KevinH

I have a '90 2+2 that I have installed an Injen cold air intake, and have installed a 3" exhaust system with Flow Master American Thunder mufflers. The exhaust system does have 2 Cat. converters, and 2 resonators as well. It seems to run rich below 3200 RPM. When it is cold, it runs fine. Once it warms up, it is definitely rich. I have installed a new temperature sensor and fuel pressure regulator. When you remove the temperature sensor connection, the idle does change, telling me that the computer is getting the signal. I have recently changed all of the spark plugs as well. I have also recently put a new water pump, thermostat, timing belt, and timing belt tensioner, though I don't believe that any of these items would, or did effect this issue what-so-ever (just some maintenance history ). The car has about 100K miles on it. I am thinking that there is not enough back pressure on the heads with the 3 in. exhaust system. Does anyone have any experience with this situation?
Thanks for any help in this matter, it is driving me crazy!
KevinH

Bryan_280zx

I dont think that your 3' pipes have anything to due with it, i dont see exaust having anything to do with a fuel intake problem. My suggestion would be your Cold air intake "Air Filter" It might not be Big enough, witch would cause a lack of air, witch leads to a higher percentage of fuel. In my mind this explains the reason for it to chanve at higher rpms were the engine is running so hard its pulling much more air and fuel... Thats my thoughts some more advice would be Get a Coldair filter that has not only air access through the sides but the top of it as well K&N make great ones but they can cost nearly $60, though there are many good ones out there Good Luck