Rb26 Engine Noise On Cold Start Up

[flavzz]

Hey all,

the past week I have had this whistling noise coming from what seems to be the turbo side of the engine.

Stock RB26. Engine noise on cold start up predominantly from the turbo side of the engine. Noise prevalent for the first 10 min and then subsides. Performance seems unnafected.

A mate suggested it may be the turbo/manifold gasket leaking which would explain why it subsides when the engine is up to temperature.

Any thoughts?

https://www.youtube.com/watch?v=XHAaE3OrryM&feature=youtu.be

Edited May 4, 2014 by flavzz

[scotty nm35]

Very hard to find a noise over the internet, you are going to have to pick up some tools and find it.

A long piece of hose shoved in your ear is the best option I think. Otherwise you will need to start pulling parts off, like the turbo's. Not the easiest thing to do with a 260.

[flavzz]

Yeah true, just wondered if someone else has had similar circumstances.

[scotty nm35]

Probably 1000's of people, but that still won't help you. Could be literally hundreds of reasons for noise like that at startup, and you haven't even pinpointed a location to start discussing options.

Try the hose trick, find the source, then you should know what you are looking at. If it's the T2 gasket, or manifold gasket, it's a good opportunity to swap out the old turbo's if they are still stock... Before they lunch your engine.

[flavzz]

All good points. Will investigate the specific location and report back. They are stock turbos and cash permitting an upgrade would be nice.

[flavzz]

Looks like it is almost definitely the exhaust gasket or one of the turbo gaskets. Either was its a rather large job to pull everything off and replace gaskets. Ideally I'd like to wait until I can upgrade the turbo's as it would be an ideal time to change them over.

[Blackkers]

Good idea, got plans for aftermarket engine management? I don't know how well aftermarket turbos go on the factory system

[flavzz]

I've got a 32gtr ecu which will have the Nistune treatment. Originally wanted to go Power FC but I liked the retention of the factory knock sensors and easy setup with the Nistune. Then it's onto turbo choice. Almost certain on -7's or -9's.

[Badgaz]

you keep the knock sensors with any other ecu as well. what makes the nistune easier to tune is the real time 3d graphing.

[flavzz]

I had read that the Nistune pulls timing when it detects knock but the power fc doesn't. Is this true? Either way I like the product and it's probably slightly more cost effective.

[Badgaz]

Yes that's right, it retains a lot the factory ecu features like the low octane map.

[jjman]

low octane map?

is this the same as R&R? (rich and retard)

[Blackkers]

attaboy too many people swap out turbos and expect the thing to work.

in Nistune there are separate fuel/timing maps called the knock maps. I'm 90% sure it triggers from exceeding a certain knock threshold. Also I don't know how good the factory knock sensors are. could someone weigh in here?

edit: I think people often mix up R&R with hitting the boost cut

Edited June 2, 2014 by Blackkers

[scotty nm35]

The main issue is, usually when pushing big power there is other engine noise that is mistaken for knock by the ecu, then all timing drops out for no reason. Makes for interesting results, like over spooling the turbo, and glowing exhausts. The PFC still detects knock but only displays it, it doesn't drop to a low octane map like the Nistune.

Any decent standalone ecu can be set up to drop into a low octane map, if that's what you are after. Personally I would want rid of it, as ethanol is rarely going to cause det anyway.It's more for petrol tunes on the edge.

[GTSBoy]

The standard knock maps simply have more fuel and less timing pretty much all across them than the normal maps do. If the ECU hears enough knock then it will switch to the knock maps. If it continues to hear knock then it will go on to further reduce timing. This is good if the knock is real, but sucks hard if it is false knock.

People have so much trouble with incorrect knock detection that a large proportion of Nistune tunes end up having the same or barely different maps in the knock maps anyway. So even if it detects knock and changes to the knock maps it won't cost you fuelling and timing. It is a nice thing to have knock maps to protect you from a bad batch of fuel, but if they just don't work as intended then they are useless.

And FWIW, R&R is not "switching to the knock maps". It takes detected knock (or falsely detected knock) to make that happen. The high load region of the standard fuel maps are simply very rich, and the matching part of the timing maps very retarded. If you run standard boost you don't go up into those regions and so don't get R&R. If you wind it up (on standard ECU obviously) and pull more aqir through the AFM, then you start moving up into progressively more rich and retarded parts of the maps. It's actually pretty easy to run off the end of the maps which just continues in the overly R&R setup.

If you exceed the max load (TP limit) in the ECU then you will hit the "boost cut" which is the nasty massive interruption to all forward progress that some people mistakenly call R&R. The truth is that in order to get to the TP limit then you have already been running in the R&R region. It's just that in 1st or second gear you can WOT it and get to the TP limit in such a short time (like a second or 2) that you don't notice that the car is running the injectors at 100% duty cycle and retarding the timing so much.

[Ben C34]

And just to add to GTSBoy's post..

As he mentioned they are called knock maps,not low octane maps.

The ecu has no idea why the engine is knocking (if it even is) so it just switches to the knock maps.

The engine will knock for a variety of reasons, obviously low octane is one but it's not like the ecu somehow knows that is the reason.

[ido09s]

with regard to your original question, i would almost guarantee that one of your turbo's has come loose on a manifold. I had many a turbo off to fix the dreaded exhaust squeel

With regard to ECU, I wouldnt worry too much about knock. If its got a decent tune in it to begin with your not likely to run into too many issues. I actually found them to more of an issue as all the ECU picks up is a noise and it could be just about anything. A decent set of headphones on the engine while its being tuned and a decent source of fuel should be all you need these days

[flavzz]

Some good info here. ido09s so you had the same sound as in the video? Did you just replace bolts/gaskets and tighten everything? Surely it shouldn't happen that often once the job has been done...

Also once I get to the Nistune the tune will be relatively mild so hopefully the issues won't be with big power causing knock. Overall it seems like a good product.

[GTSBoy]

Nistune is a good thing. Retaining the factory ECU and all the OEM smarts that went into it has its merits, that's for sure. The only reason to step up to a proper aftermarket ECU even for quite serious power increases is if you need something (outputs, boost control functionality, whatever) that you can't get out of the factory ECU. There are plenty of people making big power levels with Nistune. Things do tend to get a bit complicated though once you start making big changes - there are consequences to things that you might not expect.

Mild tuning on Nistune is a doddle.

[R32Abuser]

To add to the above, I know of several examples where the 10-20 year old knock sensors paired with both built and OEM motors falsely detect knock.

When my built RB30DET started constantly switching over to the knock maps, I simply got Pete from Nistune to wire in a couple of resistors in the ECU which mimic the knock sensors.

No more issues with the ECU pulling timing....However, no insurance against a bad batch of fuel.

As GTSBoy has said, there are consequences when you start changing things!