Duratec crank position sensor alignment - how critical?

[Shaun_E]

Has anyone replaced a crank position sensor on a Ford Duratec engine?

I have an ongoing misfire which I am struggling to cure and one of the things I did was to replace the CPS. I found TDC using the hole in the crank pulley method (M6 bolt goes through it and into block) and used the supplied plastic tool to locate the sensor in line with the trigger wheel tooth - at least as best I can as it's a bit fiddly.

Would any small misalignment cause major issues? I guess it could mean that the timing is ever so slightly out?

So far I have replaced the following:
Coil
Plugs
Plug leads
CPS
Engine loom (CPS wires now shielded)
ECU

The throttle position sensor seems fine as I can see full deflection in the Emerald software and data logging shows a smooth arc as it is moved.
Battery voltage is good.

Engine starts and idles OK but fast throttle movements cause a misfire.

[Mark Durrant]

Shaun

This could be fuel related, have you checked the fuel pressure and how old are the injectors, it might be worth getting these checked

Mark

[Shaun_E]

Hi Mark - there was a fuel issue as in the fuel pump stopped working! The connector inside the tank had broken but I've fixed that now and the pump is working fine delivering good fuel pressure. I will put the pressure gauge back on and check with the engine running but it's a damped gauge so probably won't show any transient pressure drops.

The injectors is a good shout though - I could get them checked/cleaned. 

Thanks,

Shaun

[Shaun_E]

Quick update - I put some fresh fuel in and have checked I'm getting a spark at each cylinder and it is now running a bit better. However, when I increase the revs slowly, it reaches a point where it starts to misfire but there is a lot of unburnt fuel - it pops and bangs and shoots flames out the exhaust! More thinking to do!

[TJG]

Might be worth disconnecting the Lambda sensor, getting the engine up to normal temperature and see if any improvement, also if you have access to a decent scope check the signal from the TPS as not all spikes will get picked up. Good luck!

Tony

 

[Shaun_E]

No lambda sensor but the TPS is the only other thing I haven't replaced so will look at that. 

[Tony Whitley]

I replaced my crank sensor and it didn't seem to be particularly sensitive.  Although since then I haven't had the car back on the road properly because there is an intermittent fault which kills the engine after 30 minutes or so 

[Shaun_E]

[John Vine]

A long shot...

Check the wiring where it enters the TPS connector (and in as far as the terminals).  These wires have a tendency to fracture (especially the brown) due to engine vibration.

(ETA:  Ah, just spotted that you've replaced the engine loom, so unlikely to be the TPS wiring...)

JV

[Geoff Brown]

Checking the headers for an even temperature across the cylinders can indicate the faulty injector as over fueling can cause the temperature to drop & also confuse the lambda sensor.

Most circuit testers also have a temperature testing facility.

 

[Andy135]

#10, or even one of these cheap infra-red thermometer guns would work.

https://www.amazon.co.uk/Thermometer-Eventek-50%C2%B0C-550%C2%B0C-58%C2%B0F-1022%C2%B0F-Non-Contact/dp/B08T9K8GW7/ref=zg_bs_6286456031_sccl_4/261-0672094-7398460?th=1

[Shaun_E]

Thanks for the ideas John, Geoff and Andy.

I will check the TPS and maybe replace it - yes the wiring to the connector is all new but the TPS and therefore the wire from it to the connector have been in the car a long time!

I have an infrared thermometer like Andy linked to so will check the header temperatures as suggested. Will probably be getting the injectors cleaned but would be nice to know if it's a likely cause.

[Shaun_E]

Injectors now cleaned and tested so that's them ruled out. 
I measured the header temps. 1 and 2 similar, 3 much higher and 4 somewhere in between. 200, 200, 300, 270 roughly. Suggests 3 is lean. 
I put the fuel pressure gauge back on and it showed about 3.3 bar until I put it under load when it fluctuated wildly. However I couldn't get it to seal and think maybe it was faulty so have ordered another. Could be that fuel pressure is the problem!

The guy that cleaned the injectors suggested I do a compression test so that's tomorrow's job if I can source a compression tester  

 

[Shortshift]

I'm chasing a similar problem at the moment, Shaun, on my R500D.  Cylinder #4 is not performing and the header temp is way down (circa 100 degrees) on the adjacent header temperatures.  Was OK on the last trackday of 2022 but seems to have started 2023 by not working.  Interested in Geoff's comment about over-fueling potentially being a cause of the cooler header temperature as the no # 4 plug is also very sooty.

