Service Engine Light???!!!!

[PerfectCreature]

Well, the one I have on now should not be cracked.
The one they put on the first time was my stage 1 manifold. They ended up cracking that pretty bad in the upper, middle.
Had to go home and grab the stock one so they could place on the stock one for now.
So I suppose then, they could have cracked the stock one as well, since they cracked the first one.

So, coil packs are out since the misfires are random, and the fact I got an 02 sensor code leads you to believe it is another manifold crack?
Okay, I will take it back in and have them check it-hopefully, it will not be another manifold crack. I will be really upset if they cracked two manifolds of mine in a row.

[TGP37]

Oh wait, I thought the cracked upper was still on the car. Were the codes cleared since they swapped them out?

If you think they cracked the manifold, try using a torque wrench to find the break away torque needed to loosen. If the bolt is much tighter then recommended, insist they pay to replace it. Sometimes shops have new guys and they screw stuff up w/o realizing it.

These uppers, plenums, they seem to crack often when over tightened. Which is common among non-professional mechanics.


The 02 code, running lean, can be one of several issues. When ever I hear of running lean, my 1st suggestion has always been check for vac leaks.

I believe the random misfire code will stop when the o2 lean code is resolved. Seems you need to find what is causing the motor to run lean. Somewhere, unmetered air is getting in the intake (after the MAF sensor).

[PerfectCreature]

No, the SES light went away as soon as they placed the stock manifold back on, it stayed on for about 10-15 seconds then went out. Car left the shop with no codes.
I did notice though, that the car idles now and it will sort of bounce a little in-between the tic marks. Like if it is in-between 610 and 620, it will bob to the 610, then to the 620, then to the 610.
As for the code? It came back that night, and then went away. Stayed away for a day, then came back yesterday afternoon-had it checked and showed the p0300 codes and then I think it was a p0131 code, but I could be wrong. I do know what the description said, it said bank 1 sensor 1 o2 sensor running lean-along those lines.
The SEARS center reset the codes, and asked me to try some higher octane gas and see if that would help it, and the code is back again.
As for tightening the plenum? I think it was hand tightened, or a very small torque wrench was used.
They cracked the first one and would not replace it, I highly doubt if they did crack this one too, they would offer such an honorable action.

[pocket-rocket]

If they did 2 in a row enlighten them that your lawyer will help straighten it out. If you want to check for a vac leak you can spray gasket surfaces with carb spray with the engine running, or use a propane torch around gasket surfaces with the torch unlit. If the idle changes more than normal you just found a leak.

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[TGP37]

No, the SES light went away as soon as they placed the stock manifold back on, it stayed on for about 10-15 seconds then went out. Car left the shop with no codes.
I did notice though, that the car idles now and it will sort of bounce a little in-between the tic marks. Like if it is in-between 610 and 620, it will bob to the 610, then to the 620, then to the 610.
As for the code? It came back that night, and then went away. Stayed away for a day, then came back yesterday afternoon-had it checked and showed the p0300 codes and then I think it was a p0131 code, but I could be wrong. I do know what the description said, it said bank 1 sensor 1 o2 sensor running lean-along those lines.
The SEARS center reset the codes, and asked me to try some higher octane gas and see if that would help it, and the code is back again.
As for tightening the plenum? I think it was hand tightened, or a very small torque wrench was used.
They cracked the first one and would not replace it, I highly doubt if they did crack this one too, they would offer such an honorable action.

If the o2 sensor is still indicating a lean burn (even occasional), it could be a number of things. Either the combustion is truly lean or the sensor is reading wrong. I would assume first the sensor is accurate.

Could be.....small leak in exhaust before the O2 sensor, o2 sensor itself could be loose, small intake leak after the MAF sensor, PCV valve leak (check the other valve cover in the back as that feeds metered air to the crank case for the PCV, which connects to the intake after the MAF) , fuel injector o-ring (bottom) may have torn, the valley of the LIM where the black RTV is used, that may allow unmetered air in but I'm not sure it that will make it to the PCV or not, FPR may be bad, MAF sensor may be dirty, oil air filters can skew MAF readings.....thats off the top of my head.

It's probably something simple over looked.

If they did 2 in a row enlighten them that your lawyer will help straighten it out. If you want to check for a vac leak you can spray gasket surfaces with carb spray with the engine running, or use a propane torch around gasket surfaces with the torch unlit. If the idle changes more than normal you just found a leak.

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Exactly, but they may call the bluff and you will need to hire a lawyer just to threaten litigation. It should be cheap for a law firm to type up a letter on your behalf, or write your own. Once they believe they will be taken to court replacing the plenum suddenly becomes the cheapest option.

[pocket-rocket]

Either way, they need to make this right if they are just winging it and screwing up good parts. This is why I do my own work and only take my vehicles in for tires and alignments, no offense OP.

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[PerfectCreature]

I was going to do it myself, but I work two jobs and simply do not have a day I can take off to work on my car and then have to trouble shoot problems such as this.
I had the code reappear and on my way to the mechanic that did the work in the 1st place, it dissapeared.
I am pretty stumped, I mean it could be so many things- but it is hard to figure out when the code keeps coming and going like that.
We know the simple one, P0300, but the other one, has not shown up again, cause I have not been able to get a second scan on it with the SES light on.

