Just Fuel and Sparks

  • Hi, for my sportscar project (see "Newbie" Le-Mans style car). I would like to test run the engine which is currently in a dedicated stand. So, I don't need p/s, alternator, air con etc.

    Just a simple set-up to deliver sparks and fuel. I am now building the exhaust manifold. A few queries :-
    Do I need to build in an exhaust temp' /O2 sender ?
    The engine ECU is (temporarily) not available and I don't know which year of car the K8 V6 came out of (best guess would be a '95). Is there something else that would do the job for initial tests ?
    For fuelling, should I be able to hear the fuel pump going once power is applied - Any further tests ?
    I'll only be doing short (say, 1-2 minute) test runs to start with so, shouldn't need any cooling ?
    Anything else I missed out - please let me know...
    Thanks, Dave

  • Hello,
    If you are using the standard fuel injectors then you will require the mass airflow sensor, the O2 sensors (there are 2 of them, one left one right), the throttle position sensor, crank shaft position sensor, knock sensor and EGR connector all wired to the ECU as all of these control the fuel amount and timing.
    The ECU in the K8 has the ability to learn from all the sensors and to adjust the fuel to air ratio as well as the timing.
    The easiest way to get the engine running would be to change the fuel injector rail and the inlet manifold for carbs however i have only seen this done once on a custom build car, the only other way i can think of doing this would be to control the injectors separately with a programmable ECU or dyno test the engine.

  • @rax Thanks Rax - very helpful as always. Am I correct in thinking that the K8 had 3 'generations' of ECU throughout the '90's ? As I don't know which year of car mine came from, I'm wondering if there may have been just minor upgrades to them and I could try and source any one of them, perhaps ? Yes, I believe they are the standard injectors...

  • Hello,

    No problem.
    With regards to the ECU, i don't know a lot about them as i have not ventured down that path yet.
    As much as i can remember the ecu, mass airflow sensor, dizzy and wiring harness all match up however i'm not sure though.

  • @rax I'm currently looking at 'aftermarket' systems eg Emerald, Megasquirt etc in case I can't locate a correct stock K8 one.

  • Hello,

    As far as i can remember, the megasquirt system is wired into the ecu with a bit of modification.
    I will have a look when i get home as i might be able to help you with regards to a stock ecu, not sure on generation but they are K8 ones.

  • admin

    Hi Dave,

    With regards to MegaSquirt, they do a plug and play option that connects direct into the existing wiring harness. I can't remember if it has out of the box support for both O2 sensors, but typically most of us switch to a single wideband AFR sensor that would need to be downstream once all exhaust pipes are collected into one.

    The PNP MS units come with a MAP sensor, so you can actually do away with the MAF unit if you wanted to, the thing to note here, is that you would need to install an independent intake air temp (IAT) sensor just before the inlet manifold.

    The other final consideration is emissions, you can tune the MS units for emissions, but they aren't technically legal on the road, so you might hit MOT issues if your in the UK. - Just seen your other post about the car, I guess this doesn't apply :D


  • @rax Hi Rax - as I'm cleaning the engine (working through the grime !), I am finding odd numbers cast in here and there. Found one today on the VRIS pipework. Will let you know if I find anything that may identify the generation other than "K8" cast into the block on the rear bank.

  • @jono Hi Jono - thanks for the info. Yes, it's a pure competition car (ie no road use). For the exhaust design, I'm planning a 'freeflow' 3-into-1 system for each bank. Due to the length of the primaries (quite long) and the secondaries (quite short), I may go with a sensor in each collector. The alternative would be to fit just one in a 'balance' pipe connecting the two secondaries (I think I'll need a balance pipe anyway to get a proper extractor effect from the whole system). Bit undecided as to the final design but I'll weld up some pipes and see how we go. Must get on with some carbon work on the chassis whilst the warmer weather is with us !

  • We probably won't be running EGR on the competition car. However, the ECU will almost certainly require a sensor input. I imagine we could tell the ECU that the EGR valve is (permanently) "closed". Does anyone know how we could 'spoof' this - a voltage level, resistor, jumper wire etc. ? Thanks


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