I have checked, replaced, swapped around most things in the circuit (plugs, COP and ignition sub-harnesses, TPS, injectors) and nothing makes a difference.  Cylinder compressions are all fine (very impressive, in fact) and testing both ignition and injector outputs with a NOID light at the connector terminals seems to suggest everything is fine (though the illumination when testing #4 injector seems maybe to be less bright and perhaps 'different' from the others?  Paranoia setting in??). 

I'm about to test the ECU by swapping with a fellow Club member who is local and also has a R500D so I should know by this afternoon whether this is the offending item - it wouldn't be the first MBE ECU to fail on this car, if that's the case.

@Geoff - or anyone else!  So, if the injector is fine (proven by swapping around with others) what else might cause the overfuelling to cylinder #4 only (apart from the ECU which is undergoing trial and sentencing as we speak)?

Good luck Shaun!

James

[aerobod - near CYYC]

James, I think it is worthwhile borrowing or acquiring an oscilloscope to probe the injector and ignition signals. You can buy a basic Hantek USB 2-channel one for £75 or so. The only way I tracked down a sporadic misfire on my R400D was using one to find a poor connection in the ignition circuit. The USB ones are able to be used with a laptop connected with Easimap at the same time, to log sessions with the oscilloscope inputs while driving.

[Shortshift]

Excuse my ignorance, James, but if I invested in a scope what would that allow me to see?  I'm thinking it must be amplitude and timing of each signal, one channel at a time (put another way, the magnitude of signal over time).

Is that right?

James

[aerobod - near CYYC]

Hi James,

You would be able to see the shape and voltage of the triggering signals. With the basic 2-channel scopes you can compare the signal on a good cylinder vs the suspect one to eliminate other variables at that point in time and look for signal anomalies such as voltage spikes or poor ground.

[Richard Price]

James,

'sounds like a sticky injector not closing to me.

A single injector signal is very unlikely to be operated for a little longer than the remaining three. Digital electronics don't tend to go a little bit wrong, they either work or they don't. The same logic is going to be used to time all four injectors.

have you phyisically removed the injectors, and moved the injectors to different cylinders?

[7 wonders of the world]

how were they cleaned....?

Best option if you can is to find an outlet with an ASNU cleaner and tester.

You primary temps could also indicate a balance issue with the TB's

I would also look at a leak down test, compression tests can mask very slight valve leakage

 

[Shortshift]

Apologies to Shaun for seemingly having hijacked his thread.  And thanks for the three replies above.

So...

Thanks James.  Always nice to have an excuse to buy more toys!

Yes, Richard; I swapped injectors around but the problem stayed at cylinder #4.

The injectors haven't been cleaned, Neil, but as the problem hasn't traveled with the injector when I put in a different cylinder, I don't think that's the issue.  And this issue has come on suddenly, and the car was previously flying, so I doubt I've got a leakage problem.

I might wire injector 4 directly from the ECU and see if that helps to eliminate or confirm the ECU (or the wiring and connectors) as the source of the problem.  Seems that Pin 26 is the feed/supply to the injector (cylinder #4 being the third to fire, based on 1-3-4-2) but which ground pin should I connect to at the ECU (or doesn't it matter?).

James

Edited to say (with thanks to Richard P) that Pin 26 is not the feed/supply but is, of course, the switched return to earth connection for the third injector to fire, on cylinder #4.

[7 wonders of the world]

Hi James,

Sorry my reply was for Shaun - my mistake I should have tagged it to post #13 to avoid confusion

[Shortshift]

Replying to #21:

Ah, no, actually it's my bad because I have kinda hijacked Shaun's topic...

James

[Shaun_E]

The injectors were cleaned and tested on an ASNU tester.

Suspects now are either the fuel pump or the fuel pressure regulator as I don't think that the small fuel weep at the pressure gauge would be enough to cause the pressure to fluctuate wildly which is what the gauge was showing. Hopefully a new gauge arrives tomorrow along with the compression tester but actually I think it is going to an expert as I've had enough. 

[Geoff Brown]

Shaun - The only thing I can think of now is the ECU signal for the injector or how the injector is actually operating ? 

Or am I wide of the mark after all your trouble shooting/component swops.......

[7 wonders of the world]

Shaun,

If you go for anew pump please select a reputable dealer I I was caught out by a counterfeit Walbro which failed on the return chippy run.....

Walbro are now known as Ti Automotive in the UK, I sourced a genuine one form here, there's lots on he web about how to identify genuine pumps v fake ones.

I use this version, central pick up and the strainer is sprung loaded as the normal pillow versions close up and reduce the filtration area

https://www.fuelpumpsonline.co.uk/for-lotus-esprit-turbo-22-walbro-motorsport-fuel-pump-kit-itp244-gss340-45000-p.asp