95 SHO fuel smell in the exhaust

[mannyjfk]

I just noticed that my SHO smells like fuel in the exhaust while the car is iddle. Any ideas? This is the right time because is due at the shop the day after tomorrow.

[shorod]

Does the engine idle smoothly? These engines have a tendency to leak oil into the spark plug wells which can cause a misfire. Also, if aftermarket plug wires are used, sometimes the boots don't seal well against the valve cover and that allows water into the plug wells, again causing a misfire.

If the exhaust smells like fuel, it's probably running way too rich. This can be due to the misfires noted above (spark plug not firing to burn the fuel, so in turn the fuel passed into the exhaust).

Also, if you have an aftermarket oiled air filter, this can coat the Mass Air Flow (MAF) sensor and cause the engine to run rich. In the early stages, you won't notice a misfire and maybe won't even notice a performance change, but the fuel economy will drop considerably.

Whatever the cause, you want to get it fixed ASAP. Raw fuel in the exhaust causes the catalytic converters to work extra hard, overheat, and self destruct.

-Rod

[mannyjfk]

The Sparkplugs are 2 months old and the car runs very very smooth. I have no changed the Wire Set but you think that the injectors may need cleaning? I have no clue what is the deal with the wires but they are coming off Saturday as part of the preventive maintenance.
In any event, Do you think cleaning the Injectors may help?

[shorod]

Only if for some reason they are leaking, but then I think you'd have issues with hard starting after the car sat just a short time (injectors leaking fuel from the still pressurized fuel rail into the cylinders).

Since you say the car runs fine, I'd start by cleaning the MAF sensor. I have personally experienced this causing symptoms such as you describe on my 1993 SHO.

-Rod

[mannyjfk]

I am wondering if cleaning the MAF sensor would be covered when my local shop cleans the Throttle Body? Can you elaborate please?

[shorod]

Very unlikely. If I recall correctly, the MAF is mounted on the air cleaner housing. I think there are 3 wires going to it (I do remember the IAT is mounted to the lower portion of the air cleaner housing). On the outlet side of the MAF is the air intake tube that travels a foot or two to the throttle body. The shop likely just removed the air intake tube at the throttle body, opened the butterfly, and sprayed a few squirts of cleaner on the back side of the throttle plate and around the perimeter of the intake where the throttle plate closes against.

To clean the MAF, they would need to unplug the MAF, then use a T-15 (I think) security Torx bit to loosen the four Torx bolts, wiggle the sensor element out of the housing (o-ring seal holds it a bit), then either spray off with appropriate cleaner or VERY carefully clean with a small brush or cotton/chamois swab. Then, let the cleaner dry and reinstall everything. "Clean the MAF sensor" is likely something they would itemize separately on the invoice since it sounds like an involved and expensive procedure to the customer.

-Rod

[mannyjfk]

Sounds like something I can do myself and to be on the safe side I just have them clean the injectors the way they do it and then if no luck, I clean the MAF sensor. If i am strapped for time I just go to the locat Autozone Autoparts and buy a new one for $149 and install it myself and over with that. This car is my project as you can see and I do not want to cut corners.