Trying to start my 3.9 V8

[alanius]

Hello,

My 3.9V8 is megasquirted and now I want to start it (finally).
Of course he doens't want to start, typical!

THe strange part is that my fuel pump pumps a few seconds and then it stops, I measered and saw that it doesn't has 12V.
So if my fuel pump doesn't has 12V the coils also don't have 12V => result no spark and no fuel.
First question is this normal (guess not)? And what can cause this problem.
THe solenoid for the fuelpump is good (changed allready and still the same problem). The only wire (blue-pink) that can cause this problem goes to the ECU (pin 37) as this is attached to the solenoid pin 85.

Does anyone know what to check or try as I don't know what to do at this point?

The main solenoid works perfect, EDIS module has 12V

ANy other info - tips - tricks are welcome!!!

May thanks
Regards
Alain

[alanius]

Can I connect this also to ground instead of the Ecu?

[Hybrid_From_Hell]

THe strange part is that my fuel pump pumps a few seconds and then it stops

Does anyone know what to check or try as I don't know what to do at this point?

Quite normal ! its the Fuel being at the right pressure and is controlled by the ECU

Connect up Megatune.

When you crank does the RPM show 200 RPM on Megatune ???

If not then swap around the 2 x VR sensor wires, as one way they give signal and the other = ZERO signal

Nige

[alanius]

when I crank it's 137RPM. But then it suddenly is back 0.

When I crank again, sometimes the fuel pump pumps again and then it goes to max rpm, 7900 region. When the fuel pump stops again it is back 0.

Does this mean that I need to change the wires from the VR sensor?

I know when the fuelpump stops it is actually the fuel pump solenoid that is not activated.

So all that is powered by the white-purple wire doens't have 12V anymore (coils packs, lambda and fuel pump)

[alanius]

how can the ECU know the fuel pressure?

got an external fuel pump + regulator.

As I have a thor mannifold and all is in our light weight

[alanius]

Nigel = hero!

Switched the wires and he makes music!!!!

I'm a very happy person :-D

[alanius]

now it runs, I want to 'tune' the engine correct.
I have a 4.2 map but the engine is a 3.9V8 with thor mannifold with the green injectors. Can I use that map to change - suit to the engine?

Does anyone know how much pressure the injectors need (4Bar?)? As I have an external fuel pressure regulator, so have to adjust this to a correct value.

The timing I have to set according these methode (thank you Fridge Freezer):

Do this:

Then do this:

So that your timing light shows 10deg advance (BTDC), so then you know that the number in "Ignition Advance Table" will be the real timing value you see on the engine.

If I've done that what is the next thing to do?

many thanks!!

[FridgeFreezer]

For the love of god, the ECU does *NOT* control the fuel pressure.

The ECU controls the fuel pump, it will only energise the fuel pump relay if it sees an RPM signal from the ignition input (either TACH signal from a distributor or PIP from an EDIS module).

If you have configured a priming pulse at powerup, the ECU will run the fuel pump for ~2sec and then switch it off again unless it sees some RPM:

[alanius]

I didn't changed any thing, just used the program that Nigel supplied me with the kit (allready 4 - 5 years ago).
That the fuel pressure was not controlled by the ECU I thought also, there isn't a fuel pressure sensor.
But after changing the 2 wires from the VR sensor the engine started without any problem and the RPM gauge worked fine now.

SO now I need to set the fuel pressur correct, how much is the best to use, 4bar?

What do I need to do after I've set the timing correct (like you mentioned) to suit the mapping to my engine?
Read allready a lot of threads but can't find a nice step for step methode to do this :-s

Thanks in advance!
Regards

Alain

[FridgeFreezer]

Ideally you should set the fuel pressure to the standard value, I can't remember if it's 37psi or 45psi though.

There is a step-by-step guide in Nigel's big Megasquirt guide thread, or Nigel's Tuning Thread.

[alanius]

ok will try to find the correct value.

didn't found the 'Nigel's tuning thread' after reading it a couple of times I think I understand it.

thnak you!

[alanius]

I've found on a website 3.5Bar or 50Psi, could this be correct?

[Hybrid_From_Hell]

No

Rover V8 is around +/- a bit 35 PSI

50 will have injectiors over pressure and liable to weep when closed.

Why do you need to set fuel pressure at all, you have a PRV (pressure relief Vlave) on the end of the fuel rail where it then connects to the return pipe ????

Thor top ends.

I am sure that I will have someone disagree with me but here goes.

The Rover V8 is in many flavours 3.5 being the original buick engine, then 3.9 % 4.0 and 4.2 and then 4.6

These engine configs are done via Bore and stroke.

One of the reasons I like the 3.9 serpentine unit so much is IMVHO its the nicest combination, a leaning to "Square" engine,

ie the bore and stroke close to each other which tends to have a rev type engine, vs the 4.6 which is in effect a Long stroke motor,

where the stroke way exceeds the bore, as such you get an engine than doesn't like being reved (as much)

The 4.6 was also shoved in heavy P38 RRs weighing a small bungalow, often with trailers or horse boxes etc, and the aerodynamics of a air craft hanger on wheels

this all put together ended up with a truck which seems poor on bottom end grunt and doesn't like being revved.

Simple V8 tunning is short the trumpets = more power / torque at top end, less at bottom.

THOR manifolds have LOOOOONG trunmpets to give massooosive bottom end grunt and power, which is strongly suited to the long stroke motor

and as it also doesn't like being revved the THOR top ends increased the grunt at the low and mid range at the costs of top end, as such these engines

tend to "Feel" very powerfull in a heavy truck with trialer / horsey box etc when pulling way, and the mass iof weigh once rolling means less power

is then needed to spur it on.

