12 MPG?
03-01-2006, 01:01 AM
#11
Senior Member
Join Date: Jan 2006
Location: Kirkland WA 98034
Posts: 153
when i first got my rx7 i was getting 9 mph. like 140 miles a tank. i mean it was bad. SO i did a few things. main problem was my precat was plugged. that blew out at high rpm one day while i was driving. another thing was my timing was off so i fixed that. got a new air filter, took the sparkplugs out and metel brushed them got new wires, also adjusted the Plunger thingy on the Uim that Somewhat controls fuel thats coming in and. Im sure there were other things.. but after i got done messing with everything i then saw like 20mph.. Plus More power
03-01-2006, 07:42 AM
#12
Senior Member
Join Date: May 2005
Posts: 959
Few things.
1. Your probably using an autometer gauge w/ the stock O2 sensor...this isn't a reliable tuning device ..it's good, but I've found them to be off by as much as 1 or 2 points easily..
2. A streetported motor (depending on how extensive) is going to use more fuel then a stock motor. Your taking in more air, so your stock ecu TRIES to compensate by adding more fuel. This brings me to #3
3. Get a S-AFC or alternative fuel control device. The stock ECU does not understand a lot of what is going on w/ ported motors..and a fuel controller will allow you adjust most of it's imperfections. Especially at idle and WOT.
You should be able to get about 17-18mpg on a normal SP w/ the right tuning. I would still check/replace the o2 sensor and check your timing.
1. Your probably using an autometer gauge w/ the stock O2 sensor...this isn't a reliable tuning device ..it's good, but I've found them to be off by as much as 1 or 2 points easily..
2. A streetported motor (depending on how extensive) is going to use more fuel then a stock motor. Your taking in more air, so your stock ecu TRIES to compensate by adding more fuel. This brings me to #3
3. Get a S-AFC or alternative fuel control device. The stock ECU does not understand a lot of what is going on w/ ported motors..and a fuel controller will allow you adjust most of it's imperfections. Especially at idle and WOT.
You should be able to get about 17-18mpg on a normal SP w/ the right tuning. I would still check/replace the o2 sensor and check your timing.
03-02-2006, 04:51 PM
#13
Member
Thread Starter
Join Date: Apr 2002
Location: Washington, MO 63090
Posts: 64
Originally Posted by drunkin_idiot' post='805060' date='Feb 28 2006, 07:57 PM
haha no 1988RedT2 is 100% right, that only has to do with anything when the car is at idle.
03-02-2006, 05:39 PM
#14
Senior Member
Join Date: Mar 2002
Location: Ky
Posts: 2,723
Originally Posted by jack' post='805455' date='Mar 2 2006, 05:51 PM
what does it have to do with then...it may not be a/f ratio but i know it isn't idle. it doesn't change the idle at all when i adjust it.
03-07-2006, 11:08 AM
#15
Senior Member
Join Date: Jul 2002
Location: Portland, OR
Posts: 2,467
The stock ECU runs the tuning a little rich across the board, there are some minor variations from unit to unit, but for the most part it stays to the rich side of things.
A true streetported motor isn't going to produce huge power gains and create huge fuel demand, but it can effect the readings of the input and output sensors throughout the engine, not to leave out that one or more of these sensors could be operating below recommended spec or not operating at all.
An S-AFC and a wideband O2 will help to tune in the engine and get the AFR's to a reasonable level, but first the other sensors and systems must be functioning properly.
A true streetported motor isn't going to produce huge power gains and create huge fuel demand, but it can effect the readings of the input and output sensors throughout the engine, not to leave out that one or more of these sensors could be operating below recommended spec or not operating at all.
An S-AFC and a wideband O2 will help to tune in the engine and get the AFR's to a reasonable level, but first the other sensors and systems must be functioning properly.
03-07-2006, 04:28 PM
#17
Senior Member
Join Date: Jul 2002
Location: Portland, OR
Posts: 2,467
I suppose I should have added "generally speaking" in front of the streetported motor part, but yes there are variations in styles of streetports. Most of the time its some clean up of the runners, a little teardrop work and some oil and cooling mods, everything else remains the same, in otherwords the port job won't surpass the limits of the stock systems.
If you step outside that realm, of course, there are an endless amount of recommendations for upgrades, but in this case, without knowing exactly what the details are in this particular engine I was speculating that it was a "small" streetport, and while 12 mpg seems low, I was actually getting 8 mpg in my streetported engine and increased it to 16mpg after fixing some sensor related problems.
If you step outside that realm, of course, there are an endless amount of recommendations for upgrades, but in this case, without knowing exactly what the details are in this particular engine I was speculating that it was a "small" streetport, and while 12 mpg seems low, I was actually getting 8 mpg in my streetported engine and increased it to 16mpg after fixing some sensor related problems.
03-14-2006, 06:54 PM
#18
Junior Member
Join Date: May 2005
Posts: 2
Sorry about jumping into the thread
i've got the same problem with my 86' FC, just got a rebuild with streetport by Atkins Rotary and the mechanic i'm going to can't seem to figure out why the car keeps dying out after idling for a while.
the previous engine also ran really rich and kept dying out and refusing to start for the longest time but it had close to 200K miles on it. The mechanic recommneded a new engine but the same problem still exists. The car runs really rich still (white smoke out the exhaust and smell of gas) and the mechanic kinda gave up on trying to fix the problem so he told me to bring it to another shop
i'm going to another mechanic right now and the new mechanic tells me that if this problem existed before the engine swap it might have been a bad sensor to begin with. the new mechanic also tells me that i might have been jerked around by the previous mechanic who didn't bother to do a proper engine diagnosis before recommending the swap.
well i'm $3000 poorer right now and still without a working car.....please help!
i've got the same problem with my 86' FC, just got a rebuild with streetport by Atkins Rotary and the mechanic i'm going to can't seem to figure out why the car keeps dying out after idling for a while.
the previous engine also ran really rich and kept dying out and refusing to start for the longest time but it had close to 200K miles on it. The mechanic recommneded a new engine but the same problem still exists. The car runs really rich still (white smoke out the exhaust and smell of gas) and the mechanic kinda gave up on trying to fix the problem so he told me to bring it to another shop
i'm going to another mechanic right now and the new mechanic tells me that if this problem existed before the engine swap it might have been a bad sensor to begin with. the new mechanic also tells me that i might have been jerked around by the previous mechanic who didn't bother to do a proper engine diagnosis before recommending the swap.
well i'm $3000 poorer right now and still without a working car.....please help!
03-27-2006, 09:07 PM
#20
Senior Member
Join Date: May 2004
Location: Coon Rapids, MN
Posts: 310
Am I alone here in getting 29+ MPG freeway?
S5 TII stock turbo, stock ports, E6x......
Road trip from Phoenix to Minneapolis With the car completely loaded, because I was moving, and still amazing mileage. I averaged out every tank so im sure thats accurate.
S5 TII stock turbo, stock ports, E6x......
Road trip from Phoenix to Minneapolis With the car completely loaded, because I was moving, and still amazing mileage. I averaged out every tank so im sure thats accurate.