G'day Jordan, I doubt its a turbo/boost issue (I have a 16G and its not working hard at all at 4-6 PSI boost). It sounds more like a fuel issue, which is then causing a change in boost (ie a momentary fuel reduction will reduce boost). Perhaps you should take it back to whoever did the tune and see if they can sort it.

 

Hey mate thanks for the reply.

Unfortunately thats out of the question. It was tuned in Sydney on my way through and I live in Central NT. A bit hard to get anything done here unfortunately.

Hoping someone can point me as to what might be causing it... maybe more spring tension is needed under the fuel pin?

Sent from my SM-G973F using Tapatalk

 

You have a few things that could do this.

My gut feeling says the turbo actuator. Could be a faulty spring which is pushing open and then sealing rinse and repeat, but it also sounds like the gap between boost gain and drop is too long for this.

Second if not equal I'm thinking injector pump mainly boost compensator or injectors.

All these things are hard to gauge without a professional driving the car and seeing what they feel and when.

If your handy try turning down the fuel screw a 1/4 of a turn and seeing if that helps. Could be a fuel surge issue from your pump. But honestly it's all trial and error from here.

 

Hey mate,

Interesting i didn't think about the actuator spring... ill have a look at it and see what it looks like inside. If I remove the whole thing I can open it with a vice if I have to depending the spring tension.

Wondering if it could also be something to do with the rod adjustment on the actuator? I've never checked that since I got the turbo so maybe?

Sent from my SM-G973F using Tapatalk

 

I think that would be a good first bet. I'm no expert but from listening to your symptoms and condition of your equipment that was my first guess. If the actuator spring isn't seated correctly or the arm isn't positioned correctly you can run into issues with boost stability

 

I would be looking at your wastegate actuator set-up first, and any boost controller and rubber hoses connecting them up. Make sure that is correct first.

 

Is your boost stable at higher boost pressures? Perhaps the actuator can could cause this, but I would expect issues at higher boost as the back pressure acts more on the waste gate - but I'm not an expert in this either. Other easy things to check are the boost lines to the compensator (pull the manifold end off and suck on it to see if it holds vacuum), and pull the lid off the compensator and check the diaphragm for holes and fuel pin spring seat adjustment. Perhaps there's no tension on the pin at low boost and its fluttering a little - I can't see how this is possible unless the spring has been cut or is broken, but worth checking).

That fuel economy seems unusually high. Mine averages a bit over 14L/100 (combined highway and round town) and the worst I've got is 23L/100 when heavy and towing a camper across the desert into a strong headwind. Do you know if the tuner checked the timing?

Did the tuner provide a dyno graph? If so, post it up - it might show something.

If the above checks out, then its likely ether a pump issue or a combination of fuel settings that aren't right, and I agree with Xadz that it will probably come down to trial and error between the compensator and fuel screw settings.

 

Hey mate, good ideas there.

I did some digging further today. To start with, turbo actuator spring and rod are all good. Made sure the rod is in correct adjustment with the waste gate valve shut at no boost. (See image). So its not turbo specific related.

The issue is not there at low boost or high boost. Only at cruising speeds and at about 6-8psi of boost. And even then, when I was trying to replicate it for a friend yesterday it wouldn't do it. Maybe too much of a head wind adding load? Any form of load on the engine where I needs to use more than 6-8psi stops it from happening.

The tuner didn't provide me a dynograph. I won't go into naming and shaming, but I wasn't happy with my last tune. Rocked up on the day I was supposed to be tuned. Being in Alice Springs I was on holidays and passing through Sydney at the time. The reputable company was moving shops at the time. No call to tell me the dyno was packed up. I rock up, sorry no dyno come back another day. That can't happen for me... so they tuned me on a dyno next door to them, was not given a sheet and no timing was checked. I told them I had no idea what anything was set at. They tuned it to by the spring and orientation of the diaphragm only until the AFR's were correct...

So long story short, no dyno graph and still no real idea where is sits. I have also thought about increasing spring tension a smidge. I have played with the off boost fuel a tiny bit as it seemed to be dumping alot of fuel out the back before it had boost. I've taken as much as I feel comfortable out without it lagging or being hard to idle up a climb.

Now I think I need a tiny bit more tension to try and ease off how fast the fuel comes on with any given psi of pressure. Your rattle theory could be correct?

Sent from my SM-G973F using Tapatalk

 

Its worth having a play with the spring seat. Tuning by road test is very time consuming and more steps backwards than forwards in my experience, but with perseverance I'm getting mine closer to where I want it. An option to try is to disconnect and plug the boost line to the compensator and take it for a drive. It will be down on power as the fuel pin should stay in the up position, but might be useful to see if the boost still fluctuates.

