FPR Stuffed & Back to Carb Only

Hi all. It’s been a while since my last report.

I recently went on the VMCi economy outing. The car did not perform very well. It was way down on torque in the low RPM’s below 3000RPM. In fact for most of the time I followed a lovely couple in their original 998cc clubman and I had some trouble keeping up with them on the steeper hills. My thoughts turned to pushing out my 6′ 97kg 15yo son, but thoughts of facing his mother deterred me!

Today I had a look at the EFI and as surmised in my previous posts the fuel regulator is not doing it’s job; its allowing the pressure to jump all over the place. As well the gauge is getting stuck and not returning to zero (it most probably bashed it self to death).

I decided I would put the SU bell back on returning the car to carb with ignition only control from the ECU. One of the reasons for doing this was to see how the car goes back on carb and to see if it is fuel related.

Well one thing it proved, was yes the FPR is rooted (Aussie for ‘stuffed’ for OS readers). I lowered the OP pressure to around 3PSI, but after a while the pressure jumped to around 16PSI which you guessed it; flooded the engine to such an extend it became hydro locked. End of experiment.

I’m really not too happy with the fuelling side of this conversion, but the difference having programmable ignition was very noticeable, especially in the lower RPM ranges. Due to this I’m considering returning the car to ‘standard’ which is quite easy to do. I would like to be able to use and enjoy the car with out worrying about VE maps AF ratios etc. etc….

I feel a little bit disappointed that this project has not been a total success, but maybe it has; the original purpose of this project was to help me get out of a period of major depression and to re-join the work force, (achieved), and to learn more about EFI also achieved.

As to what the future holds in store for this car….. stay tuned! Hint ‘sparks’.

Thanks all to those who have been following this thread.



Injector Dead Time 2/4 Squirts

Today I had a look at a few things to do with the tune of the EFI.

  • I never had time (unless I did but have forgotten) to find out how accurate my dead time settings were after my previous static testing. Well, one way to test if you have the dead time right is to tell the ECU to squirt only 2 squirts per cycle (I’m currently running 4 per cycle), and see if the engine idles smoothly and at the same A/F ratio (14.0:1 is what it is set at). When I first did the change, I thought I’d done something wrong, as the idle and AF ratio stayed the same. I then noticed that the injection pulse width had nearly doubled when on the 2 squirts, this meant that the dead time was spot on! Yeah! On the MegaSquirt extra forums they constantly say to get your dead times right.
  • I and ran the auto tune program, whilst driving around the local area and down to Werribee South for lunch by the sea. Initially it was a bit reluctant to rev out past 4000RPM, but soon no problems going to 6500 RPM (I don’t like taking past 6K, but I just had to see if it would go there!) and AF correct. The VE table now looks like it should, especially at the lower load points, also it has less peak and troughs. I need to do a bit of further tuning, mainly in the higher load/RPM areas, but It’s quite drivable as is. Wish there was more hills around here!
  • In the process of tuning the car, I checked and set the fuel pressure to 14.7PSI (same as the Rover SPI… 1Bar). I noticed that above 11PSI or so, that the needle of the fuel gauge started to shake by a bout 1.5 – 2 PSI. I have a feeling that the SPI pump is a bit up the shit, or maybe it’s the fuel pressure regulator. Either way it’s about time I got the fuel pressure sensor screwed in and wired up to the MegaSquirt MSX board that I have recently purchased. The MSX board has additional A/D inputs and digital I/O’s needed for this and when I go the MAF route. The ability to monitor the fuel pressure will allow me to see if I have sufficient pressure/volume.

Cheers, all comments, criticism welcome!


MSX Expansion Board & SSR

Just an update:

  • A while ago I ordered an MSX Expansion Board for the MegaSquirt III. This allows for more I/P & O/P’s.
    The reason I wanted this is I have run out of analogue I/Ps on the main board and I want to try the new functionality of closed loop control of my fuel pump. This will give me in effect a returnless PID Controller fuel system.
  • I’ve also ordered a Solid State Relay (SSR) that will be the switch for the  Pulse Width Modulation (PWM) from the MSIII. Having extra analogue I/P’s will also allow me to monitor the fuel pressure which is also used in the returnless fuel controller side of things.
  • Anyway parts and an extra wiring loom arrived today, pity I don’t have time at the moment whilst I’m frustratingly searching for a new abode.

Over-Run Fuel Cut

Just a small update:

  • I have done more VEAL tuning whilst driving car to work for the last week or so. Car is very smooth. There is certain areas within the VE table where it’s very difficult to tune, but these areas aren’t normally touched with normal driving.
  • I decided to revert to standard unleaded and was getting some pinging around the 2000 RPM mark, so I backed off the advance over most of the ignition MAP. To get the best settings, I’ll have to get on the Dyno, but I’ll wait till I’ve tried the MAF route first.
  • Today I turned on the TunerStudio ‘Over-Run Fuel Cut’ feature. Works a treat, but doco I’ve read says you should have your VE table dialled in well (I think I have). The engine did stall a couple of times though so I upped the ‘lowest RPM to re-engage fuel’ from 1100 to 1250 RPM and it’s now cured! Would be interesting to see how my fuel economy improves especially around town driving start stop where this fuel cut works more. Also I get better engine braking.


14point7 Wide-Band O2 Sensor

Nothing much really to report.

I took her to work on both days this weekend. She’s just purring along and over the last 320km she achieved better than 53MPG!

One thing I have noticed is that she backfires when starting. This has only happened since the upgrade from the MegaSquirt II to III hardware upgrade. I did see a mention on the MegaSquirt Extra forum from another user that they were having backfires on the latest firmware (same as I have). I think I’ll leave alone until the firmware goes production ready.

I’ve also put the TunerStudio software on my Netbook so I can use it rather than my MacBook Air. Reason being is that the Netbook fits really well in the L/H dash and the Mac doesn’t.

The first 230k’s were the trip I took to Marysville, so very little stop and start, the last 100k’s just local and highway trips to work. I’m very impressed!

One observation is the new 14point7 wide-band O2 sensor seems to be a lot quicker in reacting to AFR changes compared to my TechEdge. This will obviously (I think) help TunerStudio tune the VE table more accurately.

I’ve also just tested the Netbook to make sure it can connect to the ECU. It does, both by Bluetooth (I can fit an RS-232 to Bluetooth adapter on the ECU), and USB.

If I had multiple injectors running sequential injection, Megasquirt can also progressively shutdown the injectors for a smoother transition. I don’t really feel the cutoff or reengagement, maybe because the 1310 is not the smoothest engine?

My Renault has this feature, and I can feel the reengagement sometimes. I also get 6.4l/100km (37MPG) combined city/highway.

I’ll try to get some comparative MPG readings.