High Fuel Pressure? Leaky Injector? Or something else.

[JohnnyBee323]

Try the PEM first. The definitive way I see to check fuel pressure with a gauge. I don’t like that reading of 7 psi though, I don’t think the car will run at that low pressure?

I replaced the MAF sensor. Seems to be running a bit better, but think I need to drive it for a bit to either reprogram the computer or wait for the code to come back. I am thinking the faulty MAF may have lead to the low fuel pressure. However I do have a fuel pump coming in the mail. The car has over 200k miles, and hasn't had the fuel pump done since at least before 65K. Where is the PEM located on a 04 S60 2.5L Turbo? It is not in the trunk like some other models. Is it accessible, or do I need to drop the tank?

[vtl]

I replaced the MAF sensor. Seems to be running a bit better, but think I need to drive it for a bit to either reprogram the computer or wait for the code to come back. I am thinking the faulty MAF may have lead to the low fuel pressure.

Continue monitoring STFT and LTFT.

However I do have a fuel pump coming in the mail. The car has over 200k miles, and hasn't had the fuel pump done since at least before 65K. Where is the PEM located on a 04 S60 2.5L Turbo? It is not in the trunk like some other models. Is it accessible, or do I need to drop the tank?

Originally PEM was located near the fuel filter. It feels bad being there, Volvo even released a PEM relocation TSB.

Fuel pump dies when duty cycle reaches 55-60+ %. New pump should read about 35%. Mine is 45% in summer and 50% in winter, at 248k miles.

I would also replace at least the front H2OS. They work for 10-12 years and get "dull".

[JohnnyBee323]

I replaced the MAF sensor. Seems to be running a bit better, but think I need to drive it for a bit to either reprogram the computer or wait for the code to come back. I am thinking the faulty MAF may have lead to the low fuel pressure.

Continue monitoring STFT and LTFT.

However I do have a fuel pump coming in the mail. The car has over 200k miles, and hasn't had the fuel pump done since at least before 65K. Where is the PEM located on a 04 S60 2.5L Turbo? It is not in the trunk like some other models. Is it accessible, or do I need to drop the tank?

Originally PEM was located near the fuel filter. It feels bad being there, Volvo even released a PEM relocation TSB.

Fuel pump dies when duty cycle reaches 55-60+ %. New pump should read about 35%. Mine is 45% in summer and 50% in winter, at 248k miles.

I would also replace at least the front H2OS. They work for 10-12 years and get "dull".

Mine is a turbo, and read that 55-60psi is normal for a turbo. That's in the ballpark of where I am according to the scanner. Is that not correct? On cold start ups is when I am having the issues with fuel pressure, but at the moment it seems the new MAF sensor is improving that. Too early to tell.

I replaced the 02 sensors not too long and fixed all the vacuum leaks. Would I get a code for a faulty PEM? I am receiving nothing for a fuel pump.

[vtl]

Mine is a turbo, and read that 55-60psi is normal for a turbo. That's in the ballpark of where I am according to the scanner. Is that not correct? On cold start ups is when I am having the issues with fuel pressure, but at the moment it seems the new MAF sensor is improving that. Too early to tell.

In B5254T2 fuel pressure is 400 KPa, which is 58 PSI. It does not deviate much from this number.

I replaced the 02 sensors not too long and fixed all the vacuum leaks. Would I get a code for a faulty PEM? I am receiving nothing for a fuel pump.

I don't think there's a code for PEM. PEM is like an amplifier with no feedback.

[JohnnyBee323]

Mine is a turbo, and read that 55-60psi is normal for a turbo. That's in the ballpark of where I am according to the scanner. Is that not correct? On cold start ups is when I am having the issues with fuel pressure, but at the moment it seems the new MAF sensor is improving that. Too early to tell.

In B5254T2 fuel pressure is 400 KPa, which is 58 PSI. It does not deviate much from this number.

I replaced the 02 sensors not too long and fixed all the vacuum leaks. Would I get a code for a faulty PEM? I am receiving nothing for a fuel pump.

I don't think there's a code for PEM. PEM is like an amplifier with no feedback.

Right. It consistently stays at about 400 KPA. Seems to oscillate a little bit between 399-402. Not much more than that.

But if the fuel pressure is as low as 7 psi at the rail on startup, would that indicate a weak pump in your opinion or a PEM? Especially if the FRP is consistently at 400~ KPA while running?

[vtl]

Right. It consistently stays at about 400 KPA. Seems to oscillate a little bit between 399-402. Not much more than that.

But if the fuel pressure is as low as 7 psi at the rail on startup, would that indicate a weak pump in your opinion or a PEM? Especially if the FRP is consistently at 400~ KPA while running?

Let the key stay in position II for a second before cranking the engine. Those late fuel systems with no return line have some sort of a morning pressure buildup lag.

[abscate]

There is a spec of fuel pressure 20 minutes after shutdown, but no spec on cold start up, so It could bleed to zero.

In the XC90 forum, there is a detailed link to PEM waveforms by user shockwave who diagnosed a nasty fuel problem from a kinked line.

The MAF is completely independent from fuel pressure.

[JohnnyBee323]

Right. It consistently stays at about 400 KPA. Seems to oscillate a little bit between 399-402. Not much more than that.

But if the fuel pressure is as low as 7 psi at the rail on startup, would that indicate a weak pump in your opinion or a PEM? Especially if the FRP is consistently at 400~ KPA while running?

Let the key stay in position II for a second before cranking the engine. Those late fuel systems with no return line have some sort of a morning pressure buildup lag.

I have tried leaving the key in the II position thinking it would help, but nothing as of yet. Why would the engine surge up and down for about a minute straight on a hot day when starting up the engine? This is the same problem I am attempting to describe, but much worse it seems on hotter days.

[vtl]

I have tried leaving the key in the II position thinking it would help, but nothing as of yet. Why would the engine surge up and down for about a minute straight on a hot day when starting up the engine? This is the same problem I am attempting to describe, but much worse it seems on hotter days.

How old are the spark plugs? Are they Volvo original (our turbo often dislikes aftermarket spark plugs)? Tightened to the spec? Coil packs sit tight and torqued to the spec, ground contacts are clean on both the valve cover and the pack?

People often/usually miss that coil pack high-voltage ground contact and fight for ever with misfires, bad sparks and prematurely dying coil packs.

[JohnnyBee323]

I have tried leaving the key in the II position thinking it would help, but nothing as of yet. Why would the engine surge up and down for about a minute straight on a hot day when starting up the engine? This is the same problem I am attempting to describe, but much worse it seems on hotter days.

How old are the spark plugs? Are they Volvo original (our turbo often dislikes aftermarket spark plugs)? Tightened to the spec? Coil packs sit tight and torqued to the spec, ground contacts are clean on both the valve cover and the pack?

People often/usually miss that coil pack high-voltage ground contact and fight for ever with misfires, bad sparks and prematurely dying coil packs.

I purchased the car about 10,000 miles ago. The previous owner, a friend that didn't take care of the car, said he installed cheap aftermarket spark plugs in the car shortly before I bought it from him. How would your turbo behave with aftermarket spark plugs?