I hope someone here can help me.
I have a 1988 GXL with 102000 miles. For the last 6 years, the car has been mostly stored, with a short period of use (4 months) about 3 years ago. At that time I replaced all coollant hoses because of a break while driving (slight overheat involved). Everything else seemed fine and the engine, even now, pulls strong.
So, this summer I decided to start running her again and have (so far) replaced the exhaust system all the way from the manufold to the back with a straight thru system from racing beat. Here is the problem - on my way to the tire shop today (the first real drive in 3 years), I noticed the worst fuel consumption I have ever seen. She used up half a tank for the 60 mile trip. I have taken a cursory look at the fuel line and have found no leaks. Any ideas what I should take a look at?

 

Did u replace the O2 sensor?

 

when was your last tuneup?
are your tires in spec (with pressures)?

run some MMO through the engine (oil and fuel system). check your O2 sensor as mentioned, but chances are you'd be experienceing other issues if it was the sensor ...

tuneup first ... reevaluate and if it still has crappy mileage, then we can look elsewhere.

 

No, I didn't but it seems like a good suggestion. I will do that next. Any thoughts on a good make?

 

Diabolical1,

Basic things like plugs, oil, filters have been changed and tires are within spec. You mention other issues, well there is a new one of late. When I start up cold, the engine will rev up as normal but when the revs return to normal the engine will die. Subsequent starts will also die but much sooner. This problem does not occur when the engine is warm/hot. Also, normal revs are a bit low (close to cutting out).

 

not sure what you mean ... huh?

replace the filters, plugs and oil (use mineral oils for now). run some MMO through both fuel and oil systems ...

also, come up with some hard numbers so we can see what you're talking about. fill up at a gas station and note the gallons. then, see how many miles it takes for your next fill up (while noting the gallons) and calcualate your MPG ...

 

okay ... i posted while you were typing your last post. what about your plugs? and calculate your MPG ... forget the other issues that you've clarified ... and refer back to the oxygen sensor-thing ...

 

Diabolical1,
Sorry the post that confused you was meant for RotaryWeaponSE7EN. Anyhow, I think that I will try your MMO idea and also get a new sensor. Do you have suggestions about the make (manufacturer) of a good o2 sensor?
Also here are the MPG numbers you wanted. I checked the miles again and I actually drove 82 miles since I did not take a small detour into consideration. Be that as it may - I filled with 13 gallons from vapours. Then did 82 miles, so that's 82 miles to 6.5 gallons which gives approx. 12.5 miles per gallon.
Thanks for the responses so far.

 

that's only a little worse than what i get, around 14-16, no highway. is your guage going bad? mine reads fine up to 65 miles on the trip meter, than dies out and reads empty until i fill up again.

 

dashwi, bosch makes a good aftermarket sensor, the factory unit will work too. Heres a link for a aftermarket one only $40.

http://www.rx7.com/store/rx7/fcfuel.html

 

i get 230 miles to a tank or so 13 -14 gal i forget..but if your car been sitting for 3 years im sure the gas is ****..so get some new gas then tell me your reading

 

BAD GAS SCREWS THE O2 READING

 

This could be a bad or misadjusted thermowax module, located on the back of the intake. It cracks the throttle open until the coolant passing thru it heats it up.

 

just run it in for a couple 2 or 3 tanks of gas.

don't buy that $40 o2 sensor... grab a universal from autozone for $18...yes, it's made by bosche.

i get 21-23 mpg freeway when i go slow, but much tuning was involved for that.

 

OK everyone, here is what I did:
Nothing.... I ran a few tanks of gas thru and now I'm
255 for 13.5 Gal, (thx Adam, GuitarJunkie) Seems like
everything else works.
New problem: I get bad exhaust smell in the car when
she is running at op temp. Kinda weird because I just
replaced the entire system?!?
Thanks for all the suggestions and help so far.
A>

 

sounds like a leak somewhere....

 

spark plug ?
clogged injectors ?

 

I say he's also got a vacuum leak. The starting/cold engine problem screams it.



My recent mileage thread. Note the July 6 post on the last page.

https://www.rx7club.com/showthread.php?t=212848