Hi all,

Would I be correct in saying that the phase sensor in the distributor on a cosworth gives the ecu reference to tdc for the fuel injector firing? What controls the ignition timing, Crank position sensor? or does the phase sensor have a hand in the ignition timing too?


Thank for all input.

Cheers.


Tim.

 

Crank sensor is key, it is the only reference to TDC and...well crank position in general, even if it is only a crude 4 tooth wheel ( which identify each TDC...but the ecu cannot know which cylinder is which from this )

Phase sensor only identifies which is cylinder 1 for purposes of sequential injection.

As Cossie uses a dizzy.....phase sensor plays little role in ignition timing as cylinder ID is governed by the dizzy/rotor arm itself.

 

Thanks for reply, so the phase sensor dictates when the injectors fire? Or is this controlled by the cps?


Cheers.

Tim

 

Tim.

www.bigturbo.co.uk

Regards
Paul

 

Neither...both.

The ecu decides when to fire the injectors, the crank/cam sensors just give the ecu some information to use to determine what it wants to do with the injectors.

As Paul has linked, some info here, under hardware

http://www.bigturbo.co.uk/

It's a crude system, but it does still work.

 

Cheers Steve bloody links never come up for me.

Paul

 

Thanks very much, it makes a bit more sense now. It would appear that the cps tells the ecu crank position/ all timing aspect of the engine. i.e.- injectors/ignition. The phase sensor fills in the gaps telling the ecu where the engine is in sequence. So in theory could you not unplug the phase señsor once the engine has started as it would already know the sequence.


Cheers.


Tim

 

Depends on the ecu. Some might allow it, some wont.

On a crank trigger where there is no cylinder ID....it would not be a good idea. At least with something like a 36-1 where there is still a partial ID...ie TDC for either 1 or 4 ( or 2/3 ) and it's easy to recognise any disparities in a tooth count from this, then that ecu may allow you to ignore the phase sensor once running.

But on a system where the crank has only 4 teeth...with no real distinguishing features for want of a better description, then chances of any ecu allowing it to run without a phase sensor are slim ( although as this system also retains a dizzy....again it's perhaps less critical as it could never fire a spark on a wrong cylinder )

 

Thanks very much Stevie, but I imagine it could dump fuel into the wrong cylinder?



Cheers.

Tim

 

No, you have 1 injector per cylinder, it would take some monumental effort for fuel to get into the wrong cylinder lol

It may receive fuel at a different time than expected...but that's no big deal.

 

Yes thats what i meant, at a different time resulting in a misfiring cylinder. it would be quite a feat lol.


Tim.

 

And again No.

It would be physically impossible for fuel to arrive at a wrong cylinder regardless of when it is injected because there is 1 injector per cylinder with the injector located near the valve.

and it would not cause a misfire almost regardless of when fuel is injected, as well proven in batch fire systems.

 

A cossie will cut out while running if you disconnect the phase.

Do you have a problem ? Or do you want to loose the dizzy?

 

Only if it's on an L1 or L6

 

Ah now that would make sense tbh never tried on a L8 or P8 and don't think i ever will.

Thanks Tony.

 

Yes I do have a problem, I have been chasing down a misfire that occurs at 25psi. it is fine at 22psi. I have tested and changed all sensor and ignition amp/dizzy cap/leads/rotor arm/plugs IK27. I have recently replaced the phase sensor(Yet to test) I have also tried a MSD cal6 ignition amp but still does it!
I put a relay in for ignition positive using original as trigger taking 14volt direct off battery plus replaced alternator battery charge cable.
I am now looking at the gap clearance on crankshaft pulley lugs as I only checked in on one lug so maybe it differs across the four.
The fueling is fine as I have a wideband system in car the pump is getting a healthy voltage on boost as i have upgraded wiring/relay on that to.

Bit of a mystery really.


Thanks all.

Tim.

 

I bet its sometimes ok.

 

hi Costina,

No this is a constant problem, I have checked the cps gap and all are within tolerance. When I get it back together I will test, if still doing it I will regap some 071c to 0.45 and see what happens.
Its a pain!


