I just bought this GN. Im getting like 8-10mpg. Some assclown put 4.11's in the rear before I bought it. I seem to have some leaks at the crossover pipe. I also need to keep the speedometer disconnected cause the speedo makes alot of noise and the needle bangs around. Ive heard that can keep the convertor from locking up, but I dont imagine it would slip this bad. I just filled out an rpm calculator for the 4.11 gears, tire height, and the 200-R4 tranny overdrive ratio. It says I should be at about 2400-2500rpm. Im at 3200 rpm. What gives? I wouldnt think the convertor would slip that much. The seller said its most likely a 2800 stall. The o2 sensor is new, and the seller used a scanmater to check everything. He said the BLM's are perfect, and it just passed smog with great numbers. It has a misfire problem at idle and low rpm's. it had a bad vacuum leak at the base of a couple fuel injectors, which I fixed. Please help. This car is my daily driver and I cant afford all this gas.
My mileage sucks!
- Thread starter VadersV6
- Start date
strikeeagle
New Member
- Joined
- Jun 6, 2001
look at it this way - if your car has been hopped it, and it's got some miles, and some maintenance issues, and you get on it all the time, and it got 17 city when it was new, oh well.
Let's say you drive your car 1,000 miles a month year, you get 10 MPG, and you pay $2.50 a gallon for gasoline. If you got 15 MPG you'd save $83 per month. Yeah, that's nice, but it wouldn't keep me awake at night.
Let's say you drive your car 1,000 miles a month year, you get 10 MPG, and you pay $2.50 a gallon for gasoline. If you got 15 MPG you'd save $83 per month. Yeah, that's nice, but it wouldn't keep me awake at night.
rpming
tony is right , get rid of those gears, replace with stock 3.42 or i would even consider 3.23s. Since the car already has a converter less gear would work fine. I would check to see if the converter was a lock up unit because it slips so much, that could also hurt the mileage. My daily driven stock Gn got 18-20 in town and on the road cruising at 65 i got 24. Hope this helps. You can grease the speedo cable and that will take care of the bounce.
tony is right , get rid of those gears, replace with stock 3.42 or i would even consider 3.23s. Since the car already has a converter less gear would work fine. I would check to see if the converter was a lock up unit because it slips so much, that could also hurt the mileage. My daily driven stock Gn got 18-20 in town and on the road cruising at 65 i got 24. Hope this helps. You can grease the speedo cable and that will take care of the bounce.
ChrisCairns
Senior Member
- Joined
- May 24, 2001
Your bad mileage is probably a combination of all the "gas sucking" things you've mentioned.
One thing I was wondering about was why you didn't mention an SES light code....code 24 for VSS malfunction (speedometer disconnected will cause this.) If you just forgot to mention it fine, but if the light isn't constantly on then maybe someone in the past has disconnected it and perhaps there are more engine problems of which you're not aware.
One thing I was wondering about was why you didn't mention an SES light code....code 24 for VSS malfunction (speedometer disconnected will cause this.) If you just forgot to mention it fine, but if the light isn't constantly on then maybe someone in the past has disconnected it and perhaps there are more engine problems of which you're not aware.
You have to take the speedometer cable out of the case, this means remove the speedometer head and the cable is right there. If the previous owner did not change the speedometer gear in the tranny then the speedometer will be miscalibrated and will also cause this problem.
Gas milage??? Go buy a Honda! J/K! I am selling my 3.42 gears on the for sale section on this site. Hook up a tcc switch to lock up on the highway.
I run 28" tall tires, and have a non-lockup converter. I am using 4th gear in the 1320'. Plan on almost finishing OD before the line.
I run 28" tall tires, and have a non-lockup converter. I am using 4th gear in the 1320'. Plan on almost finishing OD before the line.
Well, part of the allure of the GN is the ability to pull 20+mpg on the highway while still having the power. 8-10mpg is not an option for me.
I didnt mention the SES light because I figured thats obvious. I do have the light, and its on all the time. Does the car go into limp mode with the light on like most FI cars? Would it cause an extreme amount of slippage?
