My mileage sucks!

VadersV6

Active Member
Only thing I see with the turbo, is that one of the impellar blades on the intake side has some of the coating flaked off. It almost looks like ceramic underneath. I always thught these impellars were cast aluminum or iron, so I dont know what the coating is. I dont see oil anywhere. I did just block off the PCV system, cause all its doing is drawing air through the block, through the valve cover breathers and acting as a vacuum leak. My vacuum at idle has gone from 15in. to 18-10 after doing this, and it runs ALOT better.
 

VadersV6

Active Member
Good news! On this last tank, I got almost 17mpg average to the tank, after all the fixes. I did get on it quite a few times, and was even stuck in stop and go traffic for 25 miles at one point. I calculated that if I got the right gears it would have been 20mpg. Now I have a stalling problem. Its very intermittent, so I can never tell what is causing it. Thanks for all the tips guys!
 

VadersV6

Active Member
hell continues.
I got the right rear end put in with the stock 3.42's. I put in my 50 pound injectors, extender, translator, intake tube. My BLM's are about 110 at idle with the BLM parameter set to 1. When the rpms are up, it goes to about 135. My fuel pressure is about 38 static. This is another issue I have to figure out.
I set my cam sensor. New plugs, new fuel filter. I really cant hear any leaks before the turbo and see no cracks.
I did the TV cable adjustment procedure as described on gnttype. When I adjust per that procedure, my tranny wont shift until I hit 4000 rpm. It also leaves it at about 6 lines on the cable. I have to back it off to about 4 1/2 lines to get it to shift at a reasonable rpm. Is this a sign that something is worn out in the tranny?
Problem is, I still have pretty bad mileage. I have the chip set to lean cruise, and the scanmaster confirms its working. The wheels spin fine when the car is jacked up. The tire pressure is ok, as well as the alignment.
I noticed my turbo spoolup is terrible, (wasnt always like this) but once it spools, it has awesome power. Reason I mention this, is that if my cat was clogged, it would explain the mileage and poor spool. The guy who owned the car welded some no name cat on there, on both ends, and cut off the factory exhaust flange in the process, so Its not just a matter of easily throwing on a test pipe. Anyone here ever have mileage dramatically improve after removing a bad cat?
I got the same mileage (15-16) before, with bad injectors, 4.11's, and no lean cruise.
Any more ideas would be appreciated.
 

pacecarta

LOGGED OUT
Staff member
a shop should be able to do a backpressure test to see if theres a restriction
theres a section on gnttype.org on how to do it

i had a bad cat when i got my car which wasnt plugged completetly and slowly got worse the more i tried to fix other things, kills mileage , messes up shifts, hurts performance at bottom and even worse above 65

once i cleared my blocked cat performance jumped dramatically and shifts returned to normal . spoolup was immideate

the blms show your rich and the ecm is opulling out fuel , a blocked exhaust or intake which impedes air flow would cause this or a bad chip or maf (check your translator settings) , i would look into the cat , if the car was raced with it on there it doesnt take much to burn them up .

youll alsoo need to bring back up the fuel pressure , your upper rpm blm of 135 shows its still not enough fuel
 

VadersV6

Active Member
Thanks for the response. The BLM's are high because I had to lower the BLM parameter down to 1 to bring the idle BLM's high enough...its still not high enough though. theyre between 105 and 110. If it drops too low, it goes out of the range where the computer can properly adjust A/F, so Im kind of in a pickle. So now im stuck with low idle BLM's, and high BLM's above that. The vacuum leaks were so bad with the old injectors, that my BLMs before were always about 135-142, whether it be idle or above. Now everything is sealed up so well, I have no leaks down low.
 

Buicksx3

Sure it leaks oil--so?
Chalk it up to too much Nyquil, but I re-read this entire thread twice and nowhere did I see about the O2 sensor having been looked at.
 

VadersV6

Active Member
Originally posted by Buicksx3
Chalk it up to too much Nyquil, but I re-read this entire thread twice and nowhere did I see about the O2 sensor having been looked at.
Well, I think I may have mentioned that the o2 crosscounts are rising up like normal. I was under the impression that if this is happening, the o2 sensor is ok.
I just burned 1/4 tank of gas going 33 miles. I'm gunna have to get a second job to pay for this gas!
 

scottyb

Spongebob Squarecar
Originally posted by VadersV6

I did the TV cable adjustment procedure as described on gnttype. When I adjust per that procedure, my tranny wont shift until I hit 4000 rpm. It also leaves it at about 6 lines on the cable. I have to back it off to about 4 1/2 lines to get it to shift at a reasonable rpm. Is this a sign that something is worn out in the tranny?
i

Not necessarily. If your car has a shift kit, then you may not be able to follow the proper setting procedure. After I installed Bruce's shift kit, I had to back off considerably to get an acceptable shift.
 

