Valver won't start

All aspects of tuning,modification and repairs to the BX 16valve.
Matt H
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Post by Matt H »

docchevron1472 wrote:I'm a tad bladdered, and can't be arsed to read back through all this, but, I thought you had no spark?
In which case cam timing is irrelevant, since the CAS tells the ECU where the engine is cycle.
Even if it had skipped all the teeth in the world you'd still get a spark.
That's all I needed to know...

Ta
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Post by NZ16v »

dunno if this can help, but if my old man was buggered as far as solutions went-ie citroen manuals were out of ideas too, he got another identical car over for the day, and swapped bits over to his hearts content-you got two cars, one working, one not-the answer is there somewhere!
Would rather be driving ONE 16v,than fixng TWO.
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Timmo
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Post by Timmo »

matt, if its still not going have you tried a jump lead from the battery negative to the block/cog box to check if its an earthing issue???
Timmo 8)

After all i am the Cornish one!

Its Because its French!
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Matt H
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Post by Matt H »

Timmo wrote:matt, if its still not going have you tried a jump lead from the battery negative to the block/cog box to check if its an earthing issue???
I tried this and also replaced both earth straps, and cleaned every electrical connection I could find. The answer is in there somewhere, and I now have the car in a better place to work on it, so I've not lost all hope yet!

I still think there is a more general electrical problem... but it's not the earths.

And the idea of using another car has also crossed my mind, but the the days of finding a cheap valver are over.

I was seriously looking at the Triton Green P2 in the for sale section, but I just know that I'd never get mine sorted if I had a better car, and it is too good to give up on.

Cheers,
Matt
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Kitch
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Post by Kitch »

I think you're now into checking wiring to amp, coil and TDC sensor. Otherwise is the ignition relay clicking in? AFAIK its the same relay as the fuel pump, may be worth switching them. Check they are the same first though!
prm
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Post by prm »

Kitch

The main relay and fuel pump relays are slightly different. Main relay has an inbuilt diode on the coil supply side to avoid a return signal when using the diagnostic socket and a negative return to fuel pump relay main positive supply.

Regards. P

Matt.

To possibly expand on the CAS workings

The ECU needs to see a resistance reading from this unit to energise the ignition module.

I’m not totally familiar with the inner electronic circuitry and components within the ECU.
Should imagine a small voltage is applied to the CAS prior to cranking.

Once the ECU sees an AC voltage generated from the CAS, this would then trigger the fuel pump relay and the ignition module side.
If there’s no output or incorrect reading, the car just wont start, as the CAS is indicating to the ECU the engine is stationary.
The car may fire once, occasionally, while cranking if the unit is faulty or intermittent.

The AC cranking voltage reading from the CAS maybe difficult to detect with a digital meter, as the output is pulsed.
Using an analog unit, depending on the total range used, the needle movement can be very small.
Removing all the spark plugs, then cranking with the ignition on, may give an improved reading. Possibly oscillating between zero and 6-10 volts AC
Also, might be worth checking the fuel pump operates and not locked.

Best of luck
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Kitch
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Post by Kitch »

prm wrote:Kitch

The main relay and fuel pump relays are slightly different. Main relay has an inbuilt diode on the coil supply side to avoid a return signal when using the diagnostic socket and a negative return to fuel pump relay main positive supply.
Agreed with this, just developed my own little problem on my car (have fuel, air and spark but will not fire....looking into possiblity theres not quite enough fuel) and discovered these relays are in fact not what I thought, so discount everything I said about them as b*****ks :lol:
prm
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Post by prm »

Kitch

If you’ve got a spark and fuel.. could…….???? be an electrical problem with the injector circuit.
Couple of points you may like to try.
Remove the air filter top cover and spray easy start into the inlet tract while cranking.
.This should confirm the ignition/spark side………… Watch out for any flash backs

I’ve tried injecting through the manifold blanking plug. The flash back comes out like a flame thrower, and... a new hair style. :oops:
Check the electrical multipin block connections under the plastic sleeve near the top engine mount.

