Focus 1.6 2003 - engine pinking/rattle

[William-lpxee]

Hello, I'm hoping someone can help me out here or at least give me some ideas of where to begin!

Brief background -
My engine in my car was burning oil, smoking quite badly and rattling/pinking on light acceleration etc.. so I decided to source a lower mileage (64k) engine and replace it.
Whilst the engine was out I replaced; cam belt & tensioner (also other unrelated items).
As the new engine was running perfectly in its orignial car i used all the sensor which came with it, inc MAP, cam, crank & cylinder head temp sensors.

Now the issue-
When I first drove the car after the engine swap it made the same bloody rattle but after lifting the bonnet I found one of the breathers on the inlet manifold split so I replaced all of them including the PCV valve i was so chuffed when i thought id found the cause but im now gutted as the noise is still very apparent. Now I know this engine did not do this in its previous vehicle so there must be something on my car that's causing this....but that's where i'm stuck!

The rattle seems to happen on light acceleration between 1500 - 2200 rpm
Also it doesn't happen when the engine is cold.

What i have tried -
Super unleaded, genuine coil pack, checked all pipes for damage or collapsing, tested the car on an MOT gas tester and its perfect, ive 'data logged' the car and the HEGO/lambda switches between lean and rich as it should, the map sensor reads correctely and the cylinder temp sensor is correct. Read fault codes, (none present) and re-set keep alive memory for the ECU.

HELP!

[Prickly_buzz]

Thank you for your reply,

I have been underneath and banged the cat, can't hear anything also if the cat is breaking/broken up wouldn't it rattle when being revved at a stand still?

[Prickly_buzz]

The other thing I considered is perhaps a slow switching HEGO/Lambda fault.
I'm not sure if this could be detected at idle or is there a chance this could only be apparent under load?

[Prickly_buzz]

Ok, that's interesting, I assumed it was pinking as it really does sound internal to the engine (although this is hard to tell for sure without having your head under the bonnet when it does it). It sounds similar to the 'knock/rattle' you get when pulling away and not accelerating enough...

I have tried different grades of fuel from different places and had no joy, I don't know if it makes a difference but I set the fuel grade in the PCM to 95.

It only seems to happen at around the 2,000 rpm area and only when the car is moving and as I said under 1/4 - 1/2 throttle, If im honest it has never happed on any heavy throttle.


P.S thanks for taking the time to help!

[Prickly_buzz]

Ok been out today in the car again.
I now feel it's got a lot to do with fueling reason being the exhaust tip is black & there where intermittent clouds of grey smoke coming out the back.

[Prickly_buzz]

I have done a gas test on the car and all is bang on, not ruling out the cat but seems un-likely.

Im startiing to suspect the ECU to be fair as it is the orignial and was running the previous engine. Also im running out of things to replace!

Bill

Oh and im in Kent

[Prickly_buzz]

I removed the ECU (to get the numbers from it) this morning and when i put it back on about 10 minutes later, i went for a drive so it could learn basic settings etc, the noise was no longer there, however im conviced this is not cured but it seems like the issue could well be with the ECU.

[Prickly_buzz]

Update -

I have had to keep driving the car as its all I have got and I need to get to work!

I have not found there is intermittently puffs of grey smoke coming out the back.
Also it has now developed a lack of power/flat spot intermittently when pulling away from a junction or roundabout.


I am really getting fed up with this now I just don't know what to try next, any suggestions would be much appreciated.

[Prickly_buzz]

Cheers for your reply.

Unfortunately I have already replaced the PCV valve and the vac pipes and it didn't make any difference.

I have managed to get some data, not sure if its relevant....
The noise was heard at '1' on the graph (you can see that's where I touched the throttle)




1) Long term fuel trim
2) MAP sensor pressure
3) MAP sensor voltage
4) Pre-Cat Hego Voltage
5) Post-Cat Hego Voltage

Edited by Prickly_buzz on Friday 7th August 13:47

[Prickly_buzz]

Hello guys, cheers for the help thus far.

This noise is 100% only happing on light throttle i hardly ever go WOT to be fair but if anything this improves the issue.

I actually managed to source an ECU and programmed it today, i drove 15 miles with no noises what so ever unfortunately it would seem the problem is still there however as i can still hear the rattle but no way near as loud, it so weird that changing the suspected 'fried' ECU has only helped where as i thought it would either have zero effect or cure it completely?!


Does the 2nd lambda actually adjust the mixture in anyway, my understanding is that it does not?

