Hi all

I have a MY95 WRX and reset the ECU on a regular basis using the MRT method (connectors under the dash).

It seems to me, once the ECU is reset it starts to set ignition advance by starting high and retarding advance until it detects no knock. I think this is why directly after a reset boost is limited to 'limp home' settings until the ECU has calculated the ignition curve. So does that mean the advance is calculated when off boost, or does it also calculate when in WOT? (Sorry but I know the terms open loop and closed loop - I can't remember which is which!)

Is there 2 calculation instances? one for closed loop advance and one for open loop advance?

I ask as I am one of the Dawes MBC posse and am just wondering about when first going WOT after a reset would the boost control soloniod usually limit the boost whilst calculating WOT advance?

My thoughts are that the boost is limited WOT only until the ECU has calculated the knock points etc. It should be able to do this whilst driving off boost for a while. so as long as I don't go WOT straight away us MBC people should be OK.

Can anyone pass on some knowledge?

Thanks

Justin

Someone must have an idea...don't make me take this to 22b.com!! ;)

Jay,

I don't really know, but 2 points again :

1) it will probably differ quite a lot from MY to MY.

2) A bit of info is in http://www.sidc.co.uk/faq.htm#2.4.1.1, but there is the same warning that there is a lot of debate about this issue.

I'm pretty sure that a reset on my MY99 would only remove potential ignition retardation if it would be there. On a MY01, a reset won't do much at all. But I don't know how a MY95 ECU works.

Whatever you do, don't try to trash (or put a lot of load on the car) from cold. Try to build up gradually until engine is fully warmed up, and then try to put some load on the car (driving uphill in 5th for example at 2000-3000 RPM).

Theo

Thanks EB

yeah I'm pretty much up on all that, My ECU only adjusts down not up so if a bad batch of fuel was in my car a couple of tanks ago the ECU would still compensate for it even if I had a tank of better fuel at present. I run on Optimax + OB, problem is you can't always match the fuel to OB ratio exactly as the last tankful so I reset my ECU after every refill. I only refill every 2 weeks so its not that arduous.

To reset the car properly the car should aways be fully warmed up so none of this disconnecting the battery overnight for me! MRT method always - I can get it done in 30 secs these days :)

The Dawes MBC people should be warned - now that the boost control soloniod is bypassed the boost will not be limited directly after a reset. Combine this with the ignition initally fully advanced there is a very high probability you'll get severe det on full boost if you 'rag' it straight after a reset.

Hence my original question...after a reset I drive off boost for a long time - through the gears and slowly get the revs up to 6k rpm without the use of the turbo. Only after doing this for a while do I go WOT.....NOW! when I do this does the ECU use open loop advance calculated from its recently aquired closed loop data OR does it calculate open loop advance from scratch - i.e. limit boost, full advance then retarding till no knock is present? If its the latter then the Dawes is coming off :(

My feeling is that WOT is a set map, the advance is taken from the closed loop data and the fuelling is naturally richened up a bit.

Anyone still with me? or am I talking pants;)

Justin

Firstly I don't know most of the answers, but I can say ON MY00 I have never found a reset makes the blindest bit of difference. If you reset it does not limit boost at all and drives a bit jerkily for about 500 yards whilst it learns advance settings. On an ealier car why not let it retard to the lowest common denominator for safety unless you have a truly awful batch of fuel. The bad batch of fuel thing I have never really noticed to be honest. But I wouldn't personally be doing this ever unless it was really obvious, and would not reset my ECU unless I had made a major mod. But later ECUs are more dynamic.

My advice - let it retard. Frequent ECU resets will expose you car to knock I reckon. On a road car using road fuel you will never be running absolutely on the optimum unless you compromise safety or have a very clever ECU - possibly MY01? Too many variables. Let is retard and run safely. If it is running dog slow often I suspect a problem with your car. You should not be having to reset every tank!

anymore comments?

Jay

I'm not 100% sure if the under dash connectors routine resets all the learned data or just the CEL fault code list ?? My initial thoughts were that it did, however after I had the battery disconnected for a few days for another reason, when I ran the car it was hunting a bit and initially the boost level was fluctuating too, suggesting it was re-learning ??
My MY95 WRX doesn't do this after a black n' green reset ??

cc