Hi All,
New to the forum. I have a 2007 Trailblazer LT SWB 4WD 4.2 I6 with 180k on the odometer. I've had it for 1-1/2 years and it has been awesome. I've looked around for my specific issue(s), and it has been somewhat addressed in other posts, but I've not seen my two issues together specifically, nor an explicit resolution. Hence my novel below.
For the past couple months I've had two issues:
1. On cold startup the exhaust makes a gurgling/sputtering noise. The RPMs do not jump around or fluctuate when this happens. You can hear the SAIS pump working during this time. Once the SAIS pump shuts off all the gurgling/sputtering stops and the vehicle idles smooth. The person I bought the car from had replaced the exhaust from after the CAT to the tip, and did a poor job. The flex pipe was just shoved in the muffler. I had my shop weld the pipe to the muffler, and I thought this would fix this issue but it has not.
2. When the engine is hot or cold it is slow to accelerate in 1st gear. I'm not an aggressive driver, but the few times I've needed to punch it (e.g. onramps, merging) it will not take off. The RPMs slowly rise and the car feels bogged down until about 4500k RPM, then it takes off. Almost feels like turbo lag.
I have a decent OBDII reader, and have looked at live data. I have no codes showing at all. My STFT and LTFT never leaves +- 5%. My upstream and downstream 02 are in the acceptable range of 0.1 - 0.9. This is at both idle and load. My STFT B1S2 is reading 99.2% which tells me my cat may (?) be working fine. My warm coolant temp hovers around 190 per my reader.
I'm wondering if issue 1 and 2 are related.
Within the last 20k miles I've replaced the following:
Thermostat, alternator, power steering pump/lines, water pump, idler pully, serpentine belt, trans cooler lines and new trans filter, rear diff serviced, new front wheel hubs, and new air filter.
I've yet to test vacuum and exhaust back pressure, as I have to rent those tools. I haven't changed plugs or coil packs. I haven't changed 02 sensors. I just don't know where to start since my live data is not, to my limited understanding pointing me anywhere specific. I'm thinking I have an issue with SAIS valve, a partially failing CAT, or both.
Looking for some advice for those more familiar with this platform.
Thank you!
New to the forum. I have a 2007 Trailblazer LT SWB 4WD 4.2 I6 with 180k on the odometer. I've had it for 1-1/2 years and it has been awesome. I've looked around for my specific issue(s), and it has been somewhat addressed in other posts, but I've not seen my two issues together specifically, nor an explicit resolution. Hence my novel below.
For the past couple months I've had two issues:
1. On cold startup the exhaust makes a gurgling/sputtering noise. The RPMs do not jump around or fluctuate when this happens. You can hear the SAIS pump working during this time. Once the SAIS pump shuts off all the gurgling/sputtering stops and the vehicle idles smooth. The person I bought the car from had replaced the exhaust from after the CAT to the tip, and did a poor job. The flex pipe was just shoved in the muffler. I had my shop weld the pipe to the muffler, and I thought this would fix this issue but it has not.
2. When the engine is hot or cold it is slow to accelerate in 1st gear. I'm not an aggressive driver, but the few times I've needed to punch it (e.g. onramps, merging) it will not take off. The RPMs slowly rise and the car feels bogged down until about 4500k RPM, then it takes off. Almost feels like turbo lag.
I have a decent OBDII reader, and have looked at live data. I have no codes showing at all. My STFT and LTFT never leaves +- 5%. My upstream and downstream 02 are in the acceptable range of 0.1 - 0.9. This is at both idle and load. My STFT B1S2 is reading 99.2% which tells me my cat may (?) be working fine. My warm coolant temp hovers around 190 per my reader.
I'm wondering if issue 1 and 2 are related.
Within the last 20k miles I've replaced the following:
Thermostat, alternator, power steering pump/lines, water pump, idler pully, serpentine belt, trans cooler lines and new trans filter, rear diff serviced, new front wheel hubs, and new air filter.
I've yet to test vacuum and exhaust back pressure, as I have to rent those tools. I haven't changed plugs or coil packs. I haven't changed 02 sensors. I just don't know where to start since my live data is not, to my limited understanding pointing me anywhere specific. I'm thinking I have an issue with SAIS valve, a partially failing CAT, or both.
Looking for some advice for those more familiar with this platform.
Thank you!