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GT6 Nick

Nick’s Green GT6 megasquirt - take 2

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Throttle body balance, first, second and third. Yes, it is that important, especially at idle and small throttle openings, where you spend most of your normal driving time!

I don't think the cam you are running is that different from the hybrid Newman one in my 2L, so a decent (if slightly loping) idle and perfect tractability from idle (bar some light, but irritating shunting at very light throttle in traffic) should be possible, plus your ITBs should mean no shunting.

Two fuel maps posted.

First one is my 2.5PI (std "132" cam and TR6 cast manifold)

132 bhp 140112.JPG

Second one is the Vitesse with Newman PH3/PH2 cam and 6-3-1.  Possibly more suited to you engine.  Fuelling base level can be shifted up or down by altering the required fuel number in basic settings

Vitesse PH3 20102016.JPG

Third one is an example target table.

New target table.JPG

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Thanks for those, Nick. Your Vitesse is a 2L rather than a 2.5 I think?  - I’m not sure if the Volumetric Efficiency will be as high in a larger capacity engine with the same size valves? Still, it’s a good place to start. Let the tuning commence!

Edited by GT6 Nick

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Yep, Vitesse is 2L.  The absolute values in the VE table are less important than the profile of the table - you can offset the whole thing richer or leaner by altering the the "required fuel" value.

Consider the above as starting point only. Use the target table (or something like it, that is only my best guess!) and autotune to do it properly.  You'll need a Rolling road to do the top right corner as without a flippin' enormous hill to load it down to reasonable speeds you'll either crash or end up in jail..........

There is still (after about 5 years) a TR6 running round in this neck of the woods running my original MS1 Vitesse map (in my original MS-1 ECU too) - unaltered apart from a small required fuel offset (has a PH1 cam IIRC).  We did set out to tune it but the owner couldn't control himself and it was all I could do hang on and note that the AFR (narrow band only) was going to roughly the the right places.  Drives really nicely and goes like a scalded cat.....

Nick

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Hi Nick,
Your GT6 looks great!

Here are the maps I am using on my 2500 (Mk1 PI ???) with the Triumph 25/65 cam with 0.345 lift.  Bosch injectors 19lb/2.9cc @ 3 bar.  Not quite fully fleshed out around the edges but still working well.
The Accel Enrich is still doing my head in:mad:

I tried installing a knock sensor to help set the timing but I had more trouble than John is having with his Megajolt so gave up!!

 

Cheers,
Doug

afrTable1Tbl_2018-04-08_11.31.53.table

afr 2500 25.65.JPG

ign 2500 25.65.JPG

ignitionTbl1_2018-04-08_11.31.13.table

ve map 2500  25.65.JPG

veTable1Tbl_2018-04-08_11.30.10.table

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Thanks Doug and Nick, those tables are very helpful. I've loaded Nick's Vitesse VE table and it still ran (which is useful). However, I haven't road tested it yet as the brake caliper brackets are away getting milled - so that the calipers sit centrally over the discs and don't make nasty scraping sounds.

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Brake caliper mounts have been skimmed so that the calipers sit centrally on the discs. On with the road testing!

The engine tuning is in two parts - mechanical and electronic.

Mechanical - it wasn't running on all cylinders. Was it the coils, was it the plugs or something else? Pulling the plugs showed that all were sooty and the worst ones coated in unburnt fuel. Thinking back two years to when I first got it running, the exhaust shop had forgotten to install the oxygen sensor. I couldn't figure out why the wideband said it was running super-lean while it belched black sooty clouds! The car parts shop is closed on Sundays, so I replaced the worst four with triple-electrode plugs I'd tried on the Herald. (The Herald didn't like them, so they went back on the shelf). Now we have a six-cylinder orchestra again, proving that the rest of the ignition system is working properly. I'll buy some more triple electrode plugs so that they're all the same.

Next I synched up the throttles, kinda, which helped the idle and light-throttle drivability. Those six 40mm butterflies tend not to snap completely closed though, possibly due to mechanical drag in the linkages, giving a high idle. Each throttle body pair has a small return spring, but I've ordered a long spring and linkage to help snap them shut. The idle valve is also letting a tiny bit of air into the inlets, which I 'fixed' by pinching off the hose with a bulldog clip. I'll look at its electronic settings to try and get it to close completely.

As for programming, Nick's AFR table made it run really lean, so I've richened it up full value, ie from 15 to 14. The wideband's no longer showing scarily high numbers! The next step will be to work on the acceleration enrichment and tweak the timing. I have to say, I find design and fabrication are far easier than the programming, which makes my head spin!

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No, not since it was installed. Getting under the car to remove the sensor is quite a mission. The wideband seems to be producing sensible numbers - at around 13 to 14 the car pulls well, but above about 16 it hesitates and stumbles. I just took it out again to test some more acceleration enrichment, but it hasn't made much difference. Back to the manual.

Mostly I'm concentrating on getting the mechanical side right - installing another throttle return spring so that the butterflies snap closed and it idles under 1500, and eliminating various scraping noises from the wheel wells and driveshaft. Annoyingly, there's also an intermittent ticking from the clutch area when the pedal is depressed, and finding what that is could be an engine-out job.

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Agree that mechanical tweakery, especially TB balance are essential first moves.  There is no point doing any serious idle or light throttle tuning until the TBs are balanced.  Some drowned plugs are a sure sign of balance problems.

Wideband would seem to be producing sane results.  Frankly, I wouldn't expect to get it to run clean at 16:1 AFR - too lean for this engine.  I found that I could just about get the Vitesse (2L) to tolerate a 16:1 cruise without hitching, though it made the pick-up very hesitant.  The PI with 2.5 (and so less squish) just hitched and jerked and had to be run richer.

You won't want to be much leaner than 14.5:1 anywhere except over-run and very light throttle cruise areas and not leaner than 15:1 anywhere.  More of the light/moderate throttle driving zone will be 13 - 14 and bigger throttle 12 - 13.  Both mine and Doug's AFR target tables should help with this.  Just concentrate on getting it to run nicely and pull well - the numbers are a guide and not something to get hung up on.  It wants what it wants.  As a start point some people just set the target table to 13.5:1 everywhere except 4000+ at 80 - 100KPa, which is 12.5:1

If in doubt, tune to the rich side, especially at higher loads/rpms.  Too lean in these areas can melt things REALLY fast.  But anything under 11:1 is not great either, especially on a fresh engine due to the risk of bore-wash.

My clutch, which is a fairly random collection of Toyota and Triumph bits, also makes weird noises from time to time.  Usually low key groaning and whirring.  It's been apart a couple of times (first time because it ate the cushioning springs in the centre plate - seems the 1.6 Hiace plate isn't strong enough) and second time due to engine swap.  I've made tweaks both times which changed the noises, but didn't permanently cure them.

Nick

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I ordered a set of NGK BUR6ET triple electrode plugs yesterday. $198 later... and they’ll be in next week as they’re not exactly a stock item. I was pleasantly surprised by the conversation at Repco. Usually I ask for an exact part by part number, the drongo asks what car it’s for, and then tells me what their computer says I need. Not this time. The guy typed in the NGK number, looked at the photo and called his mate over so that they could gaze at the weirdest spark plug either of them had ever seen. Triple electrodes, dude!

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:o $ 198......!!!  Wah.....! How many sets.....?  They are barely more expensive than normal ones here.  Nothing especially "performance" about them and originally intended as long life items with the wear being shared 3 ways.......  Just seems that the Triumph engines like the "side electrode" effect.

Not that weird either.  Have been standard fit in many VAG products since the early 80's.  You might want to hold back on fitting them until you've solved any over-fuelling problems as my experiences with NGK product and over-fuelling are not good!  Bosch WR7DTC are my favourites (as fitted to Golf GTI Mk2 and 3) but may not be readily available in Oz?

Nick

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5 hours ago, Nick Jones said:

   You might want to hold back on fitting them until you've solved any over-fuelling problems as my experiences with NGK product and over-fuelling are not good! 

Come on Nick tell us a little bit more?

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I, and many others, have had problems with NGK plugs (and newish ones seem worse affected) dying if their insulators get soaked with petrol.  While this can affect any plug, with most it is reversible and cleaning them, drying them, even the "blowlamp treatment" restores them to life.  With some NGK plugs however, dead is dead, whatever you try.  I killed several with my PI when it was PI.  I also had an issue with a Nissan Primera GT where (through my own muppetry) I managed to comprehensively flood it after a simple compression test.  What caused me much more confusion was why, even once I'd corrected the muppetry (re-connect coil pack!) and dried the plugs, I still couldn't get it running or get any sort of spark - eventually fired right up when fitted with a different set of plugs and the NGKs had to go in the bin.  Some  internet debate claims that it is only "fake" ones affected.  Elsewhere it is suggested that Japanese made ones are fine but European (French) made ones not.  I don't know.

They seem to be fine if they don't get petrol soaked so this was why I suggested not fitting them until there was some certainty of not soaking them!

Nick

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Thanks for that Nick, was just asking as only recently fitted a new set of NGK's, they seem still to be working ok but the car is a bastard to start sometimes though i think thats the carb set up & me flooding it.

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The NGK plugs are $33 each, and they were cheaper than the Bosch WR78 equivalent! WR7DTCs aren't available in Oz - I bought a set of four for the Herald from the Green Spark Plug Company in the UK, and remember being told that they'd been discontinued. They're still on eBay, but add in freight and the fact that the NGKs will be here on Tuesday...