Even if there were one or two faulty injectors, you should be able to get some resemblance of firing, as all 4 injectors’ fire at the same time.

With ECU checks. Ignition off. Continuity/resistance meter test, ECU plug pins, 33 to 35 and 14 to 33. These link both connection sides on the injector and ICV circuits.

Double check the fuel pump runs. Bridge out the fuel pump relay main connections. Remove the fuel rail supply hose, placed into a large coke bottle.

Careful with any spray or vapour. You may end up with……..

NO b*****ks. :lol:

Regards
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Kitch
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Post by Kitch »

prm wrote:Kitch

If you’ve got a spark and fuel.. could…….???? be an electrical problem with the injector circuit.
Couple of points you may like to try.
Remove the air filter top cover and spray easy start into the inlet tract while cranking.
.This should confirm the ignition/spark side………… Watch out for any flash backs

I’ve tried injecting through the manifold blanking plug. The flash back comes out like a flame thrower, and... a new hair style. :oops:
Check the electrical multipin block connections under the plastic sleeve near the top engine mount.

Even if there were one or two faulty injectors, you should be able to get some resemblance of firing, as all 4 injectors’ fire at the same time.

With ECU checks. Ignition off. Continuity/resistance meter test, ECU plug pins, 33 to 35 and 14 to 33. These link both connection sides on the injector and ICV circuits.

Double check the fuel pump runs. Bridge out the fuel pump relay main connections. Remove the fuel rail supply hose, placed into a large coke bottle.

Careful with any spray or vapour. You may end up with……..

NO b*****ks. :lol:

Regards
Well, spent an afternoon out there with a multimeter, but first job I tackled was to change the fuel pressure regulator and hose (just in case!) and switch the ign and fuel pump relays over with an old wiper relay just to test (I know a wiper one wouldn't last long!) No joy there.

Having printed the fuel system PDF off on this very website (thanks Luke!) I went over the car and mainly through the ECU checking resistance at whether I had 12v at the pins. All ECU pins were fine. Went through until I got to the fuel pump relay, which with the Ign set to 'M' has the 12v on the pins on the plug, but once plugged into the readout on the remaining pin is -12v, whichever way you put the multimeter! Then when you crank it over, this fluctuates between 6-9 volts as it cranks (assuming this is the output for the fuel pump?)
At the pump it's sitting at around 8v when cranking.

Tried re-earthing pump seperately, no dice. Earths in engine bay are all good and the battery is reading 12.4v and counting (it's on trickle charge).

Haven't tried a seperate 12v feed to the pump yet, that's next if no luck elsewhere. I can hear the pump trying when the car is cranking over, so I don't think my problem is with the actual pump. But the problem persists even if you substitute another relay for it.

So....erm......sorry to use your thread Matt, how you getting on with yours? :lol:
prm
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Post by prm »

Also…. Sorry Matt………. Any joy with yours? …Let us know

Kitch

Could be ???? the fuel pump is locked/jammed, especially if its been standing for some time. Or, the pump has failed.
A slight whack on the pump rubber housing with the ignition on may help.

With the ignition On… There should be 12V + …on two pins of the pump relay plug.
The thicker wires are the pump + supply and feed.
Thinner wires are the coil + supply, and feed to ECU pin 20.
You can use any std. 4 pin 25-40 amp relay with the pump circuit.


Regards
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Kitch
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Post by Kitch »

Well, bypassed the relay today so the fuel pump comes on with the igntion set to 'M' and sure enough the pump starts buzzing. Whether it's buzzing fast enough I'm not sure, as it still won't start!

Going to put 12v across it possibly tomorrow night direct to the pump and see where I get.
prm
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Post by prm »

Might be a question of just removing the fuel rail supply hose first, to confirm fuel is reaching this point.
Reconnect, and then remove the return hose to ensure the rail regulator is working.

