Cold plugs, cold weather cold start idle implications

[s1ngletracker]

Random thing I've been thinking about... would running colder plugs make my car idle poorly on cold starts in MN Winter weather? My cold idle is starting to get rough and the car wants to die more and more as the weather gets colder.

[s1ngletracker]

Ok, so today was pretty awful. Still looking for help on this. Pulled the plugs, they seem fine, I'm assuming they aren't the cause.

-Compression tested, came out normal
-Swapped out MAS for a known good one, no change
-New coolant temp sensor
-Swapped out hte ISC, which tested good, but there still might be a slim chance it is bad
-I have previously deleted the wax plug fast idle thing. I realize this impacts cold idle, however, it was deleted last winter and didn't have this problem

Things I'm going to test/change out:
-Plug wires
-Coil
-Ignitor
-Look at fuel pressure while cranking and ensure all is good there.

Could these be the cause? Are there any other ideas as to why my car just WILL NOT idle on cold starts? I have to hold down the gas for about a half minute before the car will idle on its own without dying.

Also, side question, to properly set the idle, I just need to ground out the one pin on the test connector at the firewall, then adjust the base idle screw, right? Or is there something else involved? The manual is a bit confusing on this, it talks about grounding something else out, a pin on the diagnostic connector that my connector doesn't even have.

Any help is appreciated. I realize there are few knowledgeable people here that even drive dsm's anymore, and even fewer that daily drive them in the winter, but worth a shot.

[Matt D.]

Originally Posted by s1ngletracker

Also, side question, to properly set the idle, I just need to ground out the one pin on the test connector at the firewall, then adjust the base idle screw, right? Or is there something else involved? The manual is a bit confusing on this, it talks about grounding something else out, a pin on the diagnostic connector that my connector doesn't even have.

I'm pretty sure that is to set the base timing.

I know our cars aren't much alike but my car is a bitch to start in the cold. When it's below freezing I just have to hope it fires and I do have to keep on the gas for a bit until it idles on its own. This was even before I had bigger injectors and cams and it's no different after.

[TheBlizzard]

If you car is harder to start when it gets below 30 degrees it is likely one or both of your coolant temp sensors are bad. If they are bad the ECU thinks the air temp is hot so it does not enrich the fuel enough to start it. I would check there first, if not your ECU could have issues as well.

[s1ngletracker]

Originally Posted by TheBlizzard

If you car is harder to start when it gets below 30 degrees it is likely one or both of your coolant temp sensors are bad. If they are bad the ECU thinks the air temp is hot so it does not enrich the fuel enough to start it. I would check there first, if not your ECU could have issues as well.

As I said in my post, I replaced one of the sensors (even tested the new one, checked out ok), the one for the ECU. There are 2 more, right? 1 for the A/C and one for the... fan switch? Either way I dont think either of those would have a huge impact on starting. I definitely smell gas if it takes me a few tries to start it without much success... I almost think its probably running TOO rich. Don't have a whole lot of evidence to back this up though. What would cause it to run too rich?

I'm not getting any check engine lights.

I wouldn't be thinking much of this, if it weren't for the fact that it didn't have this problem last year, not even in -10 degree weather, it would at least idle on its own.

I've had the ECU out and examined it closely, no leaking capacitors. Maybe I should have them replaced anyway?

I think i'm gonna log it when it first starts and post it up here for input.

[s1ngletracker]

ok, well, this is on hold for just a bit, due to my water pump catastrophically failing last night, the bearing failing and the pulley breaking off and bouncing around my engine bay, spewing out all my coolant and making a huge smokey mess My car IS a DSM! go figger.

[mnnice]

Originally Posted by TheBlizzard

If you car is harder to start when it gets below 30 degrees it is likely one or both of your coolant temp sensors are bad. If they are bad the ECU thinks the air temp is hot so it does not enrich the fuel enough to start it. I would check there first, if not your ECU could have issues as well.

this wouldnt throw a cel would it? my car has the same issues. it doesnt idle until it warms up

[niterydr]

Is the car tuned? Many "tunes" will not address cold start as vehicles are very tempermential in cold weather conditions.

Another issue is that when it is cold air leaks are even more vital. My truck for example, runs great, but I know there is an air leak either around an injector or the intake manifold itself, so when it is really cold, it will not want to idle without help.

So check for leaks first.
Also, since this is a tech thread, what is the vehicle and mods?