ChrisCairns
Senior Member
- Joined
- May 24, 2001
I believe (but am not positive) that the only effect of no speedmeter is lack of lockup. You already know your converter will slip more and cause lower gas mileage so do what someone else suggested until you replace your speedo cable.....put in a manual lockup switch. Which is a bitch to remember to unlock. 
hey vader (Brent) you are reading too much into this, fix the problems that are obvious, such as gears, any leaks that u may have, TCC selenoid, fuel pressure, new injectors,Maf, translater and a better chip, (which you already have most of them) I am sure it will come out just fine but dont put too much effort into trying to find out what else could be wrong, you already know the issues fix them and be done with it..
These are the two best solutions to your miles per gallon problem. I think the translator and mass air meter are the biggest solutions. However, the 4.11 gear has to go. Cars running in the 9 secound zone run 3.42 gears. Buick got this correct right from the start. Every turbo regal with the factory computer should have a Translator and M.A.F. meter From Full Throttle Speed and Style.
- Joined
- Aug 1, 2003
every one seems to be tossing out ideas and fixes but based on what ???
Im more curious as to how you figured the 411 rear using any calculator base on your cars current state
i find it very difficult to come up with any number for rear gear considering (1) you dont have a speedometer , (2) you wont have lockup so you dont have a 1-1 engine rpm to rear ratio , if the converter were locked its a 1-1 for rpm but you dont so you cant factor anything without knowing the covnverters slip and youll need to lock and unlock it at a constant speed and load to determine that figure
(3) you dont have a speedometer so no odometer so how are you detirmining distance to base a MPG ??
fix the cable , get the converter to lock at a speed above 45 and then see what your mpg is , and to be sure on your rear ratio jack up the rear and check the axle ratio by spinning the tire
Im more curious as to how you figured the 411 rear using any calculator base on your cars current state
i find it very difficult to come up with any number for rear gear considering (1) you dont have a speedometer , (2) you wont have lockup so you dont have a 1-1 engine rpm to rear ratio , if the converter were locked its a 1-1 for rpm but you dont so you cant factor anything without knowing the covnverters slip and youll need to lock and unlock it at a constant speed and load to determine that figure
(3) you dont have a speedometer so no odometer so how are you detirmining distance to base a MPG ??
fix the cable , get the converter to lock at a speed above 45 and then see what your mpg is , and to be sure on your rear ratio jack up the rear and check the axle ratio by spinning the tire
I based the mpg on the distance the work, which I know, and how much gas I put in the tank...from almost empty before putting 10 gallons in it, to almost empty again. I found a thread on how to force TC lockup by jumping the pins on the service port. I did that, and tested it last night on the way home. I did the brake test, and the converter is indeed locking up now, and the car is barking a second gear chirp at just part throttle, every time. I also had my wife following me on the way home, and got my speed from her. I'm at 3200rpm at 70mph, with the convertor locked up. This weekend, Ill be throwing in a new pcv valve (looks like the original is still in there), a new fuel filter and new plugs (the old ones are all rusty). Naturally, I am going to do the translator, maf and injectors, but not just yet. I want to make sure the car is in perfect running condition before I start modding, which I dont think is a bad idea. I'm also going to throw in a test pipe just in case the original cat is clogged. I want to get the best mpg in the meantime, until I can find a rear end, and before I start modding. Thanks for all the help.
BTW, what tranny should I have? I read everywhere that the 200r4 is the most common, but is there a chance I have a 700r4, which doesnt have as good of an overdrive ratio?
BTW, what tranny should I have? I read everywhere that the 200r4 is the most common, but is there a chance I have a 700r4, which doesnt have as good of an overdrive ratio?
Originally posted by VadersV6
I agree on the scan tool. Im screwed until next week cause of all this damn rain. You know what Im talking about led
YOUR TELLING ME!
I have been screwed the last three weekends!
Stupid Christmas
Stupid Rain
You don't even want to see my lsit of things to do...
oh and my turbo is most likely done so
Now I have turbo, fuel pump, brakes, shocks, air bags, spring cleaning, posi fluid, injectors, and I am sure I'll break something else!!!!
Good luck with your stuff.
If you can get it done by january 22nd some local guys are going to Fontana...
