Hi all,

2007 Hawk STi
I had a totally flat battery through not driving it for ages. So flat that when I connected up the charger the alarm was sounding, and the alarm would only stop if I switched the ignition on with the charger connected. so took the battery out, fully charged it, happy days.

However, if I take it out for a long / spirited run, the CEL comes on after about 50 miles.
Car isn't misfiring that I can tell. I have a PSi3 on the dash - no P codes current or historic.

I reset the ECU with the PSi3, the CEL geos out, and drive 50 miles to get home and the CEL stays out.
Twice this has happened, CEL comes on, but no stored P codes current or historic...reset the ECU and the CEL stays out....until the next drive.

Could it maybe be a misfire but the ECU hasn't worked out which cylinder yet?

It's a solid CEL not flashing CEL.

 

Could it be the battery not putting out enough power , if a battery goes flat or even low , I think below 11.5 or less damage is done to it , get a drop test done on it and see what they say , my v8’s are very battery sensitive and if the battery is not working well , loads of codes can come on 👍

 

Seems ok on the PSI3, 13.8v to 14v whilst driving.....

It has gone totally flat several times over the last year though....although only a few months back a battery place tested it - all OK he said...

 

The Driving / charging voltage is where it should be , but for that voltage to be where it is , does not mean the actual the battery is not failing , as it’s showing alternator volts , if it’s been flat a few times , it would be my first option to change , if the battery was fully charged before you put it back on the car , unless there is a drain ie lights etc then maybe the circuit is compensating for a bad battery , as the charging circuit is not on all the time , if I car is left too long and not used , then it’s worth disconnecting, or a solar charger around 30£ can slow the battery discharge process down , worth checking the voltage when left over night before you start it

 

Do they suffer from the same random lights Bugeyes used to get on high revs, a cam or crank sensor wasnt shielded enough from memory, someone else may remember it?

 

gauge on my pioneer radio shows charge 14.1v-14.8v when driving
Not sure but think 13.8v charge when driving is to low.
I have aa solar panel permanently connected.

 

The norm I know of as norm is 13.5 to 14.5 so sounds about right , 14.8 is slightly high but as long as it’s not at that level too long im sure it will be ok

 

idling norm
yes mine is higher than the norm when driving anyway
not sure what my shows at idling have no car yet with me

 

If it was hitting 15 I would be looking at a new alternator , 14.8 not all the time is high but ok

 

But why would any of this put on a CEL and with no P code?

 

The ecu is getting too much of to little voltage , im not saying it’s your issue , but you know you have battery issues , adding to that it’s been flat a few times , an ecu likes things within its parameters , its potentially another thing to check

 

Could it be the Neutral Position Switch?
I had a similar problem in my WRX, light used to flicker occasionally and somethimes stayed on. Didn't give an error code.

https://www.scoobynet.com/scoobynet-...on-bugeye.html

 

Update time.....I replaced my battery for an identical Yuasa one as before... YBX 5005 from Tayna.

I reserved one at GSF for £90, but jeez it was filthy and had been bashed around in their storage area so I walked away.
The Tayna one came in at just under £100 delivered, arrived the next day and was very well packaged.

I've been out on several mixed drives, and am happy to report no CEL...

 

Good 👍
I used Tayna as well last month and was impressed as well.