Updates.
Apoligies long as f**k - TLDR - looks pretty but still not mapped/doesnt work right.
Trip down to EfiParts on Sat for a pm dyno/mapping slot. Worst weather possible, of course! Non stop torrential rain..i honestly didnt feel like going on the morning as i hate driving this in the rain. Not because im precious/scared of rain as the car is well protected from the elements, its the fact its got semi slicks on, plate diff etc. Basically constant correction of steering so you cannot relax. Just not fun to drive unless dry. s**t slow driving and aquaplaning all over the place when hitting ruts on dual carriageways.
As most people in the uk cant acutually drive, the journey took 4 hours and just stop start traffic.
Bit of chav on to keep alert. Forget the soundsystem is alright in this with alpine stereo, amp and focal components.
Twin plate clutch and snappy throttle for miles and miles. Painful.
Arrived at Efi just in time for 330pm slot. Lashing down. Orange clio as backup full of tools and other s**t that might be useful.
A nice supercharged 197 was being finished off so short wait and strapped on.
Single roll incase it works.
Discussed with Chris the current issues with the setup, and what i had done to attempt to resolve this, but needed more help as fuel map needed work/needed to be run in a controlled enviroment to log and change parts. So this was essentially a diagnostics session in some respects if the issues could not be resolved on the day.
To recap it was going horribly lean for a split second around 64/6500 rpm which was almost impossible to tune out last time, and things were initially pointing to the fuel system. I had changed fuel pump to aem 400lph which had richened the fuelling up a point across the mid range.
The idle/low down fuelling also needed attention due to flywheel and clutch change for lighter twin plate setup. We agreed to sort this first, then start swapping parts coming back to the mid range fuel map later on.
On with the tuning.
First run up and the fuelling is lean at the top. It was noted fuel pressure was rock solid and did not drop off so that was not an issue.
We then tried the below to see if the fuelling would change.
1. To prove the fuel resonance theory, i then fitted an extra meter of rubber fuel line on the end of the fuel rail, leading to the fuel pressure regulator inlet. Essentially moving the regulator 1mtr away and rubber to dampen the pulsing.
This done nothing unfortunately. Proving not a resonance issue. Reverted back to old setup to remove pikey 1mtr coiled up fuel line.
2. Software changes. We looked at the datalogs and nothing was jumping out. All tables/settings in ecu were checked and nothing untoward that would cause the fuelling to lean off.
All we could see was egts on cyl 3 & 4 were spiking higher than cyl 1 & 2 before 6400 rpm issue the dropping after this, indicating lean then not lean on that pair. Egt sensors are very slow to respond. To rule out wiring, and voltage drop to the injectors we swapped the injector plugs around to opposite cylinders and changed the software to suit.
Again no real change. Reverted back to old setup.
Also changed injection angle and a few tricks in the software. No real change.
3. As we were starting to clutch at straws, we discussed the possibility of something on the piss with the injectors. Chris has the 980cc bosch injectors in stock so a new set were selected and tested on ansu machine. I installed them, done a run and the fuel curve did change slightly but still same issue. We tested my injectors in the ansu machine, and mine flowed 5% better than the ones off the shelf and were all bang on flow matched, so basically the changes were due to mine being slightly better if anything.
So it was off with the fuel rail again and reinstall original injectors. The pressure falls off instantly but this time i pulled the rail and ended up covered in fuel. Nice.
4. Disconnected the vvt and done a run to see if that was causing issues. No joy, it was pig rich in the mid range losing power everywhere as expected and still similar issues.
5. Fudge the ve fuel map to get over 6500rpm to see if any more data would be seen as its looking like mechanical issue. A few runs were done monitoring egt/increasing the v.e in the cells required and trying to trim cylinders 3&4. The v.e is nice and smooth around 106, and you literally have to ramp it up to a large peak of 156 to get over this lean spot and then drop the ve back down again towards the limiter as it is then stupidly rich. Its not right as it still goes slightly lean, then rich as fook.
With a pull to 7800rpm limiter we made 260/270ish hp at 7psi but again the fuel curve was s**t. You can see it holds boost rock solid to the limiter and the power curve is there or there abouts, so does not indicate any valve float issues..which it should not have anyway with supertech double valve springs and 7psi boost.
5. Final thing we tried was changing ecu to.my spare ecumaster black. This was to rule out any funky injector driver issues. Fitted, map flashed on and no change.
Vid of one of the many pulls done.
To sum it up, we ruled out quite a few things but no definitive answer over 4 hours on the dyno. Massive thanks to Chris as usual for his patience with this one. He said hes never had this issue before on one of these.
Honestly, not 100% sure where to go next. Its pointing at mechanical issues..engine runs lovely typically.
Cams in it are a bit lairy for turbo. 197 inlet/182 exhaust. Chris has tuned a similar setup and it worked though.
All i can think is, it is too much cam overlap at that rpm point for whatever reason causing potential reversion issues. With egt's pointing towards cyl 3 & 4 this is also on the longer runners on the manifold as its unequal length due to how nortech made it. We are unsure if the extra runner length is an issue or not and its causing the issue. But again you see allsorts of s**t exhaust manifolds working without similar issues. Hopefully not the manifold as it will be painful to change the design.
Another thing that could be considered is the inlet. We dont think this is an issue, as its a basic square box centre fed with trumpets in, no tapered design etc. Again any shitty inlets work usually.
Prob pull cylinder head off this winter and see if i can spot anything. Change cams to 182 inlet and exhaust as i can verify they work.
Thoughts welcome as usual. Thanks for reading.