I will take it back to them either tomorrow, or Thursday whichever day I have more time and make them run tests until they fix it.
It feels like it has more power with the light off, then with it on, which I assume is due to the misfires? But I still do not understand why the code keeps going on and off like that.

[pocket-rocket]

Even with the light off the code is still present in memory meaning the code can be pulled with the light off.

I've done two jobs at once and man that sucked :/ I hope you find your problem soon. Side note, using swype on my phone it tried to spell noob instead of soon, lol.

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[PerfectCreature]

Noob, that is an awful thing to say. ha.
Anyway, yeah, well. I am getting fed up with it. I sill bring it in and demand he find the problem, since the issue arised after he repaired my car. He is really the only mechanic to touch the engine of that vehicle.
Anyway, it will most likely be Thursday.

[TGP37]

PRocket is correct aboubt the codes remaining in memory even with the SES light off. In fact, some codes will never trip the SES light but still register and remain in memory. Disconnecting the battery will not remove them either, eeproms. Some codes are erased on their own when the issue is fixed.

If the only code you get is the P0300, then the problem might just be something really simple. Like a spark plug cable not clicked onto the plug all the way, bad fuel, bad spark plugs (I remember hearing a certain type of spark plug made these engines run terribly).

You might be on the threshold to trip the lean code from a simple issue.

I wonder if your issue is from increasing the volumetric efficiency with the better parts. Need a pcm tuning if that is the case.


One more possibility......I noticed you changed the filter, was your fuel filter plugged up? If so, the stress on the fuel pump then suddenly removing that stress can cause the pump to fail. You may just have a dying fuel pump. Checking your fuel pressure seems like a good idea before tossing more money/time at it.

[pocket-rocket]

(I remember hearing a certain type of spark plug made these engines run terribly).

Bosch.

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[PerfectCreature]

My spark plug wires are Bosch, but the plugs themselves are Irridiums from AC Delco.
As for codes? I had an O2 sensor code pop up once, but it has since dissapeared.
I am thinking it was due to revving the engine while it was in park to check and see if a loppy or odd idle/rev was accompanied with the P0300 code that set off the 02 sensor code?.
As of now, the code has not come back on and I have driven it about 55 miles.
I will keep looking out for the SES light.

It was also on my mind that the PCM my not be accustomed to having a 2.5 inch exhaust with ported heads and a ported LIM. The UIM was ported until the cracked it and I had to place a stock one on.
I plan to purchase the PCM tune from Ben in a few days, he said he actually has a file for a tune with the exact setup of my car because someone local had it done just recently-that would let us know for sure.
I plan to have another mechanic shop place on the UIM and the 65mm TB, and I will install the PCM myself afterwards, and see what sort of results I get-and if the code comes back.

If it comes back in the mean time, I will make the mechanics find it-so far so good.

[3400-95-Modified]

9 times out of 10 when you make modifications like that it will not trigger a SES light... the ECU doesn't throw codes if its not accustomed to parts, it will adjust with the fuel trims. Was the O2 code a Cat Efficency code? because any code for the O2 sensor if it's the main sensor should not be ignored. Downstream sensor who cares since its only saying the cat isn't cleaning the exhaust enough... It has no ill effects on how the car runs.

[TGP37]

The bank 1 sensor 1 O2 was lean until the cracked plenum was replaced. He said it dissappeared moments after staring the car with the stock plenum.

Though the P0300 random misfire still persisted.

I agree, an upstream o2 fault is not something to ignore, especially in a performance engine.

[PerfectCreature]

Actually, that O2 code was present after the cracked plenum was replaced with the stock one.
Though, it was present for the scan when the SES light was present on the dash, when it was scanned at SEARS. It was scanned the first time with only the P0300 code. We revved the engine in park up the band of 1-3k, then steady at 2k for about 30-45 seconds. He said he saw nothing and heard nothing odd about the idle or the rise of the RPM bands or anything.
He then scanned it a second time to remove the P0300 code, and then notice the O2 sensor code.
He recommended that I try some octane boost because the gas may be bad. I tried that, and then the SES light came back on after the SEARS guy had removed both codes. I drove it and when I had time to bring it into the mechanic that did the work on it in the first place, it turned off just as I pulled in.

When the light turned off, and I had it scanned at the mechanics shop-with the light off (He used a snap-on scanner), he stated he only saw a P0300.
I suppose given his antics about the whole plenum he could have lied and not told me it was not there (the O2 code) even thought it was still there.
Though, I cannot be sure as he did not show me the scanner, like the SEARS guy did.
The light has not come back on as of yet after about 70 miles.
I have to run a few errands that will be another 50 miles, maybe it will trip and show up again.

I have all of tomorrow off, and if the code comes back on, I will be able to stop by the mechanic and have them find the problem.
I could always just tell him the light came back on, even though it did not.
What did you mean by the O2 code is very serious in a performance engine? Could it cause damage or?