New engine fitted and now starting issues

[N4 FTW]

Hi all, as some of you know, I had the crank on my early 4.2 crack back in July. I have since sourced a new engine and this has now been fitted.

We had diagnosed and replaced the crank sensor and we had thought this was the reason the car would turn over but not fire.

But no, the car still turns over on the starter but refuses to inject any fuel or fire any spark. Any suggestions that we may have missed so far?

Thanks in advance!

[Brummmie]

N4 FTW said:

Hi all, as some of you know, I had the crank on my early 4.2 crack back in July. I have since sourced a new engine and this has now been fitted.

We had diagnosed and replaced the crank sensor and we had thought this was the reason the car would turn over but not fire.

But no, the car still turns over on the starter but refuses to inject any fuel or fire any spark. Any suggestions that we may have missed so far?

Thanks in advance!

Immobilizer?

I had to run a bypass on the starter circuit on mine, it is quite common for this to happen i am told, as this circuit handles some current...

So mine will do what yours is doing if you do not disarm it, does your fuel pump fire?

[N4 FTW]

Yes, the fuel pump primes which it normally doesn't do if the immobiliser is armed (aftermarket Cobra alarm system).

Fuel is getting to the fuel rail too.

[Brummmie]

N4 FTW said:

Yes, the fuel pump primes which it normally doesn't do if the immobiliser is armed (aftermarket Cobra alarm system).

Fuel is getting to the fuel rail too.

ECU will tell the injectors to open, so maybe here?

[itsallyellow]

I would check the ecu earth. If you plug the ecu into the lap top can the lap top see it?

[Gazzab]

Have you got a 4.5 Chip?

[N4 FTW]

Will check the earth now.

Yup, I have a 4.5 chip fitted, we have tried it with both ECU's just to be sure...

[Gazzab]

Could it be old fuel? Blocked fuel filter?

[N4 FTW]

Ok, some updates on this one.

The fuel pump is priming and pumping, the fuel is also reaching the fuel rail with no problem.

The crank sensor has been replaced.

The car turns over but we don't get any spark or the injectors opening.

I have had the Cobra alarm checked and it is working as it should be i.e. it stops the car turning over and the fuel pump priming (both of which it does), it does not effect the injectors or coil packs.

Both the injectors and coil packs were working fine on the old engine.

We have tried the new chip (a map for 4.5 bottom end, 4.2 top end) and old chip (inserted the right way of course!) but we still can't get it to spark or fuel into life.

Any suggestions? However long shot/stupid/obvious please post, we are out of things to check!

Thanks all

[Gazzab]

What else is particular to the 4.5? Are coil packs the same?

[ukkid35]

No Spark or Fuel, but new crank sensor? And no faults showing via the diagnostic software?

I'd swap the MBE now, not much else left.

[N4 FTW]

The 4.5 was just the engine with the water/oil/ps pump.

I have fitted inlet and exhaust manifolds, induction, fuel rail, injectors, alternator, AC pump etc from my 4.2

[ridds]

Check for 12V at the coil packs and the injectors.

Coils should have 12V on the supply line and injectors should each have 12V at one of the terminals.

That's a start.

Do you have engine speed on the ECU readout? Do the ECU comms drop when you crank the engine over?

[Gazzab]

M3John transplanted a 4.5 into his 4.2 - he might have some thoughts...?

[FarmyardPants]

Sounds like the ECU is not getting power/earth, or it's FUBAR

[Allandwf]

Check your voltages to the block, as it sounds like it could be an earth issue to me.

Edited by Allandwf on Monday 5th December 19:09

[coetzeeh]

FarmyardPants said:

Sounds like the ECU is not getting power/earth, or it's FUBAR

Dont blame poor FUBAR - he had nowt to do with this problem

[HarryW]

Allandwf said:

Check your voltages to the block, as it sounds like it could be an earth issue to me.

Edited by Allandwf on Monday 5th December 19:09

I'd go with this first, are you 100% sure the block/engine has a 'good' earth, I'd be inclined to use a battery jump cable to the block (lifting point or some such) to the battery -ve terminal.

I also have a vague recollection the wiring for the throttle pots to ECU is different between the 4.2 and 4.5 I'd check that next, do you get a good TP reading on the diagnostics including checking it as you open the throttle for correct(ish) readings etc.

I also recall the coil packs have a shared earth return to the ECU and the output drivers in the ECU are shared between two cylinders on each bank, firing in pairs. Thinking about it I did have one issue where the coil pack earth pin on the loom was pushed back, worth a look.

[ukkid35]

No Fuel and No Spark means something more fundamentally wrong than TPs here. My money is still on the Crank Sensor or ECU connection/operation. A dodgy earth sounds like a good call too, but wouldn't that be more intermittent?

[N4 FTW]

Thanks chaps, I will take a look at what you have suggested over the next few days.

Has anyone got a spare ECU that I could borrow just as a sanity check? I had a look in the classifieds but there aren't any for sale.