Cheers.

Tim

 

Yes they can be a pain even with the iaw software.

Are you on coilpack or dizzy?

Have you checked alignment between crank and dizzy ?

 

Are you still on the original old engine loom

 

Hi yes checked alignment all is good, its on a dizzy. Yes still running original loom. After all checks are completed the loom will be the last resort. I will probably run cables in to test for the cps/phase/coolent sensors if all efforts fail. I have cut the tacho cable off the coil neg to test as I have heard a faulty tacho can cause misfires too.


Cheers.


Tim.

 

Would have been a lot easier to sate this from the beginning lol


What plug gap are you running ? Has this suddenly occurred ? Or what has changed from it last ran correctly ?

 

Hi Stevie,

As above Denso IK27 Gapped 0.6mm, Had this problem a while came back from sea a couple of years ago and it was evident. Did not affect me before as I was running a gt2871r turbo on it running off actuator alone @21psi.(Held to redline)Then I decided I wanted less lag so fitted a GT2860rs turbo that would boost 21psi until 5500rpm and then drop to 15psi by 6500rpm. So this was the time I started asking about boost controllers which you helped me out with. I picked up the LD performance boost controller as Mark Shead suggested I had a problem with the wastegate being pushed open @ high RPM and that I needed some sort of rev based boost control correction to maintain boost at high rpm.
Unfortunately because of the misfire @ 24-25psi I cannot dial in enough correction to hold 21-22 psi @ redline because of the boost spike that occurs @24-25psi resulting in the misfire.


Thanks.

Tim.

 

Everything you're suggest says inadequate spark.

IF...IF the phase sensor or anything like that was giving a problem, the chances of it being boost related are almost zero.

And it would probably manifest itself as something more substantial than a simple misfire....although it depends how aggressive or noticeable this is that you're seeing of course.

Closing the plug gap down to say 20thou is a cheap easy test

You say fuel is fine....but what are mixtures like leading up to and during these problems ?

 

Hi Stevie,

It is quite an aggressive misfire, almost like hitting a brick wall. The fueling is textbook very very good, starts and idles/runs perfectly. I can leave it for 5months and it will start at first turn of the key.
I shall be regapping the plugs to test, I have noticed that my cts (Coolent temp sensor plug is quite loose, Could this cause misfire? I read on here somewhere that if you bridge the connector the ecu will fuel as if the engine is @ 80 Degrees. If this is the case I could warm the car up with it connected shut her down unplug sensor bridge it and see if that helps.


Cheers.

Tim.

 

Try closing the gap first.

Does the rev counter do anything strange during the problem ?

If you had a cheap USB oscilloscope, you could hook up to both crank/cam sensors and record them for viewing to see if they are dropping out at all.

If you can control when this problem occurs that would make life easier as there could be a lot of viewing there.

A very violent dropout could suggest a main trigger problem though ( whether that's sensor, wiring etc would be up to you to trace ) But again the fact it is boost related....trigger issue seems unlikely.

And are you sure MAP sensor etc is healthy ? If this was doing something strange it could cause problems. Again fairly easy to test/record with a voltmeter when driving or with a Mityvac or similar pressure source.

 

yes I will try to close the gap. The rev counter behaves normally, I shall test the map sensor when she's back together.



Thanks.


Tim

 

What crank pulley does it use?

 

Hi Loomer, It's got the standard pulley on and it's in great condition.


Tim

 

Stevie,

Just tested Map sensor, all seems good. Between pins 11 and 15 @ atmospheric pressure voltage is 1.56 I used a pump and increase pressure to 30psi the voltage is 4.96 and then slowly introduced a bleed, the voltage dropped steadily with no abnormal jumps through the whole range back to 1.56volts.

Cheers.


Tim

 

Ok it's just Ive seen quite a few on aftermarket crank pulleys that loose signal at higher rpm.

If you can run it up on a dyno, watch the timing marks on the crank with a strobe light and see if the timing jumps about up there

 

You need to monitor that on the road really in case it's rf picking up on the sensor