Honestly I left it dry, but can fill it.

I'm not so sure on if I want to chase another problem (leaking heat exchanger) while already chasing a misfire issue.

However I did find the previous owner on these forums and he was chasing the issue as well. Which obviously is not good.

What is good is compression and injectors in my car.

What he found bad was the map was oil covered and not reading boost well. He also had p301 and p300 which I'm guessing is random misfire and random misfire on cylinder 1. He also got p0069 but I haven't come across this yet, although I did have to replace my supercharger inlet sensor.

So now I'm leaning map related. The o-ring looked toasted, the plastic looked pitted and the sensor inside the plastic was dark and pitted as well. Possibly the last owner didn't use the proper cleaning supplies and the sensor is already on the last limbs?

I don't know but I'm probably going to throw more money at it with a MAP sensor, then move on to a coil pack.

Flow

Here's my codes guys. Some data too.

Throttle body was replaced last year, and was clean when I removed it the other day. I did not even touch it honestly.

Flow

Possibly thinking about just getting a canned ZZP tune and trying that.

Map sensor is older I believe, date on it is 01/2008 so I'm trying that first.

If the throttle body code comes back on, should I just buy the stock throttle body or is the LQ4 worth it and get a tune at the same time.

My intake is weird, you can probably see it in one of the pictures, but the MAF housing is larger than the rest of the pipe, then it gets bigger at the end for the throttle body coupler. Any body know what intake this is?