Souleyman

Have a problem with ECU voltage on boost.
My IAW monitor shows 13-13.5 volts on idle and on other run modes.
But if the engine is hot the voltage drops below 12V (11.5-11.8) on maximum boost and the engine is misfire.
I've replaced alternator but no changes.
Have checked the fuel pressure but it's ok (rewired).

Don't know what to do next. Need help, mates.

4x4, 803, T34, 071C-0.65mm gap, closed loop, chipped by Stu

KSA-Cossie

iTrader: (4)

Have you re-wired the pump wiring ?

Souleyman

Yes, mate, but...

KSA-Cossie

iTrader: (4)

Direct to the battery using the original wiring to activate the relay ?

Souleyman

Absolutely right. Original wiring just controls relay.

PGT

when the engine is hot, what is the battery voltage at idle?

when hot - does the battery voltage increase when you rev it above idle.

an alternator i had was too close to the exhaust manifold and the internal regulator was getting overheated when the engine had been on boost for a while - if this is the situation in your case then exchanging the alternator would yield the same result

Souleyman

I'll check this but if I remember it was more than showed me the IAW-monitor connected to the ECU. It was slightly above 14V.
And the problem with drops during the boost then already was.

foreigneRS

obviously IAW monitor is showing you the voltage inside the ECU (via an analogue to digital converter) not at the battery

Souleyman

Yes, I know mate.
But I measured sometimes ago the voltage on legs inside the ECU. The difference between points of the plate of ECU and on the IAW monitor was near 0.5V

Souleyman

I thought about this quite a pausible reason. And Stu thought as but I've changed regulator and then the whole alternator. No positive results.

LHD220Turbo

iTrader: (4)

the most important thing is to have the correct voltage at the fuel pump on boost

have you replaced any of the earth straps/ cables?

Souleyman

Yes, mate. I've made new wiring for the pump and exelent fuel preassure on boost talks about it.
I've tested pump preassure first having made some tests with fuel preassure gauge. I think it sounds like the causes of drops are not in the fuel pump and its wiring...

Lee_R21Turbo

iTrader: (1)

Change the engine loom its obviously breaking down somewhere under high load.

Souleyman

I'm afraid that you are absolutely right...
But you do not represent, as will difficultly and expensively to bring new loom from UK. And here in Russia I can't find the new necessary connectors for making the loom, though I'm able to work with an electricity.

I'll try to connect the ECU direct from battery and will test it on boost. If the voltage will stop to drop, my way is to change or to rebuilt the engine loom I think.

Stu @ M Developments

iTrader: (12)

First of all check the ENGINE EARTH STRAP. I have seen that cause this same issue many times.

If not...
Run a cable direct from the battery to pin 20* of the ecu and try again. If it works, the fault probably lies in the power relay circuit so you can just rewire that part pal. If not, run one from chassis to pins 1 and 19 and try again. This is your earth circuit. If that fixes it, the solution is NOT to rewire direct to pins 1 and 19, so please ask for further information on this topic.


Good luck.

*
I am suffering from flu at the moment so PLEASE check that number is right for the positive feed. I'm sure it is but I'm dizzy and sick at moment.

Souleyman

Glad to see you here pal

This tests are in my primary plans. I'll write here about the results.

By the way. The engine ground wire is new. I've made it some times ago. And on the last week I've changed the clutch and have checked that wire and its strap. All was in a good condition.

Souleyman

I've solved this problem, mates!

It was............................... a bad contact in injection fuse socket...
Now I have 14V on IAW display and really 14.3V on the legs of the ECU. And now it's never drops below 13.7V on IAW with all lights and others on.
And accordingly not engine stalls on boost at all.

Thanks all of you fellas for the help and advices!

LHD220Turbo

iTrader: (4)

Good news

dom123

iTrader: (1)

what do you mean by injector fuse socket?

Souleyman

I mean the connector of fuse near injection relay mate. This relay and fuse are used for an ecu injectors and for other engine systems.
Sorry for my english and terminology.

foreigneRS

i understood what you meant after i'd thought about it for a minute

Souleyman

One minute... not so long time.


By the way, merry christmas!

foreigneRS

merry christmas to you in russia. i bet it's cold there and really feels like cgristmas?

KSA-Cossie

iTrader: (4)

Glad you found it pal.

mechanic28

iTrader: (5)

pleased ya sorted it fella

Souleyman

Yes, now it's cold and snowing.
And after the new year will be colder and will be more snow than now.
Moscow streets have stopped.
Too much small crashes.
Everybody try to find some gifts for new year.
And crisis everywhere...