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Car running really lean

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mxpimp18

15+ Year Contributor
88
0
May 26, 2004
Federal Way, Washington
When my car was stock the spark plugs were really lean. Since then I replaced the fuel filter, plugs gapped at 28, and wires, 3" turbo back and mbc. I took my plugs are today were super lean still. What can be causing it? The car runs strong and no problems. Could it be fuel pump or o2? Im looking into a logger right now and then a AFC. Suggestion please.
 
mxpimp18 said:
When my car was stock the spark plugs were really lean. Since then I replaced the fuel filter, plugs gapped at 28, and wires, 3" turbo back and mbc. I took my plugs are today were super lean still. What can be causing it? The car runs strong and no problems. Could it be fuel pump or o2? Im looking into a logger right now and then a AFC. Suggestion please.


It could be your fuel pump.

What is your logger telling you?

How much boost are you running?


As for the "car runs strong" statement...well.....your car will never feel so faaaast up until it blows itself from a lean condition. Remember, that is what most of us are doing for a good tune. Leaning out the fuel, which inturn makes more power. The key is getting the car to run nice without starving.
 
I haven't got a logger yet. Just started looking at some and probably buy one this weekend. Right now boost is about 13-14 psi. So maybe get a 255lp fuel pump before the logger?
 
If you are not going bigger than a 16g type turbo then just get a 190lph and rewire it.

If not, remember you need to get an AFPR eventually if you get the low pressure and deff. if you get the high pressure.


By your thread I thought you meant you were looking at a logger while you were typingand couldn't figure it out. :p
 
if you get a logger look for .8x-.9x voltage from the o2 that will tell you whether you are really lean or not...oh thats at wot. Also if it is leaned out a bit on the low end youll pull hard, when tunning leaning out the low end gives you more grunt as you dont need nearly as much fuel as up top. Get a logger and check that out. Good luck
Andrew
 
Get a logger first and check your O2 reading. For a free "this might fix it" mod, bypass the fuel pressure solenoid if you haven't already. Mine was leaking boost and therefore my FPR wasn't seeing the real manifold pressure, and under boost my fuel pressure was actually DEcreasing. I was getting 0.00V on the O2 sensor. OMG If it doesn't solve your lean condition, at least you'll have taken out one more potential point of failure.
 
im having a similar problem, but my car is running lean ALL the time, from idle to wot its running lean (i have a autometer a/f gauge). it used to idle lean (like it should) then when i drove it would bounce around all over but ever since i had my new clutch put in, its read lean.

my fuel system has been rewired for quite some time and my plugs are fine - i just replaced them with colder NGK ones and the old ones didnt show any sign of running lean. the only thing i can think of that would cause this problem is a bad fuel filter, my friend also said my timing might have somehow been advanced but i havent touched it.

any thoughts?
 
So are you telling us that you are running lean because that is what your A/F gauge is telling you?
 
What I am wondering is what you guys are using to determine these readings. An A/F is the most pointless gauge you can buy. No one tunes or uses those for anything other than entertainment.

For those reading plugs do you know exactly what to look for when look ing at a plug after a run?? Are you changing them to make sure the results are repeated for accurancy??? Probably not. Get a logger and use real info to determine how well your car is running.

Michael
:talon: :laser:
 
boostedinaz said:
What I am wondering is what you guys are using to determine these readings. An A/F is the most pointless gauge you can buy. No one tunes or uses those for anything other than entertainment.


I have to say i dissagree with that. And which a/f gauge are you referring too? The greddy or the most common one for $50 Yes the greddy for $200+ is one of the more accurate ones but i use the one for $50 and it has always told me when i was running lean or rich. Yes almost all of the time they say rich at WOT but it has also told me lean at WOT too which turned out to be the injector circuit. Today i blew my licp off. A/F gauge was pegged at rich regardless of throttle. Another plus i like bout them is they will show signs of your o2 sensor going bad before the ecu recognizes it. I have compared the a/f gauge to my logger in the past and whatever the a/f gauge has read my logger matched it. I dont have an egt gauge and i have never had a problem tuning my car. Just my .02 :talon:
 
SpoolnTsi said:
I have to say i dissagree with that. And which a/f gauge are you referring too? The greddy or the most common one for $50 Yes the greddy for $200+ is one of the more accurate ones but i use the one for $50 and it has always told me when i was running lean or rich. Yes almost all of the time they say rich at WOT but it has also told me lean at WOT too which turned out to be the injector circuit.

I will have disagree with your disagree. I dont care if God himself made the gauge and it cost 10 billion shipped. You are still getting your info from a POS narrow band O2 sensor that is only accurate at stoich and then it goes down hill from there.


Today i blew my licp off. A/F gauge was pegged at rich regardless of throttle.

I bet the fact that your car ran like shit shortly after would have been a good sign also.

Another plus i like bout them is they will show signs of your o2 sensor going bad before the ecu recognizes it. I have compared the a/f gauge to my logger in the past and whatever the a/f gauge has read my logger matched it.

If you do regular maintenance then you shouldnt have to worry about when you O2 takes a shit, becasue you replaced it before the service life was up.

I dont have an egt gauge and i have never had a problem tuning my car. Just my .02 :talon:

Thats what I was saying in my post. People dont use it for tunning becasue they most likely, actually should, have a logger to do that.

Michael
:talon: :laser:
 
boostedinaz said:
I bet the fact that your car ran like shit shortly after would have been a good sign also.QUOTE]
That was just an example. I have gotten rich readings from a vaccum leak at idle. As for the wide bands..........i feel there a waste, unless you plan on running 10's and faster then you need them. You basically get the same readings via both o2's just one is easier to tune. I could tune my car just as good with the narrowband then i could with the wideband. Just take longer. Im not trying to sound like mr. perfect or anything, i guess i just really know my car. I feel the logger with the afc is enough in my opinion :talon:
 
You basically get the same readings via both o2's just one is easier to tune. I could tune my car just as good with the narrowband then i could with the wideband. Just take longer. Im not trying to sound like mr. perfect or anything, i guess i just really know my car.

I bet anyone that tunes cars for a living would beg to differ. Not to mention if they were that similar then all the tuners would just tune off the stock O2 sensor and make more money with the extra time they spend on the car. If you read up on wideband O2's you will see why a narrow band is far inferior to them. Ill get a few other to chime in and give you a more detailed explanation.

I feel the logger with the afc is enough in my opinion :talon:

Again, what I have been sayong this whole time.

Michael
:talon: :laser:
 
ok... lets say i dont have an a/f gauge and i have a logger... and its reading lean, what could possibly be causing this? its not just reading lean at wot, but ALL the time - at idle, at wot, just cruising at 3k rpms in 5th, always. granted, sometimes it shoots up from low lean to high lean... but thats it, never stoich, never rich.

i just raced it the other day... 6 runs at the 1/4 and 15.2 is my best (check my pro for mods, i should be doing WAY better than that i know...). what baffles me is: usually the more lean you run, the more power you gain, you just gotta watch out and not blow your engine, right?

anyone have any ideas?
 
boostedinaz said:
I bet anyone that tunes cars for a living would beg to differ. Not to mention if they were that similar then all the tuners would just tune off the stock O2 sensor and make more money with the extra time they spend on the car.


I dont want to get into a big uproar about this, im just stating my opinion. That is a good point what u said tho. Im just used to and happy with my narrowband. Havent needed the wideband yet LOL :talon:
 
Parsalian05 said:
ok... lets say i dont have an a/f gauge and i have a logger... and its reading lean, what could possibly be causing this? its not just reading lean at wot, but ALL the time - at idle, at wot, just cruising at 3k rpms in 5th, always. granted, sometimes it shoots up from low lean to high lean... but thats it, never stoich, never rich.
Dead O2 sensor? If it never cycles anymore that would be the first thing to check, they tend to be the first thing to go.

Steve
 
SpoolnTsi said:
I have to say i dissagree with that. And which a/f gauge are you referring too? The greddy or the most common one for $50 Yes the greddy for $200+ is one of the more accurate ones but i use the one for $50 and it has always told me when i was running lean or rich.

You are missing a few key points here.

First of all, while price does have a bearing on gauge quality and accuracy, you need to keep in mind where the signal is coming from. The stock narrowband O2 sensor is absolute trash for reading AFR within the range that you will normally see at WOT. Yes, it will show you if you have a problem like a huge boost leak, but keep in mind that when you have a big boost leak your AFR is probably 30% richer, or something absurd like that.

Case in point: I see 0.83-0.85 volts on my logger, at 9:1, all the way to 11:1. 0.02 volts of difference for two points of AFR is freaking useless.

