[Welcome to NBA Jam]

An odd thing happened two days ago. We had single-digit weather, and my car was outside for a large majority of it. Upon starting it, I noticed that the idle was bouncing from 1000 RPM to close to 400. As I drove, power felt intermittent, and each time I put my foot on the clutch, the revs would drop to 400, rev up to 600-800, and repeat.

After 3 duty cycles, the SES came on:

Code:
P112F

Description:
Throttle-valve angle - intake-manifold pressure, correlation: Limit value exceeded

People-friendly description:
The fault is recognized when the relationship between the indicated intake manifold pressure and the mass airflow calculated based on throttle-valve angle is not correct.

The next day, temperatures went up to a Florida-like 26 degrees. When I started the car, it idled and drove as if nothing was wrong. The temperature has been slowly climbing, and the symptoms have not come back since.

Common fixes:

• Check intake system and crankcase for leakage
• Check throttle valve (contamination, carbon deposits, icing)
• Check plug and wiring harness between intake manifold pressure sensor and DME
• Check plug, wiring harness at electric throttle valve actuator
• Replace pressure sensor
• Replace throttle valve

Two things have been done in the recent past (~3 weeks ago):

1. VANOS Recall
2. Oil change

The two possibilities I am thinking are:

1. Since it only occurred during extremely cold weather, icing causing the throttle valve to stick is very plausible

2. The VANOS recall involves removing the valve cover, meaning things like the intake and crankcase vent connections are removed. I noticed that the left-side rubber intake boot was ever-o-slightly not flush. I corrected this, but it did not seem to make any air leaks. Note that this is an aFe sealed intake, and not stock.

I did not see anything awry on the valve cover, albeit there were oil stains coming from the oil cap. They did not look fresh, so I am guessing that it occurred during the oil change. Maybe someone spilled something and did not notice it. The cap does not appear to be leaking, but I will clean it and check later. I did not have any leaks in this area prior to having the recall and oil change done.

I'm hesitant to take it to the dealer for reasons of them saying something like it's unrelated to the VANOS recall, and then charging me a diagnostic fee...though, I am under CPO I'm more likely to believe it has to do with the cold weather and icing.

What are your thoughts on this, before I ask the dealer to look at it in case they made a mistake?

[nynyny]

I'd be interested to see what you find out. When this happened to me, I was told it was a tuner code and nothing to be concerned about... not exactly a plethora of information available about it though.

Are you tuned or modded at all?

[Welcome to NBA Jam]

Originally Posted by nynyny

I'd be interested to see what you find out. When this happened to me, I was told it was a tuner code and nothing to be concerned about... not exactly a plethora of information available about it though.

Are you tuned or modded at all?

Yeah, that's the same information that I read as well. No tunes, only mod is an aFe Magnum Force Si intake.

Really the only thing I care about is, am I going to get an SES every time it gets down to single digits? I've got a bluetooth scanner to reset it, but I would definitely like to know the exact cause.

[Welcome to NBA Jam]

The code went away on its own today, which is unsurprising since the symptoms are gone.

[JETmn]

Do you have an intake or is it stock airbox? Boost leak check would be the first thing. Symptoms show up more when it is cold out.

[icenight]

Originally Posted by Welcome to NBA Jam

An odd thing happened two days ago. We had single-digit weather, and my car was outside for a large majority of it. Upon starting it, I noticed that the idle was bouncing from 1000 RPM to close to 400. As I drove, power felt intermittent, and each time I put my foot on the clutch, the revs would drop to 400, rev up to 600-800, and repeat.

After 3 duty cycles, the SES came on:

Code:
P112F

Description:
Throttle-valve angle - intake-manifold pressure, correlation: Limit value exceeded

People-friendly description:
The fault is recognized when the relationship between the indicated intake manifold pressure and the mass airflow calculated based on throttle-valve angle is not correct.

The next day, temperatures went up to a Florida-like 26 degrees. When I started the car, it idled and drove as if nothing was wrong. The temperature has been slowly climbing, and the symptoms have not come back since.

