Trailblazer running rough/misfiring with CEL after running out of fuel

douellette

Original poster
Member
Aug 26, 2012
15
hello, im working on a TB for my friend. It is a 03 TB LTZ I6. The two codes i pulled from it are P0301 (cyl 1 misfire) and the other is P0132 (02 Sensor circuit high voltage bank 1 sensor 1). While it is running i can smell fuel vapors which seem to be under the hood. I can also hear a steady clicking/tapping sound from the front of the engine.

Also, it started running like this when he ran the fuel tank bone dry. I was thinking the fuel pump mustve gone bad because of that, but after scanning the codes im thinking otherwise.

Coil on cyl 1 has been replaced with a new one. Not sure if plugs were changed as well or not. The guy was also an EMT/EMS personnel so lots of hard driving.

Anyone know where i should start looking on this TB? i am new to the I6 motors. I was thinking of checking fuel pressure at fuel rail and also checking plugs
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Welcome! Glad you made it here from the other site, which is now a ghost town.

1) Clicking fan be an aging electroviscous fan clutch or water pump. Not your biggest worry right now.

2) Plugs are definitely a suspect. How many miles, and were they ever changed? Use ONLY Delco 41-103 iridiums. The engine is extremely sensitive to using those plugs.

3) Check the O2 sensor data if you have a good scan tool. The wiring could be bad, or the sensor faulty. Sensors usually get changed at 100K miles along with the plugs.

4) Fuel can be fromloose intake manifold bolts. Happens a lot. Looking around can also sometimes spot a loose hose.

5) Does he have erratic idle with the AC compressor turned on? Not a huge issue yet, but it's a common problem with a simple cure.

6) I wouldn't suspect the fuel pump or filter unless it runs poorly at high speed/RPM.
 

douellette

Original poster
Member
Aug 26, 2012
15
the roadie said:
Welcome! Glad you made it here from the other site, which is now a ghost town.

1) Clicking fan be an aging electroviscous fan clutch or water pump. Not your biggest worry right now.

2) Plugs are definitely a suspect. How many miles, and were they ever changed? Use ONLY Delco 41-103 iridiums. The engine is extremely sensitive to using those plugs.

3) Check the O2 sensor data if you have a good scan tool. The wiring could be bad, or the sensor faulty. Sensors usually get changed at 100K miles along with the plugs.

4) Fuel can be fromloose intake manifold bolts. Happens a lot. Looking around can also sometimes spot a loose hose.

5) Does he have erratic idle with the AC compressor turned on? Not a huge issue yet, but it's a common problem with a simple cure.

6) I wouldn't suspect the fuel pump or filter unless it runs poorly at high speed/RPM.


wow thanks alot!

For a scan tool i have a elm 327 bluetooth obd2 adapter hooked up to my android phone. I use the Torque scanning app. It updates the live info a little slow, but the upstream o2 sensor seems to be changing properly from ~.2 to ~.8 volts.

Does it seem like a coincidence that it would start running like this after he ran the tank out of fuel?
Ill go try to check the intake bolts although they seem a little hard to access.
I will go take a video as well to help you guys out
 

douellette

Original poster
Member
Aug 26, 2012
15
it has about 144k miles. I might have solved the misfiring issue. Pulled the plug off the connector on the new coil and low and behold it wasnt connected right. Whoever plugged it in bent 2 of the prongs so it was only making contact with 1 of the prongs lol. straightened them and reset the PCM by pulling the 2 fuses for 10/15 minutes. Started it and runs pretty smooth. :smile:

Tried the AC, When you turn the AC OFF it wants to stall/falls on its face. doesnt seem to happen when you turn the ac on, just off. Is this the ac issue you mentioned before?

Also, i found some reciepts in the glove box for work that has been done. The fan clutch has been replaced about 4 years ago. Also one of them confirmed what the clicking/ticking is, It is actually an exhaust manifold leak at the front (cyl 1 i believe). Anyway, here is 2 videos i took.

This one is showing how its running and also the stumbling when revving it.

[video=youtube;Z8IoBYLewfU]http://www.youtube.com/watch?v=Z8IoBYLewfU[/video]

The one shows the ac being turned off

[video=youtube;t_OArZuQ7tM]http://www.youtube.com/watch?v=t_OArZuQ7tM[/video]
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Oh, and for the profile, it's a 4WD, not a true AWD like the Bravada.

And if he neglected other things, I have to mention the transfer case fluid is CRITICAL to change every 50K, a surprisingly short interval. And ALL OTHER fluids at 100K.
 

douellette

Original poster
Member
Aug 26, 2012
15
the roadie said:
Oh, and for the profile, it's a 4WD, not a true AWD like the Bravada.

And if he neglected other things, I have to mention the transfer case fluid is CRITICAL to change every 50K, a surprisingly short interval. And ALL OTHER fluids at 100K.

okay. yeah ill probably do the transfer case fluid and engine oil. Im fixing this up for my friend and selling it for him and i get to keep 30% of the sale price so trying to keep my out of pockets low.

Also, did the relearn procedure for the throttle body and its running quite well now.

Do you have a link for the cowl seal fix? and the ac fix? thanks
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Cowl seal:
http://gmtnation.com/f23/need-know-what-new-hood-seal-looks-like-1068/

I don't know of any way to fix idle issues when the AC is turned off. Cleaning the throttle body has always worked for when the compressor cycles on and off.

Might be a gummed-up CPAS.

Whatever you don't fix will only be reported here by the NEXT owner. :rotfl: We get to live with mess-ups essentially FOREVER. :wink:
 

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