Horrible gas mileage/brakes squill hardcore

**izzhemp** · 02-21-2010, 08:35 AM

I have a 1999 firebird v6 automatic tranny with 140,462 miles on it. when i first got the car i could get right around 375 miles on a full tank. it gradually got worse, so i put new MSD street fire wires, bosch double electrode plugs. didnt see a differnece after that. I then replaced the fuel filter and it stopped decreasing but didnt go bak up at that point i was gettin around 275-290 off a full tank. at this point my brake pads were dew for a change i had 5 options for pads i got the 3rd best but there not ceramic, with in the next month had rotors turned and was told next brake service i need to replace the back rotors it was the last time they could be turned. Two weeks after that i had my brake system flushed out. The following week a put an 80 series flowmaster muffler on my car. No affect on my gas milage. the following week i put on a 165 degree thermostat and a jet stage 2 performance chip. Still no difference on gas milage but there was a noticeable horse power an torque increase, an the exhaust and chip are both suppose to improve gas milage. i put a new MAF sensor in couple months ago, I also have the ws6 ram air hood, my rear tires have less then 5000 miles on them and my front have about 15000 miles on them, my alighnment was done recently and had a outer passengar front tie rod replaced at the same time. I recently switched to royal purple 10w-30 oil and usein K&N oil filter with it, and few hundred miles ago i had my tranny flushed and put in royal purple tranny fluid. As of now im gettin bout 230-250 a tank. I dont get on my car or rod on it cause for one its a v6 and two i dont wanna tear apart my car. I am throwin codes on my catylac converter/O2 sensor. An one is transmission componet slippage. My tranny only slips when ive drivin it for prolonged periods of time, or randomly it will slip starting from a stopped postion during the accelaration between 25-35 mph which i think its first gear slippin it only happens in that mph range coming out of a stopped position. so thats that on my gas situation. the brake pads still have less than 6000 miles on them and they squeal and squeek hardcore its so loud and annoying, and when i brake it dont slow down like it should and when coming to a complete stop it feels like its takin more pressure on the brake pedal than needed to stop and the stops are hard an feel really jerky ( as in when it does stop it just straight up STOPS and it kind of jerks you forward) which is understandable if your slamming on the brakes but im not i ease into it. So please anybody that can offer any info tips or help on my situation i gratefully appreciate it. Thanks everybody...ignore the typos

Israel Hemp

**pajeff02** · 02-21-2010, 09:09 AM

If you are running the original front O2 sensors, they are long overdue for replacement. The sensors degrade over time and as they control closed loop fueling this may be part of the problem. Also, as you mentioned, the cats may be causing performance and mileage issues if they are plugging up. The rear O2 sensors simply monitor catalytic efficiency and your SES could be either from bad cats or faulty sensors.

Good gas mileage generally results from a properly tuned vehicles with things like air filter, plugs, wires and sensors being in optimal condition. You could also have leaking injectors which would result in additional fuel being dumped into the engine, and this could also be causing cat issues. Lots to consider here -- and certainly a slipping transmission does not help!

**Pickle86** · 02-21-2010, 09:10 AM

Originally Posted by izzhemp

I have a 1999 firebird v6 automatic tranny with 140,462 miles on it. when i first got the car i could get right around 375 miles on a full tank. it gradually got worse, so i put new MSD street fire wires, bosch double electrode plugs. didnt see a differnece after that. I then replaced the fuel filter and it stopped decreasing but didnt go bak up at that point i was gettin around 275-290 off a full tank. at this point my brake pads were dew for a change i had 5 options for pads i got the 3rd best but there not ceramic, with in the next month had rotors turned and was told next brake service i need to replace the back rotors it was the last time they could be turned. Two weeks after that i had my brake system flushed out. The following week a put an 80 series flowmaster muffler on my car. No affect on my gas milage. the following week i put on a 165 degree thermostat and a jet stage 2 performance chip. Still no difference on gas milage but there was a noticeable horse power an torque increase, an the exhaust and chip are both suppose to improve gas milage. i put a new MAF sensor in couple months ago, I also have the ws6 ram air hood, my rear tires have less then 5000 miles on them and my front have about 15000 miles on them, my alighnment was done recently and had a outer passengar front tie rod replaced at the same time. I recently switched to royal purple 10w-30 oil and usein K&N oil filter with it, and few hundred miles ago i had my tranny flushed and put in royal purple tranny fluid. As of now im gettin bout 230-250 a tank. I dont get on my car or rod on it cause for one its a v6 and two i dont wanna tear apart my car. I am throwin codes on my catylac converter/O2 sensor. An one is transmission componet slippage. My tranny only slips when ive drivin it for prolonged periods of time, or randomly it will slip starting from a stopped postion during the accelaration between 25-35 mph which i think its first gear slippin it only happens in that mph range coming out of a stopped position. so thats that on my gas situation. the brake pads still have less than 6000 miles on them and they squeal and squeek hardcore its so loud and annoying, and when i brake it dont slow down like it should and when coming to a complete stop it feels like its takin more pressure on the brake pedal than needed to stop and the stops are hard an feel really jerky ( as in when it does stop it just straight up STOPS and it kind of jerks you forward) which is understandable if your slamming on the brakes but im not i ease into it. So please anybody that can offer any info tips or help on my situation i gratefully appreciate it. Thanks everybody...ignore the typos

