Hard starting in a little colder temps

[t_marat]

whenever temperatures are lower than 10C/50F it becomes difficult to start the car. It turns over but doesn't start, or starts runs really rough and stalls, usually no reaction to the gas pedal. I am able to start the engine after several tries, but have to keep the revs at about 1500rpm for about 30-40 seconds, then it would idle normally.

During summer I had a similar problem when the engine would not start in the morning. I had to spin the starter several times and then it would start, but still had to keep the revs high for a while before it would hold idle. This was solved by adding an injector cleaner to a full tank. Around the same time my FPR died; it wasn't letting any fuel back to the tank, fuel pressure was very high. Also, my fuel pump is rather noisy and return valve is also not working. At least I think so as the pressure drops to close to zero rather quickly. But if weather is warm, then no problems starting the car, even after it stayed idle for a couple of days.

What do you think this is? The symptoms are the same as I had during the summer. It's just now they appear if weather is a little colder.

[timandbim]

i had similar symptoms with my m20 and it was my ICV.

[Jeff N.]

A simple check is your engine temp sensor. If it's faulty, the car will not correctly trigger the cold run cycle.

[Morgenster]

The fun doesn't stop does it? ;)

I'd look at fuel pump and filter as well as the sensor mentioned above and the ICV.
Remind me again which parts were replaced?

[t_marat]

I replaced FPR and fuel filter this summer. I have been using my current fuel pump (not new) for about 2 years now, since the old one died. Apart from that O2 sensor is also new, original.
If the engine temp sensor is faulty, shouldn't it show up on diagnostics? I only had a ICV error. And if it was ICV, keeping the gas slightly pressed while turning starter, shouldn't that make the car start?

[bsell]

I replaced FPR and fuel filter this summer. I have been using my current fuel pump (not new) for about 2 years now, since the old one died. Apart from that O2 sensor is also new, original.
If the engine temp sensor is faulty, shouldn't it show up on diagnostics? I only had a ICV error. And if it was ICV, keeping the gas slightly pressed while turning starter, shouldn't that make the car start?

I don't know about a bad sensor showing on the diagnostic but I do know that injectors with lousy spray patterns cause hard cold starts and poor gas mileage. Luckily, it is pretty cheap to clean them out with a stout can of injector cleaner and some quality time at WOT.:D

Once you are reasonably sure your injectors are spraying as they should, then of course you can chase other possibles like your temp sensor. I have read stories from a couple folks here how their ill-performing temp sensor gave them fits. Especially for such a cheap part. So if you want, just swap it out if the temp sensor is an original part and run some injector cleaner through it. If these cheap and easy fixes don't work, then you have other problems (vacuum leaks anyone?).:(

Brian

[Morgenster]

I replaced FPR and fuel filter this summer. I have been using my current fuel pump (not new) for about 2 years now, since the old one died. Apart from that O2 sensor is also new, original.
If the engine temp sensor is faulty, shouldn't it show up on diagnostics? I only had a ICV error. And if it was ICV, keeping the gas slightly pressed while turning starter, shouldn't that make the car start?

Even if the temp sensor gives a bad reading it should still start. The ICV code can mean anything but I wouldn't dismiss the ICV. Starting relies on the opening of the valve according to measured engine temp.
Anyway, if normal running when warm is normal I'd definitely look into temp sensor and ICV.