SaabCentral Forums banner

engine warm up?

5K views 47 replies 13 participants last post by  mferioli 
#1 ·
is there any kind of system or sensor or something that possible enrichens the mixture during low temps to helpthe car warm up? or does the engine startup normally during any temperature?

thanks,
mike
 
#2 ·
All cars, not just Saabs, run rich at startup, even more so in cold weather.
A lot of people claim that there's no need to warm up a car, and those are the same people who burn through a tank of gas every week even though they only go about 100 to 200 miles.
Even in the summer, it's good to let the car idle for a short time in order for it to even out the mixture.
 
#3 ·
well i have this persistant problem, where the car misfires while warming up when the temps drop somewhere below 50 degrees. I cant figure out what is going on, but once it warms up a bit its fine, and it only does it when its cold. Are there any sensors that could be causing my mixture to not be going rich at startup? what specifically cotrols this? and how does that system know if the engine is cold enough to need more gas?

Thanks for the help,
Mike
 
#4 ·
The coolant temperature sensor, the one at the inlet manifold..Also, the ECU may alter the timing when cold for more complete combustion, but the coolant temp sensor must be the only one to relate this data..

When cold, the car has to run a bit rich, but no more than necessary...emissions, and this factor will become tighter and tighter - until the automakers use ion-lithium batteries and electric motors...

Warm up time (sitting and idling) no more than 20 seconds and less; then easy driving until the car is fully warm(4 to 6 minutes) ..
No doubt that there are many thermostats out there sticking open and causing un-necessary fuel consumption...
 
#6 ·
Hey cliche! I let my car warm up right until I hear the air pump shut off. About 1 minute or so. But yes, mferioli, My car does misfire when it's cold out. But the thing is, it only does so if I let the car sit for about 3 consecutive days straight in the cold, then when I start it up, it misfires, throws the Check Engine Light, and I immediately shut it off. I disconnect the negative terminal, wait 10 minutes to clear the CEL, re-fasten, then it starts up just fine. I've learned that if I'm not going anywhere, I still go out and start the car just to keep all the fluids circulating. Hope this is of some help! ;)
 
#8 ·
Is there any chance the coolant level sensor controls engine warm up? A rodent chewed through that wire, so even though my coolant is fine, it tells me I'm low. I haven't gotten around to fixing it yet, but I have noticed that my car takes much longer to warm up now...could that be it?
 
#9 ·
KSpark said:
Is there any chance the coolant level sensor controls engine warm up?No chance that I know of - this only measures the coolant level in the reservoir. A rodent chewed through that wire, so even though my coolant is fine, it tells me I'm low.Lets hope that that is the only damage - these creatures are so very destructive- always seeking warmth and food.... I haven't gotten around to fixing it yet, but I have noticed that my car takes much longer to warm up now...could that be it?
The thermostat determines/controls the vehicles warm up time...when it is operating correctly, and after 4 years or so, it becomes unrelieable. This is one of the reasons for the coolant temperature guage.
 
#10 ·
Cliche` said:
A lot of people claim that there's no need to warm up a car, and those are the same people who burn through a tank of gas every week even though they only go about 100 to 200 miles.
Even in the summer, it's good to let the car idle for a short time in order for it to even out the mixture.
What? Where did you get this info???

Idling a car, in particular a cold one, is NOT a good idea.

Read the manual and/or talk to a mechanic. A cold engine runs rich on start-up and unless it's under a load will take much longer to warm up. Running rich is a strain on the cat, and more so on the engine oil (heard of sludge?) where some fuel can get by the rings and into the oil. By the way, how many mpg do you get while idling....0!

If you love your car and want to be good to it, drive it as soon as you can after start up but go easy, keeping the rpm down but not so much to strain the engine until the thermostat has opened (needle in gauge goes up and drops a bit) and the engine is warm.

If you REALLY love your car, get a block heater and use it (I believe that all northern Saabs come with one)!! Not only will it start easier but it will warm up much faster.
 