Israel Hemp

dont run bosch plugs in it. they are horrible for gm cars. this coming from a certified gm mech he told me to never use those.

**izzhemp** · 02-21-2010, 09:45 AM

Originally Posted by pajeff02

If you are running the original front O2 sensors, they are long overdue for replacement. The sensors degrade over time and as they control closed loop fueling this may be part of the problem. Also, as you mentioned, the cats may be causing performance and mileage issues if they are plugging up. The rear O2 sensors simply monitor catalytic efficiency and your SES could be either from bad cats or faulty sensors.

Good gas mileage generally results from a properly tuned vehicles with things like air filter, plugs, wires and sensors being in optimal condition. You could also have leaking injectors which would result in additional fuel being dumped into the engine, and this could also be causing cat issues. Lots to consider here -- and certainly a slipping transmission does not help!

ill have the O2 sensors replaced how much would i be lookin at spendin for that? an everything i mentioned that ive had done to the car has been done from october to present, ill check into the sensors though for sure. An how would you be able to determine if my injectors are leaking? im hopin it be the O2 sensor and not injectors cause those prolly arent cheap to have replaced but knowin my luck it prolly is the injectors. an yes the tranny is so annoying if it didnt cost more than my car for a new tranny id of gotten it replaced by now, is it possible to convert my automatic to a 6 speed? i know id need the centerconsole and would have to install the clutch pedal but where would the slave cylinder (i think its the slave cylinder thats connected to the clutch pedal) be mounted at? it dont seem like there would be room for it on my firewall, and would the driveshaft need to be changed out as well?

**izzhemp** · 02-21-2010, 09:47 AM

Originally Posted by Pickle86

dont run bosch plugs in it. they are horrible for gm cars. this coming from a certified gm mech he told me to never use those.

i didnt know that so thank you, what would be ideal plug for my car keep in mind its the v6

**pajeff02** · 02-21-2010, 10:20 AM

O2's for our car were about $71 each at Autozone. Check your spark plugs to see if you have a rich condition. I only mentioned that as you are closing in on 150,000 miles.

**izzhemp** · 02-21-2010, 10:30 AM

Originally Posted by pajeff02

O2's for our car were about $71 each at Autozone. Check your spark plugs to see if you have a rich condition. I only mentioned that as you are closing in on 150,000 miles.

71$ not too bad, and im kinda illiterate with this kind of stuff so when you said check for rich condition what is that an what would i be looking for? and the plugs were replaced in october so there still fairly new, and i had around 138000 on the car at the time i put the new plugs in, the ones i removed were the original stock and they didnt really look that bad.

**Draik** · 02-21-2010, 10:37 AM

Ac delco spark plugs for general motors
Autolite for Ford
Bosch for Europeans
NGK for Japans
and that is all my knowledge on spark plugs ^.^

**pajeff02** · 02-21-2010, 12:56 PM

Originally Posted by izzhemp

71$ not too bad, and im kinda illiterate with this kind of stuff so when you said check for rich condition what is that an what would i be looking for? and the plugs were replaced in october so there still fairly new, and i had around 138000 on the car at the time i put the new plugs in, the ones i removed were the original stock and they didnt really look that bad.

Dark colored or black plugs (not oily) would be indicative of too much fuel as it results in carbon buildup on the plug.

