Hey guys. When I bought my Z back in Jan. of 2001, I was averaging about 19 or 21 mpg combination of freeway/city. I just figured out this last tank and im down to 14 mpg. No change in driving style. I don't beat it, don't accelerate hard, and I never drive it above 70. Whats going on? Engine has about 120K miles on it. Is a rebuild in order? I plan on modding it nicely and figured on a rebuild this summer anyhow. Will this improve my mileage??? This sucks. And with the price of gas out here, I'm not that happy with the Z right now. What else. I just changed the oil today. Hasn't been three months even. I do the oil about 4 or 5 times a year. I used ZMax micro lube today for the first time and will see if it helps any. Thanks guys!


Will

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'86 Z-28
305 c.i. LG4
Rochester QuadraJet 4bbl
Flowmaster 80 series
Chrome Tips
Dual Snorkel Air Cleaner
K&N Filter
Michellin P215/65/R15 X-Radial Plus
Lots of Mods on the way
Pioneer 4"x6" dash
Pioneer 6"x9" rear
Alpine 8" Type S in bandpass box
Alpine Amp 300x1 bridged
Sony 4000X- x-Plode Deck 50w x4
lots more to come!!!

 

BTW, plugs are fresh. New O2 sensor. Oil changed today. Tranny fluid changed less than 5 months ago. Carb rebuilt less than 7 months ago. Any ideas>!>!>


Will

 

Do a cylinder leakdown and compression test before guessing at problems. Just because you've done a tune up doesn't mean it will still run right.

Check everything. Maybe your distributor is worn out. Maybe brakes are dragging. Tire pressure? Tranny slipping?

Weak valve springs? If the heads are original then they're 16 years old. Those springs are probably shot.

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Stephen's racing page
or check out the race car

87 IROC SuperPro race car
461 big block
Best ET on a time slip: 11.447
Best MPH on a time slip: 119.42
Best corrected ET: 10.99
Best corrected MPH: 123.86
Altitude corrected rear wheel HP: 493
Best 60 foot: 1.586
Member of the Calgary Drag Racing Association


[This message has been edited by Stephen 87 IROC (edited March 09, 2002).]

 

Also, check the timing with the timing wire disconnected. Stock setting in 6* BTDC. maybe the dist. slipped.

 

Ok, I know that a tune up isnt going to solve the problem. I was just looking for input. I planned on having the heads redone this summer along with the mods. I will check the timing and what not, Cap and rotor are new.

thanks

Will

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'86 Z-28
305 c.i. LG4
Rochester QuadraJet 4bbl
Flowmaster 80 series
Chrome Tips
Dual Snorkel Air Cleaner
K&N Filter
Michellin P215/65/R15 X-Radial Plus
Lots of Mods on the way
Pioneer 4"x6" dash
Pioneer 6"x9" rear
Alpine 8" Type S in bandpass box
Alpine Amp 300x1 bridged
Sony 4000X- x-Plode Deck 50w x4
lots more to come!!!

 

Does your area use the winter blend of fuel? we see some funky stuff happen, like pinging out of the blue with no changes, when the winter blends show up here. Try a dif grade of fuel and see what happens to your mileage. I know I lose quite a bit due to this.

 

I'm having the same problem.. But I need to change my O2 sensor and plugs. I just changed my MAF Sensor, MAF Power and MAF burnoff relay just last week. I have a major power drain somewhere.. I can sit at a redlight and all of a sudden my ampmeter drops from 13 to almost the 8.. :S I get the code 44 constantly now.. (O2 sensor..) But a rear tire comes first tomorrow.. watchout for parking curbs that have steel rods protruding from them I didnt see it tonight when I backed outta my parking space and... BOOM! theres another 100$ this week..
Let me know what ya find out man.
Angelictorment@hotmail.com

Later,
CJ

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1987 Z-28 Iroc-Z,305 TPI
Dual Ram-Air w/ K&N filters and ported "intake Y", Bosch platinum plugs, w/ 10mm wires, removed airpump(belt) and A/C pump ( who needs it I have windows and T-tops ), March underdrive pullies, 10degree timing, throttle body by pass, 170 degree thermostat. And some cool looking red pedals...lol Thanx Teke._ ________________ _ Future mod. True Dual exhaust. Straight pipes no Cat and no muffler. heheheh

 

A really good four wheel alignment is worth its weight in gas. Don't underestimate it. How long since it was done?

 

I was going to say o2 sensor, but i see you already changed that. However it could still be the o2 sensor. I bought a "wells" once and it took about a week for it to go back to running like it was. Put a different o2 sensor in and ran great.

Could also be bad gas, distributor, ignition modual, or the last resort maybe your computer. I would try your o2 sensor first, then ignition modual.

Is your car hard to start? if so i would go with timming and ignition modual ($50 for a good one) let use know what the problem is once you fix it.

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89' red iroc-z
386 stroker 10.5.1
ross pistons
eagle h-beam rods
Mini ram
slp cam 224 230 @.05 535 544 lift
1.6rr
edelbrock performer heads p+p 2.02 1.60
Hooker super comps, Mufflex 4' exhaust
Ford 9' 4.11 gears, detroit locker, 31 spline
baer rear brakes,line lock
converted to speed density
Ed Wright computer chip

89' red Iroc-z
t-tops grey leather
all stock

 

Thanks for all the help guys. My car starts right up. Never had any trouble until about a month ago the starter began to slip a tad. So I changed it out. I bought an 02 sensor from NAPA auto parts. Maybe a "higher end" one would do me better? Thing wasn't all that hard to change. Did in about 10 minutes, but had to wait for the comp to reset before I could reconnect the batt. Anyhow. I have played around with different fuels. I have come to the conclusion that people in California are getting screwed. Gas out here has ZERO power. I seriously wonder whats going on. They had midgrade lowered to 88.5 here for a while to try and "lower" gas prices. Funny how they slash the octane along with the price. Anyhow. The car runs great. When I mash on it at WOT it picks right up, but could use a little more UMPH. Smokes very little on start-up, my guess is seals??? Other than that, I keep getting a SES light. Need to get it hooked up. I always thought it was the 02 sensor, so I changed it out. But apparently, that wasn't the problem. Well, keep the suggestions coming. Where can I go to have this thing scanned so I can get the code??? Like I said, car runs fine, minial ping and what not, feels alright power wise, but is proly a shadow of what it used to be. THANKS GUYS!!!


