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N52 power delivery/hesitation

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Hi

Its coming up on a year from I bought my e61 530i and while a lot of progress has been made I’m still not 100% happy with the power delivery of the engine. There’s a good amount of power up the rev range and lower down is a lot stronger than it was but there are still noticeable steps at 2500, 3500 and 4500 rpm. Below 2000 rpm can be a bit lacklustre at time as well and there is the occasional hesitation with larger increases in throttle opening.

Ive checked for codes and currently there are none on the dme (got one for the drivers heated mirror and codes for the led repeater light I fitted). In terms of what’s been changed to get it here it is today:

(Genuine BMW parts)

both DISA valves

vanos solenoids 

pcv separator 

map sensor

rocker cover gasket

oil filler cap

valvetronic motor gasket 

sump gasket 

oil filter housing gasket (doubt if it related to this problem)

(non genuine parts)

LuK clutch and flywheel 

intermoto bank 2 post cat lambda sensor 

ngk plugs

castrol edge 0w30 oil

 

Ive also cleaned the vanos filters. One was badly clogged with sludge.


Almost everything I’ve done has made a noticeable improvement to power delivery of the engine. Only the oil filter gasket and pcv separator had no noticeable impact.

 

So the question it where do I look now? Thinking of replacing the vanos filters as they are relatively cheap but open to other suggestions.

 

There’s no wandering idle speed and I reset all adaptations yesterday and noticed  no major changes to the engine running which is a first as any other time I’ve done that it ran extremely badly until it adapted making me think I’m close to as good as I can get.

 

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As a new 530i owner I will be interested to hear thoughts on this.

My low end is decidedly lacking in normal auto but in S / M it pulls much harder, I was wondering about the accelerator position sensor. Is it a pot which could be warn at the lower positions? I don't know but would assume it is a pot which then give a PWM signal to the engine ECU but I don't know, time to do some reading.

 

PS. Of the three that I drove before buying mine this one was the liveliest engine but they were all a bit lacking low down, oddly this one had the highest mileage at just over 150 000 miles.

 

Edit: I forgot to say that the tick over appears to be correct, the needle is rock steady but you can hear a slight fluctuation in the engine note, I assume that the MAF and oxygen sensors are making adjustments to fuelling but is is well within their range so no rough idle or error codes.

 

Edited by Keith_H

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@Keith_H unfortunately I’ve no reference as I broke the first rule of car buying by buying the first one I saw and have been paying the price since. I’ve ticked off almost all the common problems with these engines. It is entirely possible that it’s now as good as it gets. The problem is that I had a drive in a z4 with a 3L m54 engine and the power delivery through the rev range was smoother than my n52 engine. That’s not to say that my engine is lacking power, it brought on the tc light during a rough gear change at about 60mph (was a wet road). It’s just the noticeable steps in power while accelerating through the rev range.

 

If you feel you are missing some low down power and know your way around a spanner here’s what made the biggest improvements to mine:

Vanos filters/non return valves. Cost little to nothing to remove and clean.

Vanos solenoids. Again cost little to nothing to remove and clean but if this shows an improvement I’d budget to change them for genuine ones as cleaning seems to be a temporary fix. Cost about £100 each.

DISA valves. In my case I had codes for both when I scanned with the bmw tools. If these have failed don’t be tempted by cheaper aftermarket ones. They don’t react quick enough so still give codes. Budget £250 for each.

 

 

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3 hours ago, RandomName said:

@Keith_H unfortunately I’ve no reference as I broke the first rule of car buying by buying the first one I saw and have been paying the price since. I’ve ticked off almost all the common problems with these engines. It is entirely possible that it’s now as good as it gets. The problem is that I had a drive in a z4 with a 3L m54 engine and the power delivery through the rev range was smoother than my n52 engine. That’s not to say that my engine is lacking power, it brought on the tc light during a rough gear change at about 60mph (was a wet road). It’s just the noticeable steps in power while accelerating through the rev range.

 

If you feel you are missing some low down power and know your way around a spanner here’s what made the biggest improvements to mine:

Vanos filters/non return valves. Cost little to nothing to remove and clean.

Vanos solenoids. Again cost little to nothing to remove and clean but if this shows an improvement I’d budget to change them for genuine ones as cleaning seems to be a temporary fix. Cost about £100 each.

DISA valves. In my case I had codes for both when I scanned with the bmw tools. If these have failed don’t be tempted by cheaper aftermarket ones. They don’t react quick enough so still give codes. Budget £250 for each.