Would recommend with any fuel flow or pressure checks it’s a two man job, just encase. The pump generates a fair pressure.
The rail regulator maintains a pressure to the injectors at about 3 bar stationary and reduces by approx 5-15 psi with the vac hose attached and engine running.

Did you try any easy start spray?


If the voltage to the pump drops as you mentioned. Amps may go up, possibly indicating a locked or sticking pump ??

Regards
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Kitch
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Post by Kitch »

Well just to totally spin things around......the pump is fine! I re-charged the battery fully last night (the one that flattens it, then recharges it)
Now I have 13.4v between the terminals of the battery, rather than 12.2v ish. The car still spins over, just a bit quicker. But crucially there is now 10.8v at the pump (with the pump running).

Still won't start though! Relay by-passed or not. I borrowed a fuel pressure tester from work and it blew the end off! Petrol in eyes burns, fact!

So....I have fuel in the rail at high pressure, and the plugs are wet with fuel when I remove them. The plugs are sparking if I remove them and hold them against the engine while cranking. Nice thick blue sparks. Cam timing is also fine.
But still no start up!

I've been told of a theory however, which says that a spark plug mounted in the head attempting to spark under compression will have more trouble than one in the open, such as when I remove them to test for a spark. Something to do with air volume? So I wondered if it's possible my problem is in fact ignition related, not fuel. I don't have any plug lead testers, but may be able to get hold of some tomorrow.

There is still always the possibility that my injectors aren't firing at the right times. Guess the ECU controls that?

Now the coil is only about 18months old and has only covered around 2k miles, but I checked the resistance across pins 2 & 3 and got 1.2ohms, when apparently I should have been getting 0.8ohms. Checked 2 & 4....nothing. Should have been 6500ohms! Now I'm not sure exactly how a coil works, but I'm guessing that's not right. I couldn't find the resistance figures for the ign amp to test that sadly.

The only pin test on the ECU plug that has so far failed is the coolant temp sensor one, which refuses to register anything. Seems odd, but even with this unplugged the car still ran!

So tomorrow I'll see if I can get a HT lead/plug tester, maybe even order a coil if I can find one cheap enough!

Matt.....any joy with yours? :lol:
prm
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Post by prm »

.Keep at it. Been there.

I think the pump has a stall out pressure of about 90psi.
Also had a full facial from a split supply hose..

It will most probably end up being something quite simple.

Process of elimination time.

Check the resistance across ECU pins 35 to 33. 6-8Ω.?? Let us know. Injector circuit.
Injectors are timed and pulsed via the ECU with signals from the CAS.
35 to earth. Reading. Zero
If I remember you’ve got no engine management dash light.
But check 35 to 17.
23 to 25. CAS. Reading, around 500Ω
22 to 6. ATS. This time of year, around 3kΩ
13 to earth, CTS. Again 3kΩ

CTS and ATS have approximately the same readings static.
With the CTS. If there’s no reading, should imagine ECU will set the injectors to the absolute minimum pulse time.
As the engine warms up, CTS resistance reduces along with the injector pulse duration, then, trimmed by the ATS.

Stupid question I know. :oops: Firing order on the distributor cap OK??
Cap centre carbon pin not stuck/retracted?

4 to earth should be zero.

Next unit to check is the AFM. The multipin plug connections can sometimes work loose.

Regards
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Kitch
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Post by Kitch »

Pete,

Actually checked most of that already, so can take some comfort in the fact I was already on the right track.

Bought home a timing gun today, just to check I do actually have a spark in situ. Hooked it up to no1 lead, turned over....I have a spark.
Hooked it up to no2 lead, turned it over....engine bloody started! :?

I believe the common abbreviation for this is WTF :?: :!:

It now starts, stops and re-starts fine, although this was always the case when it's warm. The test will be to see if it can start from cold again tomorrow. This is not ideal....because now I don't know what's causing it :(
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