Hunting Idling/Near Stalling

[nosubstitute]

I had headers fitted a couple of weeks ago. Having stuck with the 'quiet' Wortec setting I switched over to 'loud'.

I took it out for a once over and discovered that once on the move and coming to a stop it would virtually stall, I had to give it throttle to keeping the engine from dying. I decided to take it for a 20 mile trip up the motorway using different gears accelerating and decelerating to see if it made any difference. Well it seems to have done, the car is now idling as it did with the 'quiet' setting.

My questions is why it wouldn't idle properly at first given that now it's fine?

[doleboy]

It might be that the computer decided to re-learn the idle for some reason - normally takes 5 minutes or so of hunting up and down to get itself together. If you'd pulled the BCM fuse to drop the long term fuel trims , or the battery was out for an extended period, that would trigger the process.

If the car worked for a while after changing the pipes and then went off, that's odd - maybe plug leads slightly loose or damaged? How many miles on the car?

[Wolfracer]

I thought MF had killed my car when they pulled the fuse.... your engine sounds like its about to go kaput! I was quickly assured that the computer would sort it out, and need about 10-15 minutes just sat at idle to get it right again - and they were right.
tbh though headers whouldn't upset the mix that much to trigger massive recalibration surely?
I'm sure someone with more knowledge than me will comment soon...!

[ringram]

In theory the closer the base tune is to good the less learning there would need to be.

Could be other stuff like gummy idle air control valve on older cable throttles. Or some crud on the o2 sensor causing erratic fueling etc.

Did you get a check engine light?

[nosubstitute]

It was running fine with the additon of the headers in quiet mode, it was the changing to the loud mode that seems to have set the idling (temporarily) out of kilter as after a good run it's now fine. Does the air flow differently between the two modes? Could that be it? I did not have a remap after adding headers as I wanted to keep costs down and more after the sound rather than power/torque.

The outcome is it is now running absolutley fine but those few miles after changing the path from quiet to loud it needed throttle to keep it idling and I was wondering what the cause might be.

[Wolfracer]

nosubstitute said:

It was running fine with the additon of the headers in quiet mode, it was the changing to the loud mode that seems to have set the idling (temporarily) out of kilter as after a good run it's now fine. Does the air flow differently between the two modes? Could that be it? I did not have a remap after adding headers as I wanted to keep costs down and more after the sound rather than power/torque.

The outcome is it is now running absolutley fine but those few miles after changing the path from quiet to loud it needed throttle to keep it idling and I was wondering what the cause might be.

Surely if it was directly linked to the change in plates then surely it would happen to everyone who has electronically switchable exhausts... that would tend me to believe there was an external factor involved.
BTW i have same set up as you nosubstitute and mine has always suffered a little flat spot when cold, just above idle, but goes when warm. maybe just needs a little tune as still running the catback tune. (before i got headers)

[nosubstitute]

I guess I'll just have to put it down to 'one of those things'. The main thing is it is running fine now.