 

Yeah Roger, might give that a go.



Sent from my SM-G973F using Tapatalk

 

Your wastegate should have some pre-load I would think - not just closed.

 

You might be onto something there, ill see if I can add 2mm preload (quick google says that should be minimum preloaded, which right now it has none) and see what happens. If I do this I'll set my pump back to where it was (I did mark it) so im testing one change at a time

Sent from my SM-G973F using Tapatalk

 

Just pulled the line to the compensator like what was said. Drove almost the same. Boost leak! Going hunting for a boost leak, could be the pump pin fluttering as the leak seals and generates more and less boost?

Sent from my SM-G973F using Tapatalk

 

At least you're slowly eliminating possibilities and finding new ones. The waste gate pre-load is an important element well picked up by GQShayne, as without pre-load it could be blowing open with small amounts of EMP/boost. Taking the vacuum hose off the compensator should have made a noticeable difference as boost comes on, so hopefully you find something there.

 

Hopefully your boost leak will be easy to find by process of elimination. Lack of pre-load will cause boost drop-off so that will not have helped matters either.

 

Well I can tell you two things. I couldnt find the boost leak. So I replaced all the lines. I had a heap of spare boost line sitting around.

And I put 2-3mm of preload on the wastegate. Holy Mother of mary did it pick up a few ponies... No idea how that works, but I think its simultaneously gained a crapload of low down torque and possibly fixed the issue. I won't know for sure until I get on a highway (will try tomorrow) but bloody hell it gained some off the line pick-up.

The vehicle was always a bit boost spikey off the line too, it would soot like crazy and then suddenly gain lots of boost. Figured it was a combination of the pre load and giving the Android spring on the pump a little more tension. Thats changed the power band and the boost levels to be much more linear with the torque band. Its also shifted my boost point down lower of all things.

Will let you know how I go tomorrow. Really appreciate the help, thank you [emoji481][emoji108]

Sent from my SM-G973F using Tapatalk

 

Now aren't you all a bunch of cluey bastards! [emoji13]

Yep! That wastegate preload was the issue!

All forms of pulsing are gone. Must have been cracking the wastegate under small pressure causing some pulsing of power when the boost pressure fluctuated?

Either way appreciate the help fellas! I made a small adjustment to the IP Android spring height, increasing the tension slightly, and that gave me a much more linear power band than I have and should help fuel economy at highway speeds too as it would have been a little soft for 6-8psi at highway speeds. I have a feeling being so soft it was pouring in more fuel than it needed at any given boost setting.

Probably needs 1-2psi more boost which i can give it this arvo as nailed up a hill for 2 minutes or so @140ish it will creep to 500 deg EGT's so ill cool that off a tiny bit in the top end with some boost. But water temps don't budge over 90 deg. Cant recommend that Quikazz fan and DT79A enough [emoji108]

Sent from my SM-G973F using Tapatalk

 

Nice you got it sorted mate. Something to consider looking at your typical fail W/Gate actuator bracket. The more preload you adjust onto the actuator the more that flat bracket will flexes. Its a pain in the ass trying to get a good spool when the bracket flexes just as the gate opens. At higher rpms i have seen brackets like that flex enough to cause torque humping on a dyno chart especially when you get up to 2:1 emp:imp. 20 psi boost and about 40 psi exhaust pressure acting back on the gate flap flexing the bracket. Very un-nerving when you dont know what it is.

 

Nice you got it sorted mate. Something to consider looking at your typical fail W/Gate actuator bracket. The more preload you adjust onto the actuator the more that flat bracket will flexes. Its a pain in the ass trying to get a good spool when the bracket flexes just as the gate opens. At higher rpms i have seen brackets like that flex enough to cause torque humping on a dyno chart especially when you get up to 2:1 emp:imp. 20 psi boost and about 40 psi exhaust pressure acting back on the gate flap flexing the bracket. Very un-nerving when you dont know what it is.

Thanks Oldmav, ill keep that in mind! It only runs 15psi now and will probably go to 18 or so but that's about as much as it will ever run. Being a shorty 150hp is enough to make it feel like a rocket ship. Certainly does it for me. Plus living out here, im after reliability over horsepower

Sent from my SM-G973F using Tapatalk

 

As OldMav has stated your actuator bracket will more than likely be flexing even with your 15psi. Hook up a bike pump to the actuator, pump it up and watch the actuator and bracket as the actuator opens the wastegate. I have a similar bracket to yours, when I checked mine the amount of flexing was considerable. I braced the bracket no more flexing which results in full movement of the actuator shaft to the wastegate, instead of some movement being wasted with the bracket flexing.