1st Gen R53 Cooper S Cold start idle, any reason to use an AFR gauge?

Background: my 05 MCS is starting to have cold start idle symptoms. Since the weather has changed (colder) the cold start stuttering in AM isn't as bad as summer -- summer fuel mix(?). I've researched and checked most everything mentioned on MA except replacing the fuel filter. Puzzling really. :confused5: To recap that experience: anytime the motor is cold, starts up fine but as is settles to idle below 1k the motor stumbles ever so slightly. If I blip the pedal it recovers fine. Then once warmed up she runs like a champ. Even at stop lights. no codes thrown so far.

It feels like the initial cold start fuel pressure or AF isn't right. I rescued this last november off a used lot in GA. It had no history. Not sure if it was tuned and at idle that tune is off (just an idea). I'm in winston so may give Chris Sneed a call.

Question: My Q on AFR gauge is that could tell me if the AFR is too lean at start. But might be talking out my arse there -- MA feedback would be helpful thoughts?

Thanks.

 

All comments are helpful -- even Dave.o's comments.

I've always run an additive called FP60 through my vehicles. Have a 98 saab 900NG with 280k miles running like a charm; original drive train. I R&R the plugs and wires when purchased ~78k miles (90k now). When I pulled the plugs last month they looked normal, torqued to spec. #4 had a little bit more darker brown on it than the others but still looked ok to me.

yea coffee with age is best. once you go bolder you never go back

 

Check. It's good. No corrosion.

 

EML P1498 code

and like that it happens... Fault code P1498, unmetered air after compressor - or at least what I can find on MA. It pop'd during warm up this AM. I'll do more investigation this weekend; inlet duct assembly, MAP pipes,etc..

I'll post any findings/solutions/beer selections...

 

Discovery this weekend - hopefully solved the problem

Thanks Nat. Good call. I pulled the IC and it had silicone boots (came with the car, not alta); silicon boot on SC output side was stiff and probably leaking. I noticed the "gutter" in the OEMs that the silicone didn't have which, once oil accumulated on the bottom, was probably the catalyst for the leak (guess). Anyway found some OEM boots locally and they seem to seal much better. Also, noticed a boost tube to a sender I hadn't noticed before hooked up the SC via a T-connector. Pulled that out of the equation connecting the OEM set up.

I'll drive it for a week and see if that resolves the code and cold start.

Thanks guys for the help.

 

Must be something with summer mix that aggravates this problem as its back - P1498. Had zero problems all winter. Anyway feedback from others on the following:

I still can't find any vacuum leaks so turned my attention to MAP sensors. I did find something but not certain its my culprit or even an issue.



I back probed both sensors with the following results:

TMAP
Pins 1/2/3 /4
KOEO: 0.0V / 1.78V / 4.99V / 1.87V
Idle: 0.0V / 1.62V / 5.0V / 0.88V


MAP (near thermostat)
Pins 1/2/ 3/ 4
KOEO: 0.0V / no connect / 4.9V / 3.9V
Idle: 0.0V / no connect / 5.02V / 1.78V

According to Bentley Pin 2 on TMAP should read @60F 3.9V (KOEO) and 1.25V (Idle, ambient and operating temp). Could this be my issue?? :fingerscrossed: Would appreciate a confirmation before ordering one.

 

Thanks Nat and Dave0. I'll look into both -- I'm at 96k so timing chain guides are due.

I'll update again ltr