Edited by Prickly_buzz on Monday 10th August 20:43

Not sure if these gas readings shead any light...


Idle -



~2500 RPM

Edited by Prickly_buzz on Monday 10th August 21:46

[Prickly_buzz]

bearman68 said:

Pumaracing said:

bearman68 said:

O2 sensor looks as if it's working OK, because you can see the blip in accleleration, but don't understand a consistent 0.15v reading

This can only happen if the ecu is not responding to the low lambda voltage and injecting more fuel which should then bump the mixture above stoich, generate high lambda voltage which then immediately triggers a cut in fuel, repeat ad infinitum.

Yes, agree with you Puma, and would comment the ECU reading is unusual since the LTFT is 0% too. However, the O2 sensor has some imput, but is not always the limiting factor, and I'm looking at this thinking there is some fundemental underlying mechanical reason for the lean running. I would defo be tempted to run a smoke test on the inlet side of things, check fuel pressure that type of thing.

Im starting to think there is something mechanical causing this especially as im running out of things to replace!
I have cirtainly removed, checked and checked again all the vac pipes and i replaced the PCV valve. I have removed the idle valve and made sure the gasket is sealing correctly.
How would i go about checking the fuel pressure and any idea what its supposed to be? I know these focuss can suffer with fuel pumps, its never given me grief but it is the original and done 117,000 same with the CAT.

Edited by Prickly_buzz on Monday 10th August 22:03

[Prickly_buzz]

Pumaracing said:

I'm puzzled by some of the information we'd been working with. At the start you said the lambda voltage was oscillating normally which it clearly isn't from the trace supplied and you also said that exhaust gas readings were normal when they are massively abnormal at 2500 rpm. However we shall soldier on.

Let's now be very clear. Does this problem go away and the car accelerate normally at higher rpm and/or higher throttle openings i.e. with much higher fuel demand? If so then it can't be fuel pump or filter. However something is apparently not supplying fuel properly in this brief rpm band at light throttle. I will have to sleep on it.

I'm really sorry if I've supplied incorrect or conflicting information, I'm just trying to give as much detail as possible but I'm no expert! I am really grateful for your help as I am at my wits end and have spent a lot of time and money on trying to get a reliable straight car.

I tested the car this morning and can confirm that if I accelerate from a standstill I will hear the 'rattle' roughly 3-4 times through the rev range.
If I cruise along at say 40mph for a few minutes and then come off the throttle for a few seconds then reapply it I get the rattle nearly every time. (again sorry if this wasn't clear to start with but it can be hard to replicate the rattle however I think I've got used to when it does it now.

If its not the ECU causing it to run lean what else on the management side would have an impact on this?

Edited by Prickly_buzz on Tuesday 11th August 09:51

[Prickly_buzz]

Pumaracing said:

Have you checked/replaced the throttle position sensor?

I have not checked the TPS, the replacement engine had one fitted already so I left it on, small chance that both are faulty (not impossible). Suppose it could be wiring issue but would I not get a fault code?

[Prickly_buzz]

227bhp said:

Is it worth trying to record the sound so we can hear it?

I did give this a go but it wasn't easy to pick up over engine and road noise with a microphone, I will attempt it again tonight.

[Prickly_buzz]

does the post cat lambda sensor just 'sniff' to make sure the CAT is efficiently working or does it actually have any control of fueling?

[Prickly_buzz]

Ok this gets more complicated and irritating....

It would seem the 'grey' smoke was in fact 'blue' smoke I was unsure to start with however I have since checked my oil and I seem to have lost 1.0litre in around 2000 miles.

Still getting the rattle and still only when warm....

I'm starting to think this is like a crankcase issue, maybe higher crankcase pressure not venting somehow? Unfortunately that's where my technical knowledge ends!

Edited by Prickly_buzz on Monday 17th August 19:34

[Prickly_buzz]

I have driven the car this morning for around 15 miles and there was no noises or smoke at all.

The ONLY thing that changed is the weather, it was damp, cooler and lightly raining....

Does this give any clue as to what it might be?

[Prickly_buzz]

The only thing I haven't changed from the original set-up is the Cat. Its got the sensors which the working replacement engine came with, ive also changed the coil pack, plugs, leads, 1st lambda sensor even the ECU for a know good one!

[Prickly_buzz]

Right I've now changed the CAT and fitted a genuine fuel filter and I've still got the noise.

I'm thinking possibly fuel pump weak maybe? But I'm just guessing