Lean running Legnum on the dyno

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
So folks my 2000 Leggy was tuned by Steve today. We ended up getting 156.9awkw out of it which was not bad considering:
  • The dyno at Rajab racing was reading low for everyone
  • I appear to have the stock muffler welded to the 3" custom exhaust
  • My intercooler is too small
However, we *really* struggled to tune it and at a couple of points we were going to throw in the towel. To tune it Steve had to add 7-8% more fuel than in any other Legnum he's ever tuned. Steve can chip in with his own comments but he said at the end of the day it was like a car running a pod filter, but I don't use one.

We tried:
  • Swapping out the MAF. Didn't change anything
  • Replacing the Fuel Pressure Regulator. Didn't change anything
  • Replaced the Fuel pump. Helped a little bit (the one already in the car might have been a fake Walbro)
I briefly asked the original owner about the injectors. He said they are stock but were cleaned with new seals and filters installed. I'm not sure if this is a clue or not yet.


Anyway at this point I'm not fishing for answers. I just want a repository for somewhere for me to put my thoughts and solutions if and when I find any.
 

d3ck5

Leaving Skid Marks
Location
Melbourne
First Name
Dexter
Drive
VR4, VR6
hey Ed

nice to meet you yesterday. pretty awesome day all round with a great bunch of guys.

here are some cheap injectors you may want to consider http://www.ebay.com.au/itm/Mitsubis...=AU_Car_Parts_Accessories&hash=item35e078303e

also, the other thing you might want to think about, is how you might be able to diagnose the problem correctly and fix it.

i mean, if you go about changing X, Y, and Z, how will you be able to know if its worked without affecting the car and the current tune?

itll get to a point where really all youll have are possible answers without proof to test it? either way, i guess you could just visually check the parts in questions, and yeah your injectors may be the start.

happy to lend a hand seeing as i just did it less than 24 hours ago :p
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Yeah Steve said he has a bunch of injectors lying around from all the 1000cc conversions he's done. I've replaced a lot of injectors back when I was tracing issues with my old Honda VFR800. Not that I was that good at diagnostics, mind. I just became really good at switching parts out.

What I need is a wideband sensor I can record data from into EvoScan. That's really the only way I think I could trace before/after when making changes.
 

Size1

Leaving Skid Marks
Location
N.S.W
First Name
Simon
Drive
00 legnum vr4
Were the filters and seals that were replaced genuine?
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Previous owner says yes all genuine parts.
 

jungle

3 AYC Bars
Lifetime Member
Location
QLD
First Name
Simon
Drive
1 PFL & 1 FL Legnum
What cooler is it and what size?
Please explain the exhaust system, not that I think it's that.

I gather it's a manual not auto. Other than the low power figure does is have any other issues?

When Steve said its using 5-7%more fuel than others, does he mean that at eg 11.5AFR he needs to run 11.1 in the map for the car to actually produce 11.5?

Sound like it has a resolution problem ie MAF, but I'm sure Steve gave you some ideas. If it were injectors they'd be wrong everywhere no t just under load. But seeing he has a heap swap me out and cross that off the list. Plus you changed the MAF
That way fuel is sorted - pump and injectors. Did he check fuel pressure? Regs are usually pretty good but u never know...

Or the thing is just restricted massively and can't get the exhaust out causing an inlet restriction but again that depends on your answer above.
What CAT are you using and how many cell is it?
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
What cooler is it and what size?
Please explain the exhaust system, not that I think it's that.

I gather it's a manual not auto. Other than the low power figure does is have any other issues?

When Steve said its using 5-7%more fuel than others, does he mean that at eg 11.5AFR he needs to run 11.1 in the map for the car to actually produce 11.5?

Sound like it has a resolution problem ie MAF, but I'm sure Steve gave you some ideas. If it were injectors they'd be wrong everywhere no t just under load. But seeing he has a heap swap me out and cross that off the list. Plus you changed the MAF
That way fuel is sorted - pump and injectors. Did he check fuel pressure? Regs are usually pretty good but u never know...

Or the thing is just restricted massively and can't get the exhaust out causing an inlet restriction but again that depends on your answer above.
What CAT are you using and how many cell is it?

I'll answer in sequence as best I can.