**izzhemp** · 02-21-2010, 01:24 PM

Originally Posted by pajeff02

Dark colored or black plugs (not oily) would be indicative of too much fuel as it results in carbon buildup on the plug.

ooohh...alright thanks alot that really helps, so i can diagnose the problem my self or atleast narrow down the possibilities of what it is with out havin to take it to the shop and spendin 60 bux just to be told whats wrong with it. now all i need is a day of decent weather (i dont have a garage i know i suck haha) so i can get this takin care of. thank you very much. you wouldnt by chance have a theory on my brake problem would you? or know where to find the measurements for the front seats on our cars ive been tryin to get my interior done for bout a month only thing holdin me bak is those measurements and if i get them my self i can get the materials my self and save a couple Bill$ on it

**pajeff02** · 02-21-2010, 01:28 PM

What brand and type of brake pad are you using? Some are simply noisier than others. Did you "bed" the pads after install? Also, note that our brake caliper pins are known to seize up and cause premature brake issues. Were they disassembled, cleaned and re-lubed with synthetic caliper grease when you changed out the pads?

**Pickle86** · 02-21-2010, 01:59 PM

Originally Posted by izzhemp

i didnt know that so thank you, what would be ideal plug for my car keep in mind its the v6

like the other guy said get ac delcos they are awesome i run them in my bird

**izzhemp** · 02-21-2010, 02:14 PM

im at work so i dont have my recipts handy, but i went to oreillys website and im 80% sure these are it. an all i did when i changed my pads was put some little packet of lube on them that was availbale at the counter, but it was the first time id ever changed brake pads i know i put them on right and i checked the pistons on the calipers to make sure they was functionable but i didnt clean the calipers or anything....i didnt know

Brake Best Select - Brake Pads

Part Number: SC750

* Rear
* Ceramic
* UPC: 441769029978

Warranty Info

Limited Lifetime Warranty
Detailed Description

BrakeBest Select brake pads feature the new QuieTech shim design. Sealed with a polymer based friction modifier, the new QuieTech shim neutralizes pad to caliper vibrations - resulting in quieter, smoother stops.

* 100% asbestos-free friction in both semi-metallic and non-metallic formulations
* Platform-specific formulations for light trucks, SUVs, mini-vans and cars, including Ceramic, Semi-Metallic and NAO (Organic) friction materials.

Manufacturer Information

BrakeBest Select brake pads feature the new QuieTech shim design. Sealed with a polymer based friction modifier, the new QuieTech shim neutralizes pad to caliper vibrations - resulting in quieter, smoother stops.

* 100% asbestos-free friction in both semi-metallic and non-metallic formulations
* Platform-specific formulations for light trucks, SUVs, mini-vans and cars, including Ceramic, Semi-Metallic and NAO (Organic) friction materials.
-------------------------------------------------------------------------

Product Details
Also Available At
Compatibility
Brake Best Select - Brake Pads

Part Number: SM749

* Front
* Semi-Metallic
* UPC: 441769029961

Warranty Info

Limited Lifetime Warranty
Detailed Description

BrakeBest Select brake pads feature the new QuieTech shim design. Sealed with a polymer based friction modifier, the new QuieTech shim neutralizes pad to caliper vibrations - resulting in quieter, smoother stops.

* 100% asbestos-free friction in both semi-metallic and non-metallic formulations
* Platform-specific formulations for light trucks, SUVs, mini-vans and cars, including Ceramic, Semi-Metallic and NAO (Organic) friction materials.

Manufacturer Information

BrakeBest Select brake pads feature the new QuieTech shim design. Sealed with a polymer based friction modifier, the new QuieTech shim neutralizes pad to caliper vibrations - resulting in quieter, smoother stops.

* 100% asbestos-free friction in both semi-metallic and non-metallic formulations
* Platform-specific formulations for light trucks, SUVs, mini-vans and cars, including Ceramic, Semi-Metallic and NAO (Organic) friction materials.

**izzhemp** · 02-21-2010, 02:16 PM

Originally Posted by pajeff02

What brand and type of brake pad are you using? Some are simply noisier than others. Did you "bed" the pads after install? Also, note that our brake caliper pins are known to seize up and cause premature brake issues. Were they disassembled, cleaned and re-lubed with synthetic caliper grease when you changed out the pads?

and i dont know what "bedding" the pads is

**transamgirl89** · 02-21-2010, 03:15 PM

Originally Posted by pajeff02

What brand and type of brake pad are you using? Some are simply noisier than others. Did you "bed" the pads after install? Also, note that our brake caliper pins are known to seize up and cause premature brake issues. Were they disassembled, cleaned and re-lubed with synthetic caliper grease when you changed out the pads?

