SES light help.....

[Jason97T/A]

I had the dealer replace my Smog Pump under recall today. I also have two other codes settin off the service engine light now though. One is the EGR. The guy said that it is probably caused by the lack of backpressure because I have no cats. He said if the EGR was screwed up I would have a hesitation at idle more than likely. After I get my car out and going and warmed up, when I stop at a stop light, the car will kinda stutter a couple times off and on, I told him this and he said it might be the EGR is actually screwed up then. Has the lack of cats ever screwed up anyone elses EGR on there T/A or camaro? I am going to call Dal and see how much he charges for the EGR and solenoid. How big of job is it to replace this gadget?
Also another code is for the bank 1 sensor 1 O2 sensor. That should be fairly easy to replace wouldnt it be? Probably have to spray a lot of penetrant around it though wouldnt I?
Well any thoughts would be great.
Thanks
Jason

[Joe 1320]

I've heard some really strange things from service techs. Some of them true, others are BS. I have personally never seen removing of cats cause the EGR to malfunction. Perhaps Fred could chime in here.....

The EGR is not hard to swap, it's just the clearance under the cowl can make you wish you were a contortionist. Hopefully you aren't a 6'9" gorilla with 26 inch arms.

Before you spend a dime on a new sensor, make sure you really check the harness and connections. On two occations a service tech told friends of mine their sensor was toast. They came by my garage to do the fix, I unplugged the harness, cleaned the connections and the sensor started working just fine. Ya never know unless you dig into that first. If it is bad, the o2 sensor will most likely require a penetrant to get it loose. I prefer PBlaster. That is great stuff. If it is stubborn, you might need to start the car and get a little heat into the sensor to make it easier to remove. There is a specialty tool that is very helpful. It is an o2 sensor socket. It looks almost like a spark plug socket with one side carved out to permit the sensor wire to not be destroyed or pinched. Once you get the faulty sensor out, be sure to clean the area really well with alcohol. This step is what 99% of the techs don't do. The chemicals in the penetrant can kill an o2 sensor quickly. Even residual stuff left behind can shorten the new sensor's life. It might not kill it right away, but it can shorten the life considerably. A little dab of anti sieze on the threads (keeping it away from the sensor bulb) will help the next time you have to change it.

[Jason97T/A]

Originally posted by Joe 1320
The EGR is not hard to swap, it's just the clearance under the cowl can make you wish you were a contortionist. Hopefully you aren't a 6'9" gorilla with 26 inch arms.

Enough of the tall jokes, I'm 6'6". haha
How easy are the bank 1 sensors to get too? What did you use to clean the connections on the O2 sensor? How much would a new EGR run me? Is there anyway to check this component? I could have sworn I had it replaced a year ago. And also what all comes with the EGR, the valve and solenoid?

[Joe 1320]

Originally posted by Jason97T/A
Enough of the tall jokes, I'm 6'6". haha

DOH!

Originally posted by Jason97T/A
How easy are the bank 1 sensors to get too?

Fairly easy... it is right above the manifold to downpipe flange if it is the primary sensor. You didn't mention if it was the primary or secondary, I am assuming that the number "1" that you posted is referring to the primary. The secondary sensors are located after each cat and are responsible for measuring the effectiveness of the cats.

Originally posted by Jason97T/A
How much would a new EGR run me?

Don't know. Try Jason Cromer at Sam Taylor Buick (877)726-8295
on some stuff he's less expensive than Dal. It wouldn't hurt to check locally. On inexpensive parts, sometimes it's just as cheap to get them locally instead of paying shipping charges. You'll have to do the footwork on this one.

Originally posted by Jason97T/A
Is there anyway to check this component? I could have sworn I had it replaced a year ago.

The EGR is a mechanical valve that is electronically controlled. The mechanical valve itself must be removed and sometimes can be cleaned and reinstalled. The EGR tube can also get plugged, but that is a little harder to do.

Originally posted by Jason97T/A
And also what all comes with the EGR, the valve and solenoid?

Those are seperate. Most of the time it is the valve itself that goes south. Exhaust gases along with particulate matter like carbon pass through this valve and can eventually clog it up..... especially if the car has been running crappy for a lengthy time. The solenoid is merely an electronic actuator.

[Injuneer]

Looks like we're on the "exhaust backpressure" topic again.

The system checks EGR operation by looking at how the MAP reading changes when the EGR valve is told to open by the PCM. The blip in the MAP pressure is caused when the exhaust gas starts to flow into the intake manifold. Its entirely possible that if your exhaust system has a reduced backpressure compared to a stock exhaust, the system will not detect any flow. A low back pressure exhaust, or removing the cats is often enough to set the SES light under some driving conditions. Seems like the 96/97 OBD-II test is very sensitive, compared to the earlier OBD-I test. In a 93-95, you can delete the EGR valve completely and the PCM usually (but not always) will not be able to detect its absence.

If EGR is faulty, there could be a problem. If the valve doesn't close fully, and exhaust flows into the intake manifold when it isn't supposed to, the idle could be rough and there could be stumbling at low loads, and missing at higher load and RPM. The EGR system should not flow any exhaust into the intake at idle, at WOT, or above 3,500rpm.

The second fault would be a failure of the valve to open. If it didn't, the PCM will still be reducing fuel, because the EGR would normally be displacing air, and quenching the combustion chamber temps.... that's why they use EGR. So the mixture would go a little lean, but the long term fuel corrections should be able to pick that up and correct the shortage of fuel.

As far as the O2 sensor code, Bank 1 Sensor 1 is the pre-cat sensor on the drivers side, and its on the base of the exhaust manifold, where Joe describes. It would be helpful if you could remember the exact code, e.g. Pxxxx, because there are several different codes, and not all of them would require the replacement of the O2 sensor. If you had a "Bank 1 Sensor 1 Lean" code, it could be misfires, or a leak in the exhaust system on that side.