I am not sure what you have left to prove. So your MAF sensor was off.. big deal.. many of them are. The beauty of a closed loop EFI system is that the computer will make the needed fuel corrections so the motor continues to run efficiently.

Now at WOT you will have a problem as you are which is why you need to take your car to have it dyno tuned with a wideband O2 to monitor the a/f ratio and make the necessary adjustments to your PE table with tunercat or LT1 edit. Problem solved.

 

Yeah but then what happens when my defective MAF gives up and I have to buy a new one that is properly calibrated? so you saying to solve my problem I have to dyno tune and reprogram my PCM and that will fix the engine part that is causing the fuel problem at the same time? What if my MAF is bad and I dyno tune it with that MAF? what if it craps out on me and I replace it with a Good MAF? My expensive Dyno Tune will be out of wack again... meaning more money for dyno tuning again. What if my problem is an electric noise problem? the MAF is soo close to the Ignition Coil its very possible its picking up some electromagnetic interference... What if My Oxygen sensors are bad? Does Dyno tuning will fix my Oxygen sensors?

Man when you said "Problem Solved" my first thought was "this dude is only lying to himself. Anyone can wrap duct tape on a bag radiator hose... did he/she trully fixed the problem?


The only thing I need to do is find and fix my problem.

too many things that I get a headache thinking of the posibilities.


Sorry man. I wanna find the culprit of my problem. I dont want to put a band aid and pretend its fixed. Besides its a pastime for me.. I enjoy investigating this kinda things and if I dont find the problem so what... for me its the journey that counts.



Marvin

 

i guess you could put $200 in a new MAF. You could also try to recalibrate the MAF tables so its closer to the true air flow but thats a lot of work! What i would do and im not sure if it would even get you close but it seems reasonable would be to find the median rpm/gps which you figured and adjust all the values below and above to equal it. You mentioned bad O2 sensors... they are not even used at WOT so they arent an issue and theres no fix besides buying new ones.

 

I will worry about WOT tunning after I fix my problem. Thanks for the suggestion of buying ones. Mine are due for a change and you just reminded me.

Marvin

 

have you logged it with a new MAF on?

i logged mine with a new MAF and none of the readings changed...

 

No I havent. You see thats precisly what I am trying to avoid... buying a new MAF just to find out my problem was something else.. Thanks for the info.

Marvin

 

as am i

thats why i borrowed a friend's MAF ... one thats got like less than 2k miles on it and runs fine in his car.

 

I have good weather today. I am gunna yank the EGR valve out. cleant it and check for leak proof seal. As soon as I get the money I an swapping the O2s . They have 142k miles on them so its time for new ones.. My scanner readings show them doing full swings from like 800mv down to 40mv and then up. also with the Key ON engine OFF they show 450mv. I see nothing wrong with those readings except that they maybe switching slow... I have no way of testing it so I am just gunna swap them with new ones.

I am gunna Idle the car and tap on the MAF as the instructions say..I doubt the MAF is bad yet even though I have weird readings because I read on a post of a Corvette C5 where they had the same problem.. Swap a new MAF and the problem continued... They eventually found a bad ground connection that was driving then crazy and bald

I need to test for electromagnetic interference from the Coil though cause its sitting so close to it...

I am just having fun right now.. I know there is an explanation to the problem.

Has anyone of you guys tried the MAF translator instead of programin the PCM?

Marvin

 

how did they figure it out that it was a bad ground? i'd like to test this theory

 

I have not tried one but all they do is manipulate the output frequency of the MAF so the PCM reads a higher or lower gps.. problem is that it changes the frequencies across the entire range so it will only exaggerate your problem.

 

Thats what I was afraid of.

Today I did another WOT run with the MAF connected and I removed the Plastic tube that connect the MAF to the Airfilter box. I didnt know how good it was till I downloaded the data to my PC.


Here is the difference as tested today.

With the Tube connected my car did 47MPH in 4.5 seconds
With the tube disconnected my car did 69MPH in 4.5 seconds

With the Tube connected I had pingin and Knock retard
With the Tube disconected I had No timing retard at all

Tube connected max airflow @ 5450 rpms = 228grms/sec
Tube Disconected max airflow @ 5325 = 267grms/sec

I still dont think my MAF is the problem. I did all the wiggle and tapping on the MAF tests and there was not glitch..

I didnt cleaned my EGR today cause I dont have the right tool to remove the passenger side nut on the EGR. I need a wrench instead of sockets. I pushed the EGR in again and it doesnt move freely... I can feel carbon deposits braking up when I move it... the engine stalls though so the passages are good.


I will messing with the car... I am thinking now of making my own Cold air Kit. My friend in California owned a corvette and the air filter was huge... roughly three times (if not more) bigger than my LT1 air filter..

What can possibly make the PCM pull gas at low rpms? the car runs just perfect when I disconect the MAF yet the car runs perfect with the MAF connected but only at High RPMs.

I'll keep you posted.

Marvin

 

Here is the post where I got it from:

http://web.camaross.com/forums/showt...f&pagenumber=3

Its the one who said he has workd on a few corvettes..


Marvin

 

Update: Update:

I reconnected my MAF and the BLMs dropped to 108 both and my integrators were swinging around 123. I did the Tapping testing and the readings are solid. I wiggle the wires and no luck.

I do have a theory though:

I noticed my oxygen sensors take about 1 second to go from 40millivolts to about 847 millivolts but then they appear to have a different speed going in the opposite direction. So my theory is that although the 02's do a full swing, they maybe spending more time at one of the ends than the other... therefore making the PCM believe the car is leaning toward too rich or too lean.. I havent figured it out yet. I found some information about oxygen sensors and I am gunna read it tonite... Ideally I will find out what is the expected time for the 02s to swing back and forth and if my 02's are slower and speding more time at one end of the spectrum then I will attempt to figure out if that will cause my computer to read my car as too rich.

Another theory of mine is that its is posible that during speed density mode the computer is reading min/max readings from the oxygen sensors but not the amount of time they spend on each region above and below 14.7 fuel to air ratio, therefore is not affected by an 02 that spends a larger amount of time on the rich side for example.

If my calculations are right my oxygen sensors will quickly drop to low readings but will take a slow up the voltage ramp swing, making the PCM believe the car is getting too much fuel .....


Its a theory but if true that would explain why my Car runs rich when its not.


Marvin

 

Update: Update:

Still chasing this "pig rich with MAF connected" problem. I am reading the Chiltons book and it states that a failure in the Canister purge piping and or valve will make the car run rich/stumble/misfire.

Will check into that.


Marvin

 

What page in the CHILTONS Manual do you see this?
I think this might be my problem in stumbling and running rich on my car.

Is there a fix for this?
The information your giving me is very helpful, at least there is someone taking the time to solve everyones problem.
Thanks