sudden drop in mpg's ideas??

[sn95gtvert]

my mpg has dropped dramatically over the last few months. the last mod i did to my engine was my 1.7 roller rockers. i remember getting a bit over 18 mpg's in town, and the last long trip i took i was getting between 24-26 mpg depending on if my top was down/wind/mountains ect...

on my last tank of fuel i netted 11.6 mpg, a lot of my driving was hwy miles and back country roads. i did one run against my friends fox but it was a 1st-3rd rolling race that only lasted a few seconds. my car smells hella rich when sitting at idle.

could this be caused by bad cats?

I've checked my plugs they are light brown no white black or wetness found altho they still stink like fuel. my fuel filter is about 2 years old now so i could probably use a change there. i also checked my plug wires when i did the rocker swap, one came out with a 2 ohm difference reading more resistant (number 1 spark plug wire also the shortest) i have some spare Taylor wires but they don't have the angle tips so my headers will toast them.

what do you guys think could be causing my sudden drop in mpg's???

 

[CC'S95GT]

o2 sensors could be the prob too.

 

[sn95gtvert]

i replaced those about 2.5 years ago, if they are failing already i will be kinda pissed. also my car is on its 4th alternator in nearly 3 years. dunno if that matters much but damn napa's remaned parts dont last.

 

[95Grandtouring5.0]

^ Apparently you don't know sensors. They can break for no reason at all even if you very recently replaced them.

 

[DFG_magic]

^ Apparently you don't know sensors. They can break for no reason at all even if you very recently replaced them.

Why put it like that? The man is just voicing his frustration on NAPA parts. No need to break his balls. I'm sure we all know ANY sensor is vulnerable and can be defective right out of the box. vert, does your car still have EGR? Could be sticking.

 

[sn95gtvert]

egr is on the intake but it is plugged, so is the header and the smog ports on the back of the heads. the sensor is still hooked up as well as the vacuum line. all my egr codes cleared after doing this. i havent had a cel in a year +. its been a few months since i have done a koeo koer tests, but last time all was fine.

 

[sn95gtvert]

the car runs fine and does not smoke. it does burn a small amount of oil cause i had to take the baffled out of the valve cover. it purrs at 750-800 rpm all day when left at idle it doesn't buck or act funny at low crawling speeds. i checked and reset my tps when i did the rocker swap it was dead on .98

dunno whats causing this and its just kinda buggin me. im broke enuf without having to pay the extra gas costs.

 

[sn95gtvert]

i think im going to replace my grounding straps, and probably my battery terminals, i'll run the koeo koer tests again and see if the o2's are failing or if anything else comes up.