The car is perfectly in order, new plugs/o2 sensor, problems fixed, running/driving great, still can't manage to get better than ~15mpg on the highway though! No check engine codes stored and is driven lightly (3k shifts, no boost) during my testing mileage...

it's only been a few hundred miles since i reset the ecu, does the "first tank" usually get horribly bad mileage like on other cars?

I didn't replace the plug wires, they looked fine and the car doesn't run in any way that i'd suspect an ignition problem

thanks

 

You probably need a fuel system overhaul...particularly injector cleaning. Mine were in bad shape before cleaning. Dripping injectors will waste a lot of fuel. See the link in my sig for the work that I did (FPD, injector cleaning, recall kit, etc).

It is A LOT of work, but totally worth it. I get about 19 mpg when I commute in my FD and about 22 mpg on the highway. I was getting about 11 mpg in my FD before I did the work.

Sonny

 

BoostFrenzy how many miles on your engine? An engine with weak compression will also give you these kind of results.

My stock Fd with 94K original miles still gets 17 city and 25-26 on the highway. I also still have excellent compression because I keep carbon buildup down with consistant cleanings.

 

63,000 miles and no steps to decrease carbon (what should i do?)

 

Please elaborate on this The only thing I do is "get on the gas hard" a few times a week

 

I have a highly modded single haltech street ported FD and I can get 24mpg...you my friend have a problem.

 

lmao my only mods are DP and CB, did full fuel system overhaul and I only get ~17-18 mpg on the freeway (300-320 per tank if Im nice to it).

 

check the fpr. pull the vac line off it and see if it has fuel in it.

 

how do you get to the FPR?

 

Here:
https://www.rx7club.com/showthread.p...&highlight=atf

I do this every 6 months!

For the record short burst at WOT isn't always going to clean things fully. For that you would need to have extended periods of boosting (drag, road course, ect). Once carbon developes it's very hard to remove the carbon. The main problem is the carbon that developes in the corner and side seals grooves. Those are the seals that are most prone to sticking because these seals are under less stress and heat when compared to the apex seals. Remember that apex seals get heat from both sides and the corner & side seals do not! Also the sping tensions on the side & corner seals are much weaker. The lower tension is neccessary because there isn't much movement with those seals however, the less movement and lower heat in that area is an excellent condition to allow for more carbon build-up to delelope in the grooves. Hell every engine that I've pulled apart that had weak compression (mainly rear rotor) had 1 or 2 stuck corner & side seals. The rotors that had good compression had seals that still moved freely(regardless of mileage).

 

Mileage seems to be VASTLY improved over city driving, watching the gauge which I know isn't going to be scientific but for a rough estimate, it's getting *AT LEAST* 25mpg, maybe a touch more, very happy about that.... however, when I get off the highway and stop for gas, I notice it *ONLY* seems to leak oil *AT SHUTDOWN* at which point it gets on the cat/airpump line etc and burns off (smokes), anyone ever ran into this before?

If it's running it never leaks and burns off...