ECU adaptation problem - SOLVED - MAF on backwards!

[fredfelcher 0]

Hope you'll bear with me - I've got a G, not a C :shock:

 

It's an OBD1, 95 VR and it runs well - normally. I decided to 'fiddle' a couple of days ago and check/tighten the induction system, MAF, PCV and filter (BMC CDA). I put it all back on and went to get some V-Power. Probably my imagination but it seemed even more powerful and responsive than normal. On the way home, I stalled at a roundabout; this has not happened before.

 

"Oh good!" I thought, "I've eliminated a major air leak and the ECU adaptation is too far out, I'll just do an ECU reset and enjoy the extra few bhp I've found for free." I noted that the Lambda values (Group 006) were: idle 1.109, part 0.899, full 1.016 before I disconnected the battery.

 

I did the 10 minute 3rd/4th/idle sequences, then the 20 minute drive (OK, with a bit of boy racer silliness thrown in but hey - these Type R's need a lesson now and then...). I pulled over and checked the Group 006 values but they were all exactly 1.000 except the 'Active' value which was fluctuating as expected. Also, I had a couple more stalls sporadically and noted the ISV adaptation in Group 005 was exactly 1.000 (can't remember before, but not 1.000).

 

I thought perhaps having the laptop plugged in from straight after the reset might have prevented the ECU learning somehow (although never heard of this), so unplugged and it did drive a bit better after another 20 minutes or so, but kept idling at 1000rpm after overrun, dropping down to 650rpm after a few seconds. I did a Basic Settings, but reading tonight, perhaps it was too soon.

 

I've been out again tonight, done the same things (laptop only plugged in later this time) and it's the same story - no adaptation and idle dropping to 1,000 initially then 650 after a few seconds. I did notice that this was always true if I decelerated from high rpms (eg over 3000), but if I coasted to a stop in gear and declutched at around 800rpm then the revs usually went to 650 - which is how it always was before.

 

I also noticed, when doing Basic Settings again tonight, that now the Lambda is fluctuating around 1.035 to 1.080, whereas before it would go from 0.970 to 1.025; I think this means it's lean. There are no other driveability problems - in fact it feels a bit quicker than before but perhaps that's in my head. There are no fault codes stored (I cleared an ISV code after those early stalls and it didn't return).

 

So, eventually, to my question:

 

Why won't my ECU adapt?

 

Is it because I haven't left it long enough. Am I being too impatient? Is it because the engine did stall on one occasion during the 10 minute 'quick learn'?

 

If the wife will let me, I'll take it all apart again tomorrow and also clean the ISV - but that was working flawlessly immediately before I fiddled the other day - coincidence? I took my time putting it back together and checked all the hoses carefully for cracks and holes before putting them back. I squirted some contact cleaner on the MAF element too, but I've done that before many times without problems.

 

Any help would be much appreciated.

 

Oh, and thanks if you made it this far without giving up; I thought all the detail would be important!

[RW1 0]

Clear one thing up for you..... plugging in the laptop will have no effect of what the ECU is doing with the preset values in Group 6. Think you've just looked too early and done things too quickly.

 

The way the preset Lambda values behave at the end of the short drive sequence is.....

You should see an initial value in the idle field after 12 minutes. (Part throttle value may have been computed as well.)

The part throttle along full throttle take about 30 mins to compute.

 

ISV adaption at 1.00 is not unusual. The duty cycle in the next field should be about 55% +/- 5%.

 

I wouldn't do "Basic Settings" - (select B.S., rpm blip to 3,000 and idle for 2 mins) until after about 2 or 3 hours driving time. The driving time doesn't need to be continuous. Can be done over a few days. This will let the ECU settle down to more stable values.

 

I have found if you thrash it around too much, it can induce stalling occassionally after ECU set up. Do the drive sequence again for the first 10 mins with a bit more relaxed approach, then just drive around without thrashing it but do use the revs smoothly.

Try it that way.

 

.

[fredfelcher 0]

Very very many thanks for the quick reply RW1; comprehensive and informative as expected! :cheers:

 

Now a small apology:

 

When I checked the induction system over, the MAF was on erm... backwards :epicfail:

 

I've just been out again, with it the right way round now of course, and everything is better including the adaptation values.

 

So, no code thrown for the MAF (presumably as there is still air flow it doesn't know anything's wrong) and the adaptation not happening was the only obvious symptom!

 

Once again, thanks for replying and I hope I didn't waste too much of your time! :oops: