ECU or Sensor fault?

Hi Guys

As some of you may already know at the moment I’m having trouble with the car starting badly when it’s cold:

http://www.mkivsupra.net/vbb/showthread.php?t=96020

But I’m wondering if anyone could shed light on this. When i try and start the car it starts after 20 seconds of cranking. But if I reset the ECU (tried this a few times) either straight after or leaving the car for a while or even over night it starts straight away like it always did. Plus after resetting the ECU the AFR's are now lowering to 10.1. If I leave the car and don’t reset the ECU the problem get worse and worse until when it does starts it feels like its running on 4 cylinders. But again if i reset the ECU then the problem goes away.

Any help would be much appreciated!!!!

Rob,

Have you seen this thread mate:

http://www.mkivsupra.net/vbb/showthread.php?t=92923&highlight=emanage+ecu+problems

I would personally finger point the ecu to begin with and then work out from there. If the ECU is playing up and you check everything else first, then you'll simply go round in circles.

Who fitted and tuned the thing - anyone on here

What injector lag time are you using? this can make a very big difference, it may have lost the setting, if its running very rich try reducing it. resetting the ECU won't actually do a lot at idle and cold start as it runs a cold start map.

Hi Guys thanks for replies just looking at that top thread. Here are a couple more screen shots of the parameter setting if you want to check them

Looking at you other thread the airflow adjustment map has -18 in the idle area settings, can you tell me why? as you have got the injector adjustment in the global injector settings? so this could have things to weak on cold start in these temps, have you tried re setting at "0" in the airflow map?

Looking at you other thread the airflow adjustment map has -18 in the idle area settings, can you tell me why?

No matey i cant i didnt map it and am not sure why the adjustment has not been done in the injector map.

as you have got the injector adjustment in the global injector settings? so this could have things to weak on cold start in these temps, have you tried re setting at "0" in the airflow map?

So because im running 650cc injectors basically if i reset the airflow map to 0 under 3000 rpm and adjusted the injector map to something simular to below?

And also leave the the airflow map adjusts over 3000rpm alone?

Also any ideas why the car would be running to rich i.e. afr of 10.2 most of the time?

Again matey thanks very much for any advice

Hmm its a bit of a contradiction, the injector settings are set for your larger injectors, which should in effect have the car fuelling more or less correctly, (Ian C wouldn't agree) but someone has obviously reduced the fuelling more in the airflow map around the idle/low load RPM area, in an effort to get your rich AFRs in check,

1/What wideband are you using to check AFRs?

2/have you checked your fuel pressure?

3/you could try zeroing the first block of four to six squares of the airflow map, and see if things in prove.

4/ or you could try reducing the injector lag time down to 1.2ms and see if that helps, as i'm wondering if someone has adjusted the airflow map in an effort to compensate, as if the lag time is set too high it will make the AFRs rich.

Having said all that we must not neglect to try checking the fundamentals first, IE, fuel pressure as i said,

the fact that you say it has only recently started to behave like this (your sure that no adjustments have been carried out to the maps?)

it is possible that your STD lambda is playing up, or that the ECU water temp sensor is faulty, it will cause the ECU to think the engine is stone cold all the time causing rich AFRs.

Hmm its a bit of a contradiction, the injector settings are set for your larger injectors, which should in effect have the car fuelling more or less correctly, (Ian C wouldn't agree) but someone has obviously reduced the fuelling more in the airflow map around the idle/low load RPM area, in an effort to get your rich AFRs in check,

 

 

 

1/What wideband are you using to check AFRs? .

AEM wideband

2/have you checked your fuel pressure?.

No but i think that is the next job.

3/you could try zeroing the first block of four to six squares of the airflow map, and see if things in prove.

4/ or you could try reducing the injector lag time down to 1.2ms and see if that helps, as i'm wondering if someone has adjusted the airflow map in an effort to compensate, as if the lag time is set too high it will make the AFRs rich.

Try that and it did start but the car was running really rough.

Having said all that we must not neglect to try checking the fundamentals first, IE, fuel pressure as i said,

the fact that you say it has only recently started to behave like this (your sure that no adjustments have been carried out to the maps?)

it is possible that your STD lambda is playing up, or that the ECU water temp sensor is faulty, it will cause the ECU to think the engine is stone cold all the time causing rich AFRs.

I defiantly have not touched the map since it was mapped so i think your right i have just re clean the temp and lamba sensors but it’s made no difference. The weird thing is that i got the car start using a lower lag time. I then put it back to 1.8 as it was in the original map and the car wouldn’t start so I reset the ecu and bang she started fine

I think im going to see if i can borrow or buy a new lamba and temp sensor and see if that make a difference.

If you can think of anything else matey it would be greatly appreciated

"Try that and it did start but the car was running really rough."

Are you meaning that you tried zeroing the airflow map or reduced the lag time or both?

you say the car started fine when you reduced the lag time, how did it run?

and the fact that you reset ECU and it started leads me to think that it could well be either the lambda or ECU temp sensor, as all the re set does is lets the ECU revert to all the std parameters until it gets its first feedback signals.

"Try that and it did start but the car was running really rough."

 

Are you meaning that you tried zeroing the airflow map or reduced the lag time or both?.

I left the airflow map alone and adjusted the lag time.

you say the car started fine when you reduced the lag time, how did it run?

It did start but ran badly

and the fact that you reset ECU and it started leads me to think that it could well be either the lambda or ECU temp sensor, as all the re set does is lets the ECU revert to all the std parameters until it gets its first feedback signals.

TBH that is what im thinking i put a post in the wanted section for a new or working lamba and temp sensor so i will see if i can get one next week and see if it makes a difference.

I will keep you posted matey cheers Ricky

Set both injector lag times to 0.0, see how that works.

-Ian

Also I note you've got adjustments in the water temp map - I've found that causes it it run rough - try zeroing those as well

Er in fact they are ludicrous settings, +5% duty under all temps? Why on earth put that in and cause yourself a headache?

-Ian

Thanks Ian i will try that in a minute and let you know

Also I note you've got adjustments in the water temp map - I've found that causes it it run rough - try zeroing those as well

 

Er in fact they are ludicrous settings, +5% duty under all temps? Why on earth put that in and cause yourself a headache?

 

-Ian

Not sure why the adjustment is there TBH I didn’t map it. You've hit on something though Ian results:

1) Lag time 0.0 and water temp map to 0.0 the car started but ran really rough

2) Lag time 440cc = 0.0, 650cc=1.2 and water temp map to 0.0 the car started fine as normal

The car did have a problem starting when i first had it mapped but only when it was hot the guy changed the lag timing and it start when hot ok. But obviously in the middle of winter when it’s very cold outside the opposite is happening.

Do you think any of the changes made will have any adverse effects when driving on boost?

I can't see any reason to adjust the water temp injection map, the std ECU should cope fine if the rest of the injector/air low maps are right, that would explain why i was thinking that the ECU water temp sensor was playing up, if adjustment was set up on this in the hotter weather then it would be out in these temps.

Totally agree! I suppose because really i'm still learning with this mapping and adjustment I don’t really want to question the experts i.e. yourself, Ian or the guys that set it up so when i see something like that i just leave it. But saying that I would have thought that the increase in fuel as the temp went up would be to keep the engine cool and to help stop det? So therefore an adjustment at the lower end is not necessary? So the increase adjustment in map should be a staged over the temp range? Or am i way off? Feel free to tell me shut up

Totally agree! I suppose because really i'm still learning with this mapping and adjustment I don’t really want to question the experts i.e. yourself, Ian or the guys that set it up so when i see something like that i just leave it. But saying that I would have thought that the increase in fuel as the temp went up would be to keep the engine cool and to help stop det? So therefore an adjustment at the lower end is not necessary? So the increase adjustment in map should be a staged over the temp range? Or am i way off? Feel free to tell me shut up

I'd say it's the other way around - the adjustments will be low down. Engines will be mapped at operating temperature and then an adjustment table will be used for when the coolant is cooler than operating temp. There may be some additional fuel added under overheat conditions but that's by the by.

The stock ECU deals entirely in injector duty - how long it opens the injector for in milliseconds. So it's adjustment table for water temp related conditions and the best example of that is a cold start, and it is going to be based on adding x milliseconds of duty at y coolant temperature. Bung in 50% bigger injectors and your x ms of cold start extra duty is going to add in 50% more fuel than it used to, and the engine doesn't actually need any extra fuel at this point.

So I tried to pull fuel out with the water temp map seeing as water temp is the way the stock ECU knows it's cold starting. Alas, this feature of the EMU doesn't seem to like our engines and it makes it run rough. You could hear the engine clear up and smooth out as it warmed up and left the load site with the adustment in it. So I do some jiggery pokery with the airflow map in a couple of loadsites instead to cater for cold and warm start. A carry-over from the Blue anyway which didn't have all these fancy extra maps

Having +5% fuel all the way across the water temp map simply adds 5% under all circumstances. It's bizarre because if you wanted +5% everywhere you'd put it in the injector map and then adjust it on a loadsite-by-loadsite basis, not cludge it into some ancillary map and confuse yourself in the future when you wonder why it's overfuelling. Plus you'd never really need +5% *everywhere* anyway unless you did an engine capacity increase. It's just weird

-Ian

Thanks Ian That makes sense now.

I think it needs some fiddling with TBH for example it start fine this morning but tonight on the way home again when it was cold it wouldn’t So I backed off the lower end of the temp map and it started.

The car drove ok but the AFR were at 15.7 dropping to 17.1 when driving under 3500rpm off boost.

But then after driving for 20 minutes stop the car and it wouldn’t start. So i changed the injector lag time from 1.2 to 1.8 (as it was in the original map) and it started fine.

Plus the idle has dropped to 500-550 rpm?

I'm still not ruling out the possibility that either the lamba/temp sensor is not faulty.

Anyway i took a datalog of the drive home today

2912007.zip

Just an update. I bought and have changed the O2 and water temp sensor.

The car is starting well from hot but is still having problems from cold. It is running much better on day to day driving as well.

Have notice on the water temp input on the datalog that it is always at 130 regardless of engine temp

Going to check all the wiring again on the harness and emanage but after that i think this one has beaten me