Lachstock and Four Turbo Charged Cylinders ['04 NB SE]

[ManiacLachy]

The flu is definitely a bastard this year! I think I've finally seen the tail of it.

Right, track day. The TLDR version: nothing catastrophic, but could have been better in many ways. Still a fun trip away with friends and track time.

The detailed summary begins as I was going through the Fortitude Valley, merging on to the Storey Bridge - about 15 minutes from my house - when I gave the car the beans to get up to speed and I had a missfire! A little more testing and I found any time I was in boost over 4k I'd get the missfire. That's not what you want to discover when you plan to be up the revs for extend time on track in a couple of hours.

Outside Ipswich, near Queensland Raceway, we pulled over in a servo for a break and I tried to take a deeper look. It seemed the #3 coil plug was loose. All the others seemed fine. I swapped #1 and #3, and #3 was now solid, #1 was loose, so it was an issue with the lead's plug attaching to the spark plug. With a good hard press it seemed to seat properly. Maybe when Autoworks crew removed everything to fix the valve cover gasket if they didn't get everything quite right when putting it back together, as I've never had the issue previously.


Investigating the miss-fire

I did a pull on the way out of the servo and no missfire

Though I did hit 11.8 psi, running only wastegate spring and expecting ~8psi

We got to Morgan Park with plenty of time to spare and got setup. I unwound a little pre-load from the wastegate actuator, and set my boost cut to 12psi to better manage boost. I didn't see what I was hitting the rest of the day, but I didn't hit boost cut at all so that's good.

My friend and I were both running in the Novice group. Soon on track I had 2 issues, the missfire was back, making it hard to get on the power. But more alarming was a creaking groaning noise under hard right turns (Morgan Park is mostly right handers). I came in after about 5 laps to investigate, but couldn't see the issue, maybe scrubbing on the tub? Bouncing the car gave no odd noises. I was going to go back out, but our session was over.

Session 2 I just decided to send it. I was timing my laps with Race Chrono on my phone in my pocket. Not the most accurate or detailed, but it gives me an idea on times. In the 1st session I did 1:49. In the 2nd session I beat that every lap except my warm-up/cool-downs, with a best of 1:40. My friend who's a better driver and with more power, same tires, but not as much suspension was doing 1:32 for reference. I was still getting missfire despite re-seating the plug. At the end of my fastest lap I noticed my coolant was running hot, 115*, so I immediately went on a cool-down and came in. I was happy with my session, I'd made good improvements but with room to grow still.


Waiting to go on track

I was a little concerned on the heat, but there was nothing coming out of the car, and no milkshake anywhere. I tried to really seat the plug in properly for the final session, it wasn't loose to the touch and felt solid. But 2 laps into session 3, the missfire was still going hard, and the noise I was hearing from the suspension was worse, not only on right handers anymore, but anytime I was getting into moderate G forces. It felt like "don't drive me" noises, so I came in. End of the track day.

Dinner and drinks with my friends that night, re-capping and generally having a good time. No issues on the drive home Friday, still the missfire, a little suspension clunk when turning, that's been there for a long time. I suspect street driving it doesn't sound too bad, but under track conditions it's more noticeable. Got home, no issues.


QLD country side on the way home (from my friend's black NB)

The car is now in the air on jack stands to investigate. I'll change the spark plugs, and revert to OEM ignition coils for the time being to hopefully fix the missfire. The clunk/groan needs some digging. A few thoughts are the downpipe bumping the transmission, sway bars/control arms. I'll do a thorough nut and bolt check, including the mounts, subframes and PPF. Hopefully something will click as being not quite right.

[ManiacLachy]

8 year anniversary last week!

The car is currently up in the air, part way through the post trackday nut and bolt check. I think the Jass frame rail brases are a little loose, so I'm tightening them. I don't think that's my issue though. I suspect my 949 endlinks are worn out and part of the clunk I hear when street driving, but probably not the noise I was getting on track. The investigation continues!

[plohl]

Not uncommon for exhaust to hit subframe, bracing or half shaft on right handers. If you have a look you might be able to see evidence of it hitting, or if you give it a good world and it has lost of lateral movement it could be the culprit.

It'll get worse the more lat g's you have.

If it was a rotational knock, you should check wheel and axle nuts.

Or left front wheel bearing. They're generally the first to die.

Sent from my Pixel 4a (5G) using Tapatalk

[ManiacLachy]

I hadn't considered wheel bearings, it sounded and felt more connected to the tub but I will give them a check regardless. Thanks.

[rascal]

I’d also check wheel bearing. They are an annoying consumable for any car that sees trackwork.
Since it’s in the air already, just grab the wheel at 12 and 6 and wiggle to see if you get any movement.

End links typically clunk not groan, so might be your street noise but unlikely to be track noise.

One other thing to check is lateral movement of the sway bar. Hard cornering can make the bar slide through the bushes and then it can intermittently rub on or contact other parts. You can buy clamps that clamp it in place, or the trusty hose clamps work fine too.

