Among the list of things that are wrong with my car that I cannot pressently afford to fix...
For about 5 months now I have been experienceing Bad Gas mileage and Reduced Power.

From the beginning.
5 months ago I noticed the problems so I pulled codes and had KS code. I changed the KS and the code has since never come back.

This however did not fix my problem. I still am getting bad mileage and poor power. (Normally got 24-28MPG depending on driving, now I get 18-20, maybe 23-24 on a long interstate trip)

My car's vital stats as of today.
Battery: 12.5 volts
Alternator: 14.2 volts
Oil: just changed, now on rinse cycle of Auto RX
Fuel: 93 octane (as always)
Tire pressure: 32psi all around...(cause i know someone will mention it)

My spark plugs are fairly new and look normal. My air filter is clean. I replaced my fuel filter (i found the old one was not dirty anyway though). I have tested all of my coil packs. Tested the resistance between all 6 of the possible pin choices (+1 -2, +1 -3, +2 -1, +2 -3, +3 -1, +3 -1) All 6 tested with the exact same values and met requirements of haynes manual. I have tested both front O2 sensors using the Volt meter backprobing method (though I don't think this is as usefull as an oscilloscope where you can actually see the signal). Both O2 sensors oscillate between .1 and .9 volts at 2000RPM (passed per Haynes manual). I tested the MAF. It recieves 11.9 volts to red wire (slightly less then battery) and .22 volts at white wire with ignition on. 1.5 volts to white wire with engine idling and it goes up to 2.2-2.5 volts when I give it some throttle. All within spec of the haynes manual (though once again I don't think this is a very usefull method of testing). I tested Cam shaft position sensor resistance and it was within spec. I tested TPS. 5 volts supllied (per manual). Closed resistance was .65 (higher than manual specifies) and 4.0K at WOT (Correct value). I will replace TPS but I don't think this is the problem since the power loss is pressent even at WOT.
This is all i can think of at the moment...

Now to the rest...
The car sometimes has some problems starting (usually cold, but sometimes warm). It will crank and just won't want to turn over. so I stop and wait a second and then try again and then it turns over. sometimes when it does turn over it will try to die (sit at 200 or so RPM) for about a second and then it will wake up and go to normal idle. I also have developed the infamous timing chain rattle at startup. I have also had an intermitant problem (so far has done it twice). I will be sitting idling for a long time (5 minutes while waiting to pick up my girlfriend, and once while sitting at a long light) and all the sudden the RPMs will shoot up to 1000 - 1200 and sorta oscillate for a second and then fall back down to about 800 (higher than normal) and sit there for a while and after maybe a few minutes the idle rpm drops back down to 650. This has nothing to do with fans turning on. It seems to me like a sensor is starting to fail intermittantly.

one of my theories at the moment is that the KS is picking up the timing chain rattle and getting pissed off (to explain Bad gas mileage and power). As for the starting issue all i can guess is maybe a sticking starter (or the TPS being out of spec)...

Any idea would be very nice. I cannot afford to just start replacing things... I have played that game before. And sorry for such long post.

 

Cliff notes > you.

Winter fuel maybe?

Get a dyno to see if you're really down on power

No CEL's = hard to find problem, so I don't know.

Before I changed a few things, I was getting the same mileage on the highway as you, and same citiy mileage. (aftr your 'problems' occured)

 

Clean the TB, IACV, run a bottle or TWO of Techron through.

Fill up, drive it around normally, record the miles driven since your last fill and the gallons you use to refill it again on the pump. Don't just assume you used 16.5 as so many on here do.

miles drive / gallons pumped to full tank again = true MPG.

 

I doubt the whole winter gas thing... but I guess it's possible... even though this started in august...

I forgot to mention... no, I don't have any codes... I have run sea foam through it. I guess I can try running some cleaner. I have cleaned the IACV (it wasn't very dirty when i cleaned it) the Throttle body didn't look too dirty either. I will clean it though when i get a chance. I don't know about EGR system. Could this be an issue here?

I calculate my MPG every time I fill up. I always top it off. So when I fill up i just divide the miles on my trip odemeter by how much i put in (usually 16.5 - 17 galons)

Also I don't have a dyno sheet from before this and I don't need a dyno to tell me I am not getting full power. I also forgot to note that the power issue seems worse some days than others. Yesterday I had to practiaclly floor it to make the car move (I know weather affects the power but yesterday was 70° and low humidity and no different than day before, or the day before that). A preppy girl in a civic was almost keeping up with me... (no I don't race a lot but she was being a ***** so I had to )

 

have you checked the mafs ? i had similar probs recently due to a failing mafs. i never got any codes.

 

MAF is high on my list of suspects. I Guess I will try to find one in a junk yard...
I am still hoping for some more suggestions, cause I really can't afford to just start replacing things... I need to have a good idea, and get this on the first or second attempt.

 

sorry, just went back and saw that you did check the maf, mine also read within those specs but after checking it several times i decided to sit and watch the meter for awhile. when the car finally started to run badly, the volts out of the white wire would drop down into the .6 range and try to stall then jump up to the 2. range and back and forth. it would run rich, gas smell and black smoke. then it would stall and be hard to restart.

 

MAF? Bad ECT sensor? That could cause you to run rich and cause ur car ot turn off... hmm, are the o2 sensors new? My o2's were fine, no codes, but my gas mileage was crap, changed them anyways and im getting 22mpg city, havnt done highway.. before was 17mpg city.

 

What was the problem? Was it really the MAF?

 

Do you have ngk spark plugs in there? Generally, other brands don't seem to work as well in our cars.

It's hard to say what's wrong, especially with no codes. Seems like you've done most of the basic maintenance. Outside of that, it is conceivable that sensors may be on their way out but not dead enough to trigger a code. I feel for you! Have done the parts-swapping thing way too much as have most DIY'ers who have done the basics and don't know where else to work. Before you go down that road, you might want to just get the dealer to run a diagnostic. It may cost you up to $100 but they can probably tell you what's wrong before you go swapping parts that were good. I would only do that after you thoroughly convince yourself that you've checked everything and before you go into part-swapping mode.

 

yep, after 3 months of mental torture i got a maf on e-bay for 60 bucks and it's been fine for two months now.

and of course, thanx to alot of help from the org too....

 

Tomorrow I will check out the engine coolant temp sensor. There is a MAF for $89 +7.50 on ebay with a one year waranty... I may get it... I think I will try spraying some electronics cleaner on the MAF tomorrow and see what happens, maybe it's just dirty.. or maybe it's not even the problem

(I just got a multimeter so I am like testing everything on the car finally lol)

 

Has this 5speed ever been rebuilt? (As mine was in it's final throes it had so much internal friction that it was like driving with the e-brake half-engaged). As you can imagine, the fuel mileage went from a little low for about 20k to simply terrible (like 15mpg) as the tranny got closer to death.

Dave

 

I agree, its taken from 15 to 18 gallons to fill my tank and if you assume it only takes an average you'll get the wrong mileage. The 18 was after driving 20 miles with the gas light on. Talk about running on fumes.

 

throttle position sensor????

 

thats not cool at all...

 

What mods do you have?

 

none...unfortunately...
less you count the strut bar...