hey folks, just got a question about some really poor gas mileage my car has been getting. I've done a search and have gotten some ideas. I just want to explain what my car has been through so as to maybe get a better clue as where to start. Filled it up, now 115 miles later Im down to quarter tank and thats probably less because i know how screwy our gas tank readings are. I've done mostly city driving, but not bad traffic city driving... only mod it has is a CAI and is stock everything else. The plugs and wires were changed (delco plats and taylor spiro pro 8mm wires). Poor gas mileage problem also existed with my old plug/wires. Also when one of my o2 sensors got unplugged my car threw a code of course. when i got it scanned it showed the o2 sensor codes, but there was also a code for the TPS in there as well, plugged back in my o2 and cleared the SES code and no SES light has come on since, will a TPS Sensor prob throw an SES code or is it one of those that doesn't? and will the unplugged o2 cause the computer to throw a TPS code as well?? I also had a gas smell coming thru my vents when i had the heat on, but that seemed to have gone away since I have stopped over filling my gas tank. Its a 97Z with 70K miles on it. Idles right around 800rpm or so when warm. I know you all are really good at diagnosing problems, so your help is always appreciated.

Thanks

 

wow nobody at all?

 

Does is blow a lot of black smoke of you get on it?

 

Wow, thats really bad. I have a 97 in california and the worst I ever got stock, even in the city, was about 15. I get my best gas mileage when I take off like a granny from stops but I have never only gotten 10 miles to the gallon even when floored everywhere with my supercharger.

The gas smell is caused by the excessively high fuel pressure (or at least thats what I think). I installed an AFPR set to 38 psi and no more smell.

One cause, although rare, could be a sticking injector. How do the plugs look? Do they have carbon deposits on them and foul easily? A very rough idle is a symptom of fouled plugs.

Hal

 

Not sure about the code question but I would check your fuel filter, clean your air filter, and maybe try to Seafoam it to clean out the engine. Do a search for directions and get help from sombody who knows what they are doing. If problem still persists at least you are not out a ton of money and are sure these are done.

 

If it only reaks of gas when the heater is on check around the injectors for leaks. If an injector is leaking around its top it would come out onto the intake around it. A minor amount of discoloration around some is normal but a major amount is not. Also, does it reak of gas under the hood (I mean reak, a little amount of gas smell is also normal).

Hal

 

have you tried replacing your 02 sensors?

is it possible that you have a leak in the fuel lines someplace?

 

thanks for the replies...no black smoke that i can notice. and I have not replaced my O2 sensors yet (think i should since they are 70k miles old) the fuel filter hasnt been changed either. the Air filter is about 3 months old on the CAI. I will check the fuel injectors for leaks now that its warming up outside an wont freeze my *** off. It is possible i have a fuel leak b/c car was in the shop to have the intake leak fixed and some transmission work ( thats how my o2 got unplugged in the 1st place) and something could have been damaged. I will check all these things you all have recommended, and if you have any further recommendations I will really appreciate it as well. I must fnd out what's going on with this car of mine.

Thanks