Brief background: CEL light came on. Scanned for codes:
P2017 Self-adaptation of mixture formation to limit value of engine control module (P0170) at idle speed.
P2086 Self-adaptation from the mixture forming (left engine) (P0173)
Other errors (not related to above):
B1439 (Central locking secure time to long. air capacity to high) - Other PSE errors too.
B1217 Rain Sensor
Here's what I've done so far:
- Checked for leaks in vacuum hoses. Found no leaks.
- Replaced MAF sensor with genuine Bosch sensor
- Replaced Air Filter
- Replaced Fuel Filter
- Replaced Transmission connector plug. Trace of oil on the plug. It wasn't leaking on the ground or going up the cable to the control module though.
- Last week, code P200F Right O2-probe before KAT (P0130) came up. So I replaced all four O2 sensors. The error code P200F now gone.
- Erased all codes
- Reset ME Adaptation
- Reset transmission adaptation
- I double checked the status of the transmission connect plug. A very small trace of oil on the plug, but nothing on the pins/wires.
P0170/P0173 keeps coming back. The engine at times seems a little rough, but it's not bad. Maybe I'm being picky. I don't know. I would think the slight roughness is probably caused by whatever is tripping the error codes. I'm getting 25.5-27.5 highway MPG, so it's not eating gas too aggressively.
Other work done to the car (not associated with this problem):
- Replaced the motor mounts
- Replaced the transmission mount
- Replaced the rear flex disc
- Replaced the differential fluid
- Replaced transmission fluid, gaskets, filter
- Front headlamps - Crystal view to remove foggy/yellow finish
- Replaced serpentine belt, idler pulley, tensioner pulley
- All wheel alignment (by dealer)
I spent hours researching the potential causals of this P0170/P0173 issue. I found many potential causals:
• Ignition coils
• Cam and crank sensors
• Oil sensor for leakage contributing to oil intrusion in wiring harness
• Defective fuel pressure regulator
• Leaking camshaft adjuster solenoids
• Crank case vent hose located under the intake manifold. It should be checked for leaks/cracking and also operation of check valve in the hose. The check valve should flow only one way.
• Check fuel pressure and ensure that there are no leaks at the regulator internally or externally
• Make sure there are no vacuum leaks at the intake manifold gaskets or tears in the air supply hose
• Intake air leaks
• Injector defects or carbon build-up,
• Air Flow Sensor defects
• Pressure regulator defects, such as a blown diaphragm
• Fuel tank purge control valve defects or EVAP system leaks
• EGR defects
o EGR pipe clogged?
• Vacuum leaks of any kind.
• Mechanical engine wear, such as, chipped valves or leaking rings.
• Weak fuel pump
• clogged or leaking injectors
The car seems to run fine. No stalling, etc. The only issue is that (perceived) rough idle every now and then.
With the engine off, 0 psi. With the key is position #2, 54 psi (3.7 bars). With the motor running, 60 psi (4.1 bars). After the engine is turned off or position 1 or 0, it quickly goes down to 0 psi. Is this normal?
Btw, I didn't need a special adapter. The connector on the pressure gauge fit nicely on to the test port (schrader valve)
Brandon posted that residual pressure should hold for 30 minutes at 2.5 bars min.
You have pressure leaking somewhere, Leaky injectors would flood the engine and made it hard to start hot. When this is not happening, that means the check valve is bad.
Goes to show how much I don't know. The check valve you are talking about is the one in the fuel pump? Does the entire fuel pump need to be replaced for that? thanks again! The funny thing is that I don't have any problem starting the car, stalling, etc.
I think it is attached to fuel pump, but I don't drive gasoline for years, so loose touch with details. I would call knowledgeable parts supplier and ask or maybe one of professional technicians on the forum will answer.
Hmmm....I found a crack in the vacuum hose connecting the pressure sensor (0115420617) and intake manifold. So, I replaced that hose and the one next to it which connects the check valve (0021408460) and intake manifold.
That seemed to resolve the pressure reading at the fuel rail test port. However, I need to run all the tests listed above.
