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88 CRX
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I've got a d16y8 in my 92 4dr and i got about 31mpg on my stock wheels, about 30 when i got my 15" rims (added weight and width/drag) and about 29mpg when i got my AC fixed. Just yesterday i'm at the pump and i come up with 26mpg! At 2.55$/Gal i can't deal with this! Plus i've been driving pretty conservatively for this tank. I'm gonna do a tune up, but that basically amounts to plugs and wires because i've replaced the air filter and fuel filter already this month and my oil still should be good.

I'm thinking about going with a basic I/H/E just to get some more pep and mpg (how much can i expect?) and i'd also like to find some programmable ecu solution to do some real tuning with. But for now, any quick fixes? Anything to check? Anybody want to save me?
 
J

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make sure your brakes are not dragging, check your tire pressures (also for better mileage pump them up a bit from stock i think is 32 cold try 37psi cold ) the ride will be a little harsher but you provide you with less rolling resistance, and after all its free....

Also make sure you dont have any problems because more than 4mpg difference is a sign of a problem, are you sure your not just stuck in traffic a long time ?


-Juan
 

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Discussion Starter #3
Good thought on the brakes, though i'm pretty sure they're ok. As for tires, i ride 38-40psi, though i have one with a slow leak.

I really want to know two things, what else should i check for failures? and what can i upgrade to improve my gas milage, even if nothing is wrong? (and how much of an improvement can i expect?) I know some people on this site get better milage with a turbo, while others get more than double, i must be doing something wrong here!!
 

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d16y8 on an obd1 computer MIGHT be the cause... do you have your base timing set correctly? I believe it is 12 degrees for the y8. But then I don't know if the ecu is compensating for that since it expects generally 16 degrees of base timing (for a d16z6).

Also, how is your o2 sensor? When that starts to go, it may not trigger the CEL but you could be getting bad readings that cause you to spit out more fuel. Either clean it with a torch or replace it.

How is your ecu setup? Chipped? If so, do you have closed loop mode enabled? (basically, o2 sensor enabled) If not, you need to enable this or else you have to tune your maps for economy, not performance.

How's your driving? Low throttle? Keeping your windows open can affect your MPG, but not that much.... it may be a coincidence, but I put my stock airbox back on with a K&N flat filter and I got my 40 MPG back when driving to Quantico everyday (70miles to and from). Before, I'd get barely 25 MPG with my short-ram intake driving only about 10 miles to and from work.
 

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Discussion Starter #5
Setup is d16y8 w/ a stock p28 ecu, stock intake box without all the crazy piping, stock 96ex cat back and exhaust (car is a 92dx)
I don't know what my base timing is, i'm guessing that's the ignition timing? I just got a timing light but i can't seem to figure out how i'm supposed to know if i'm getting an accurate view of those little marks, i only see one sight on the timing belt cover so i'm not sure how to line it up. Windows are almost always up, but the ac is blasting. Probably irrelevant but the main relay is failing, though i'm fixing that tonight.

What sort of intake would you reccomend for best fuel economy?
 

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stick with stock, but get a K&N flat filter.

A/C will suck some of that gas down, but not that much...

to check your timing... if you have a cheap gun, it's probably set at zero. Just set it at zero and then attach the lead to the plug on cylinder #1. Fire the light and check to see that the RED mark lines up with the marks on the block. The white mark is for TDC and only when you use the gun's timing adjustment knob. (don't worry about it... just use the red mark for stock timing... set the gun to zero!) Just turn the distributor to shift the mark side to side. You MUST have let the car warm up and the service connector must be jumped (like when you check codes). Also I think the idle valve plug needs to be unplugged.
 

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also, if you haven't done it for awhile, change the tranny fluid, that can bring down your gas mileage too.
 

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achilles1981 said:
also, if you haven't done it for awhile, change the tranny fluid, that can bring down your gas mileage too.

k never heard of that one, are u talking just the thickness of the oil or what, how does this make worse gas mileage?
 
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i'm running a p28 ecu on my 1.5 mini me and i get about 28-33mpg around town. but once on the highway i get more than 40mpg.

i thought something was wrong too. but driving around town wastes a lot of gas.
 
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makku said:
d16y8 on an obd1 computer MIGHT be the cause... do you have your base timing set correctly? I believe it is 12 degrees for the y8. But then I don't know if the ecu is compensating for that since it expects generally 16 degrees of base timing (for a d16z6).

Also, how is your o2 sensor? When that starts to go, it may not trigger the CEL but you could be getting bad readings that cause you to spit out more fuel. Either clean it with a torch or replace it.

How is your ecu setup? Chipped? If so, do you have closed loop mode enabled? (basically, o2 sensor enabled) If not, you need to enable this or else you have to tune your maps for economy, not performance.

How's your driving? Low throttle? Keeping your windows open can affect your MPG, but not that much.... it may be a coincidence, but I put my stock airbox back on with a K&N flat filter and I got my 40 MPG back when driving to Quantico everyday (70miles to and from). Before, I'd get barely 25 MPG with my short-ram intake driving only about 10 miles to and from work.
I agree with Makku check your o2 sensor. and try and pipe in cold outside air to the filter area, use some ducting. This will be good for 2-3mpg if you stay off the throttle....
 
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