V9X surging and powerloss fault P0488

[matthewe2108]

Hi everyone,

Just chasing abit of help regarding an issues with my STX 550 V9X motor, this car by no means is standard, few days ago I got the fault P0488, I have had this fault a few times over the years and usually is a sticky EGR valve, so I though enough is enough and got a reflash so EGR is turned off. Power is great BUT! When the car is cold it sounds like the EGR is stuck open and the car sounds like it's gained a few cylinders BUT I have the blanking plate in the EGR circuit, so there is no possibility that it is recirculation. Also when driving it feels like it's in some sort of limp mode as It takes me nearly 100% throttle to get up to 100kmph. If I stab the throttle it makes good power and makes boost to 255kpa so there is no boost leaks nore is there any more fault codes coming up, I have checked my Map sensor and appears ok, Also cleaned my MAF sensor aswell.
This powerloss limp mode was also happening before the reflash when the EGR fault came up, got me thinking that maybe it's not a sticky EGR and there is another problem, hmmm it's a long shot, I am very mechanically minded and electrician by trade and this has me stumped. I have done obvious things like clean earth terminals and check plug connections etc.. any help would be much appreciated.
Cheers Matt

 

[Hansie]

Hi everyone,

Just chasing abit of help regarding an issues with my STX 550 V9X motor, this car by no means is standard, few days ago I got the fault P0488, I have had this fault a few times over the years and usually is a sticky EGR valve, so I though enough is enough and got a reflash so EGR is turned off. Power is great BUT! When the car is cold it sounds like the EGR is stuck open and the car sounds like it's gained a few cylinders BUT I have the blanking plate in the EGR circuit, so there is no possibility that it is recirculation. Also when driving it feels like it's in some sort of limp mode as It takes me nearly 100% throttle to get up to 100kmph. If I stab the throttle it makes good power and makes boost to 255kpa so there is no boost leaks nore is there any more fault codes coming up, I have checked my Map sensor and appears ok, Also cleaned my MAF sensor aswell.
This powerloss limp mode was also happening before the reflash when the EGR fault came up, got me thinking that maybe it's not a sticky EGR and there is another problem, hmmm it's a long shot, I am very mechanically minded and electrician by trade and this has me stumped. I have done obvious things like clean earth terminals and check plug connections etc.. any help would be much appreciated.
Cheers Matt

Hey Matthewe.

Did you check the turbo boost solenoid yet?
Check vacuum aswell

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[Hansie]

Feedback?

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[matthewe2108]

Hey Matthewe.

Did you check the turbo boost solenoid yet?
Check vacuum aswell

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Solenoid does appear to be working, but making a lot of weird noises and erratic clicking, put a mates boost solenoid in and still no change, but he did also mention that his car is doing a similar thing aswell. So I have ordered a new ones through Nissan regardless and will change it out. We tried bypassing the solenoid altogether, car made full boost and done it extremely quick. Rang Nissan and they told me that it could possibly be a short in the brake circuit wiring. Checked my 7 Pin plug and everything in the rear of my car, also checked brake pedal switch and all working fine. Still scratching my head. Car is still doughy and has lazy pickup and go. But when Flored it seems to go alright. Does anyone know much about these Varriable Vane turbos on these cars?

 

[Old.Tony]

The vanes adjust how much impact the exhaust stream has on the turbine.

This might not be the turbocharger at all. I wonder if it's a faulty EGR valve. At idle and at full throttle the EGR valve will close. At all other times it will be open part of the way. If it's opening too much, two things will happen: the turbo will spool less, because the EGR feed is off the manifold BEFORE the turbocharger, and combustion will be greatly dampened.

Have you considered blocking the EGR? If it's been blocked already, it would be prudent to check the blanking plate - a couple of people have reported failures in their aluminium blanking plates.

 

[matthewe2108]

The vanes adjust how much impact the exhaust stream has on the turbine.

This might not be the turbocharger at all. I wonder if it's a faulty EGR valve. At idle and at full throttle the EGR valve will close. At all other times it will be open part of the way. If it's opening too much, two things will happen: the turbo will spool less, because the EGR feed is off the manifold BEFORE the turbocharger, and combustion will be greatly dampened.

Have you considered blocking the EGR? If it's been blocked already, it would be prudent to check the blanking plate - a couple of people have reported failures in their aluminium blanking plates.

Hi Tony, I drove home last night from work approx 300km burning roughly 19LPH and that was only at 100KMPH, was very worried how rich the car was running, still very doughy and could only manage 5th gear. This morning I got up and checked my EGR blanking plate and it is still intact. EGR valve is still seized. Unplugged the EGR loom as I have it turned off in the computer. Drove the car around town all day and not one issue. Still has me baffled as to what the issue is. I don't think I have seen the end of this dilemma.

 

[nedm1989]

Could there be a short in the EGR solenoid?

 

[matthewe2108]

Could there be a short in the EGR solenoid?

possibly, I did plug it back in today after a service and car still drove fine. ah well I will just have to wait and see if it plays up again.

 

[S.Mack]

smae issues

Hey matthewe2108,

Any updates on your issue? I have exactly the same symptom's on mine and have been trying to systematically nail it down, no luck yet.

Cheers,

 

[matthewe2108]

Hey matthewe2108,

Any updates on your issue? I have exactly the same symptom's on mine and have been trying to systematically nail it down, no luck yet.

Cheers,

Sorry for late reply, I found once the EGR was deleted in my tune, you have to disconnect the plug to the EGR valve, I’m guessing mine was stuck at 50% open which alters the tune respective to the % of the EGR valve. So even with the EGR turned off it still altered my tune until I disconnect the plug.

Regards Matt