Cel p0171
10-13-2011 | 02:22 PM
#26
Thread Starter
Shinka
Joined: Sep 2011
Posts: 123
Likes: 0
From: Virginia Beach
Apart from the coils having no white burn - they were tested via an OHM reader.
Though, I'm going to consider your method...
I'm thinking this could be a bad ECU. The car isn't searching for idle so I ruled out the transmission knock sensor.
Though, I'm going to consider your method...
I'm thinking this could be a bad ECU. The car isn't searching for idle so I ruled out the transmission knock sensor.
06-25-2012 | 03:36 PM
#29
Registered User
Joined: Dec 2011
Posts: 31
Likes: 0
From: Reno, NV
You still have a vacuum leak. The code and symptoms point to it.
I had a vacuum leak for over a year. A very slight one, and only affecting the rear rotor (rear intake tract seal from UIM to LIM), so I didn't have any manifested problems, and using vacuum leak test methods kept showing it to be solid. But it showed on the logged engine data, and once that was pointed out to me, I pulled apart the UIM and immediately found it.
With any vacuum leak, essentially the engine is pulling in air that is not passing the MAF, causing the MAF information to be inaccurate. Depending on how big that leak is, and where it's located, it could manifest in several different ways. A small vacuum leak makes a bigger difference at idle than it does higher than idle, because of the % variance that the difference in airflow is. For example, your engine should be pulling about 5.5 g/s of air at warm idle. If you have a 1 g/s vacuum leak, you have a 20% variance. Bring the RPMs to 1,300rpm for a cold idle, and you are closer to a 10 g/s or so, which is only a 10% variance. Difference vacuum leaks could change the relationship as well, so don't take my numbers as hard-fact.
In your case, the cold idle is "overwhelming" the variance, but at warm idle, it's significant enough to be noticeable.
I had a vacuum leak for over a year. A very slight one, and only affecting the rear rotor (rear intake tract seal from UIM to LIM), so I didn't have any manifested problems, and using vacuum leak test methods kept showing it to be solid. But it showed on the logged engine data, and once that was pointed out to me, I pulled apart the UIM and immediately found it.
With any vacuum leak, essentially the engine is pulling in air that is not passing the MAF, causing the MAF information to be inaccurate. Depending on how big that leak is, and where it's located, it could manifest in several different ways. A small vacuum leak makes a bigger difference at idle than it does higher than idle, because of the % variance that the difference in airflow is. For example, your engine should be pulling about 5.5 g/s of air at warm idle. If you have a 1 g/s vacuum leak, you have a 20% variance. Bring the RPMs to 1,300rpm for a cold idle, and you are closer to a 10 g/s or so, which is only a 10% variance. Difference vacuum leaks could change the relationship as well, so don't take my numbers as hard-fact.
In your case, the cold idle is "overwhelming" the variance, but at warm idle, it's significant enough to be noticeable.
06-25-2012 | 03:42 PM
#30
If you can get at the live data to see what it's doing, we can know for certain. Your description really isn't enough to go on. There are many reasons for rough idle, with the most common is failing ignition.
06-25-2012 | 03:50 PM
#31
Registered User
Joined: Dec 2011
Posts: 31
Likes: 0
From: Reno, NV
well unfortunately I have changed all plugs, wires and coils. I havent had the extra cash lately to take it in and get it tested due to wedding costs so unfortunately I have no live data. All I can go off of is what I have observed. I have checked all visible hoses and all seem to check out. I am going to take apart the UIM this afternoon. Any specific things I should be looking for?
06-25-2012 | 03:59 PM
#32
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Joined: Dec 2011
Posts: 31
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From: Reno, NV
This is my most recent description of the problems I have been having. Not sure if it will help any
06-25-2012 | 08:02 PM
#33
Your description in that thread does sound much like a vacuum leak. Where are you located? Getting the live data is usually easiest through an ODB2 tool, and most shops or dealers will give you trouble if you just ask for some of that. However, lots of us have them, and you can get one that reads the live data for about $40 or so.
06-25-2012 | 08:29 PM
#34
Thread Starter
Shinka
Joined: Sep 2011
Posts: 123
Likes: 0
From: Virginia Beach
Oddly enough, my leak came from my airbox.. Wasn't a tight seal, I had changed my intake and everything cleared up.
Where are you located? Find a rotorhead and learn from them for a day, has helped me tons.
Where are you located? Find a rotorhead and learn from them for a day, has helped me tons.
06-26-2012 | 04:55 PM
#35
Registered User
Joined: Dec 2011
Posts: 31
Likes: 0
From: Reno, NV
Your description in that thread does sound much like a vacuum leak. Where are you located? Getting the live data is usually easiest through an ODB2 tool, and most shops or dealers will give you trouble if you just ask for some of that. However, lots of us have them, and you can get one that reads the live data for about $40 or so.
07-05-2012 | 11:02 AM
#36
Registered
Joined: Apr 2010
Posts: 156
Likes: 0
From: newfoundland
I recently installed the turbox exhaust with race pipeand now I am throwing the infamous 0171 code and when I hear lean it scares the **** out of me. I check for vacuum leaks and I found the plastic nipple is cracked off from where the vfad iow i have a aem cold air intake, didn't know want to cover it with so used some thick duck tape for now but it Is still throwing the code . Any help
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