3800 Regal owners

[troy1]

new upstream borg O2 and the same old stock after cat O2. The surge when the car is warming up on take off around 2500 RPM is kinda strange. In town mileage of 18-20 I think is respectalbe but the hiway 23 MPG is BS Might take it to a engine guy I know and let him have it as us tranny guys are dumb

[BNaylor]

Originally Posted by troy1

new upstream borg O2 and the same old stock after cat O2. The surge when the car is warming up on take off around 2500 RPM is kinda strange. In town mileage of 18-20 I think is respectalbe but the hiway 23 MPG is BS Might take it to a engine guy I know and let him have it as us tranny guys are dumb

Is the Borg Warner 02 sensor OEM? Hey, it is good to have knowledgeable tranny guys especially with the history of the 4T65E. Just a suggestion but send GMMerlin (Kevin) a PM. Maybe he can help you with his bag of tricks. Just tell him Bob referred you. He is a good man and should help once he gets to your email. Good luck!

[tman]

Threads have been merged due to an accidental deletion by troy1. All is now well. Procedd to enjoying the thread

[troy1]

Thanks tman I KNOW I BROKE IT How about deleting some of the dulicates up at the top of Pg 2! #16 & #17

[troy1]

Pulled the Vac line off the fuel pressure regulator to see if fuel was being sucked in thanks to a ruptured FPR but that dont seem to be the answer either. I am serious thinking about just buying a CAT.

[tman]

troy, I deleted the second one, but you can do that yourself on your own posts. hit the edit button on the bottom right of the post and hit delete in the minisection there, and then click the new delete that popped up.

Proceed to the next post, nothing to see here, move along.

[troy1]

Thats what I thought I was doing before IC my mistake now.

[fantastic]

93 Regal. I'm getting about 22-24 in city and 28-30 Hwy. That is average between summer and winter. At 120 km per hour my rpm is 2100-2200. It also seems the faster I go the better milage I get.

[troy1]

Car went to the shop tonight SO hopefully they find something I'll keep you guys posted.


How fast is 120km >> 80mph?

[katana1981]

Originally Posted by fantastic

93 Regal. I'm getting about 22-24 in city and 28-30 Hwy. That is average between summer and winter. At 120 km per hour my rpm is 2100-2200. It also seems the faster I go the better milage I get.

yeah i wasn't sure if I was crazy of not but at 115-120 km/h, its where I get the best gas mileage.. is that normal?!?!

Driving at 100-105 km/h, my rpm is about 1600-1700 but I get 26 mpg;
Driving at 115-120 km/h, my rmp is about 2000-2100 but I get 32 mpg.

Is it explicable?

[troy1]

Well got the car back they found no problems they checked 19 things other than the sensor data. So buy a CAT take a chance or maybe a rear O2 sensor which is in spec. It would be interesting to see if the vac gauge drops out on the road at 80. If the CAT was just starting to go bad would it show up under a load before sitting in the parking lot looking at the vac gauge?

[BNaylor]

Originally Posted by troy1

Well got the car back they found no problems they checked 19 things other than the sensor data. So buy a CAT take a chance or maybe a rear O2 sensor which is in spec. It would be interesting to see if the vac gauge drops out on the road at 80. If the CAT was just starting to go bad would it show up under a load before sitting in the parking lot looking at the vac gauge?

You forgot the banghead smilie..lol. Seriously, if I were in your position I'd probably run that vaccum test while on the road. I did a similar test with a fuel pressure gauge and taped it to the driver's side wiper.

There is one other test that can be run on the exhaust system to test for backpressure or CAT acting up but it is a real hassle. The dealers normally have the test fixture or check with any mechanic friends. One can be fabricated if you are willing to go through the trouble. The test is run with a 0 - 5 psi low pressure gauge. A connector (tee) is needed where bottom is male thread 18mm X 1.5mm pitch and the top is female 18mm X 1.5mm. It has to have a fitting to connect the gauge. The fixture is threaded into the front 02 sensor bung and the 02 sensor is threaded in at the top. Engine is warmed up and brought up to operating temperature. Then rpms are taken up to 2000-2500. The gauge should not read greater than 1.25 psi.

The CAT is still a possibility and under "poor fuel economy" it is near the top of the list in the GM service manual, especially with all the other tests passing.

[troy1]

Its all I do all day long where can you find the parts to fab up on of those testers? Do you think the intown mileage would stay up 18/19 and the hiway would fall if that CAT was bad? Its in the 30's around here but I dont think mileage should drop that much If I could get what you get 28 that 4.5mpg better I suppose I could nurse it around untill spring and see if comes up or just spend the 50 and replace the cat The thing that gets me is I really dont seem to have a loss of power just mileage if the CAT was bad you would think my performace would suffer also

[BNaylor]

Originally Posted by troy1

Its all I do all day long where can you find the parts to fab up on of those testers? Do you think the intown mileage would stay up 18/19 and the hiway would fall if that CAT was bad? Its in the 30's around here but I dont think mileage should drop that much If I could get what you get 28 that 4.5mpg better I suppose I could nurse it around untill spring and see if comes up or just spend the 50 and replace the cat The thing that gets me is I really dont seem to have a loss of power just mileage if the CAT was bad you would think my performace would suffer also

Check these out on Ebay to give you an idea. Little different. GM recommends a 0 - 5 psi gauge whereby these are 0 - 15 psi. Also, based on what they claim you can plug into the 02 sensor bung without having the 02 sensor physically installed. Testing methodology is still the same.

http://motors.search.ebay.com/back-p...Z1QQsofocusZbs

Normally bad CATs will degrade performance but I guess it depends how far gone it is. On our '99 Regal LS the first indication was gas mileage. The performance appeared to be good but after the CAT was replaced it was much better. You could feel the difference in the seat of your pants. Luckily it progressed to generating a CAT efficiency DTC error code.

It seems like replacing the CAT outright is the cheaper and most hassle free route to take, especially if you get a hi-flow type. Hopefully that alone may help improve your mileage.

[fantastic]

120 km/h is 75 mph. Eventually I want to drive at 140 km/h to see if the milage goes down. It is very strange that the milage gets better the faster the car goes. It would be nice to hear why this occurs.