i have a 1992 nissan maxima (DOCH)...it eats alot of gas and i was wondering what you guys do to help it not eat so much...? thanks

 

My 93 seems to be using a good bit of fuel as well. In addition, I've been having some performance issues. I believe that in my case, the MAF has been malfunctioning. I just swapped in a MAF I picked up off ebay. I haven't had much chance to drive it, just around the block once, but it feels as if it is running better. Once I have a chance to drive it some, I'll let you know if that solved my poor fuel economy problems.

Generally, poor fuel economy is often related to the vehicle being in a poor state of tune. Check air filter, fuel filter, plugs, wires, distributor cap and rotor, and related sensors like MAF, and O2. In addition, if the injectors are leaking, or stuck open you will use too much fuel, same if trans is slipping, and I'm sure there are other possible causes I'm just not thinking of right now.

 

check you ECM codes, maen... eet do ze trick sometimes. </horrible_russian/german/mexican_hybrid_accent>

i got a code for my o2 sensor. i replaced it, no more code. i'll have to see my MPG at next fillup. Seems to be going through gas rather quick right now post-sensor -- 60% tank indicated after just 80 miles.. but then again fuel gauges are not very accurate always... only the pump will tell.

 

i get no codes, no cel, my 92 dohc auto seems to get crappy mileage. 12mpg city, sometmes hard to start. I get major carbon buildup on the muffle, spark plugs get carbon bad too, just replaced...i have new TPS, new O2...the harness to the TPS tho is corroded, not sure if its the prob tho..i have had it unplugged a few days now, seems to have started alot better, but it hesitated this morning. i think my prob is the harness or i have a stuck open injector.....but all 6 plugs look the same, just heavily coated with carbon.

 

Sea Foam,,,,

 

http://i164.photobucket.com/albums/u...r/IMG_2084.jpg

on the left, 2 of the bosch plats i put in in october. on the right the NGK my car came with. only 3-4k miles on the bosches. how do yours compare? way blacker? my car had a busted o2 sensor and ran rich.

 

the circle around the white part has a thicker coat of blackness on it on mine...

 

got a pic (use macro-mode on the camera)? how many miles on your plugs if you know? remember those are after only 4000 miles, tops.

 

no pic, but they have less than 4k on them thats for sure....maybe 1k 2k tops. just a bit ago i was going to the store..i remote started it and stood at tailpipe....first 1 sec smelled normal, but i smelled fuel for a few secs after... i think im going to need to just get all new injectors. anyone know what that will run me if i do it myself?

 

The only way to do it is $600 new from the dealer or internetautosupply.com Thats about $100 per injector.

Id just use an ohm meter on them and see how they spec. Check your coils make sure they aren't cracked.

Does your thermostat work properly? Every maxima should have the temp needle just below level and reach that level quickly.

~Alex

 

no cracks visible on coils, all injectors spec at 11.2- 11.5 ohms....had new thermo put in 3 years ago, and temp needle is at that level. very cold days, cold motor, takes a few minutes to warm up, normal for every car ive ever seen, not sure what you mean by quickly. coolant temp sensor works properly as well.

if one or 2 injectors were leaking it would only show on those plugs correct? all plugs look identical, coated with carbon around the ring/thread part.

 

ill clean my muffler off and after driving maybe 50-90 miles it goes from shiny chrome to black, im pretty sure its carbon. if i was burning oil would it cause a carbon like build up? oil is blue smoke right? i have seen black smoke sometimes, usually only when its rough starting or i have to try a 2nd time to start.

I think im going to go pay 15bucks and get emissions testing done. how well would that help you guys diagnose my problem? I dont really want to pay 600 and replace injectors and find out a sensor is acting up. thanks again

 

do you have any top end power or does it feel choked off? It could be a clogged cat...

~Alex

 

Do you smell gas after the car is driven? if so check the Gas tank filler, air tube hose, at the base of the filler neck. sometimes the hose gets small cracks and leaks after shutting the car off, until the pressure inside the tank equalizes. Just a thought!

 

exhaust leak?
vacuum leak?
wrong gasoline?
bad alignment?
2 bad coils giving you a V-4? I've been there.
more...?

Its difficult to diagnose using city-milage. Why dont you fill up the tank all the way, do 100 miles on the highway with cruise control (so your foot is not a factor), and then fill up again right away to see how much gasoline was used.