Will a boost leak cause this code? I plan on pressure testing the system, but just thinking out loud. Or should I just clean my throttle body. This is starting to pissmeoff...

 

http://www.obd-codes.com/forums/viewtopic.php?t=2098

http://www.obd-codes.com/forums/viewtopic.php?t=2067

http://www.obd-codes.com/forums/viewtopic.php?t=2034

 

Ok so the Causes are:

1) MAF: Dirty or Faulty
2) Vac leak
3) Fuel Pressure or Delivery problem

Somebody help me figure this thing out here...

I plan on:

1) Cleaning the MAF and Air Filter
2) Clean fuel injectors
3) Clean plugs (they are 500 miles old)
4) I don't have a FP guage to see if the FPR is bad
5) Inspect fuel lines (it does'nt smell rich)
6) Intake Gasket leak??? (Is this at the throttle body?) If so, I think this is the cause of my problem....
7) Inspect/replace all VAC and PVC hoses (a quick list of the not so obvious would be great)
8) Check for Exhaust leak < 1st o2 sensor (so that's exhaust manifold to the o2 housing)???
9) EGR valve gasket leak (f84K me)

Help. Noobs, stay away, I'm fired up...

Thanks.

 

Can it be an "air volume" problem, where the MAF can't measure the volume of air it is seeing (I have a snorkle running from the brake duct to direct more air at my "open element" air intake.

The MAF is a piece of shi#...

Somebody...

 

Quote:

Originally Posted by 4-BNGR

Can it be an "air volume" problem, where the MAF can't measure the volume of air it is seeing (I have a snorkle running from the brake duct to direct more air at my "open element" air intake. ..

So, if I'm understanding what you're saying, 4-BNGR, the extra cold air from your snorkle is upsetting your MAF, or are you telling us that in your case the MAF has no problem reading the extra air? If indeed there is a problem with the MAF coping with the extra air, how did you deal with it.

BTW, I think I'll try your setup. What diameter of hose did you use for the snorkle, 5"?

 

I can't confirm the cause of my PO172 that's why I'm posting like a mad man. It could be so many friggin things...

As to the "volume" question. It is my hypothesis that if the MAF is "reading" too much air volume (more than allowed by computer parameters) then it will throw the PO172 cel. I've been using "dryer hose." I noticed that prior to cleaning my MAF, I never had the PO172. After cleaning, I have (should've left it dirty). The reason for the cleaning was that I blew a hose off at the throttle body - fouled the crap out of my plugs, and did the whole clean/change thereafter. Now with the MAF being clean, I think it's seeing too much "volume" of air with my "dryer hose" mod.

So, if this is causing my CEL (PO172), logically I would suggest you do not do this mod. Why did I do it? Because I'm a BMW/Euro tuner guy - where this mod is a great power maker on Euros...

There's also the possibility that the Intake Air Temp sensor has failed - IDK?
Ultimately, it is my understanding that the MAF can't cope with measing the extra vloume of air...

Back to topic at hand, anyone have any thoughts as to the "cause" of my CEL?

 

Do you work for the govt or something?

Thats a whole afternoon of work, try the most likely and easiest first:

1. Hook a wideband up to it to see if it's rich for sure, if you dont have access to one then do a log and check the IPW vs airflow to get an idear. If rich, then..
2. Pressurize your charge system with your boost leak tester, I know you have one since you've driven an Evo for over 100,000 miles.
3. If not really rich thencould be something else

Intake gasket is on the head, If you pressurize that part of the system you can find leaks there as well as vacume leaks, 10 psi is enough

Oh, an exhaust leak will make it lean at idle , not rich

 

Did you get tuned with a dirty MAF?

If so then that might be the problem - if the maf was dirty (reads less air than actual) the car would go leaner and the tuner would richen the fuel, now the maf is clean the computer will see more airflow and likewise more fuel - rich

 

I thought the p0172 code, was for one of the three.

1) O2 sensor
2) Mas
3) fuel pressuer sensor or something with the fuel sensor.


correct me if im wrong

 

I wish I worked for the Gov. Cush job, great pay, and great benefits...

I will do the boost leak. I hope that resolves the issue. But back to my question - if the MAF is seeing too much air "volume" will this cause the CEL?

Nope, not tuned with Dirty MAF...

Asta-

PO172 is for 1) MAF 2) Vac leak 3) FP or fuel delivery problem.

 

Found this? Toyota...

"As more air comes in, the wire which is heated to around 200 degrees Centigrade, is cooled by the passing air (and resistance lowered). As a result, the computer sends even more current through the wire to keep it heated such that the wire's resistance is kept equal to a reference resistance value. By knowing the amount of current required to keep the hot wire equal to the reference resistance value, the ECU indirectly knows the volume of incoming air. There is also a thermistor in the MAF sensor so the ECU knows the temperature of the incoming air and takes that into account."


I need a friggin Scotch

 

Will too much air volume cause the MAF to throw a PO172 cel?

From K&N

"While rare, there have been cases in which a K&N product has caused a CEL to go on because the product is allowing so much more airflow into the engine than normally expected. The extra airflow is a very good thing, but the computer warning is intended to check for leaks in the air path to the engine. Well in these cases it is K&N and not a leak that is causing the increase in airflow, so the light simply needs to be reset. A car could run with a K&N product for a long time with no CEL and then one day it happens. Combinations of factors can suddenly cause airflow to rise above the limit resulting in a CEL light. An example would be when there is a variation in normal driving conditions such as a vehicle that is under heavy acceleration, going up a hill, on a cold day. All three factors would tend to increase airflow. Once again we would stress an occurrence such as this would be rare indeed and would not be indicative of an actual problem, just high airflow."


This is a poor resolution. The ECU will dump fuel to compensate for the increased air and as a result foul the plugs. K&N = deouch bags.

 

You're still on stock injectors?

 

Ask the guys on www.obd-codes.com. they are pretty knowledgeable over there....thats where I went for help when I had my p0172 code

 

I'll give it a shot... Thanks.