swapping to FI

[megaladon6]

if the plugs were fouled with lots of black crap/carbon, and especially if they looked wet, check the carb tuning for it running rich. actually white and glassy plugs could also be the carb, running lean. when you did the tune up, did you check the distributor timing (and according to the procedure)?

 

[Vern]

Change the O2 sensor. A bad one will drop your mileage measurably.

 

[1988montess]

ill try those. like i said the plugs are all good theyre new. but ill see wha ti can find out.... im not good with engine stuff yet... i can definitely smell gas from the engine, but its an old v8 so i dunno....

 

[85 Cutlass Brougham]

Do you mean the exhaust smells like it has excessive unburnt fuel in it? If so, or if you have black smoke, you have an engine management issue, maybe even an exhaust leak from a blown exhaust manifold gasket or a cracked manifold. Could also be a leaky air injection system. These would all give a false lean reading to the O2 sensor and cause the ECU to richen to compensate, thus making it use too much gas. Also, if you are not that good with engines yet, learn by making this one run right first. Don't involve yourself in a complicated EFI swap as your first effort.

 

[megaladon6]

what did the old plugs look like?
vern: good call on the o2, i forgot about that one 😳

 

[1988montess]

im mechanically inclined, ive just never done a swap before. i have friends that can help me out. i have done everything on my car myself but dont know much about engines, just a little more than basic knowledge. i can swap sh*t out just not an engine. the plugs were old and some burnt but it was sitting for 6 years not being driven. i have a HUGE exhaust leak, hence getting a new exhaust done. i dont know what else to say, i feel like im defending myself here....

 

[megaladon6]

this is the problem with the internet and long-distance diagnosis. the way i write something is not always the same as the way you read. it, and vice versa. we're not attacking you in anyway, just trying to help. and some of the things that are obvious in person, are unknown online.
double check: is the exhaust leak after (downstream of) the cat? either way i'd pull the o2 sensor and check it's condition or just replace it. (they're about $30.00) they are VERY important on those old systems, and are prone to false lean readings when they get old.

 

[1988montess]

this is something ill have the exhaust guy look at while im there. thanks for helping out, it just seemed like you figured i dont know anything. all i was saying is that i dont know what else to check for, ad that i dont know how to swap an engine.

 

[85 Cutlass Brougham]

ill try those. like i said the plugs are all good theyre new. but ill see wha ti can find out.... im not good with engine stuff yet... i can definitely smell gas from the engine, but its an old v8 so i dunno....

I was merely responding to this quote. I would check to see if it has an exhaust leak before or after the O2 sensor. You can also check the O2 sensor with a digital volt ohm meter. I forget the actual voltages that should be present, but it is easy enough to find that online as it is a generic set of outputs you measure for.

 

[dan2286]

ill try those. like i said the plugs are all good theyre new. but ill see wha ti can find out.... im not good with engine stuff yet... i can definitely smell gas from the engine, but its an old v8 so i dunno....

I was merely responding to this quote. I would check to see if it has an exhaust leak before or after the O2 sensor. You can also check the O2 sensor with a digital volt ohm meter. I forget the actual voltages that should be present, but it is easy enough to find that online as it is a generic set of outputs you measure for.

It should fluxuate from around 0 to 1 volts. It is supposed to go back and forth , a regular dvom wont be able to accurately keep up with the voltage change. A labscope or a dvom with a graphing feature would be much more accurate.