My engine is obviously running too rich, I have a strong smell of gas, backfire on throttle lift, and my mpg is lower than it was 8 month ago.
I changed my O2 sensor about 6months ago, because from time to time, I had an error message about this sensor. After that I still had error message but rarely and never more than 1 or 2 miles (in short words better than before but not solved). The other sensors deliver correct values.
Then I had to check the TStat and my regular mechanic started to mess (I think he set a wrong timing or tuned without shorting the good wire), so I gave back to him, and he did a better tune. But to me it is not perfect. I have power, but I smell fuel way too much, I have backfire on throttle lift (which was not the case before).
I control my fuel efficiency too and it is worse than before, may 2-3mpg difference, which on my low value is a bunch.
The engine is stock crate.
I have absolutely no experience in tuning engine. What can I check and how?
For info it is not a cat problem,I have open pipes...
Thanks for your help.

 

you either have bad injectors or a leaking regulator. pull the hose off the regulator and see if fuel comes out when running.. be careful with raw fuel

 

I will check and post news. Thanks.

 

The timing has been "corrected" or at least improved.
I have a slightly better fuel mileage.
Much less fuel odor.
Less backfire but still some.
O2 sensor now seems to go crazy like 80% of the time, on highway at least.

 

Hi, I have the same problem. I have, but haven't put it in yet, is a 3 wire heated O2 sensor. I was told that, a heated O2 sensor, gives the ecm a more accurate air fuel mixture. My car was running way too rich the other day, and now it will start, run for a few seconds, and then die!

 

Time it yourself. Your timing could be retarded. It's also a cheap easy thing to check.

 

I'm also having the same problem, except for the back firing. My car runs like **** and starts to jerk back and forth at the lights in town. On top of that I get out of the car smelling like gas. Changed the plugs and 02 sensor and same **** still happens.

 

Did you ever get it fixed ? In having the same problem and was wondering what yo did ? Im gonna order a fpr and try to cut back on the fuel pressure and see if that helps . Thanks

 

I am going better by basically some good tweaking on the engine but there still things I need to do to be perfect...

 

I had the same problem on my 87 iroc 305 it was a bad computer so i swapped it ran good for 3 days then when bad again then I checked all my relays and found the fan relay pins where shorted replaced those relays havent had the problem since.