Jump to content

Megasquirt Timing Issues


istruggle2gate11
 Share

Recommended Posts

Hi all, (especially Fridgefreezer, Nige, Hoss and Geof :rolleyes: )

I have a little bit of a gremlin in trying to start my RRV8 using megasquirtnspark, it seems close but still a no show. Im getting the odd back fire, a good smell of fuel and of course a spark.

Initially, I had a problem with no vr sensor input, but that has been rectified now - cheers Fridge.

So, Im now left with what just seems to be a timing issue as all the senders etc register on the laptop, the ecu lights fire and I get a very good spark.

Can anybody see the error in how I am set up? I have used the following....

FITTING :

Set V8 to TDC marks

Remove V8 Pulley

On pulley CAREFULLY prise off the dust shield (Rear of Pulley), .....

then Remove the dome shaped spacer (next in from the rear) - then throw it away !

(if you want the trigger wheel to be a couple of mill away from pulley place the ring in a lathe and cit out the centre as a big washer,

then fit between pulley and ring)

Undo the 6 bolts holding the pulley together, and buy some more..... 6mm longer !

Clean up the face that is now exposed on the pulley where the wheel is going to sit, and fit wheel loosely.

Pop 2 or 3 small bits of blue tack in between pulley and wheel

Slide Pulley back onto engine, making sure TDC still 100%

FROM the rear looking outwards, move the teeth on the wheel so that wherever you have the VR Sensor mounted the

CENTRE of the sensor is Lined up with the 5th tooth AFTER the spaced one, ie

Line up the spaced tooth with the sensor (whereever your mounting it) then GO ANTI-CLOCKWISE looking from the back of the pulley towards the front of the engine - Count 5 teeth, and on the centre of the 5th thats the one you want centre of the tooth. - level with the centee of the VR Sensor

Squeze the blue tack, also paint some tippex on the tooth and pulley as a line up

Remove CLAMP in vice and drill through the 6 holes with a sharp 8mm or 10mm drill they vary between pulleys

Bolt up (remove blue tack !)

Replace dust cover

Job Done, if the timing is not 10 degrees exactly make the VR sensor adjustable on a slot to take up minor adjustment

Nige

post-400-1170929414_thumb.jpg

post-400-1170930184_thumb.jpg

post-400-1170930205_thumb.jpg

post-400-1170930529_thumb.jpg

Added the following:

post-400-1170932280_thumb.jpg

post-400-1170930195_thumb.jpg

Edited by 898kor
Link to comment
Share on other sites

Just a thought

There are 2 possible positions for TDC, if you have the wrong one you'll be 180 degrees out on the timing.

The way to check is to set the Pulley to TDC where the tigger wheel is where is should be, then remove Passenger side rover cover and check BOTH valves are closed, the wriong TDC would mean the exhaust valve would show as open.

If it is wrong reset the pulley to the other TDC !, then realign the trigger wheel correctly

Nige

Link to comment
Share on other sites

Nige - is that true for wasted-spark? Since it will fire once on the "real" TDC and then once on the "exhaust" TDC (when the opposite cylinder in the firing order will be on it's compression TDC).

Rog - I think this may be of relevance:

Please note: VR sensor users must use "Time Based cranking" when in MSnS mode.

Yours is set to "trigger return":

post-21-1170933226_thumb.jpg

BTW here's a good piccy of the trigger wheel setup:

CrankTrig_36-1.JPG

Some random bits from the MS-Extra setup pages:

Rover V8 firing order = 1, 8, 4, 3, 6, 5, 7, 2 This would be 2 rotations of the crank, so 720 degs.

To fire this engine in wasted spark we would fire 1+6 together (as these are opposite in the firing order), then 90deg later we would fire 8+5(again these are opposite in the firing order), then 90deg later 4+7 then finally a further 90deg we would fire 3+2, this repeats every crank revolution.

Trigger Angle (deg) is the angle Before Top Dead Centre (BTDC) when the selected trigger position (Trig Pos) Tooth (if using wheel decoder) or the Vane on the crank or the Points in a locked distributor, etc, passes the sensor. This is used by the ECU to calculate when to fire the coil(s) as it knows that every time it receives a trigger pulse it is at xxdeg BTDC and the entire spark map is worked out when to fire from the Trigger Angle. When the engine is first started this is the angle that needs to be altered to get the spark fired at the correct time, this is done by setting the "Fixed Angle" (this ignores the spark map and holds the sparked angle to the value you enter) to around 10deg and, using a timing light, ensure the ECU is firing the coil at the Fixed Angle. If the timing is not being fired at the fixed angle then alter the "Trigger Angle" until the timing is at the fixed angle. Once the Trigger Angle has been changed so the Fixed Angle is being fired by the ECU then change the Fixed Angle back to -10 so the ECU will follow the spark map.
Link to comment
Share on other sites

Nige - is that true for wasted-spark? Since it will fire once on the "real" TDC and then once on the "exhaust" TDC (when the opposite cylinder in the firing order will be on it's compression TDC).

