What can cause engine runing too lean

[Slow5.0]

I have problem with my car and what I find is this , engine runn too I MEAN too lean 14.7 at WOT and 18s at idle or cruising
My injectors are good and everything else looks good , I check every sensor, swap PCM and CCRM because I have extra , any way it still runing lean

 

[mytight95]

How did you get the air fuel ratio like that. If it wasn't a wideband then i would say to ignore those numbers. Second this sounds like it would be a MAF sensor problem, im sure you have cleaned it, but what do you have a pro-m or what? Just my thoughts, maybe your pressure reg. is clogged up or something.



jsut some thoughts



jason

 

[BlackVert]

I have problem with my car and what I find is this , engine runn too I MEAN too lean 14.7 at WOT and 18s at idle or cruising
My injectors are good and everything else looks good , I check every sensor, swap PCM and CCRM because I have extra , any way it still runing lean

14.7 doesn't sound too lean to me. sounds about right. 18 at idle sounds too rich to me. but i'm no expert

has it always been lean? did you just change something? are you getting a engine light? my lean conditions have always been from a vaccuum leak.

 

[Slow5.0]

How did you get the air fuel ratio like that. If it wasn't a wideband then i would say to ignore those numbers. Second this sounds like it would be a MAF sensor problem, im sure you have cleaned it, but what do you have a pro-m or what? Just my thoughts, maybe your pressure reg. is clogged up or something.

Guy who messure that air/fuel ratio have wideband (something)
I clean my MAF and I try my other one and I try one from guy who have wideband , same thing, voltage is there and everywhere and everything looks perfect but still run too lean
I have adjustable FP regulator 2 months old and I tryed swap with my stock one same thing

14.7 doesn't sound too lean to me. sounds about right. 18 at idle sounds too rich to me. but i'm no expert

has it always been lean? did you just change something? are you getting a engine light? my lean conditions have always been from a vaccuum leak.

14.7-1 at wot and 18up-1 at idle thats too frickin lean

 

[robertdale]

Ok to make sure the car is running that lean you should pull a few spark plugs and check the color. If it is lean then the ceramic around the electrode should be white. May even have green specks indicating detonation. If they are white then we need to know if you have replaced the fuel pump or is it still stock. If it is stock that could be your problem if not then I would lean towards the mass air meter.

Edit... sorry i didn't see that you have already tried other mass air meters.

 

[Stump1000]

I'd put a fuel pump in it, i had a lean condition and it was my mass air meter. I swapped and felt like i picked up 50 hp

 

[Slow5.0]

I have 255lph high pressure Walbro fuel pump old 6 months and pump still works

 

[robertdale]

then pull the plugs, the wide band might be reading wrong.

 

[302fordracer]

I would get a friend with a similar stang and start swapping parts to find what it is when you have found it give the parts back and buy the one you need. Course this is under the assumption that plenty of mechanics have seen the car and can't figure it out. If it hasn't seen a scope then I would hook it to one. But I am sure this has been done so that is why I reccomend swapping parts with a friend..I am curious though would a MAF set off the engine light..because wouldn't the sensor then be getting freaky results of too much air and tell the ECM?

 

[Slow5.0]

Here is the thing , guy whi help me with my Stang is mechanic ONLY for Mustangs , he build a lot fast Mustangs , he have 94 Mustang 374 with blower run 10s on 1/4 , he is like I don't know how to say , he know everything about Mustangs except this my problem , we work in last 2 weeks over 20 hrs and still didn't find whats wrong, he try swap stuff from his Stang onto my Stang, I have a lot spare stuff plus I buy tons new stuff like
I thisnk this is like 100th time I said , I check , clean and change EVERYTHING
ECT , IAC , IAT , MAF , TPS , Ignition Module , All spark plugs , wires , distributor cap , rotor , INJECTORS , air filter , fuel filter , fuel pump, O2 sensors , PCM , CCRM , everything , fuel pressure is 38 just like before , compression is good (137-150psi) timing is like before , everything looks normal but still runing too lean , looks like misfiring, I mean everithing , there is no vaccum leak between Upper and lower intake and lower to heads , I don't know what to do
I didn't check vaccum with Vaccum tools , I check for vaccum leak but no leak

What else I can do
He said something tell computer (PCM) to lean down
BUT There is no CEL code NON we try like 50 times NO CEL CODE's

 

[nmcgrawj]

hmm i have no idea. But maybe a vaccum tool to check the vacuum acurately would tell you something.

OR i know there a guys on here with Tweecers. Would something like that with the controls and options you have be able to see and change something?

Since it seems like the computer is causing it, then wouldnlt the tweecer overwrite the computer or whatever signals are coming into it to make it run lean?

anyway, i hope you figure it out but you might want to ask tweecer guys if they eliminated a lean condition by using a tweer or a similar tuner

 

[Slow5.0]

What If I get some air without MAF measuring , one hour ago I try pull CAI from TB little bit it run same without check engine , but when I move whole CAI from TB idle dropes down and CEL come on and set 136 and one more code about "self adjusting"

 

[nmcgrawj]

that wont work & im not sure what that will solve. The maf measures how much air is coming in, unhooking it wont allow it to do that. SO the engine thinks its not getting any air when its getting a lot. That will still give a bad mixture and from my experience the car wont run worth a dayum.

I still think your next move should be talking with some tweecer guys. Maybe someone experience with it will chime in here soon.