VadersV6

Active Member
Well I noticed that the idle o2 cross counts are going up an average of about 3-4 counts per frame. But the o2 millivolts seem pretty responsive.
 

VadersV6

Active Member
Since the site wont let me edit, I have to edit here.
Is it normal for my o2 counts to rise that slowly at idle?
I also noticed my fuel pressure after shutdown, drops alot faster than before. Like 10psi every 5 minutes. acceptable?
 

Buicksx3

Sure it leaks oil--so?
A couple more notes, since I fell asleep last night before I could finish: as far as your welded cat/exhaust system dilemma goes, Summit sells a nice Hooker system for $279 which has the proper flange welded on and includes a 2.5" test pipe with a slipjoint & flange to mate everything up. In addition, O2 crosscounts should be checked at a steady cruise, say 50-60 MPH. Are you running a stock O2 sensor or a heated one?

Turbo spool is lazy as it's too fat on the bottom end (that's an obvious one.) In reading the preceding two pages, you've thrown a lot of new parts on this car all at once, and sometimes it's beneficial to remove all the "hoarsesh!t", simplify the combo and start over again. For example, put a known good stock MAF on the car, a set of injectors that are easier to tune (Blue Tops or 009's), and donate one of those chips to be reburned to match. Then, take baby steps from there once the car is running in a good state of tune.

Anyway, enough rambling!
 

fitz3820

Active Member
To get true MPG you have to go by miles driven vs. gallons burned.

The fuel gauge is way too inaccurate to go by. My gauge seems to stay on Full for a long time but at 1/4 tank - I better start looking for gas - just tha nature of the beast.

Like all the other guys have said - start with the basics, tune-up check for vacuum/exhaust leaks.

Have you done a compression/leakdown test? - make sure the motor is healthy.
 

VadersV6

Active Member
I'll be doing a compression test very soon.
I calculate mileage by how many miles between gas stops. I always put in 10 gallons, and drive till I hit empty again.
Weird thing is, I burned 1/5 tank this weekend and i didnt even drive it:confused:
The garage is locked up so its not like someone is stealing it from me. I smell no gas leaks, and I cant see any.
I threw some fuel lube in the tank last night, and my slight fuel injector leakdown problem vanished.
I could really use an experienced GN guy that can drive the car and tell me if it feels right, and how to get things fixed.
 

pacecarta

LOGGED OUT
Staff member
if you want to calculate mileage , first off forget you have a fuel gauge its meaningless other than to let you know you shoould look for a gas station not for mpg calculations . my tank shows readings all over from near emty to1/3 full with no change in fuel level just driving around or how you park it .
you cant do the 10 in and drive till low , could be 2 gallons left could be 5 gallons and still read near empty.

fill the tank , drive 150 or so miles go back to same pump and fill it again , record the gallons to fill now do the math - miles traved / gallons, now drive for another 150 or so miles and fill it again do the math and then add this figure to the last MPG figure and divide by 2 thats your MPG calculated over 300 miles of your driving.
 

VadersV6

Active Member
How's your engine running?
Car is long gone :-( Blew a turbo and it ran debris through the engine. Had a new turbo that Lou czarnota put on for me for free (great guy), but it was too late. Then the rings went in number 2 I think, I did bodywork on the side and then alot of things went South in my life. Car ended up with the whole side covered in rust and ended up selling it for close to nothing in 2011. Huge regret of mine, but the GN wasn't a priority at the time. I've been looking up old threads of mine reminiscing. I want to get another one but the prices have skyrocketed :eek:
 

GNRick

Retired member
Car is long gone :-( Blew a turbo and it ran debris through the engine. Had a new turbo that Lou czarnota put on for me for free (great guy), but it was too late. Then the rings went in number 2 I think, I did bodywork on the side and then alot of things went South in my life. Car ended up with the whole side covered in rust and ended up selling it for close to nothing in 2011. Huge regret of mine, but the GN wasn't a priority at the time. I've been looking up old threads of mine reminiscing. I want to get another one but the prices have skyrocketed :eek:
I still see them pop up in the $ 10k to $15k price range. Check out the one on Dayton, Ohio craigs list. Might be worth checking out if its nearby.
 
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