Everyone,

My V70 has been slowly developing a problem with cold starts and I want to make sure I can diagnosis it this summer before the cold stuff hits this winter :) On cold starts (i.e. sitting overnight, even sometimes after sitting throughout the day) I am getting a shudder or stumble where the engine seems to miss for a short period, maybe 5 seconds or so. After that, the idle evens out and I have no driving problems. My guess is that I am losing fuel pressure over night and the pump can't make it up fast enough on a cold start so I get the stumbling until the fuel pump catches up. Does this sound plausible or am I way off base? Any other thoughts on what this might be? What is the best way to go about diagnosing this?

Thanks!
Brian

Everyone,

I finally got some time to look at this (the 145 is back and running!) and I did check the battery...it appeared fine, even when starting... voltage never dropped below 11 V or so. I also searched around for an Idle Air Control until I realized...the 2001's don't have this, they use the electronic throttle to maintain idle. I have put cleaning the the throttle body onto my todo list but haven't had a chance yet. Any other thoughts on this issue?

Thanks!
Brian

It could be one of the 5 coils not liking the contraction. 50-60F is hardly cold!
It still sounds like it is getting too much fuel and a plug or two are wet during cold start.

Klaus
--
Did you do your Random Act of Kindness today?

I would suspect the Idle Air Control valve. It's pretty easy to pull it out and clean it out using throttle body cleaner (just soak it and shake it - repeat a few times).

When it's clean you can give it a good coat of WD-40 inside to keep it lubed and keep the water that condenses inside from affecting it.

I try to clean mine about once every couple of years as a pre-emptive measure.

--
1998 V70 AWD->FWD->AWD Turbo 220k+

Slightly off base. Your fuel pressure will go to zero after about an hour or so anyway, that is why you hear the pump 'prime' when you turn the key to posII. If the fuel were to return to the tank because of a failed valve, it would take a lot of cranking to get the fuel back into the injector rail and pressurized, like 10-15 seconds.

You do have copper plugs in your 2001 T5 M? And they are clean and gapped at .028?

Klaus
--
1967 220 belonging to C.A. lives on

Klaus,

I do have copper plugs in my V70 and I did gap them when I did the install but I don't remember the exact value I gapped them to (0.028 sounds right though). The plugs have about 12K miles on them. Do you think the plugs have weak spark when cold?

If the fuel pressure drops to 0, then is it just possible the fuel pump can't generate the pressure quick enough before I start the engine? I guess I can test this by holding the key in position 2 before starting.

Thanks,
Brian

Because the fuel line is always full of fuel, it only takes the pump a split second to boost the pressure.

One of the things about cold temperature starts being hard is the condition of the battery. It needs to be fully charged.

Also, when the ECT sensor is cold, it will lengthen the injector time. If that is combined with a small vacuum leak, you will be over-rich during the start process.

Klaus
--
1967 220 belonging to C.A. lives on

Klaus,

I recently had a smoke test so I am fairly confident I have no vacuum leaks. Also, by "cold" I mean Portland cold, so maybe 50-60 degrees when I start up. I also usually drive for at least 30 minutes so I believe my battery is always fairly fully charged.

Thanks,
Brian