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Checking For Spark & Fuel


need4speed
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As well as my engine being fully rebuilt it has also been squirted.

Obviously in order to aid cam/lifter bed in I would ideally like it to fire up without too much dicking around. Otherwise I could end up wiping the cam lobes and lifter faces.

Therefore if there is any way I could check that I will be getting a spark and fuel pressure before I start turning the engine over for real that would be a bonus. I can't think of anything but that doesn't mean there isn't a way ;)

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Fuel pressure is easy - just wire the pump to run and check at the schraeder valve. Depending on what version of MS you are using you could also pull the whole fuel rail off and run it through test mode (MS2 upwards).

I think you can also test spark on MS2 as well? Havent tried it yet myself,

Just had a google, looks like you can:

http://www.msextra.com/doc/pdf/html/Megasquirt2_Setting_Up-3.4.pdf/Megasquirt2_Setting_Up-3.4.html See section 2.14

Then if you have a known good map that should start and run it you should *fingers crossed* be ok.

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Thanks quagmire. This Schraeder valve you mention. I assume that's the valve on the fuel rail that looks like a tyre valve?

Also I'm running MS1 so I guess there's no way to check for spark without turning the engine over?

Edit: would something like this be suitable for measuring the pressure at fuel rail http://www.ebay.co.uk/itm/SPX-fuel-pressure-gauge-and-hose-VR-2047-a-/221834883243?pt=LH_DefaultDomain_3&hash=item33a663b0ab

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I've never fretted about the "special startup procedures" or "wiping out cam-lobes at first startup" nonsense.

Millions of cars the world over are first-started with the entire engine having been assembled dry, and with no special procedures regarding 'priming' the oil-system or using crazy 'running-in' oil formulations.

These cars then go on to cover billions of kilometres without significant cam- or cylinder-bore wear. Few cars are scrapped because their engines are worn-out.

Just go for it: light the thing up then drive it hard! One of the best engines I ever built was started-from-cold then 'run-in' by being driven crazily across the UK motorway-network from Reading to Glasgow because we had to meet a scrutineering deadline. After seven hours 'running in' at 5500RPM we then did the Scottish Rally - and came third in our class.

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what would happen if it sat in the garage for a few weeks or months?

you could hand crank it but really by the time you've fired up the start button and the starter motor has got it churning over, the oil pump should have pressurised (you could apply grease to the oil pump.... that's what use to be done, not sure if it's still done or with a crank driven oil pump) which in turn will pressurise your oil system, and hence the oil pressure light goes out...

spark.... you could turn the engine on and put an allen key in the end of a drill, and spin it close to the reluctance sensor, which may in turn fire up the EDIS, and may register a spark if you removed one the of plug leads and installed a plug in the end of it sat on the block to provide a ground.... may work, never given it any thought before.... are you over thinking the problem....?

remember...I know nothing.... hat coat tin hat....

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I'm not concerned about oil pressure on startup. There are tricks to achieve this on the rv8. It was more fuel pressure I was concerned about. Baring in mind my whole vehicle is new.

Everything is dry with regards tank/pump/fuel lines etc. I guess when I turn ignition on for 1st time I will hear the pump priming until pressure is achieved??

Also wondering how long I should attempt to crank before swapping the VR wires round, as this seems to be a common fault causing lack of spark with newly megasquirted engines..

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your shraeder valve question (not sure if I saw it answered).... yes, same as a tyre valve.

gauge, I'll say any guage will do.... (there is a caveat behind this.... in that petrol doesn't like some types of plastic and hose hence it may not last too long but more than long enough for your one off testing (tyre gauge would work, but obviously spraying fuel around the engine compartment before turning it over is not good.... I'll leave that one's judgement to you). The pressure to the injectors will be a few bar (think the pump rating is well documented on the web and probably in any of the other EFI manuals on the RV8).

VR sensor, provided you have fuel and spark, and youre confident of timing and the trigger wheel is on the right way (and Nige has not sent you a 35-1 trigger wheel ... I think it was someone installed for someone else on here to see the head scratching.... ) I'd just swap the wires after turning it over for a few turns and it does not even attempt to fire

Pump running.... no, it will keep running, a pump only delivers flow, a pressure relief valve regulates the pressure on the fuel rail, and the injectors squirt the fuel off the rail, as the fuel flow from the rail increases (as you accelerate and the engine turns faster) less fuel is diverted back to the tank and that what was an excess fuel is squirted out of the injectors

(sorry it sounds a bit condescending it's not suppose to be...)

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by keeping the fuel flowing via a bypass valve / pressure relief valve it maintains a minimum flow rate through the pump which aides in cooling the pump.