Another case in point: A friend of mine who road races watches his O2 drop several tenths when he road races, due to the sensor heating up.

Read this:

http://www.cmperformance.com/techinfo_oxygen.html


I have compared the a/f gauge to my logger in the past and whatever the a/f gauge has read my logger matched it.

Again, just because it matches the logger doesn't mean it's a good way to tune. Just because you can get three idiots to tell you the same thing, doesn't make it right.

I dont have an egt gauge and i have never had a problem tuning my car.

What does "never had a problem tuning" mean?
 
SpoolnTsi said:
As for the wide bands..........i feel there a waste, unless you plan on running 10's and faster then you need them.

No. You can run 8's without a wideband if you want, but if you want the car to make the most power possible, you need to know as much information as you can. Widebands fill in one of the biggest holes in tuning information.

You can tune by looking at plugs only (no logger, no wideband, no narrowband, no EGT). Does that mean that all of these things are useless? No, they allow you to tune better, just like a wideband does.

You basically get the same readings via both o2's just one is easier to tune.

Wrong. Read the link above before you make a comment like this again.

I could tune my car just as good with the narrowband then i could with the wideband.

Very wrong.
 
kpt4321 said:
What does "never had a problem tuning" mean?


Im just stating that i havent felt the need for a egt or wideband when tuning my car. Atleast not yet anyway. Every car is different. I guess i just really know my car and how to work with it from doing it so many times. And plus the experience of doing it for other people really helps getting the feel for how things differ from car to car and how to correct them. I just cant see what the advantages would be if i were to have a wideband in my car as to a narrowband and if there really worth that kinda money?? Why couldnt you just by the Greddy a/f gauge for $200+ in place of the wideband? Their accurate for readin a/f mixtures :talon:
 
I just read the post Kyle put up. If you read that you will get all of your answers to the questions you just asked. ;)
 
SpoolnTsi said:
Your telling me i could tune my car better with a wideband as to a narrowband? enlighten me please. Thanx for the link too :thumb: Very resourceful :talon:

You are not understanding the different types of sensors. If you look and read you will see why one is far superior tothe other tunning wise. Like I said earlier the stock O2 is only accurate at the point of stoich (14.7:1) after that in either direction it is horribly inaccurate. This is commin gfrom the people who make these items. Kinda weird how they also make wideband sensors also since apparently they are pretty much the same thing.

You wouldnt use a wideband in place of a the stock O2 you would use it strictly for tunning on the dyno. You can buy kits that let you cruise around and tune with a wideband, but you still would replace the stock one.

Google it and see what you find and you will see the light.

Michael
:talon: :laser:
 
boostedinaz said:
You are not understanding the different types of sensors. If you look and read you will see why one is far superior tothe other tunning wise. Like I said earlier the stock O2 is only accurate at the point of stoich (14.7:1) after that in either direction it is horribly inaccurate. This is commin gfrom the people who make these items. Kinda weird how they also make wideband sensors also since apparently they are pretty much the same thing.

You wouldnt use a wideband in place of a the stock O2 you would use it strictly for tunning on the dyno. You can buy kits that let you cruise around and tune with a wideband, but you still would replace the stock one.

Google it and see what you find and you will see the light.


LOL i hope to see the light. KPT is right. I must be missing some points here and i sure as hell dont see them. Maybe, someday ill just breakdown and lay down the money to get one and see what i can do with it. But y couldnt you just get the greddy gauge? There pretty accurate for a/f ratio's. I dunno. I dont even know why im draggin this on. I know you and KPT know your shit when it comes to this stuff. No offense to anyone else ;) :talon:
 
SpoolnTsi said:
LOL i hope to see the light. Maybe someday ill just breakdown and lay down the money to get one and see what i can do with it. But y couldnt you just get the greddy gauge? There pretty accurate for a/f ratio's. I dunno. I dont even know why im draggin this on. I know you and KPT know your shit when it comes to this stuff. No offense to anyone else ;) :talon:

I may be a bit confused here in this guage you are talking about. Post a link if you can. Is it a complete package with sensor and all or is it just a Greddy gauge? If it is just the gauge then it doesnt matter because it is still getting its info from the stock narrow band O2 sensor. Expensive doesnt always make it better.

Michael
:talon: :laser:
 
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