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Enes
Enes, VOLVO Master Technician
Category: Volvo
Satisfied Customers: 4973
Experience:  15+YEARS WITH VOLVO AS THE MASTER VOLVO MECHANIC&Ase
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volvo v40 1.8 gdi Hi. Have a 2002 v40 1834cc gdi. Has recently

Customer Question

Hi. Have a 2002 v40 1834cc gdi. Has recently had a new head gasket and de coke. Since it has been rebuilt, the engine runs well from cold until it gets to normal operating temperature, upon which the engine idle goes up and down all over the place until eventually it stalls. I have an error code coming from the fuel rail pressure sensor. Every time it is cleared it re appears. Is it a common fault for this sensor to malfunction? Or is it perhaps indicating a problem with the high pressure fuel pump? Both sensor and pump cost a mint, so would appreciate it if this could possibly be something simple !!
Submitted: 4 years ago.
Category: Volvo
Expert:  Enes replied 4 years ago.

ENES :

hi

ENES :

are you online

ENES :

send me the error codes so from scanner what you have

ENES :

soi can look the code info

ENES :

also tell me will the car stall if hold gas pedal >?

Customer :

Hello. I cannot give you the exact error code as it was a friend who plugged it in. The car doesn't stall when it's cold it revs up great and idle's well to. It is a strange fault, when it is warm the idle fluctuates from 950 rpm to around 2000 rpm. If you try to rev the engine sometimes it will stutter at first then suddnl jump up to around 4000 rpm. Other times it just dies as soon as you press the pedal. The engine can also stall itself while the revs are going up and down to. Might be a good thing to tell you that it appears to be using lots of petrol to. I have cleaned out the throttle body to. I am suspicous of a gasket spacer plate that fits behind the fuel pump. I noticed it had a small offset hole on there but when I refit the pump I'm unsure whether I have fitted it the right way around. At a quick glance it didn't seem to serve any purpose. Maybe I was wrong. I will be checking this soon.

Customer :

It just seems strange that before the gasket and decoke it run ok, and now it keeps bringing back this fuel rail sensor fault.

Customer :

The egr valve was completely blocked before the decoke to

Customer :

If the wiring plug was removed from this sensor would it simulate these symptoms? Perhaps I have a bad connection.

ENES :

with no error code i dont know what to tell you

ENES :

i will exit maybe other techs know

Customer :

Ok, I understand the code is needed to make an accurate determination. I know there are circuit malfunction/ low pressure/high pressure codes etc etc. Can you answer this for me. On the fuel pump, which is a mechanical pump driven from the camshaft on this, high pressure I believe because it's direct fuel injection.There is a black plastic shaped spacer/gasket behind it or in front of it?? I cannot remember which way or which side round this thing was. Even a Haynes manual doesn't give me a detailled diagram of how to put it back. It has one anyway and seeing as the rest of the joints on this are gasketless face joints I'm thinking have I put it together wrong. What do you think??

Customer :

Usually, I am usually quite good at taking things to bits, but I'm suspicous about this pump. I guess I just have a hunch. Was it a gasket or an outer cover. If I have spaced the pump away from the head it may cause the error at the sensor as a result of an incorrect function of the pump.

ENES :

i send you request to other expert

ENES :

i dont know the answer im sorry

Customer :

Me neither. I have had this car for three weeks now trying to get it to run right. The original problem it had was the head gasket was leaking lots of oil. That is now fixed. Upon dismantling it it became obvious that it had lots of carbon build up in the egr valve and inlet manifold. I have removed the inlet manifold again and am going to clean that out as it is the only component yet to be cleaned. It seems to me that as it only plays up when the engine is warm says an air leak or a faulty egr valve or something else leaking or blocked on an engine breather pipe or something similar. I am not convinced that the fuel supply is at fault now. I'll keep an open mind anyway, and if it still plays up when I rebuild it again I will get it on a scanner again and make note of the exact codes. Watch this space because you may still give me the answer I'm looking for.

Customer :

This engine I believe is meant to run on high octane 100ron fuel. Our unleaded fuel here is 95ron and I also suspect this is half the problem with this car. Super unleaded (97ron) costs much more and I think the owner has been running it on the cheaper 95ron stuff, resulting in the carbon build up.

Customer :

ok......I cleaned out the inlet manifold as best I could. I found that there was a slight air leak where the egr valve bolts to the inlet manifold underneath. I replaced the gasket and sealed it with hylomar blue as well. The running problem appears to have gone now. Would this air leak have caused the problem I described above?

Customer: replied 4 years ago.
Turns out I had an air leak after all. All I want to ask is would this cause engine idle to go up and down, as though the ecu was fighting to keep it running?
Expert:  Enes replied 4 years ago.

let me ask you this did you ever replace the fuel pressure sensor ? if fuel pressure sensor dont work it can give you problem like you have it, so right now to test you need advanced scanner from volvo to read how the fuel pressure works it can be pump or the sensor to test you need to use gauge and scanner but to buy scanner and gauge you better take it to a shop let them test the tools to buy are expensive, low octane fuel can do it you build more carbon but dont give as much problems it would not give you the fuel pressure code try running fault codes check again with scanner and test fuel pressssure and rest pressure .

BUT IF YOU HAVE AIR LEAK OR VACUUM LEAK THAT NEEDS TO BE FIXED AIR LEAK OR VACUUM CAN EFFECT MANY PARTS AND HOW CAR RUNS ALSOI WOULD CHECK FOR ANY AIR LEAKS FIX THAT AND SEE HOW IT GOES .

Enes, VOLVO Master Technician
Category: Volvo
Satisfied Customers: 4973
Experience: 15+YEARS WITH VOLVO AS THE MASTER VOLVO MECHANIC&Ase
Enes and other Volvo Specialists are ready to help you
Customer: replied 4 years ago.
I didn't replace the sensor no. It will be connected to a scanner again, and I will make note of the exact codes. I am satisfied with your answer to my question. I am wondering about that sensor still because the head went away to be skimmed before I rebuilt it. the sensor wasn't removed from the cylinder head and I am wondering whether it may have been damaged in the process. It needs to be plugged in again anyway to reset the check engine light.
Expert:  Enes replied 4 years ago.

i would try this cancel the fault see if comes back if comes back the sensor do go bad more than fuel pumps but you need to check with gauge and scanner what reads wrong either can be wrong fuel pressure from pump or bad sensor what again controls pump output .to reset check engine light you need scanner to reset it only

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Enes
Enes
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