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My car was not running right and black smoke was coming out of the exhaust. I thought is was coming out of both sides, but is was just the right side. There were a few codes, so I had Bosh platinum plugs installed, a new wire set, high flow air filter, distributor cap, and rotor. I also had to have a water pump and thermostat installed (do not use Dex Cool as your coolant, see problems online)

Car still drove like garbage. Found that the PCV hose had a hole in it, so all codes but P0300 (random cylinder missfire) went away. Replaced fuel regulator and got same code. Found one of the fuel injectors not sealed and replaced (passenger side). The car still ran like garbage (a lot of black smoke on right side) and my service light was on/blinking.

I brought it to the dealership for a diagnosis and was told the following:

Diagnose
-set up tech 2
-stored codes P0300, P0174,P0151
-check compression-160PSI in all cylinders-good
-fuel pressure good 42PSI-injector test-within factory spec
-check 02 sensor-bank 2 low
-may have vacuum leak under intake manifold

All of my 02 sensors were replaced recently, so I think that code is showing because it is covered with soot. If there is a vacuum leak under the intake manifold, shouldn't it be affecting both sides of the car? The right side is the only one that has the black smoke coming out.

What else should be looked at? Anyone know a mechanic who knows Vettes in Somerset or Morris County (NJ)?
 

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Discussion Starter #3
I don't have the computer to pull the codes, but all of the symptoms are exactly the same. I am 99% sure it is the same code. What do you think? My mechanic has been working on it, but at this point I think I am going to go the dealership and get ripped off. I should have gone there in the first place. They should be able to find the problem ( I would think).:huh:
 

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Discussion Starter #4
Apparently, there were more codes, but they could not find a definite cause.

This is what the dealership wrote:

Diagnose-set up tech 2-stored codes P0300, P0174,
P0151-check compression-160PSI in all
cylinder-good-fuel pressure good 42PSI-injector
test-within factory spec-check 02 sensor-bank 2
low-may have vacuum leak under intake manifold

Any thoughts?
 

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P0300, Multiple Engine Misfire Detected

P0174, Fuel Trim System Lean (Bank 2)

P0151, HO2S-21 (Bank 2 Sensor 1) Circuit Low Input


Looks like you prolly have a bad oxygen sensor and prolly a vacuum leak. It could be a line or maybe even the intake manifold has a small leak in it.
 

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Discussion Starter #6
Thank you, my mechanic is going to take a look at it. I would have had the dealership do it, but they were expensive and said they were not sure if that is the problem. I hope it is because I don't know what else it could be.:huh:

If you have any other thoughts or if someone else has any input please let me know. Thanks!
 

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Discussion Starter #7
Why is the missfire just happening on the passenger side? If there is a manifold leak, wouldn't it affect both sides?
 

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Now I could be wrong on this....but if the engine had overheated before, it may have messed with the intake manifold gasket on the right side. So maybe when that cylinder is on its compression stroke-during the valve overlap-some leaking is occurring on that side of manifold against the cylinder head. There for creating maybe a rich mixture in that cylinder, which could be giving you that black smoke. Again, I could be wrong. Good Luck.
 

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Why is the missfire just happening on the passenger side? If there is a manifold leak, wouldn't it affect both sides?
Yes - a vacuum leak should affect both banks.

Here are my random thoughts about your situation.

1. The good news is that your compression is good on all cylinders. Mechanically, then, your engine should be good to go.

2. Your mechanic (or you) need to put a vacuum gage on the engine and see if you have a leak.

3. Swap the O2 sensors and see if the problem moves with it.

4. Black smoke usually means a rich condition. Have your mechanic do an injector leak down test (start by putting a pressure gage on the fuel rail, pressurize the fuel system, and then observe how long it takes for the fuel pressure to drop).

5. Here's why your O2 sensor could be showing a lean condition (P0174) even though you have black smoke. It's due to your misfires (P0300), because all the unburned fuel (causing the black smoke) will be high in oxygen content, which is what the O2 sensor is reading.

6. I'd pull the plugs on the passenger side and inspect them. You're looking for a specific plug covered in black - and that may be the source of your problem. If the leak down test shows a problem, then that plug may be pointing to the bad injector.

This is not a complete rundown of what should be done, but it's a start. If I think of anything else, I'll post back.

Steven
 
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