Rog - I think this may be of relevance:

Yours is set to "trigger return":

Cheers John, I will try that, along with some suggestions from Nige over the spark table (it seems I was trying to start with 35° of advance!).

Will keep you all informed, ta.

Link to comment
Share on other sites

I think for your initial 1st start you want to fix the timing, not use the map. Once you have confirmed it's running at the fixed angle (EG everything is where you expect) then you can faff about with the spark map. Doing one thing at a time can make life a lot easier!

Link to comment
Share on other sites

I think for your initial 1st start you want to fix the timing, not use the map. Once you have confirmed it's running at the fixed angle (EG everything is where you expect) then you can faff about with the spark map. Doing one thing at a time can make life a lot easier!

Hi Fridge,

You don't happen to have a base spark map for a 3.9 do you ?

Cheers,

Andy

Link to comment
Share on other sites

Fridge: My Cranking Timing is set to Trigger Return and it starts (sometimes take a bit more cranking when cold), but will change it to Time Based (never spotted that in the manual lol)

808kor: Have you tried upping the Req. Fuel figure or done the calcs for your engine & injectors? 14.8 seems low (lean) to me for a 3.9, i think i worked out a 3.9L to be 19.2 and i run 22.2 but have been erm.. fiddling with the VE table

Can anyone else confirm this?

Link to comment
Share on other sites

Fridge: My Cranking Timing is set to Trigger Return and it starts (sometimes take a bit more cranking when cold), but will change it to Time Based (never spotted that in the manual lol)

808kor: Have you tried upping the Req. Fuel figure or done the calcs for your engine & injectors? 14.8 seems low (lean) to me for a 3.9, i think i worked out a 3.9L to be 19.2 and i run 22.2 but have been erm.. fiddling with the VE table

Can anyone else confirm this?

Hi Tom, in a word no, but I will give it a shot, just starting to panic now!

Link to comment
Share on other sites

Roger,

Are you using EDIS? If so, you may well have a plug in the wiring tail you got with the EDIS controller. If you pull this out it will disconnect the timing signal from the Megasquirt, forcing the EDIS into limp home mode (fixed 8deg timing, if your trigger wheel and sensor are spot on). Get it running with this first before bringing Megasquirt into the equation.

The other thing that springs to mind is have you got your coil packs connected up correctly (EDIS controller to coil packs as well as HT leads). The cylinder number markings on the coil packs are irrelevent (almost certainly wrong for your engine anyway) - what matters is which coils you've connected to which wires from the EDIS controller. Once I'd worked it all out I painted the correct cylinder numbers on my coil packs...

Link to comment
Share on other sites

Since Rog isn't about:

1 - No Rog isn't using EDIS, he's using four coil drivers in the ECU itself. This is why I suggested setting the fixed timing to a certain value (setting -10 makes it use the spark map) so you have one less variable to worry about.

2 - Coil packs are RV8 GEMS type so their order should be correct from coil to plug, however between MS and coils couldn't hurt to do some triple-checking :ph34r:

3 - No I don't have a spark map for anything, ask Nige or Geoff :P

4 - Rog, don't panic, it'll get sorted. Panic leads to horrible bodges.

Link to comment
Share on other sites

Went for a run tonight and it definitely starts better with Time Based cranking :)

Thinking back to when i first got it running, i tried mucking about with different Req Fuel values with it ticking over and remember it barely ran on 14ish values.

I got the 22.2 value through the following:

3.9 Injectors are 18.25 lb/hr at 43.5PSI (found this figure somewhere on this forum)

3.9 Fuel Rail standard runs between 34 and 37 psi

Ran this through Injector flow rate calculator at http://www.csgnetwork.com/fiflowcalc.html

Gives: 16.37 lb/hr

Run through Megatune Req. Fuel Calculator using:

4554cc

8 cylinders

14.7 AFR

gives 22.2 req fuel

or using 3947cc gives 19.2 req fuel

or is my maths wonky :unsure:

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy