Tacho Failing above 2500 RPM, ok to ignore?

[rebuilder86]

Hi all.
I bought a 1999 ford transit 2.5 Diesel , 4EB enigne which i believe is the 85 kw version.....
2 weeks after purchase, the tacho is begining to ail when revs are above 2500 rpm.
I know how to diagnose this on a petrol engine, but i know next to nothing abotu deisel engine computer management.
Will this failing tacho signal have any impact on required inputs to the ECU?
The current fuel economy of the van is working out to 10L/100km which i think is good.

Further, do these things have a diesel particulate filter of any kind? if so i would be almost certain that this one needs to be replaced, as the previous owner did close to ZERO maintenance. how would one go about checking that?

[vanfox]

First off, buy the Haynes' book, no. 3019. By fail, do you mean it drops and bounces?
The tacho doesn't communicate with the ECU, it's driven from the alternator. Look for a loose connection on the side of the alt.r, also check the alt.r regulated output voltage. Mine is iffy at the moment, also, if the belt is squealing, very common, that will affect the tacho 'cos the alt.r ain't turning full speed and your battery ain't charging.
No DPF fitted. Like I said, get the book.

[rebuilder86]

yeh i decided to check the alternator connection because my litte bit of reading showed the alternator supplied the RPM signal for the tacho. unplug it, no tacho, plgu it in, tacho works jsut not over 2500. I read on this form, that this is indicitafe that the alternator is about to die completely.
Damn good news that it doesnt get used by the onboard computer.
Speaking of which, is there actually even an ECM/ECU on this thing??
What woudl it do, everythign is controlled by the injector pump it seems.

[rebuilder86]

ok today, after being broken into, front window smashed and my tools stolen, leaving the police station the battery light turned on and hte tacho stopped wokring al together. so i tink that means charging problem and probabyl alternators stuffed.
But then after replacign the broken window wiht some plastic, starter her up adn after a minute or so the battery light went out and the tacho started workign again. sadly, this miraculous recovery was AFTER i ordered a new alternator online.
Anyone have experience wiht these symptoms? Hopefuly the alternator is stuffed so i didnt just waste my money.

[MinorMatt]

My experience is if the tacho is playing up then alternator is about to go.


Turbos are ECU controlled, non turbos arn't

[rebuilder86]

HI mat, thank you so much for that. I think it may have been a reply of yours i read on here previously that said that, so you are the reason i am not scratching my head wondering whats going on, and for that i thank you a lot.

[rebuilder86]

so i guess that also means, turbos have the lucas epic pump, which i suspect has ability to change injection profiles based on ECU outputs to the pump.
And non turbos use the other ones, listed as CAV industrial or BOSCH??
What sensors are involved in the ECU on this ting. Im goign to just geuss maybe, boost pressure (manifold pressure) rpm, throtle position, and temperature sensors?

[cherniy_chack]

The speed of the crankshaft ECU receives from the crankshaft position sensor, coolant temperature, boost pressure and air temperature from the respective sensors.
Fuel supply and timing injection injection pump Bosch and Lucas CAB depends only on the position of the gas pedal and the settings of the injection pump.

[Pmacnz]

I have just been through the same dramas with the tacho failing intermittently.
I thought it was the alternator wiring as it was very dodgy so replaced the plug,
Unfortunately it did not improve the situation and the alternator died a few days later.

[rebuilder86]

Yep im driving it today and i found loose connections on Left side battery and the main positive connection on th alt. However cleaning and tightening them did nothing.
Interestingly, and ecouragingly, when i started it, the batt light was on, and the tacho was dead, but after stabbing the throttle a bit it came to life, a bit like how my internal regulated alternator in my 1980 toyota 4k motor behaves; Doesnt start charging (doesnt get an exciter signal) unless u rev it above 1500.
So 8 think that indicates that its a self ezcited alternator, and that is probably related to the part that the tacho senses, and thats probably dying.

[rebuilder86]

OK an update.
I was driving the thing in its semi broken state, up until the other day when i left the lights on overnight, and drained both batteries they have now been charged and one is showing a health of 40 % REPLACE and the other is GOOD and is at 85% health. Both ar 800 amp AGM batteries, not just flooded lead acid.

