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Greg, Technician
Category: Car
Satisfied Customers: 7055
Experience:  17 years Shop Owner /Technician. 27 years experience,
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Hi there ...did the compression come out the same ,on all the

This answer was rated:

Hi there ...did the compression come out the same ,on all the cylinders. Yes the compression come out the same ,on all the cylinders.

Is the misfiring always there ?
No the misfiring is not always there.

I would take the valve cover off and check for the valve springs , make sure they are not broken.
I have take the valve cover off and check for the valve springs and they are not broken.

Also when you took the compression ,did you have all the spark plugs out ?
Yes I take all the spark plugs out and the compression is ok.

just want to make sure that the head gasket is not burn between cylinder 1 and 2.
There is no gasket burning between cylinder 1 and 2.

Best regarts Guðni
Thank you.
Hi Guðni.

What problem are you having .

Is there any malfunction codes .

Rgds Greg
Customer: replied 3 years ago.

Hi I have this code P0172


Kindest regards



Hi Guðni.

Do you notice any drivability problems, for this code you may not feel any problems .

This means that an oxygen sensor in bank 1 detected a rich condition.

P0172 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty.
There could be a vacuum leak after the MAF sensor
There could be a fuel pressure or delivery problem, bad injectors, low fuel pressure .
Bad O2 sensor .

Check these issue then get back to me if needed.

My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back with the reply box below and not the poor or bad service button ,

For further assistance there is no extra charge after accepting.

Rgds Greg

notice any drivability problems

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Customer: replied 3 years ago.

Hi Greg, thank you for your response.


There is no MAF sensor in this car and the O2 sensor is all right.

And we checked the catalytic converter and he's all right as well.

We mesured the fuel pressure and it's 12 bars, but somtimes it went down to 3 bars, is that normal ?


The outgoing pollution in idel was 1,21 co and in higher rmb he was 1,7 co.

Best regards,

Hi Guðni.

The fuel pressure drop is what is causing this P0172 code . fuel pressure regulator is probably the problem .or a faulty fuel pump .

Give me the make model and engine size so i can check what your fuel pressure should be .

Customer: replied 3 years ago.

The car model is 2001 Dodge Caravan Sport. Engine size is 3.8.



Best Regards,


Hi Guðni.

Fuel pressure regulator maintains fuel system pressure at about 53-63 psi (365-434 kPa).
if the pressure drops and does not stay with in the specs then test the fuel the fuel pump
as this model has the fuel pump regulator mounted on the fuel pump.

Replace fuel pump Guðni then you will be good to go.

Need further assistance then please get back to me .

Rgds Greg
Customer: replied 3 years ago.

Hi Greg.


We finally changed the fuel pump regulator and we still have the same problem.


Do you have any more ideas ?


Recheck for malfunction codes will like to know if you have any misfire codes .

Customer: replied 3 years ago.


No there are no codes (but the car is lacking a spark/or one cylender).


We measured the car with this computer :

Name: INNOVA 3160

And the resaults was:

Calc load (%) 6.3

ECT (%) 92

STFT B1 (%) - 25

LTFT B1 (%) - 25

MAP (kpa) 34

Eng RPM 788

Veh speed (km/H) 0

Spark Adr(*) 13.5 - 17

TPS (%) 14.5

O2S B1 S1(v) 0.235 - 0.920

STFT B1 S1 (%) -25.0

O2S B1 S2 0.765

STFT B1 S2 99.2

MIL DIS (km) 0


This resault was from another computer:

CO 1.21 to high


The cooling wift is always running.


The problem started when we hit the brakes, or stopped very suddenly.




TPS looks a bit high

You are also getting a lean command which means you are getting too much fuel .so the fuel is being commanded by the ECM to subtract fuel flow.

High negative fuel trim corrections can be caused by :
MAF sensor problems,
High fuel pressure,
Leaking fuel pressure regulator diaphragm,
Faulty evaporative emissions components,
Leaking injectors,
Defective O2 sensors,
Exhaust leaks/pinholes before the O2 sensor,
Coolant temp sensor problems, and base engine issues such as low compression and incorrect camshaft timing.

Most common issue will be the MAF sensor, high fuel pressure /bad weak injectors .

Rgds Greg