  • Autobahn88 cooler. 590 x 200 x 70mm. Here's one on eBay.
  • The exhaust is a hand-built 3" full system including dump pipes. Looks like a stock muffler welded to it though as the previous owner gave me the entire OEM exhaust system (which I threw out) and there was no muffler on it.
  • It's a manual. New TME-supplied clutch kit fitted to it recently by me. Holds power no probs.
  • Steve was saying (for example) he had to set target AFR ratios of 8:1 in the tuning software to get a result of 10:1 on the wideband. I think Steve should probably chip in here to provide a bit more detail.
  • The drop in AFR only occurred on boost, but again we should re-check that with Steve
  • Couldn't check fuel pressure. Big job to fit in a T-junction with Schrader valve on these cars and we didn't have the time or tools. I mean, I have a fuel pressure testing kit at home but didn't think I'd need to take it with me...
  • The fuel pump (both old and new) are missing the spacer that goes behind the O-ring that seals it against the feeder pipe in the tank. The previous owner dodgied a solution using a stacked layer of O-rings. Steve had to do the same as that bloody spacer only comes with the car, not with the pump. We *assume* this is enough to hold pressure/flow.
  • Unsure about the cat. Came with the car, and it's welded in - not removable. I can only tell it's there because there is a distinct cat-shaped lump in the exhaust just after the O2 sensor with welds either side of it.

The more I think about it, that dodgy job with the O-rings seems like a possible cause. It may be good enough to hod pressure at low boost - i.e. basic fuel rail pressure - and then the FPR pushes the rail pressure up as boost rises. If the O-ring job can't hold the necessary 60+ psi of pressure it could force back past the O-ring and back into the tank, therefore causing lower than expected rail pressure.

Hmmmmmm.
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Here's where the spacer is supposed to go. Picture a stack of fat O-rings acting as the spacer.

Walbro pump.jpg
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Spoke to Steve, agreed step 1 is to fix the fuel pump O-ring spacer.

I'll dig out my fuel pressure testing kit too, and see if the parts that came with it will fit on the Leggy. It has a bunch of T-joins and stuff.
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Was the additional fuel across the board, or only in particular load/rev ranges?
Steve will have to answer that. That question hasn't been asked directly but all the conversations we had included the words "leans out only on boost", so I'd say it's only in particular load ranges.

Quote from Steve: "I don't think it's airflow related I think it's fuel as the manifold pressure pretty much correlated with the airflow I'd expect to see through the maf".
 

naughtika

OzVR4 Stalker
Location
Brisbane, QLD
First Name
Christian
Drive
'96 Galant VR4, '17 MB A180, '25 Macan GTS
Steve will have to answer that. That question hasn't been asked directly but all the conversations we had included the words "leans out only on boost", so I'd say it's only in particular load ranges.

Quote from Steve: "I don't think it's airflow related I think it's fuel as the manifold pressure pretty much correlated with the airflow I'd expect to see through the maf".


if it only leans out during high load, I believe it would be the fuel pressure getting thrown back into the tank.. so culprit will most likely be that o-ring
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
My fuel pressure test kit has an included T-piece, so I'm going to grab a spare fuel line that I can cut and insert that T-piece with Schrader valve into it for fuel pressure testing.

I'll run some before and after fuel pressure tests, unless the fuel line bolts refuse to come off. :)
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Something else I should (and can) test is the amps pulled by the fuel pump on boost. If the pump is working harder it should pull more amps. I happen to have an ammeter handy too, but getting that hooked up for on-road testing might be tricky.
 

Hotwire

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Location
South Australia
First Name
Lee
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97 COTY
The reason I asked is we are seeing very similar behaviour with a car here in SA and are yet to resolve the issue. He has similar setup, and also has replaced the fuel pump. He has not yet removed/replaced injectors but by the lean out under the highest load points, it was definitely pointing to fuel related also.
 

Hotwire

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Location
South Australia
First Name
Lee
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97 COTY
I will add, he was able to test fuel rail pressure under idle and load, and was seeing around 40psi at idle, 60psi under load (from memory) but we have no figures to benchmark that against.
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
I will add, he was able to test fuel rail pressure under idle and load, and was seeing around 40psi at idle, 60psi under load (from memory) but we have no figures to benchmark that against.
Jap service manual states:

  • Idle, no vac line to FPR: 289-309kpa (~42psi)
  • Idle, with vac line to FPR: 230kpa (~33psi)

Sounds like you're in the ballpark for idle. I think these are 1:1 regulators so 1psi of boost should equal a 1psi increase of rail pressure. If the car was running 20psi of boost you'd expect that 60psi figure.
 

Hotwire

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South Australia
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Lee
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97 COTY
Car is running around 1bar/14.7 psi boost, so plenty of rail pressure.
Injectors are out the car being cleaned at present so will see what change that makes.
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Car is running around 1bar/14.7 psi boost, so plenty of rail pressure.
Injectors are out the car being cleaned at present so will see what change that makes.
Looking forward to hearing how that goes. The injectors in my car were cleaned, but I don't know who by or how well. I've personally had old injectors cleaned in the past on one of my bikes, resulting in worse performance (they were probably too old to be cleaned). However in that case they leaked and caused rich running.
 

Kaldek

2 AYC Bars
Premium Member
Location
Melbourne
First Name
Ed
Drive
2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
Ran EvoScan logging all the way to Mits-Fix and back when I drove there to get the pump spacer. Seeing knock counts up to 7 when boost comes on. It's not consistent though.
 
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