Now, with that informaton, can anyone confirm a reason for what i was experiencing:
WHen driving, when the battery light was off and tachowas responding, car felt fine. WHen tacho stoped responding and battery light came on (alternator failing) the car felt gutless. Is it possible that the ECU and turbo only work when the alternator is working ?? perhaps only working when at a good 14 volts?
How exactly is it possible that a compression ignition engine can perform differently with a failing alternator?

[cherniy_chack]

rebuilder86 ,answer a several of questions.
1. Does the control lamp of the generator light up when the flasher is turned on?
2. Does the control lamp go out right after starting?
3. Need to give speed so that the lamp goes out?
4. Does the tachometer start after the lamp has gone out?
5. At what speeds does the lamp go out?
6.Do you own a Mitsubishi generator?
My son has a FT with a fuel pump EPIC, the control unit starts to lose power at about 11 V-when the battery is completely discharged.
This FT with a Bosch injection pump can work without a battery at all, only the cut-off valve needs to be modernized.
Remove the steel core from it.
If the generator warning lamp does not come on when the ignition is switched on, then the excitation current is not supplied to the generator.
Self-excitation of the generator is possible if you give a large engine speed.
The generator will start working, the tachometer will start working.

[Frag]

If your van is the 85kw version you say,that makes it a 115bhp epic turbo with intercooler,pretty rare.
If it's still running the EPIC pump,it won't like being run without the alternator charging and low system voltage.
The epic system gets its RPM signal from crank sensor / flywheel so Rev counter not working won't matter,no charge or low voltage may cause 'issues'...

My old 76ps Hallmark mk5,had a Rev counter which never used to work properly if the heated screen was on,rest of time it worked ok.Van was charging fine and no warning light issue.
I didn't bother to replace the alternator just to fix this problem

[rebuilder86]

ok thats an intersting development.
Its registered as having engine code 4EB, and my research showed that the 4EB was the 100PS one. I dont have an intercooler. Straight from turbo to intake.
i thought 100PS was 74 odd kw?? not 85??
Sorry i see, i wrote 85, no idea what mae me write that, it is 74 kw.

Cherniy
1. Does the control lamp of the generator light up when the flasher is turned on?
i cant remeber, but now the light is on all the time, that is, the battery light. i suspect that is the same as the generator light right?
2. Does the control lamp go out right after starting?
Nope.
3. Need to give speed so that the lamp goes out?
It was lie that while it was failing, but now its completely failed and is never extinguishing the light.
4. Does the tachometer start after the lamp has gone out?
It was starting after the light went out during the dying stages but now its just cactus.
5. At what speeds does the lamp go out?
It was going out at 2500 rom, but now jsut constantly on adn intensity of the light behind it is varying wiht rpm.
6.Do you own a Mitsubishi generator?
Im not sure. i havent taken it out yet. im pretty sure its a mitsubishi not a bosch.

[cherniy_chack]

i cant remeber, but now the light is on all the time, that is, the battery light. i suspect that is the same as the generator light right?

2. Does the control lamp go out right after starting?
Nope.

When the ignition is switched on, does the indicator light come on and does not go out after the start?
Do I understand correctly?
I'm well versed in the schemes and design of automobile generators of maschins until the year 2000 of release.
Most likely on your machine there is a Mitsubishi 14 V 90 A generator.
Such generators were installed on cars with injection pump Lucas EPIC.
Here is his photo.
https://img01-olxua.akamaized.net/img-o ... orozhe.jpg
Most likely an integral voltage regulator has failed in the generator.
Here is his photo.
http://www.autoelectrica.com.ua/im/L/P198-IM757.jpg
Its price is about 20 dollars.
Replacement of this site at home is problematic.
It is necessary to remove and completely disassemble the generator using a soldering iron and tin to dismantle the old assembly and solder a new one.
Properly assemble the generator.
It is better to entrust the work to professionals.
But they will find many more defects and repairs can cost like buying a new one.
I'm not sure, it seems, the price of a new Chinese generator Mitsubishi for FT to 2000 is about 100-150 dollars.
Replacing the generator is not difficult.
I wish you success!