2.2 E85 erratic idle when temperature is cold?

[Fulhamsteve]

Hello all.
Quite confused by the problem my e85 has started suffering from over the past few days.
When the temperature outside is warm and its dry, the car runs the same as it ever did. However, if I start it first thing in the morning, when it's cold and damp, it won't idle properly, fluctuating rapidly between about 500-2000rpm and shaking violently for a few seconds before stalling. It starts heartily and idles fine for about 20 seconds before starting this behaviour. I don't know if it was coincidence but it seemed to start the first time when I turned my blowers on full to demist the screen. It seems to correct itself if I unplug the MAF.


What are we thinking? I have so far checked for vacuum leaks (would have to be massive to cause this I'd have thought), cleaned the IAC valve and cleaned the MAF sensor. Nothing looks too abnormal from the live data I've seen, fuel trims are fine and the MAF is reading normally. The battery voltage was a little low (12.2v) but rises to 14.5v when running, so the alternator is fine. Both o2 sensors are behaving normally. DISA valve was rebuilt about a month ago and the car has not displayed any DISA related symptoms since it was rebuilt.

 

[enuff_zed]

When you disconnect the MAF it then runs on a default setting. If this runs fine then I think you are looking at an issue with the MAF.
Cold, damp air is much denser and holds more oxygen, so the fuelling has to adjust to compensate for that.
I think I would start by trying a replacement MAF tbh.

Are you 100% certain there are no air leaks. Check the corrugated pipe above the main inlet as that is the usual culprit, sometimes the hole is hidden underneath it.

 

[Fulhamsteve]

Thanks for the reply!

There was a crack in one of the pipes. The large intake pipe connected to the throttle body has a small rubber hose coming off and this was slightly cracked, but I have sealed it until I can buy a replacement. The others seem fine from what I could see.

(Edit: believe this is the pipe you mentioned)

About the MAF, is there a way I can test this before buying another? I have checked my OBD scanner and it seems to be responding as expected to RPM but is there a better way to check it?

 

[enuff_zed]

Thanks for the reply!

There was a crack in one of the pipes. The large intake pipe connected to the throttle body has a small rubber hose coming off and this was slightly cracked, but I have sealed it until I can buy a replacement. The others seem fine from what I could see.

(Edit: believe this is the pipe you mentioned)

About the MAF, is there a way I can test this before buying another? I have checked my OBD scanner and it seems to be responding as expected to RPM but is there a better way to check it?

Yes that's the pipe I meant.
I'm not aware of any way to test the MAF other than by replacement I'm afraid.
Unless you can find another member nearby who would allow you to do a diagnostic swap?

 

[Mike6]

Think you can buy a cheap one on eBay to test with. Think it's not recommended to run permanently but it might help narrow down the fault

 

[Fulhamsteve]

I'll just update this in case it benefits anyone who has similar issues. I don't know that the car is totally fixed yet, it's a bit early to say, but over the past few days including some very early starts and generally wet, cold conditions, this issue has not presented itself.

The steps I took were firstly to charge the battery, which was not exactly low but not fully charged either. I then unplugged the electrical connectors for each sensor (i.e MAF, both cam sensors, crank sensor, DISA) and cleaned them with contact cleaner. Removed the plastic vanity cover on the engine and removed each ignition coil to check the condition, firmly replaced them to make sure none were loose. Sprayed the inside of the coil and the electrical connections around the wiring loom around the injectors with WD40 to disperse any moisture. Found that the bumper-side part of the air filter housing was missing a clip and not seated fully allowing air from the engine bay to be drawn in after the filter so seated this properly and bodged it into place. Finally, filled up with V power, ran some injector cleaner through and gave it a good 45 minute drive at motor way speeds. The car did display a very slight misfire at idle when first starting up after the battery was reinstalled but this soon cleared and after the long drives it was running nicely again. Starting yesterday at a very cold and wet 06:30 and it didn't miss a beat. Hope this helps!

 

[chanlon1]

Fulhamsteve, hate to resurrect an old thread, and we dont even know if you still have the car but wondering if the problem did seem to go away, to reappear?????