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Megasquirt MS1 - Another tuning help request post..


Fatboy

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Morning gents,

Please bear with me on this post as I’ll try and provide as much information as I can think of. If you have suggestions or are able to help, let me know - any assistance would be much appreciated as I’ve been struggling with finishing this build off for an embarassingly silly amount of time…

  • Engine is a 4.6 V8 with tophat liners. Fully rebuilt and Megasquirt installed (in 2013, ahem…)
  • MS-1 v3, 029v. Loaded with Nigels 4600 Base Program.
  • Injectors are new Bosch 0280155900. Supposed to be a good solution and used by Ford in 4litre, 6 cylinder engines.
  • Req Fuel is 19.4 (4600 displacement, 8 cyl, Injector Flow 200, AFR 14.7)
  • Plugs are NGK BPR6ES
  • Lambda Sensor is a Fuel Parts 86400 narrow band, 4 wire Zirconia. (From Nige, with the kit).
  • Timing has a trim angle of 5 degrees. I checked TDC with a hose connected to an old plug shell, run into a bottle of oil so I’m confident it is correct. Then figured out the trim requirements following Fridges recent response in another post.
  • Throttle Position low is 12, high is 208.
  • PWM valve is a Bosch unit.
  • Leads are ex-Nige Magnecor variety.
  • I subscribed to TunerStudio at the start because I'm not very confident with this type of stuff and wanted to develop a familiarity with the programme I wanted to use long term. This seemed to be the favourite, so I went with it.
Over recent months I’ve changed plugs, leads, injectors, Lambda sensor etc. but just cannot get it to run properly...
It starts fine, ticks over okay. Warms up and drives but the O2 sensor goes out of range therefore it won’t autotune. Tonight, ticking over, the O2 was at 1.4V but as soon as I take it down the road it climbs to 4.5v…
When I take the plugs out they are black so seems to be running rich…
I took the photo below to show the typical gauges when stationary. From there, the O2 only get worse when it is running..

Megasquirt Gauges

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He says narrowband in post... Ahem. Could it be something to do with the non-standard injectors?

I'm just throwing that out there. Maybe sweet fanny adams to do with that.. I just wish I was at your stage lol.

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What does it smell like?

A narrowband won't tell you much other than whether its rich or its lean.

From your photo the vacuum reading is pretty low, though that may be to do with it running badly. Pulsewidth of 4.7ms at idle seems pretty high- with normal injectors it would be high enough! That's near double what my 3.5 uses with Vauxhall injectors.

I'd be inclined to remove fuel from idle to get it showing something. Just pull fuel and listen to it- if it's mega rich then you should find the idle speed increases as you lean it out, keep going until idle speed starts to drop again and then add a bit of fuel back in.

If idle drops immediately as you lean then it was too lean to start with, so go back the other way...

With a happy idle I'd then take a smidge of fuel from most of the rest of the table and take it for a run, then another smidge and keep going until you get the NB sensor seeing something useful.

What i'd really do though is fit a wideband- Spartan2 from 14point.com is excellent and I have fitted two now, one to my 90, one to my Dad's 110. No connection other than happy customer....

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A standard zirconia narrowband lambda sensor will output 0-1.1v as the absolute limits of its range, I assume you'd know if you'd bought & fitted a wideband sensor & controller, so that leaves the possibility that you have used the original Range Rover titania sensors which are resistive and will basically cause the ECU input pin to "float" up to the internal supply voltage of 5v.

Universal zirconia type sensors are cheap from motor factors, you may need to weld a bigger bung in though as (I believe) they have a bigger thread than the Ti type.

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Oops, missed that.

Would guess either mis-wiring or possibly a faulty input on the ECU then. What happens if you disconnect the lambda?

You can make it work without the lambda by setting the correction to 0%, stops it trying to adjust on the fly.

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Thanks for the pointers everyone.

Bit of an update - I had a quick check tonight.. The gauge shows 0.2v if I disconnect the sensor from the loom.

The black wire from the loom (should be earth) is providing 12v... I've written a note on the wiring diagram that it should have been earthed at the ECU so I suspect I got it mixed up with the White/purple trace wire that should T'd into the supply to the fuel pump (it is showing earthed).

I'll check the other ends of these wires at the ECU after work tomorrow.

Had a look for a Spartan2, the 14point.com website doesn't exist but 14point7.com does. Nearest dealer in Holland so I've ordered one. ?

Promise I'll keep this updated as I make progress, thank you for the participation!

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If you're ever in doubt about the lambda wiring (pretty sure I've had one that didn't conform to the std. colours) either run the engine or remove it & heat with blowlamp whilst measuring volts across the wires - if you get the tip just glowing with a blowlamp you'll usually get some voltage out of it.

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So.... accessed the relay board and was grateful I'd labelled the group of cables from the Lambda sensor. I remember reading something saying that the ground cable from the Lambda needed to be earthed near the ECU and because there were no spare points on the board, I'd stuck a male spade terminal on it and used the Earth terminal on the spare relay plug... except I hadn't, I'd stuck it into one of the terminals that is live.

Pulled it, connected it to the proper negative point and started it up. Voila! Lambda stayed below 1V and got the first time ever, auto tune actually started to work.

Took it for a quick run and can see a difference already, might even auto tune it again tomorrow on the way to work! ?

Thank you all for the help, can't believe it was so simple.

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  • 3 weeks later...

I fitted the Spartan2 wideband and adjusted the settings with some gladly received guidance from Quagmire.. While fitting the wideband, I split the earth cables from the sensor and earthed the heater -ve to the chassis, leaving the sensor -ve going back to the relay board. (As recommended in the literature).

  • Fitted the wideband.
  • In the Project Properties / settings / tab, changed the EGO O2 Sensor to the Innovate PLX 0-5V 10-20:1 AFR. (Same setting as Spartan 2).
  • Then, on the main Tunerstudio screen, went to Basic settings and changed the sensor type from Narrowband to Wideband. I also changed the switch point.
  • Then set the following AFR target table (copied from one of Bullbar Cowboys posts on here)

2016-06-27%20Target%20AFR_zpsp0oowkby.pn

Then took it for a spin....

The starting point was the last tune from the Narrowband:

2016-06-27%20Narrow%20Band_zpshfus95wq.p

and it did start to make some changes in every cell it hit... but weirdly, the Lambda sensor gauge stayed red, on the 0 to 1v scale for the Narrowband. I checked the settings and they seem right so assumed maybe it needed to calibrate.. However, it was changing cells and the volts from the Lambda seemed okay..

thumb_IMG_5668_1024_zpskx0549dp.jpg

After +/-20mins, it started to hunt at low revs, and didn't seem very healthy but at more than half throttle, it was fine. The final wideband table was:

2016-06-27%20WideBand_zpsispynwsq.png

I had wired up the LED from the Spartan2 which blinks when it isn't at the right temperature and it was only blinking for a few seconds after the engine started. The sensor is at a point in the exhaust beyond the Y piece so getting gas from all cylinders..

Again, I'm baffled. I've checked and rechecked it but just can't figure it out. Any tips will be sincerely appreciated.

Thanks for reading this far.

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What Bowie said - what's the question?

Hunting at idle could be due to very lean - RV8 likes a rich idle, 12.5 - 13.5 would be my choice for the bottom corner - or simply due to having O2 correction turned on down there, which is not usually done.

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Don't bother tuning to AFR at idle, do it by hand till it sounds right, then set the 4 cells around where idle is to pretty much the same number,m that will avoid the hunting.

Spark can also cause hunting, but not so common.

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