Common fixes:

• Check intake system and crankcase for leakage
• Check throttle valve (contamination, carbon deposits, icing)
• Check plug and wiring harness between intake manifold pressure sensor and DME
• Check plug, wiring harness at electric throttle valve actuator
• Replace pressure sensor
• Replace throttle valve

Two things have been done in the recent past (~3 weeks ago):

1. VANOS Recall
2. Oil change

The two possibilities I am thinking are:

1. Since it only occurred during extremely cold weather, icing causing the throttle valve to stick is very plausible

2. The VANOS recall involves removing the valve cover, meaning things like the intake and crankcase vent connections are removed. I noticed that the left-side rubber intake boot was ever-o-slightly not flush. I corrected this, but it did not seem to make any air leaks. Note that this is an aFe sealed intake, and not stock.

I did not see anything awry on the valve cover, albeit there were oil stains coming from the oil cap. They did not look fresh, so I am guessing that it occurred during the oil change. Maybe someone spilled something and did not notice it. The cap does not appear to be leaking, but I will clean it and check later. I did not have any leaks in this area prior to having the recall and oil change done.

I'm hesitant to take it to the dealer for reasons of them saying something like it's unrelated to the VANOS recall, and then charging me a diagnostic fee...though, I am under CPO I'm more likely to believe it has to do with the cold weather and icing.

What are your thoughts on this, before I ask the dealer to look at it in case they made a mistake?

I had this happen to me the past few days when I start my car. Haven't had any codes thrown or noticed anything while driving. My cars stock. I just figured it was the cold weather, although not single digits. It has gotten into low teens.

[Welcome to NBA Jam]

Grr. Came up again. Whenever it gets below freezing, I'll get these symptoms + a CEL. I am under CPO warranty and am tempted to bring it in. I'll hear the engine knocking for a bit in the morning, then about 10 seconds later it'll rev to about 1.2k and settle down.

My best guess is that the throttle plate is sticking, even though it doesn't actively use the throttle plate beyond warmup. I'm going to first try cleaning it, and if that doesn't work, I'll bring it on in.

[JETmn]

When it is below zero mine has been cranking 6-8 times before it finally fires up. I put straight gas in it last night and forgot to pay attention this morning to see if it started up faster without E30 in it. My idle has been pretty solid though and no CEL.

[Welcome to NBA Jam]

One other thought before I take things apart this weekend:

I completely forgot that the charge pipe goes directly into the throttle body

Cold weather = plastic shrinks = small cracks widen. Charge pipes cracking at the neck is common on both the N54 and N55. It is also plausible that the charge pipe has a small crack near the neck that opens when it's sufficiently cold, allowing air to escape. This could account for the mass air pressure measured by the MAP sensor in the intake manifold to differ from the mass air pressure measured by the angle of the throttle body, which is at a slight angle on warmup.

This would also help explain the engine running normally after warmup, since the plastic will expand and close the gap again.

[JETmn]

Metal contracts more than plastic does, so that would not be the issue. Air is more dense though, so if you have a boost leak at all it will cause more of an issue in the cold than the warm. If you did have a crack in the charge pipe it would cause a bigger issue now than when it is warmer.

[Sidewinderpb]

Mine had the same issues last winter, and would even die on every cold start.

I've returned to stock for this winter (with the exception of the JB4) and haven't been having the issues. Do you have a catless downpipe by any chance?

[Dark_Knight_335]

Originally Posted by Welcome to NBA Jam

One other thought before I take things apart this weekend:

I completely forgot that the charge pipe goes directly into the throttle body

Cold weather = plastic shrinks = small cracks widen. Charge pipes cracking at the neck is common on both the N54 and N55. It is also plausible that the charge pipe has a small crack near the neck that opens when it's sufficiently cold, allowing air to escape. This could account for the mass air pressure measured by the MAP sensor in the intake manifold to differ from the mass air pressure measured by the angle of the throttle body, which is at a slight angle on warmup.

This would also help explain the engine running normally after warmup, since the plastic will expand and close the gap again.

Oh wow...I'm getting the oscillating idle in the really cold weather...wondering if it's cause for concern.

[JETmn]

Running straight pump gas I no longer have the long cranks on startup. I am really leaning towards getting an AP to stack with my JB4.

[JETmn]

It was -21*F this morning and the car took about 10 cranks to start. No way it would have started on E30. I am glad I switched!

[N54S63tu]

any fix for this issue, have same exact code 28a0 ( P112F )

so far changed, valve cover, maf, map sensor

[Welcome to NBA Jam]

Originally Posted by N54S63tu

any fix for this issue, have same exact code 28a0 ( P112F )

so far changed, valve cover, maf, map sensor

Ended up being the intake. Went back to stock and it fixed the issue immediately.