So heres the dealio.....

I have an 86SE V6. 200,000km th125 auto tranny. Oil, fuel filter, dist cap, ignition coil and modual all just changed.
Problem.....I have the worst gas milage ever....about 130km to $30 worth of fuel....i drive my car hard...but not that hard. Also....my car is hesitating, and while under consistent pressure on the gas pedal it lurches (the rpm's and oil pressure rise and fall drastically).

any ideas?

I have my car booked to go into the shop this friday morning. that gives me 2 days and one night to work on it.

please help me fix my car!

any suggestions are welcome

- Phil

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"When enough is enough, thats when you know.....your halfway there"

I vote o2 sensor failure! Because it happend to my DD achieva a few times, due to the wire falling out of the connector.

Did you change these parts because had the problem or thay caused the problem.

If doing it before, I'd get or borrow a fuel pressure gauge from a parts store and check the fuel pressure. Should be around 40psi. and steady. Will change pressure if you blip the throttle but should change more than about 5psi. (the pressure regulator changed pressure with vacuum)
If the pressure is low it could be the fuel pump, regulator, or broken rubber hose inside the tank.

You did put the heat sink grease on the module?

quote Originally posted by Dodgerunner: Did you change these parts because had the problem or thay caused the problem. If doing it before, I'd get or borrow a fuel pressure gauge from a parts store and check the fuel pressure. Should be around 40psi. and steady. Will change pressure if you blip the throttle but should change more than about 5psi. (the pressure regulator changed pressure with vacuum) If the pressure is low it could be the fuel pump, regulator, or broken rubber hose inside the tank. You did put the heat sink grease on the module?

I did all this before, my car quit on me a few months ago while driving so i thought it was the ignition module, so i changed it, turned out it was the ignition coil....yes i put the grease on the module....the rest i have just repaired or replaced along the way. If the o2 sensor goes will it throw a code? Because when i maintain highway speeds the check engine light pops on and off.

I can't remember how to check the codes though....
hmmm....

- Phil

quote Originally posted by Phil86SE: Problem.....I have the worst gas milage ever....about 130km to $30 worth of fuel....i drive my car hard...but not that hard.

and I thought I was getting bad fuel economy.... at about 140km/half tank right now - best was 415kms/33L. Only had 130km/tank twice - and those were really quick trips to where I needed to go..

I'm not too much on the technical side, but fuel pressure & mixture ratio seem like good options to check out, as well as the O2. Are the revs seeming a bit high, or other than the little lurching - odd shifting/slipping?
Good luck!

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http://fiero.ssarge.net

quote Originally posted by sargeants: and I thought I was getting bad fuel economy.... at about 140km/half tank right now - best was 415kms/33L. Only had 130km/tank twice - and those were really quick trips to where I needed to go.. I'm not too much on the technical side, but fuel pressure & mixture ratio seem like good options to check out, as well as the O2. Are the revs seeming a bit high, or other than the little lurching - odd shifting/slipping? Good luck!

Revs and shift points seem sluggish...idle is fine though. I wish i could get 130km to half a tank. this fuel economy and gas prices are killing my bank account!

- Phil

i would like to kno the problem here cause i get about 180 miles to a tank (86 gt 2.8 4-speed) and its driving me nutts my 85 se 2.8 4-speed gets about 240 to a tank...

Tony

sounds like a vacuum leak to me. Does it idle abnomally high??

quote Originally posted by Phil86SE: If the o2 sensor goes will it throw a code? Because when i maintain highway speeds the check engine light pops on and off. I can't remember how to check the codes though.... hmmm.... - Phil

My 87GT is doing the same thing. According to the codes it's the O2 sensor.

To pull the codes: Remove the black trim around the cigar lighter to expose the ALDL. Jump A & B terminals with a wire or paper clip and then turn the key to run. If you get code 12 (flash, flash-flash), run like hell because that's the self destruct code!

quote Originally posted by turboguy327: sounds like a vacuum leak to me. Does it idle abnomally high??

it idles at 900rpm like concrete

i will buy a new 02 tommorow night

- Phil

quote Originally posted by turboguy327: sounds like a vacuum leak to me. Does it idle abnomally high??

no well sometimes the 86 around 1500 then after 30 seconds it goes back to 900 or so...the 85 dosent... the only real differance between the 2 is that my 86 has 150xxx and the 85 95xxx...

quote Originally posted by Black86gtFastback: no well sometimes the 86 around 1500 then after 30 seconds it goes back to 900 or so...the 85 dosent... the only real differance between the 2 is that my 86 has 150xxx and the 85 95xxx...

I've got a similar issue with the higher revs for short periods of time; also when mine sits for a while running it'll rev higher then settle back and have an SES... I'm pretty sure it's the O2, but just haven't gotten around to getting it fixed yet *marks on calender to get O2 replaced @ 160xxxK*

The SES codes would be the first thing to check, chances are that will tell you what to look at. From the sounds of it either the O2 is dead as a nail, or you have a CTS/IAT sensor problem. Intermittant SES light sometimes indicates an EGR issue, ignore that if thats what it says. O2 will not always set a code, as with all sensors, as long as the sensor is in range, it will not trip, so the O2 could be shorted at .5V or the CTS could read 275* at a cold start and the ECM wouldnt see a problem. But since you have an easy place to start, check the codes.

You're running a stock thermostat right? Ever check the timing? Have you tried parking the car someplace clean and flat so you can see if you are leaking gas? Could be a loose fitting or bad hose just dumping it on the road.

I dont know how you plan to tell if you're fixes work though, two days isnt going to be long enough to run through a tank of gas, and the shop is going to be P'ed to find out you tried to fix the problem, and might have, but you dont know. Thats kind of like taking a car to them and saying, well I think theres a problem, but there might not be, but something tells me there is. If it was a look at it and see somthing broke problem, it would be okay, but this isnt.

I would suggest you reschedule with the shop, you're either going to waste your money or their time.

[This message has been edited by 86GT3.4DOHC (edited 03-15-2007).]

sry guys i was wrong if it doesnt always idle high

I would start by pulling the codes.I agree,could be the O2 or Vacume leak.Might be the EGR or a rusted out EGR Tube.I allso agree that it could be the fuel pump or the pulsater (noise supressor)is causeing an internal leak (fuel pressure test).Possibly the throttle position sensor,pull those codes.Try takeing some throttle body cleaner and spray it in the port on the inside bottom of the intake just below the butterfly.You might allso try removeing the IAC and clean the tip (Do Not submerge in solvent).