The GT6 over-fuelled when it first ran in 2016, as the exhaust shop had tucked the O2 sensor out of the way and then, because they couldn't see it, forgot to weld in a bung. I couldn't see it either, and wondered why, even though the sensor read 22.4 (ie super-lean), the car was belching black smoke. One cylinder died, then another, then she just wouldn't run. Eventually I worked out why, but by then the damage was done. Those were standard plugs. It's running much leaner now, so I think the danger of drowning the plugs has passed.

In an effort to bring down the idle, I fitted a return spring to the throttle shaft yesterday. Each set of two throttles has its own axial spring, but these don't seem to be enough to snap the throttles closed.The shaft rotates clockwise as seen in the photos below, so the arm rotates upwards. I checked and it doesn't hit the bonnet, which is always a concern in a GT6.  I was about to go for a drive yesterday and see if the idle is lower, but got sidetracked when a friend popped over on his Goldwing (he only lives 200km away so is virtually a neighbour) for a coffee.

P4220005.jpg

P4220007.jpg

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Ah..... inlet manifold porn!

The plugs'll be fine if they don't get wet and may even be fine if they do - probably Japanese made in your part of the world and people say those are ok.

The price though......  Even Halfords (UK motoring accessories chain not generally noted for cheapness of spark plugs) only want £ 8 and online they seem to be between £ 4 and £ 6.  I know the Aus $ price would be knocking on double even if all else were equal but...... ouch!

They should last well though - supposed to do 25k miles.  They do at least that.  I had the same ones in the Vitesse from 2005 to 2015  (MoT history shows 32k in that time) and only swapped them then in honour of the new engine.  Still have the originals as spares.  I took a set out of my first Audi 90 where the centre electrode had worn down to  little three-cornered spike - no idea what they'd done but based on the ones I've seen at  I'd think 50k ++

Look forward to the next report

Nick

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Six new NGK triple electrode plugs, made in Japan (so the boxes say), now fitted. And just like that, the idle and reviness are back. I've uploaded Doug's ignition advance, which looks a lot like a TR6 PI advance, and the engine seems to like it.

Today's road test (dodging the cops as always because it isn't registered yet) shows that although the wideband says it's running an AFR around 14, it's definitely running rich judging by the pups of black smoke. I'll take Craig's advice and recalibrate the O2 sensor. Easy for him to say, he has a hoist! 

Tonight I'll read up on how to log data, so I can gather data to see how to set the MAP to throttle position sensor crossover for the throttle bodies. 

By the way, has anyone found a good table of injector dwell / dead time / latency? I'm using 0280 156 080 injectors. 

Plugs.jpg

NGK triple electrode.jpg

Edited by GT6 Nick

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Right, the O2 sensor has been calibrated, which is a five minute job once you've crawled under the car. I haven't tested it yet to see if it runs leaner, because I've been packing my motorcycle for a ride around Australia. So for the next six weeks, the GT6 will sleep, waiting its turn. Craig - don't think I'm rude, but I plan to bypass Melbourne this time. That ferry to Sorrento should give me a head start on the Great Ocean Road, and avoid Melbourne traffic.

The pig avatar, by the way, is because my bike's name is Piglet. It even has little piggy decals.

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On 4/2/2018 at 10:24 AM, GT6 Nick said:

I’m pretty sure that the interference is magnetic, as Rob says, caused by the magnets in the motor. I could move the crank sensor, but sitting it above the pulley means that I can replace the fan belt without disturbing the sensor. So, I’ll move the fan. In the short term though, it doesn’t seem to be causing poor running, and the effect is only noticeable when the engine isn’t running.

 

Interesting found a similar problem by chance yesterday at Abingdon, but also don't think its causing any running problems.  For hot days and to try and keep my carbs as cool as possible I have added an over ride switch to the fan so that I can keep air blowing through the engine bay, even with engine off. Up until yesterday I had only used it with engine running but fan not triggered by coolant temp. Yesterday I was using it to keep things cool without engine running, when I suddenly noticed the rev counter flicking, most of the time it would stay on zero, occasional flick to 1-200, and even more occasionally jump to 1K and hold for maybe half a second before dropping back to zero. It was repeatable by turning fan on or off.   Now to have the fan running I need the ignition on, which meant the MJ was powered, and I'm taking the the rpm signal from pin 6 on the MJ.  So not sure 100% if the signal is being generated by the fan proximity to the VR sensor, or if the MJ is making it up, but fairly certain that its probably the cause.  Didn't notice any running effects, but again don't know how much the fan is on when high speed running, or what any symptom might be.

Alan 

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