Test #2 says to disconnect the vacuum hose from the diaphram pressure regulator. Would somebody mind identifying what that diaphram pressure regulator is and where it is located? If I had a part number, I could look it up on EPC and look at the diagram.
You will have to double check with your engine number, but I believe you are like me and have the Pressure Regulator BUILT INTO the Fuel Filter. (One reason why they are on the expensive side...) Here's a pic
For future refererence, or if anyone is following this thread:
After replacing the two vacuum hoses, I'm now getting rpm surges. Never had that before. It is very noticable when braking to stop - especially between 1000-2000 rpms. A 300-700rpm surge kicks in 2-3 times on its way to idle (around 700rpm). The surge is not very noticable at idle. I also notice the rpm needle move just a tad (lets say 100 rpm) when traveling at high rpms on the highway using cruise control. No addiitional codes. Still have P0170 and P0173.
I've read so many posts and articles about similar symptoms, I'm just about sick. Some thoughts:
1) Vacuum hoses. I already inspected all vacuum hoses (except for the electric change over valve hose - see below) and replaced the suspect hoses. I can order and replace every vacuum hose, vacuum connector, and air hose I can find on EPC. About $75 in parts. Does anyone know how to access the vacuum hose from the electric change over valve (A0025401897) to the intake manifold? This hose routes behind the back of the air pump and up a conduit into the intake manifold. I don't see any way to access the intake end of that hose without ripping out lots of hardware - and I'm not sure which hardware to rip out! One thought. The vacuum hoses I replaced all seem to be the bulk generic vacuum hose (1179970982). Autohausaz says that its a 3.5mm (approx 1/8") inner-diameter hose. I used local parts store hose that was only 7/64" ID hose. Should that be a concern? I know it sounds petty (1/64inch difference), but I'm not going to leave any stone unturned. Finally, maybe I can use a hand-held vacuum pump/gauge to check the pressure of the various vaccum lines. Is there a list of the vacuum lines and what pressure each should have?
2) Take off the EGR valve and a) inspect/clean the EGR exhaust line, b) check the EGR valves. This is probably the top action item on my list.
4) Other posts indicate fuel pump and/or fuel filter. The fuel filter was replaced on July 2 with a Mann OEM fuel filter. I don't feel like laying down $200+ for a fuel pump just to see if that fixes the problem. But, the car has 146k miles on it. I've owned it since January (139k miles). The prior service records do not indicate when (or if) the fuel pump was last replaced. I don't think it would be frowned upon to replace it under those conditions. But still, $200+.
5) MAF replaced with original Bosch. I seriously doubt its a bad MAF sensor.
Anyone have any additional thoughts or suggestions? thanks!
If your fuel pressure is still at 0 when resting then your check valve is shot. It is integral to the fuel pump on your car. I looked through your data (and may have missed it) but are you seeing good, constant fuel pressure when you see these idle issues? For reference, here's my thread on one fix for extended crank, not your issue it seems but there is some cheesy goodness in there on how the fuel pump works and some expected pressures at the rail.
Thanks for the response. After I replaced the two vacuum hoses, I didn't seem to have any issues with the fuel pressure at the rail. I saw 58psi with the key is position #2. When the engine turned on, the pressure went to 60psi. After I stopped the engine, I monitored/measured the fuel pressure for 30 minutes. After stopping the engine and removing the key, the pressure was:
I'm thinking that the fixed vacuum hose had an affect on the fuel pressure at the rail. Or is it a red herring?
I haven't monitored the fuel pressure since the surge doesn't seem to happen at idle and I don't think it would be very safe to put a pressure gauge on the fuel test port and drive the car with it on. I did notice that with the car in park or neutral, if I rev the engine to 2500 rpms or so and let off the gas, it doesn't surge on its way down. I also reset the transmission adaptation. no change.
I just went out and checked the fuel pressure at the rail. Key in position #2, 58 psi - steady - no needle movement on the pressure gauge. After I start the engine, the needle moves rapidly between 58 and 62 psi. Is that normal? Should the needle remain steady with the engine running at idle?
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