 

 

Thank you for the order of priority list.

I have a A4 binder full of receipts for work done by the owner before the one I bought it from, seems like it was well pampered at one time. There was a bill for vanos solenoid or solenoids replacement I will have a look see what was done.

I was thinking of pulling the vanos filters and cleaning them so will do that one.

I have a lot of vacuum on the oil filler cap so the CCV probably needs to be done,  I will pull out the big DISA before ordering the CCV, if it is toast I will order both of them and change everything when the manifold is off.

 

When I first got it Carly showed a whole host of codes mostly due to low battery I think but also the oxygen sensors on both banks. I cleared all the codes, the only one to return in five months has been 'rear right fan' (I forget the exact wording) but I am not bothered by that as I sit in the front of the car. :)

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@Keith_H sounds like you got a good one. I’ve had the low battery raft of errors as well. Gives you a bit of a fright the first time.

As for the order of checking parts, I was basing that on cost. Though in saying that cleaning the vanos filters had one of the greatest impacts as well but that was more down to the state one of them was in.

As far as I know the genuine BMW vanos solenoids should be good for about 100k so if they have been changed already then you should be fairly safe.

Like you, my car is round 145k miles mark, but in my case it looks like mine has had basic servicing up until I got it.

As for the ccv, price it with BMW as when I got mine it was only £10 more expensive than the aftermarket equivalent.

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1 hour ago, RandomName said:

@Keith_H sounds like you got a good one. I’ve had the low battery raft of errors as well. Gives you a bit of a fright the first time.

As for the order of checking parts, I was basing that on cost. Though in saying that cleaning the vanos filters had one of the greatest impacts as well but that was more down to the state one of them was in.

As far as I know the genuine BMW vanos solenoids should be good for about 100k so if they have been changed already then you should be fairly safe.

Like you, my car is round 145k miles mark, but in my case it looks like mine has had basic servicing up until I got it.

As for the ccv, price it with BMW as when I got mine it was only £10 more expensive than the aftermarket equivalent.

Both vanos solenoids were done at 90,000 miles by a BMW independent in 2012, there is no indication on the invoice to show they were genuine parts though. Interestingly the same invoice shows a £400 labour charge to strip the rear hatch and repair the wiring.

This was the highest mileage car that I saw but it came with the best history, that is up to the previous owner who used it as a posh dog van for two years not spending a lot on it. Despite the doggie liner the boot area, in the wheel well and behind the side cubbys looked like the floor of a grooming parlour.

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57 minutes ago, bmwmike said:

You sure you're not just feeling the DISA flaps opening? The RPMs are about right.

Could very well be the case. I’ve no reference to compare mine with hence consulting the collective knowledge on here. Given the number of problems I’ve had so far I could be a bit paranoid.

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My n53 has two flaps and it also is not perfectly linear to the red line. Depending on which gear you are in (masks it I guess) there is a fairlu obvious step around the RPMs you mention. I questioned that on another forum and someone said it was probaby the flaps hence why I mentioned it here. 2 different engines I know, but very similar intakes. 

 

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@bmwmike yeah I believe the b52 and n53 share a similar inlet manifold setup. It’s a bit of a relief to hear that I’m not the only one to notice this behaviour and even more relieved that it seems to be normal.

As you say, it can depend on gear or even throttle position as to how obvious the step is. Oddly on mine it can be more pronounced at mid throttle, but then that might be down to the fact that the engine is slightly slower moving through each step than at full throttle.

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Quick update on this one. When replacing the aftermarket DISA valve with a genuine one I noticed there was still more oil in the  inlet manifold than I was happy with. Having changed the pcv separator with a genuine bmw one a couple of months ago the only thing I could think of that might cause it was the pipes for the pcv as I’d not replaced them. I managed to disconnect them without them braking, or so I thought. Ordered up and fitted new pipes, cleaning the manifold as best I could. Now the power delivery seems a lot smoother, though I’ll not know for sure till it gets more driving. Plus there’s better power below 2k rpm.

 

While it was out I checked the pcv diaphragm in case it had went but thankfully it was good. Decided to dismantle the old pipes to see if I could find any blockages but all was clear. The only thing I found was that the pipe between the separator and inlet manifold was extremely brittle, breaking with the slightest amount of force. I can only assume that it had cracked during one or more of the times I had to disconnect it and was causing a slight vacuum leak. I’m hoping the leak was enough to prevent the separator diaphragm from sealing correctly as this would also explain the oil in the manifold.

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