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Hey there techs, I’m hoping you can give me some insight into what the issue seems to be with my vehicle. It seems to be related to a sensor or fueling issue. Vehicle is 2009 Buick Lacrosse, 3800 Series III engine.
I replaced my Water Pump and Rear Valve Cover Sunday, and the last time I had removed the fuel rail I installed new O-Rings I lubed them up with Petroleum Jelly as per every damn Mechanic I’ve ever known. Bad idea, O-Ring swelled and melted. #3 Cylinder O-ring melted and got glued to the LIM, and the pintle cap broke free at he seam and got left behind in the manifold. I ordered a reman injector from GB Re-manufacturing via Rock Auto and they told me it’d be here today, but once it shipped they set it back to next Monday. Picture in attachments:
The pintle cap only seemed the encase the injector nozzle and body so I grabbed some loctite, high temp, high vibration plastic super glue and glued it back. I GENTLY placed the injector in a vise and applied just enough pressure to seat it just as the rest of the injectors were. I lubed the O-Ring up with water based equate KY Jelly. I slid it in nice and gentle. B)
I filled it back up with coolant and took it out for a 50 mile drive to ensure everything was ok while running real time Torque readouts and diagnostic info.
A couple times I noticed the fuel trim read as low as -15 for a few seconds with cruise control on. At one point I stopped a light and switched from the diagnostic scanning to real time info to see my AFR sitting at 17:1 a few seconds after coming to a complete stop.
My diagnostic info is as follows. I’m seeing some info saying misfires counts but when I check each individual cylinder I’m seeing no misfire, I’m not getting a misfire code nor am I seeing and KR or rich/lean codes. I did accidentally spill a bit of coolant on the area where the wires plug into the circuit underneath my ignition coil packs.
02 Heated Monitor Bank 1 – Sensor 1
Misfire Counts for last/current drive cycles (Calculated)
Min: 4,128 Max: 41,253
Current: 3,136Heated Catalyst Monitor Bank 1 (This particular one has been showing out of spec since I got the scanner a few months ago)
Min: 4,177 Max: 1
Current: 6,752MID: $81 TID: $18
Fuel System Monitor Bank 1
Min: 4,144 Max: -24,423
Current: 6,272MID: $81 TID: $20
Fuel System Monitor Bank 1
Min: 4,128 Max: -24,262
Current: 8,320MID: $81 TID: $39
Fuel System Monitor Bank 1
Min: 4,128 Max: -24,237
Current: 14,720MID: $90 TID: $03
Low Sensor Voltage for Switch Time Calculation
Min: 61.62% Max: 450:7%
Current: 655:2%MID: $e1 TID: $0a
Sensor Period (Calculated)
Min: 4,128 Max: 41,252
Current: 2,784Two manufacturer defined MIDs with no identifying info: MID: $f0 TID: $ab and MID: Sf0 TID: $fa both reading too high a value.
Last one is EWMA Misfire Counts (Average) for last 10 drive cycles.
Min: 4,144 Max: 41,113
Current: 3,056I disconnected the battery and had a misfire on Cylinder 6 about a week ago due to the 02 wire touching the #6 spark plug wire.
However when I look at the misfire counts for all 6 cylinders both calculated and over the last/current and last 10 drive cycles I’m seeing 0 misfires.
I have a feeling this may be due to the redneck repaired injector, I know they’re extremely sensitive and I may have done something to it when I placed it in the vice for a couple hours. Then again it doesn’t explain the sensor readings unless they are 02 sensors.
Any input into what may be going on is much appreciated. I’ll scan the engine for P0 codes and be back momentarily.
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No fault codes stored in the ECU. For the majority of the drive my FT didn’t go above or below 6%, and AFR except for the one spike stayed at 14.77 with cruise on, 12.8 under WOT which is normal.
I apologize for asking this here, I realize this is a thread for techs to discuss among themselves but I don’t have the $$ for dealership. I was banned from one of the best forums for 3800 info due to disagreeing with a mod over the possibility of coolant getting into oil from the LIM gasket (I had to replace it a couple weeks back after a broken coolant elbow fell into the LIM trying to retrieve it). The mod who banned me is also a mod on 3800pro.com and everyone has quit replying to my posts since then so I have nowhere else to go.
Could an exhaust leak at the flange before the cat cause these issues? Sometimes when I start the vehicle I can smell exhaust coming from directly under the cabin/front seats and given how bad the last 2 winters were I do believe the flange where the downpipe connects to the cat is rusted out and leaking.
I took automotive technology for a few semesters before giving it up for a factory job, my experience level leaves me at 8-10 starting out and with all the tools + tool box combined with the cost of my medication I opted out for a better starting rate and good insurance. If I recall correctly a leak would cause 02 sensors to to read incorrectly and therefore cause the PCM to adjust accordingly. Given the diagnostic information could this cause both of the issues with 02/Catalyst and fuel system sensors?
Read up on O2 and heated catalyst monitors, appears to be a bad 02 sensor.
Despite my AFR reading normal under idle and WOT operation the O2 voltage dancing back and forth between lean and rich. Reading it in real time I see voltage as low as .12 and as high as .68. Fuel trims don’t show any lean or rich conditions so I’m assuming one of the three O2 sensors are bad causing wacky readings. Could also be the exhaust leak. I’ll start with an exhaust flange repair kit and take it from there.
Took it out for a second spin after it cooled down and completed another drive cycle, heated catalyst, only a single fuel system monitor and low sensor voltage came up this time. None of all that extra stuff.
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