And for the guy who said something about an alignment, I had one done not 4 months ago. Thanks.

Will

COULD MY CAT BE PLUGGING MY EXHAUST??? thinking about a 3" in/out with my headers and 3" cat-back to come in the summer!!!




------------------
'86 Z-28
305 c.i. LG4
Rochester QuadraJet 4bbl
Flowmaster 80 series
Chrome Tips
Dual Snorkel Air Cleaner
K&N Filter
Michellin P215/65/R15 X-Radial Plus
Lots of Mods on the way
Pioneer 4"x6" dash
Pioneer 6"x9" rear
Alpine 8" Type S in bandpass box
Alpine Amp 300x1 bridged
Sony 4000X- x-Plode Deck 50w x4
lots more to come!!!

 

Do they put alcohol in with the gas?
If there is alcohol then they can mix small amounts water in with the gas .

------------------
Seth
1985 Camaro
2.8L T-5 3.42LSD
Car is on it's 5th engine and #5 is a peace of junk, it will get it's 6th soon
Mods, up graded to a internaly balanced 88' 2.8L motor(<junk)
ported exhaust mainfolds
home made big air intake
gutted cat
Accel 8mm stainless steel plug wires

 

I've long thought that the gas here has been "watered" down. It just feels like crap. NO power, no pick-up. Every once in a while I get lucky and get a good tank from some off the wall 76 station. But all the ones in the city give me really bad mileage and the car easts it up. Anyway, keep em comin guys, I really wanna figure this out!

Will

------------------
'86 Z-28
305 c.i. LG4
Rochester QuadraJet 4bbl
Flowmaster 80 series
Chrome Tips
Dual Snorkel Air Cleaner
K&N Filter
Michellin P215/65/R15 X-Radial Plus
Lots of Mods on the way
Pioneer 4"x6" dash
Pioneer 6"x9" rear
Alpine 8" Type S in bandpass box
Alpine Amp 300x1 bridged
Sony 4000X- x-Plode Deck 50w x4
lots more to come!!!

 

Three words here...Top Engine Cleaner!!! Buy some from your local GM dealer....When you get home, disconnect snorkel from Maf and TB....Open butterflies and spray it into the intake....Fill it all the way up (until it starts to run out of TB..Close butterflies...hook up snorkel...crank engine and watch all the white smoke come out of your tailpipes (along with all the carbon build in your intake and on your valves and pistons.....Repeat until you have used the whole can!!! TRUST ME ON THIS I did this myself this past weekend and I could not believe my eyes.....Put a white sheet under your pipes and then do the process above...Your sheet will turn BLACK GUARANTEED!!!! Let me know when or if you do this, so that I can know your results


Later and Good Luck

Just read your sig and I see you have a carb.....No biggie, just take air cleaner off...warm car up to running temp.....Have a friend rev motor to about 600-700 RPM...Spray WHOLE CAN into carb...Engine will hesitate (that is normal...Just make sure friends keeps revving so it will not die)...Once can is gone, let car sit for about 15 minutes, then crank up and blip the throttle until white smoke is gone...Now go run it to get all the crap out of your cylinders...Hope this helps


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1989 Formula 350
K&N air filter, air foil, TB Bypass, AFPR (set at 48 psi), A.I.R. yanked out, Accel 8mm wires, Fireball external coil, Pulley (just the crank), gutted MAF, corvette servo, Hooker super comp. shorties, 3" exhaust all the way back, No cats, Flowmaster 40 series muffler (one in one out turned down)
http://www.theformulasource.com/owne...php?siteid=144

So they made him get rid of it...For decency ya know....But it came back the next day...

[This message has been edited by 1fastformula (edited March 10, 2002).]

[This message has been edited by 1fastformula (edited March 10, 2002).]

 

So the stuff is called " Top Engine Cleaner"??? I will go to the dealer and buy some this week. Any Idea on how much its gonna run me, and are there any alternatives that i can buy at a parts place ??? Thanks for the info man.

Will

------------------
'86 Z-28
305 c.i. LG4
Rochester QuadraJet 4bbl
Flowmaster 80 series
Chrome Tips
Dual Snorkel Air Cleaner
K&N Filter
Michellin P215/65/R15 X-Radial Plus
Lots of Mods on the way
Pioneer 4"x6" dash
Pioneer 6"x9" rear
Alpine 8" Type S in bandpass box
Alpine Amp 300x1 bridged
Sony 4000X- x-Plode Deck 50w x4
lots more to come!!!

 

About 7 bucks a can....Buy two just in case you need to double dose....But I doubt you will (used my other on my Nissan 4x4)

------------------
1989 Formula 350
K&N air filter, air foil, TB Bypass, AFPR (set at 48 psi), A.I.R. yanked out, Accel 8mm wires, Fireball external coil, Pulley (just the crank), gutted MAF, corvette servo, Hooker super comp. shorties, 3" exhaust all the way back, No cats, Flowmaster 40 series muffler (one in one out turned down)
http://www.theformulasource.com/owne...php?siteid=144

So they made him get rid of it...For decency ya know....But it came back the next day...