[Roadrunner]

Check your control arms haven't slip forward on the bushings.

[ManiacLachy]

I've been slowly nut and bolt checking the car from tail to tip. I found the frame rail braces were a little loose, so clamped them back down. Also my Supermiata endlinks with spherical bearings were quite loose, likely causing a bit of a clunk, and replaced them with some Whiteline ball joint type that I had laying around.

Nothing else seemed obviously wrong. Control arms were all solid, wheel nuts were tight, sway bar clamps and brackets were good, the exhaust wasn't near the transmission and a shove wouldn't make contact. The exhaust is being pulled towards the front though, and the muffler is a bit high, I think I'll take it to an exhaust shop and get them to reposition the hangers slightly to remedy both.

A mate came over this weekend with his Golf R and wanted to un-boyracer it a little by replacing the huge rear defuser and damaged front lip. While he was working on that I finalised my checks and got the MX-5 back on the ground. I also checked my shifter boots, I put in the Miata Roadster SSK kit about 100k km and 7 years ago, I thought they might be perishing and a source of heat into the cabin, but they were in perfect shape.


All cars welcome in Lachy's Garage

I took the time to replace my spark plugs after my blowout issue, but had a super hard time getting #1 out. The socket just wouldn't turn the plug, it kept popping off like the socket was the wrong size. But the socket fit both the new plugs, and the other plugs in the head. Shining a light revealed there was something in there on the sparkplug, after a bit of faffing around with a magnet and a hook thingy I had in the tool box, I managed to extract a copper washer.


Where did it come from?

This is probably what was preventing a good fit of the plug lead! I can only thing its from inside the plug lead and some how fell out? Bizarre.

I also found the threads of #3 dripping in oil. Google tells me this is likely oil in the well due to a leaky valve cover gasket. And I know I had a leaky gasket because that's what Autoworks found to be the source of my leak before the track day. So 4 new plugs went in, the leads seated securely. Good to go.

Except, some monkey left a door slightly ajar and the battery is fully dead! The trickle charger didn't even recognise the battery to begin the charge process.

[Lokiel]

Copper washer from a previous spark plug?
Maybe PO added it to seat it better and it slipped all the way down?

... regarding "the door slightly ajar", you sure this guy wasn't responsible (gets jealous y'know):

[ManiacLachy]

I think the last person to change the plugs was Dann, some years ago when he tuned me up for E85. Maybe the guys at Autoworks dropped something in there? They would have had to pull the leads etc to do the valve cover gasket. It's really odd, the washer was on the top side of the plug preventing the socket and the leads from locating correctly.

As for Hobbes He does get jealous, of absolutely everything I do that isn't directly involving him. But I can't blame the doors on him, pretty sure that was me

I tried to jump the Mazda with my partner's Fiesta, but it didn't work. It did however revive the battery enough that the trickle charger would work, so I left that on overnight and the next morning it fired up!

So, we went for a beautiful winter's day drive over Glorious and had a picnic on the other side. I can confirm no more spark issues.


Perfect top down weather

However, for the very brief moment I wasn't blocked by a grey nomad or an L plater and could actually push the car, the groan/creak/vibration is still there. It seems to be a combination of speed and load. I wanted to experiment a little more and note what would and wouldn't cause it, but of course I hit traffic again.

It doesn't seem to be just cornering forces, or just speed. But I'll need more trial and error to confirm. Although I couldn't get any play from the wheels, I'm suspecting wheel bearings.

I have a set of SADFab rear hubs on the shelf from a buy with Lokiel some years back, they might be first place to start, then if needed I'll have to pick up some fronts. Looking at some videos, it seems a shop press is needed, not sure if I should pick one up, or pay the pros. Repco have a decent 12 ton press for about $255 (with Auto Club discount), which is 2.5 hours labour in today's market. So it's probably cheaper to buy the press.
https://www.repco.com.au/en/tools-equipment/garage-tools-equipment/shop-presses-vices/mechpro-blue-hydraulic-shop-press-12-tonne-mpbsp2/p/A5435851?rgfeed=true&cid=google-shopping&utm_source=google&utm_medium=cpc&region_id=100303&gclid=EAIaIQobChMI7fa0v8jy-AIVZ5JmAh1cQgSVEAQYAiABEgIEOPD_BwE

Unfortunately, my trolley jack has decided it doesn't want to keep the oil on the inside anymore, so I'll need to fix that first!

[ManiacLachy]

I took the car for a quick spin on the weekend, I wanted to get out an drive the car in this beautiful winter weather, but also wanted to check/test a couple of things before I started making any changes.

First, I wanted to check my boost levels on wastegate. Since I swapped to the new Tubrosmart IWG75 actuator, I've been hitting 10-12psi without any boost control. This is more than I want on spring only pressure. Ideally the spring would deliver ~8psi, and then I could bring that up to ~12psi with boost control.