THANK YOU!!!! I can't tell you how many times mechanics completely neglect doing this! My caliper pin got stuck so bad we couldn't get it loose with a hydraulic hammer. A lot of times this does happen and did happen to my 99 Firebird. If those caliper pins get stuck, chances are they're pinching your pads and that could be the cause of the awful noise.

**transamgirl89** · 02-21-2010, 03:16 PM

Originally Posted by izzhemp

and i dont know what "bedding" the pads is

**izzhemp** · 02-21-2010, 03:22 PM

Originally Posted by transamgirl89

THANK YOU!!!! I can't tell you how many times mechanics completely neglect doing this! My caliper pin got stuck so bad we couldn't get it loose with a hydraulic hammer. A lot of times this does happen and did happen to my 99 Firebird. If those caliper pins get stuck, chances are they're pinching your pads and that could be the cause of the awful noise.

i didnt take it too the shop i did it on my own, and ya i prolly look pretty stupid not knowin what bedding the pads is...so why dont you tell me so i can stop lookin stupid

**pajeff02** · 02-21-2010, 03:58 PM

I have never used ceramic pads before, so I'm not even sure if you need to bed them. Bedding the pads involves a series of starts and stops where you get up to around 20-25 mph and then bring the car to a stop with a semi-firm pedal. You do this anywhere from 10-20 times and it heats the pads. This process, known as "bedding" acts to season the pads and helps them last longer.

If you have some free time on your hands, it may not be a bad idea to lube your caliper pins. It's a simple process and is cheap insurance considering the cost of brakes and rotors. Here's what you do:

1. Put the car up one end at a time and remove the wheel you want to work on first.

2. Grab a coathanger and cut it to fashion a short hook that is several inches long. This will give you something to hang the calipers from when they are removed from the bracket. You never want to let them hang by the hose.

3. Unbolt your caliper using a socket and a wrench on the flat part of the pin to keep it from turning.

4. After the caliper is removed, pop the rubber dust boot off of the bracket as you slide the pin out of its hole. If the pins are seized, you will need to also remove the bracket to work on them. The worst one I had was on the front of our T/A -- I had to turn the pin with a wrench as I heated the body of the casting with a propane torch.

5. Once the pins are pulled, clean as much gunk as you can out of the holes and also clean the pins and boots. If they are bad, you can run them on a wire wheel or polish them with emory cloth. I flush the holes out with brake clean and twist the corner of a shop rag down the bores. I then blow them out with compressed air to remove any remaining debris.

6. Liberally coat each pin with synthetic caliper grease. The grease will want to push out as you insert the pin, so I always slide it in and out a few times and add some grease. When it is fully lubed it will almost have a vacuum effect and hold the pin in as you try to pull it out. Don't forget to reinstall the boot before inserting the pin and make sure it fully seats to form a good seal.

7. Reinstall you caliper and wheel (bracket first if you had to remove it) and then go on to the next wheel.

Unless you experience problems, the whole job should only take about an hour. Again, it is cheap insurance and our cars are known for seizing the pins if not properly maintained.

**jagfan93** · 02-21-2010, 04:27 PM

Originally Posted by izzhemp

i didnt know that so thank you, what would be ideal plug for my car keep in mind its the v6

Delco 41-101 Iridium, Oreilly has them for around $6.99 ea, worth every penny.

**Smittro** · 02-21-2010, 04:48 PM

Front o2s and rear o2, cat prolly should have been replaced 60k ago mine took a dump @ 76-78k-ish High mileage can also cause reduced fuel mpg's. Get the RP oil out of it and use the K&N to hold down your trash can liner. Have the tranny reprogrammed for firmer shifts. What do you mean "you dont rod on it cuz it's a v6???" If you just put around all the time that's not good for her either. I don't beat on mine either but I put her to the floor to blow out the carbon build up on the valves. Won't hurt to feed some speed into her once in a while. (Smittro does'nt condone street racing) But the interstate is a good place to get her up to a speed you're comfortable with and sustain it for a while.. But to be totally honest with you she's just wearing out and getting tired bro..