It is again IMHO a bodge from LR, and why JE race engine are 4.5 as then the engine is "Squarer" than 4.6 long stroke.

I am not a lover of the 4.6 with all its issues and even then when sorted a Long stroke motor, adding a THOR top end is like

fitting a hexagonal wheel to a bike that currently has a triangular wheel - its still not as good as a simple round wheel....

THOR Top ends fitted to 3.9 = horrible engine, gaining a bit at the bottom end, and loosing much in middle and top

Nige

[elbekko]

Rover V8 is around +/- a bit 35 PSI

The Thor injectors expect 3.2ish bar (IIRC). The fuel rail has no pressure regulator, it's internal to the pump.

[alanius]

Nigel I know you don't like the THOR mannifold but I had everything allready (for a few years).
also I got limited space in our light weight and if I remember it correct the thor is lower then the gems.

we don't intend to race with this, just have fun and drive off-road, we also have a 3speed auto box in it so on normal road he isn't the fastest (before with the 3.5V8).

The power was with the 3.5 was good enough, we just changed the engine (eventually) because we liked the megasquirt system and to gain a bit more power at lower rpm.

If we don't like the thor we can still change (hope I don't have to do it) to a gems intake

Elbekko, thanks for the information, can I set the fuel regulator correct.

[alanius]

I wanted to set the timing correct today. But when I actually had to do it I didn't understand it at al :-s

Need some more explanation step by step how I have to do that or where I can find this?

Also I have a 4.0 trigger wheel so no marks at all.

[alanius]

I changed the values in the ignition advanced table to 10 (a lot of work to do).

But what do I have to next, keep the table open or burn in into the ecu or...?

Th spark settings table I also found and know that I only have to adjust the trim as the stroboscoop doesn't match with the 10degree.

Connected the stroboscoop lamp to the first cilinder, but I have no marks on my trigger wheel. What do I use as reference to see if it is 10degree or not? Trigger wheel is from a 4.0 V8.

When I've completed that is the old spark table still in the ecu or not? If I just put all the values back in the table?

Does it matter that this is from a 4.2 and not a 3.9?

How can I increase the tick over? Rpm as it is a bit low. Engine stalls most of th times.

EDIT: Think I just found the answer for this; wil be solved when I start datalogging and tune the VE table. Correct?

A lot of questions but it is still a bit of chinees for me :-(

[Bowie69]

To check the timing, I used a hollowed out spark plug in cylinder #1, with a bolt through it, turn it so the piston touched the bolt, marked the pulley lightly with a file, against a self-made pointer, then turned the engine back the other way until it hit the bolt, marked pulley lightly again, and then put a third much deeper mark half way between them and that is 0 degrees

Then... you can mark 10 degrees wither way by measuring the diameter of the pulley and using this formula to work out how far in mm it is along the circumference of the pulley:

pi*d*(10/360)

So for 10 degrees on a 180mm pulley you get 15.7mm (3.141592654 * 180 * (10/360)), measure this distance along the pulley in both directions and put a deep mark in the pulley with a file. Note: you will have to measure your own pulley, 180mm is a complete guess!

Tickover will be down to a bad tune or your base idle is not set correctly.

[alanius]

Just took a pulley from a 3.5 and saw that the 0degree is on the same place as the woodruff key.

Is that always? As i just saw on my 4.0 pulley that there is also a white line on that position? Or isn't that a good methode for reference?

I didn't tune anything so far. First wanted to check this first before I did anything else.

Do you also know how I have to work with the tables to check the timing?

[alanius]

a few steps forward (I guess), marked the pulley with 0° and 10° before TDC (thanks Bowie69 for the info).

Then I made a lip to mount on the engine as a fixed reference point.

When 1st cilinder was at TDC I alligned the lip with the 0°, hope this is correct?

Then I put in the ignition advance main table 10 and 'burnt' in the ecu (don't know anymore how he asked this exactly)

wired the stroboscope lamp and putted it on 10°, started the engine but just the 0° mark was almost correct, so I turned on the stroboscope lamp to 7° and then the 0° mark on the pulley alligned with the fixed point.

When I've put the stroboscope lamp on 0°, the fixed lip almost alligned with the 10° before TDC on the pulley, guess here is also a difference of 3° (if it was possible to have -3° on my stroboscope lamp it would allign on the 10° mark)

so stuck again, what do I have to do now? change the value in the 'trim angle'? If so what do I use -3 of...or did I something completly wrong in the steps before?

thank you for the information!!

[alanius]

Filmed the gauges from the attempt:
http://s31.photobucket.com/user/alanius/media/20130609_144548_zps4276f33d.mp4.html

I guess the gauge from the advance, stays on 10° that is because I "programmed' it on 10°
engine stalls at the end of the movie, hope this is solved when I try to tune the VE table.
The strange noice is from the fuel pump, not the engine

[RangeyRover]

Be very careful with timing guns / strobes with adjustable timing dials. The last one I used on a wasted spark system gave a half reading. Set the dial to zero and compare indicated value to megasquirt value. If both match then all good. Do not rely on the dial to give you valid data.

[Bowie69]

Ditto, simple is best in all honesty.

[Mr Noisy]

Scared the carp out of me when my snap on light gave me 24 degrees advance at idle!!

Turns out it was an advance light so it was actually 12 degrees which was perfect