I've checked that the canister wasn't leaking - an issue with my original older IWG75. So now I wanted to check if there was an issue with the boost passing through the EFR's boost solenoid. So, I did some pulls with boost going through the solenoid to the IWG75, and then again bypassing the solenoid. Both delivered ~10psi. So, I need to swap the spring to one of the lighter ones.

The other was to check on the groaning/creaking, see if I can replicate it. I couldn't though. It doesn't seem to be speed or RPM based, but more down to g-forces, which I couldn't replicate on those roads. So I guess as far as street driving goes, it's not a major concern, but I would like to resolve it before I go to the track again.

I will note that since updating the firmware on my Joying headunit, it's been far more stable using Android Auto, and connecting to the Megasquirt. And I really like the Focal speakers I installed, what as it, 2 years ago?

[The American]

If you’d like some help with the hubs, I have a shop press and a selection of items that can be used to persuade the bearing out/in

[ManiacLachy]

I might have to take you up on that, thanks!

[ManiacLachy]

No pretty pictures this time, just a wall of text, sorry guys.

TLDR: After some initial trouble, I tuned my boost to give me 11psi in open loop EBC.

The other week I took the car out to attempt to tune some EBC on the light IWG75 spring. I found a nice deserted road in an industrial area and did some runs to test wastegate pressure first. It peaked at just under 9psi, which is great and pretty much just what I wanted, it should allow me to run up to somewhere around 15psi if I wanted it.

My EBC solenoid seems to start to work with 20% duty cycle, and stops working at about 70% duty cycle. It's perfectly normal and expected that a solenoid has a limited range of effect. So, the next step was to set the duty just below that 20% minimum for all RPM ranges and slowly up the EBC duty across the board over several runs, and increasing in increments until I hit boost cut at 12psi at the peak efficiency RPM, somewhere around 5500rpm I think.

With that plan in mind I did some runs in 3rd gear to around 6500rpm (about as fast as I'd want to go!) with data logging enabled, pulled over stopped the log, upped the duty cycle, started logging and did another run. And so on. After about 6 of these runs I thought I'd see where my boost was at.

It was still peaking at just under 9psi - no change at all!

WTF? Well, this has been a waste of time. Either I have something miss-configured or the solenoid isn't working. Either way, nothing much I could do about it in an industrial estate, so I went home.

Later I did some testing and my solenoid wasn't firing. I disconnected the plug to investigate, but couldn't see an issue, reconnected. Then retested and it was working. Loose connection maybe?

Finally last weekend I got out in the car again, did some runs, but I was short on time so I didn't do it quite so methodically as planned. I took some big jumps to find boost cut, then knocked it back a hair to achieve ~11psi. Then I bumped up the duty before and after the RPM where cut was achieved. In the lower RPM I can have the duty cycle maxed out, this keeps the wastegate completely shut to achieve faster spool-up. Then the duty tapers down to hold my desired boost. So far so good, the car is feeling faster again!

This is all open loop EBC though, its rough but it gets the job done and it's better than either a manual controller, or simple wastegate spring pressure. To change to closed-loop control might take a bit more work, trial and error, so I'll need plenty of time, a clear stretch of road, and somewhat cool weather. I don't expect to get all of those for a while!

[ManiacLachy]

I've had the car up on jack-stands for a couple of weeks, trying to find time to do a few checks. Time is scarce these days!

First was to check play in the front wheels. While checking the possibilities of wheel bearings a little while back I noted the front wheels had movement on the top to bottom plane, but not on the left to right, which from my Googling suggests ball joints, not bearings. It turns out my ball joint castle nuts aren't tight. So after fighting with the cotter pins, skinning my thumb, and getting them tight again the play is drastically reduced. This was likely the casue of clunks over off side bumps.

Next up, I looked over everything under the car again trying to find what could be causing the groan under load. I found some soot over one of the v-band clamps in the exhuast, maybe not fully sealed?


Tell-tale sign

So I removed the clamp and the muffler section swung on it's hooks and created a sizeable gap.


Roughly 30mm of gap here

To close the gap, the muffler needs to be pushed hard towards the front of the car, and when tight the whole exhaust is under a lot of tension. My theory is that this causes the groan under load, g-forces and engine torque are twisting on the exhaust which has little room for play and it's vibrating and causing the noise.

I undid other clamps and hoped to twist the down pipe in such a way that it positions the forward section a little further to the rear, but with very limited success. It seems the exhaust is 20-30mm too short. I've got it all cinched up again, but I think a trip to the muffler shop is in order, they can extend one of the straight sections and get it all done up right.

Finally, down on the ground for a quick test drive, not conclusive yet, but the clunk seems gone, so that's a win. I'm not sure if I alleviated the groan in the exhaust at all, you really need to be on it to bring out the noise, not reasonably possible in a populated area.

I have a few other jobs I want to get to which should be possible on the ground, nothing critical but for peace of mind. I also just want to use the car more often!

[StanTheMan]

Not many shops can weld stainless. Certainly not here in Sydney at least. Maybe Brissie is different? This is a ready made kracken system?