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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #1
found this web page. tried to email the guy at the bottom, but it no longer exhists. i would like to know the following questions about the article. if anyone has done this and knows the answer, please post....

here is the link first.

Combustion chamber cleaning


now my question/comments from the email i tried to send relating to the article:



would a Glass jar be suitable? does it attack spoons?

did you put the fuse back in before cranking over? (i would assume so but you didn't say it)

what are you talking about when you say PCV hose? where is this?

Any specific brand/size to look for in combustion cleaner?

i am planning to do this on my GA16DE. i'm revieving low fuel mileage (27-31) but no pinging as far as i can tell. i just replaced my spark plugs form the Bosch plats to the NGK V powers (BKR5E-11) hopeing this would do the trick. i was searching to double check my gaping, when comming across this article. i remembered taking a peek into the cylinders with a flashlight, and could see what looked like black carbon on what i assume is a cylinder head. (dry and rough looking) i passed this on as normal untill i read your article and now wonder if i should try this. i could set it up for next weekend, i'm just about due for an oil change anyway.
 

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Sentra Specialist
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1,902 Posts
Piston tops on any gasoline burning engine will always look black. Cleaning them will not restore your fuel mileage. Check your oxygen sensor [or have it checked]. If they go bad, you won't know it. The car will run fine. But you will lose fuel mileage for sure.
 

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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #3
i already changed that, its brand new as of last week end.

i just installed NGK V powers.

(the guy said they were plats but i konw he lied, says nowhere on the box, and the model number confirms that, i looked it up. he probably didn't know, most of those 40year olds at parts stores like Chevys around here. yuck. if you gotta go ameraican, go FORD!)

i had the Bosch Plats, which of course hot type plugs, this should help, i havn't driven more then 20 miles on them yet.

so this cleaning option is my next line of defense, the 02 sensor change did nothing for me. my oil change is due in at least 2 weeks if not sooner, so i figured i could give this a shot.
 

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Sentra Specialist
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Ok, fair enough. But here's one more item you should be aware of. It costs pennies and you can do this yourself easily. There is a Nissan factory service bulletin for an insufficient ground to your air mass meter. Check out: http://www.se-r.net/car_info/problems/index.html#Erratic Idle and jumping idle. Yes, I realize your car is not an SE-R, but the engine electricals are the same, and this bulletin applies to both GA and SR engined B13's.
 

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You may want to try a fuel system cleaner. I use STP complete fuel system cleaner twice a year. This stuff works great and it contains "no alcohol" so it's safe to use and it wont eat up your injectors like some other brands do. BTW have you replaced your fuel filter lately, a clogged one will rob you of power and mileage. I try to keep my car in top shape and even with my auto and 97k miles on the clock i still manage about 325-350 on a tank of gas...
 

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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #6
yes, the fuel filter has been changed, along with the pump. i'm checking out that new link....some of the vocab words have gotten me here, like AAC. i'm gonna refer to my Haynes to decifer what the hell he is talking about.
 

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Sentra Specialist
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It stands for Auxiliary Air Control. This regulates idle speed. By the way Scarecrow, what was the highest gas mileage you ever regulary got with your B13? Is it an automatic?
 

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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #8 (Edited)
the highest i've gotten is 31, pretty much all highway. my last tank with the new o2 yeilded 27-28, mixed driving.

thats SE-R mileage, but without the preformance. to me thats not very good!


yes, automatic

i did the idle test earlier today, the tps was removed and the idle was steady, but low, the engine was shaking more then usuall. i figured this was normal for such a low idle, but i don't know how low exactly. i don't have a tach. i removed the red AAV plug on the other side of the intake header, and idle stayed the same. then i pluged them both in reverse order, when the tps was put back in the engine wavaily speed up to usuall idle speed.

that second thing AIV, i have no idea where it is, its not in the manual as i can tell
 

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bitter old man
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1,456 Posts
That combustion chamber cleaning procedure is suspect. Most of the cleaner will drain though the ring gaps and end up in your oil.

If the combustion chamber is building up enough carbon to need cleaning, there is a problem elsewhere that needs fixing, like bad rings or valve seals.

Pyrex is a high-temp glass. Glass cookware is usually Pyrex; look on the bottom. Many plastics WILL tolerate harsh chemical solvents. Be more worried about paint in the area in which you use it.
 

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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #10
is there any other way to tell if you have bad seals or rings or whatever?

i havn't noticed any smoke out of the exhaust, if anything its just when you start the car, sometimes, there is a puff or two.

what other general problem areas are there for bad fuel mileage?

so far i've herd:

the thread topic

spark plugs

ignition wires

fuel filter

o2 sensor

dirty or clogged throttle body

i've pretty much checked or replaced all the above options, i'm still stuck around 31mpg as a record high.
 

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Sentra Specialist
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All along, I have been thinking this, but have not had the inclination to say it: Maybe that's all you can expect? What have you heard the other automatic GA16DE B13 drivers are getting? I would really like to know, as I have a '92 SE-R, which I am thrilled to get about 31 mpg with [which is about 6 mpg better then my 4WD B12 wagon].
 

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Driver
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736 Posts
On the last two tanks on my B14, with "economical" mixed driving and an automatic, I've gotten 25-26mpg. The car is in top working order, and yet that's the best mileage it can manage. Just something to get things into perspective...
 

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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #13 (Edited)
thats the mileage that se r's are rated for!

i have heard of a couple others who have been getting 32-36 mpg. Patscott for instance says he hasn't gotten below 33. my friends 200SX gets around 35 average.

my car's preveious owner stated to be getting close to 40mpg, she did all highway travel. so i know my car CAN do better. specially now where i drive nearly 60miles round trip 3 days a week.
 

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My mpg has dropped significantly since I bought my car. I have a 13 gallon tank like everybody else, and I used to average 300 to 330 miles per tank on mixed highway and city driving. Now I can barely get 250 to 270. I took a trip to Austin this weekend from D/FW (about 225 miles one way) and squeezed 340 miles out of the whole tank until the gas light came on. Something else also concerns me about that stupid gas guage. After the light came on at 340 miles I filled up, and only pumped 9 gallons in the tank. That means I had 4 gallons left when the gas light came on and it was showing below E. When I fill up, it never gets to F. If I fill up and drive home immediately and let the car sit overnight, the needle magically rises up to F where it should be, then when I drive a little while, drops back down to 3/4 where it was when I filled up. I have a GXE LE so it has that 120 MPH speedo and an 8 grand tach cluster with the gas guage on the left.

I have 38 grand on my car as of right now. Am I due for a tune up to help that mpg anyway? I've already changed the fuel filter. I just need cap, rotor, plugs, wires and MAF reground? I don't know what to do about the damn gas guage, I'll just leave that alone.
 

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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #15
i never let my fuel go too much below the 10 gal mark, wich is just below the 1/4 left mark. i hear from a bunch of people that to run it that low, specially during winter months, is not safe.

1. an empty tank is more dangerous then a full tank (fumes)

2. (winter) if water somehow leaked in, its less harmfull on a full tank. (delouting properties i guess)

3. the sludge or junk in the tank is more likely to get gulped up by the fuel pump, clogging various parts of the system, specially the filter or pump itself.

i don't know how true that is today, i'm sure gas is much better refined now a days. and pumps better filtered. but i still follow it since my car does have the original tank with 140k. i'm sure its possible to have some junk floating around in there. I also hear that you shouldn't get gas when the refueling tank is at the station for the same junk reason.

as soon as i get to my mileage mark, i fill up. the needle does slowly rise up to full. i can drive about 50 miles before it drops to the actual F mark. i've never even seen my gas light turn on. i usually hit halfway at around 200mpg give or take.
 

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bitter old man
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1,456 Posts
  • Keep air out of the tank and there is no danger.
  • Water does not dissolve readily in gasoline. Any water in your tank will settle to the bottom. The fuel pick-up is attached to a float that rides at the top of the liquid level. If the water is deep enough, when the gas is consumed the pick-up begins ingesting water.
  • There is a filter over the fuel pick-up. It will prevent large particles from entering the fuel pump. There should not be any sludge in your tank. Water, yes. Sludge, no.
Do avoid a gas station in which the truck is unloading. Think Italian salad dressing when you shake the bottle.

I never filled up before the light came on. More than once I pumped over 12 gallons. I did stick to name-brand stations as much as possible.
 

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That is a perfectly fine way to do the Combustion Chamber Cleaning. I did it just like that almost a year ago and it improved throttle response and idle quality, and well as eliminating my persistant pinging.

As far as mileage, my 91 SE w/ GA and auto consistantly got 36-42 MPG on the highway. Keep in mind this is 90+% highway mileage at an speeds around 60-80MPH.

Not sure what I'll get when it is running again w/ the 5 speed manual.
 

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Ive got a pickle 4 an arm
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340 Posts
Discussion Starter #18 (Edited)
so youve tried it and are satisified with the results. thats good to hear, was there a change in gas mileage before to after?

my car's 140k are also 90% highway driven. the prevous owner drove highway every day she used it pratically. i only did about a few thousand miles in city while in shcool. then college life put me into highway travel.

as i said before she stated getting nearly 40mpg. i know that she drove it more easier then i did, but a 10mpg drop due to driver style is terrible! its gotta be something else.

i never really paid attention to my mileage untill last year, so i don't know when it dropped. my friend in his 200sx was telling me how much mileage he got, which got me wondering. i checked it to my dismay. i was getting worse fuel mileage then my dad's 01 Maxima!!!! yet his car is obvously more powerfull. i was very pissed about this. i since brought it up a tiny bit, teaching myself to be easier on the gas, but i don't think i can take being more granny style driving.

oh yea i never go higher then 80, thats my personal limit. to me the car just doesn't feel comfortable any higher. my dads maxima, i have to watch myself so i don't do 90...:D
 

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I hit the famed 109 mark in my B14 driving down to Austin on I-35. On a bone stock suspension it feels like the car is hovering above the ground and one false move (maybe a pebble in the road, a slight change in wind direction, or perhaps a blank stare from a cow on the side of the road) will send it flying off the road in some spectacular tri-axis spin and they won't be able to identify my body when it comes to a stop.

Yes, we have lots of cows in Texas.
 

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Did some conversion and I'm getting around 350-380 km per full tank, usually about 39 litlres.

That works out to be 21-26 mpg. Mixture of highway 30% and urban areas 70%.

I don't floor the gas from stop to go. Mostly gentle acceleration.
Mine is an auto trans and I have 230,000 km travelled on it. Does it sound like time for a major overhaul ?

I've replaced new plugs, fuel pump and filter, distributor, plug cables , TPS and cleaned the TB. All these and I'm still getting the same mileage for over a year. But prior to the TPS replacement, I actually got 18-20 mpg and lot's of black smoke at the exhaust.

Intending to replace the coil and O2 sensor to improve on mileage.

So far I've added STP's fuel injector cleaner twice in a year. That didn't help much and actually brought the consumption higher !!

I've a friend who drives a 5 sp manual and he's getting around 30 mpg.

I've read somewhere that there is a TSB on the fuel gauge & sender that it reads incorrectly at 3/4 and lower ranges. Mine does that all the time, so I rely on the distance reading to gauge.

I'm using 95 octane for the above. I've tried 98 and 100, but results aren't that significant.

What do you guys (with auto trans) say ? Is higer consumption 's inherent of auto trans cars ?
 
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