In industry / buildings we sometimes use inverter driven (variable speed) pumps which ramp up and down to the demands of flow, but on a fuel pump there is absolutely no benefit (soo small for "savings"), short cycling a pump (turning it on and off) is not good either although (again in industry / buildings) you can use a device called an accumulator vessel.... basically it's like an expansion vessel (diaphragm in a tank / tube) with air or nitrogen (basically a compressible gas on one side) and the fluid on the other, and you charge the vessel to the pump "off" pressure, then as the system demands odd flow patterns, the pump has a switch "on" pressure that re-starts the pump.... again you wouldn't use that in a vehicle as there is no benefit. You can also use the same principle to smooth flow and demand (if you deal with electronics.... it's basically like a capacitor)

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No worries. I didn't think you were being condescending at all :)

I won't use a tyre gauge. I don't fancy spraying petrol everywhere. I've spent far too long on this to watch it go up in flames on 1st start lol.

I'm also trusting Mr Barker sent the correct trigger wheel ;)

On any other engine I wouldn't be worried at all. I've started engines I've rebuilt or repaired before and not been bothered about cranking and cranking until it went, but the rv8 is supposed to HATE that to the point that cam/lifter interface is compromised.

Maybe I'm overly worrying about this aspect of things??

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cam and lifter is lack of oil, as long as you have grease in the oil pump to aide in priming (or any other recipe recommended....) then you should not have a problem after the first few turns of the engine and the oil pressure light drops out (just keep an eye to make sure it drops out though)... ... may be able to backfill with an oil can too from the rocker cover maybe.....

... someone will be along shortly wiser than I for any other guidance / advice....

When's the first key turn planned?

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..When's the first key turn planned?

Shouldn't be long now. But then I've been thinking that for a long time. Life always seems to get in the way :(

I really am getting close now though :) 99% of the vehicle wiring done. Cooling system all but finished - just need to sort cooling fans. Exhaust manifolds fitted - just need to sort a td5 system from downpipes back. That's about it apart from some small details. Need to sort brakes and clutch pipes etc but that doesn't stop the big key turn :)

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MS will run the pump for ~2sec when power is applied IF it is set to fire a priming pulse:

cranking.png

After that it will run the pump when it sees ignition events (so PIP from the EDIS if that's your setup) and shut off again ~2sec after the last ignition event.

Neither the ECU nor the pump know anything about fuel pressure.

Chances are when you fire up 1st time the idle will be way high due to all the farting about with idle valves etc. that usually goes on, which I believe is what you're supposed to do to bed the cam in.

Biggest stumbling block will be whether you have any sparks or not (EDIS will 90% of the time "just work" and the other 10% when you've wired it up wrong "just not work", it doesn't really do in-between states ^_^ ) you can check the minimum (VR sensor working & wired correctly) by pulling the coil pack connectors off and cranking it over - the MS should show the correct cranking RPM (100-400) from the EDIS PIP input, if you get that you're going to get some sparks.

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Thanks for that John. So should my cranking/prime table match the one you have shown above?

I'm certain my wiring is correct, but then I guess most folks think that before they try to start it ;)

I will just need to hit it and hope for success..

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On any other engine I wouldn't be worried at all. I've started engines I've rebuilt or repaired before and not been bothered about cranking and cranking until it went, but the rv8 is supposed to HATE that to the point that cam/lifter interface is compromised.

Maybe I'm overly worrying about this aspect of things??

You are right to be concerned - take this from a bloke who killed a new camshaft and lifters by cranking a 3.9 trying to get the oil pressure up!

The Rover V8 needs oil splash from the crankshaft to lubricate the cam lobes and this is best achieved on a new camshaft, by running the engine at 2000 to 2500rpm for a minimum of 20 minutes. Allowing the engine to idle at all is a bad thing!

The purpose of the above is to work-harden the cam lobes to stop them picking-up on the lifters. Cranking and idle speed allow the lobes to dwell for too long on the lifter, when they have the maximum pressure on them from the valve spring, this creates friction which in turn causes scuffing and ultimately failure of the camshaft.

Using special grease on the lobes and lifters during assembly helps, but of course during cranking most of it gets wiped off; this is why instant starting is so desirable, to get the oil splash going.

It is OK to stop the engine during the 20 minutes to check for leaks etc, but do not let it idle!

Cheers Charlie

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You see! This is why I'm worried! I don't like the idea of wrecking my brand new Real Steel stump-puller or brand new genuine LR lifters because the thing won't start up...

So I'm asking the MS guys what things would you double-check to give myself the best possible chance of it starting up straight away?

Baring in mind that everything is "dry". How many times, or for how long will I need to switch the ignition on to make sure there is fuel in the lines/fuel rail etc.

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Baring in mind that everything is "dry". How many times, or for how long will I need to switch the ignition on to make sure there is fuel in the lines/fuel rail etc.

Bit academic really, it'll start when it starts! Fuel system should prime within one or two runs of the pump (no need to turn the engine over, just put power on). Beyond that as long as the EDIS side is happy & the timing is within about 90 degrees of correct, it'll probably fire. Running it under no load for a while it won't really matter if the timing is out so if it fires you're golden, just make sure the oil pressure comes up. The lifters will sound like ar5e for a minute or so until they pump up.

if in doubt, adjust the idle stop, over-tighten the throttle cable or unplug the idle valve hole, doesn't take much air to push the idle over 1500rpm.

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