Hi

Just after some input here - as I'm a little lost tbh

Sapphire 4x4
P8 ECU Closed loop, wasted spark
Siemens 55, T34

i'm having this problem that on idle an low load cruising, the AFR is rich

about 10.8-11.2 on idle
low load cruising have the AFR at 12-13

its almost as if it exits CL operation on idle and low load cruising.

By increasing the load but under closed loop operation, the AFR sets at 14.7



I have checked all sensor for faults on the IAW monitor, and all readings are fine.

I have fitted new lambda sensor - but still the same
I have also ordered new MAP sensor as an trial - just waiting for it to arrive - not that anything seems wrong with the old but was worth a try.

I have reset the ECU (P8) but in doubt if the learning procedure should be done with hot or cold engine (I have tried Both)

What am I missing - the readings are very consistent, always the same.

Also I have considered that it was the AFR gauge that gave wrong readings, but the once in a while popping from the exhaust at low load, indicates that fuel is dumped into the hot exhaust

hope for input

thanks

 

do you have try to adjust from ecu CO screw?

 

Is the fuel reg ok?

 

Thx
But its on a P8 so no co screw infortunately

 

Thx
I would assume it is - I have 3 bar at idle with vac pipe connected and it seems to rise as should when driving. I have fuel press gauge installed.

 

If its weeping some small amounts it may be enough to upset idle etc but not show up on pressure guage.
Just ideas here mate as i had similar probs albeit not on P8 though.
I see a video of fpr test it took 2 minutes plus to show the leak after pulling the pipe off the inlet, as said worth a check to eliminate that.

 

Cheers mate I get that
Will check it

 

well fuel reg wasn't leaking - but a good suggestion

I noticed that turning on the lights and if the cooling fans was on, the AFR got closer to 14.7
so it seems that putting electrical load on it, makes it go a bit leaner.

help needed

 

Does that mean less power going to the fuel pump and slowing down the flow just enuff to make it leaner.
Just a random thought !

 

its rich not lean,afr get lower the richer you are

mark

 

TPS calibrated correctly?

 

would make sense, but the fuel pressure stays the same 3 bar at idle


I think he refers to that it goes leaner when I put electrical load on it

I think I can rule out the most common sensors, as they are bang on according to my IAW monitor. TPS i have tried several settings between -0.35 to 0.25 degrees.

Lambda shows 20% correction on the IAW at idle, by slowly increasing rpm still have it at 20%. But rapid throttle movements makes it change.
So that tells me that it does adjust the fuel but on idle it cant correct enough - only the "20%"

When starting from cold its really rough splutters and misses. This got me thinking if spark plugs could cause this - if they are too cold or the gap is too small?

I should mention that on boost its perfect

 

Any further progress on it?
Back to the basics again but is the fuel filter good and are the injectors clean.
Have you tried the new map sensor and I was thinking maybe try a different cts and new plugs.

Mike

 

Thanks for the interest mate

I have tried a few things
Checked for leaks on inlet and exhaust side, but nothing showed up.

Map sensor hasn't arrived yet, but tbh I don't hold much hope, as the reading on the IAW seems to rule it out.


but one thing I have completely missed to is that I have to drive without the ISCV connected, because it plays up and makes a strange sound when connected. I put it down to that because it was very rich it behaved strange, but now I am unsure if it could be related.

I haven't checked injectors or filter
How could filter cause this?
the point of the injector I can understand - I guess you refer to if one of them was leaking?

It is also extremely rich on cold startup for a couple of minutes, coughs and misses until it get a little heat into it, if I leave it to idle. But if I drive off right away it drives ok from cold.

now that I put that in writing, it makes me think if you could have a point that it could be injector related....a leaking one perhaps??
I have also considered if it is the chip that needs adjusting, or if my ECU reset method is wrong.

damn car....

I should mention that on boost its very good

thanks for reading

 

Its a minefield mate as it could be many things you definately seem to know your stuff with the IAW checks.Im only posting suggestions at basic level as you know ,hope someone comes along from a professional view.
The filter is something I,d service regulary , As for me saying injector it could be a case of they need cleaning with bad spray pattern dumping fuel rather than spray. I actually think its something else tbh I would imagine injector issue would be acrosss the rev range not just idle and low loads.

Not sophisticated suggestions but you didnt mention them so I have so readers can see more info from you.

hth
Mike

 

If this is P8, can you try another P8?
One of the failures the P8 suffers from is failure of the adaptive ROM, and it only affects off boost performance - but its more common after its had a couple of years of a Pectel board fitted it seems.

We can certainly tweak the chip to suit your car after you have exhausted all other avenues of course mate.

 

Also - please explain more about the ISCV behaviour - it may give me a clue.

 

thanks Stu - the man with the knowledge - it would make perfect sense
And fully in line with my thought that I did something wrong when trying to reset the ECU. I don't have the history of the ECU, so could easily be the case. I will try another ECU and get back with my findings


it hunts, and idles high - in kind of a different way than if its sticking
And it gives a kind of metallic noise - rather loud. Could also sound like air, that gives a whisteling sound. har d to describe

But I will look into the ECU and see if that also cures the ISCV - I guess it could be related

thanks

 

Well it wasn't the ecu

I've sent you a mail with my findings

Thanks

 

Thanks mate, will take a look.
Might be time to try a fuel map recalibration for you.

 

Has the base idle been set correctly? could you post up snap shot of iaw screen Stu might be able to see an issue from that.

Fuel pressure check
try another cts
Also bulkhead connectors on a 4x4 saff are not the best same on a escort cos.

 

I just stumbled on my own thread here, and found I have completely forgot to update it - I think its always good to update this kind of threads as it gives people searching in the future a conclusion.

Conclusion:it all turned out to be me being a fool.
When I specified my engine specs to Stu, I completely missed to inform about my Hart inlet.....

So result was that the airspeed in the inlet was way slower than with a std, inlet, the fuelling was way off.

So I would also like to take the opportunity to give a huge thank you to Stu, for not only trying to solve my problem during several months, but also just changing the chip spec, absolutely free of charge not even charging for postage to DK - not even a sour comment for me wasting his time.....

top top man, and that should end this thread