[s1ngletracker]

The car is for all intensive purposes, bone stock. 93 Tsi AWD with a 7 bolt.

I am currently replacing the head and head gasket, i'm going to make sure all boost leaks are addressed when that is done, and I'll update the thread.

[89_Colt_GT]

mine takes 10 turnovers to start and i need to let it warm itself up too. when its warmed up it'll start right away. Can't it just be beaten on and run everyday :/

[TheBlizzard]

Originally Posted by mnnice

this wouldnt throw a cel would it? my car has the same issues. it doesnt idle until it warms up

Yeah it should throw a cel for sure because it will go into a default fuel map. And yes singletracker if one of those sensors are bad it will affect the starting in cold weather immensely. Under 30 degrees. If the head and leaks don't fix it I would next check tue ECU.

[iceminion]

I've been daily driving my DSM's for about ten years now, so I would say that I have some experience with this.

First off, for your water pump:
-I always keep the belt as lose as possible.
-I understand that there is an "official" way to check tension, however I have chosen a better way.
-losen the lock bolt on the alternator tensioner.
-start out lose, it should squeal on startup.
-turn car off, tighten tensioner bolt one turn, try again
-if squeals, tighten one turn, try again.
-tighten bracket tensioner "lock" bolt(short).
-reinstall AC fan.
-further adjustments may be necessary, but when using used pumps, used belts, and dirty pulley teeth, this is the best method.
-overtightening the belt causes bearing failure, remember this.

OK, now on to why your car is taking a while to turn on:

My gut feeling that there are a lot of things contributing to this:

First off you have two separate issues that are linked.

however you must recognize that there are two separate issues or what I say will not make sense.

Issue #1 - delayed start.
Issue #2 - dies once running until cylinders heat up.

To resolve both these issues, treat for the following:

-Poor injector spray pattern (have lots of supporting evidence, build your own injector testing station, easy to do, will share info by request)
-Deleted fuel pressure assist solenoid (we all delete this, we all don't care, but it does affect startup in the cold, put it back.
-Verify that your fuel pressure remains between starts, if the fuel pressure valve in the fuel pump has been damaged/removed, all the pressure bleeds back into the tank and you'll have air in your fuel rail.
-Your CAS is 180 degrees off, trust me, it is, set engine to TDC and set CAS to alignment notches and re-install.
-throw away your blacktop CAS, buy a greentop CAS.
-re-gasket your CAS, believe it or not some CAS sensors get damaged by oil creeping into the chamber, take the security screws out (have tips for that) replace with torx security screws, clean up sensor, use "the right stuff" for a replacement gasket. (do NOT touch the stuff on the inside)
-Your ECU is damaged, come to terms with it, its true, talk to keydiver, you need to replace IC104 (thats how it's labeled on your ecu.
-I do have good ecu's from cars that start instantly.
-I also have good, "new" gen (black) IAC's if you need a known good one.

Let me make a transition here to ECU repair/maintence/testing because it is part of this. Now test your idle control system:

-Adjust BISS to idle 750 RPM when hot (if your vehicle does not stay hot, this will not work because your car is in warm up mode, im gonna post up about thermostats in another thread, read it).
-Drive at over 30+ MPH (to hit the cruise control VSS switch engagement point)
-Come to a complete stop in "N" or "center" on the shifter, only use brake pedal.
-During the slowdown, your RPM NEEDS to be 900-1200 RPM (IF IT IS NOT YOUR SH1T IS BROKE, ASK FOR HELP)
-Once your car comes to a complete stop, the idle NEEDS to drop back down to 750 RPM(IF IT IS NOT YOUR SH1T IS BROKE, ASK FOR HELP)
-Rince and repeat, if the car does not do this reliably there is something wrong with your idle control system.

Now that your idle control system is working, your stock 93 turbo 7-bolt engine will start up almost instantly, idle better, warm up faster and just work better.
Dirty/damaged CAS sensors also contribute to 2G's random misfire issue, I've done 6 2G 6-bolt swaps, all work great with the stock ECU, no misfires at all, thats why its a "random misfire" nobody knows why some cars just work great after the swap, I do.

I have several examples in my driveway that are proof that DSM's turn on almost immediately in case you have any hint of disbelief.

If this is a little dis-organized, I apologize, I will revise it when it isn't 3AM.
If I come off as an asshole, sorry, kinda hard to give technical support for your car and for your emotions at the same time, read around the things I say that piss you off, absorb the information, move on.