#12 ·
KSpark! If you know for a fact that you just changed out the T-Stat with a new one, dude, trust me! Change the coolant temp. sending unit! It's the small brass colored piece sticking out of the head between the upper radiator hose and a heater hose! whenever i would take off, with the old one, the gauge in the car would always drop to the 1/4 mark, always! BUT, and I mean BUT! I never had a problem with getting heat.


So, if you don't know when you've changed the T-sTAT, or even if it was done, I would definitely replace it! It's totally easy. Just 2 1/2 bolts on the back of the head (Driver's side) slightly bend the metal mounting plate to the side, so youcan take the housing off, take out old one, put new one in with new seal, (small hole vertically aligned at top) re-tighten, and you'r done! Simple! Good luck! ;)
 
#13 ·
I got the info from experience.
I used to just start and go, driving easy of course. I filled up at least every week and a half to two weeks, which, considering I was only driving about four to five miles a day and doing that only five days a week, was unacceptable.
I started waking up a little earlier and letting the car warm up for anywhere between five to ten minutes depending on how cold it was(This was all between late October and early March), I ended up filling up about every five weeks, my O2 sensor problems disappeared, and I was more comfortable, which, to me, is the most important thing of all.

By the way, I am a mechanic. So is my father. So are most of my friends. We all say the same thing.
 
#14 ·
can anyone explain what components are included in the "engine warmup system"? The owners book specifies that there is a system, so does it must then be made up of several componenets, right?also earthworm, I couldn't find that coolant temp sensor online, do have a link to where I could buy one? At least I couldn't find one that specifies its in the manifold, maybe Im just confused as to what Im looking at. By the way, is the fuel control module getting engine temp info from that sensor? or is that the engine control module
 
#16 ·
During the winter months, I used to let the car warm up for 5-10 mins sometimes. I then had a UOA done, and there was lots of fuel in my oil.

So next oil change I started the car, waited 30 seconds (no matter what temp) and my next UOA I had zero fuel dilution. The fuel dilution was attributed to my excessive idling.

Start the car, let it sit for 30 seconds, and then keep the revs below 2500, you'll be fine, and it hasnt affected my mileage.
 
#17 ·
mferioli said:
can anyone explain what components are included in the "engine warmup system"? The owners book specifies that there is a system, so does it must then be made up of several componenets, right?
The oxygen sensors generally control the fuel/air ratio, until they enter "Closed Loop". The sensors themselves have a heater element inside them to help them heat up faster so that they measure correctly. If the heater element inside the O2 sensor is faulty then it could cause a richer condition than normal.

A bad O2 sensor usually throws a CEL but that always isn't the case. A sensor can appear to be fully operational to the ECM but infact its "Lazy", its not operating in specified perameters, but is transmitting data.
 
#19 ·
thanks for the input guys, I did recently replace the forward O2 sensor so that should still be good. Is the coolant sensor I linked to above the correct part I'm looking for?

I think I'll start with that temp sensor as O2 sensors are pricey. My thermostat seems to be working fine as she is warmed up in 5 min max, and my gauge rides right in the middle all the time. I should replace it though, It might be original. But that wouldn't be my problem anyways, as the misfiring starts within about 15 secs of startup and can last for 2-3 minutes before clearing. No heat would really be built up and trapped in that time. If I drive the car right away and keep the rpms up It usually won't run rough at all, making me think its a fuel issue. It seems that that whole warmup system is just not working as designed right now.
just as a note I did pull all the plugs and regap them to .024, greased and checked all connections on both ends, and cleaned the distributor contacts.

Thanks for thinking about this, I'd be idling myself if it weren't for all your input.
Mike
 
#22 ·
mferioli said:
is there any kind of system or sensor or something that possible enrichens the mixture during low temps to helpthe car warm up? or does the engine startup normally during any temperature?

thanks,
mike
I suggested the temp sensor could be suspect ,but, please, measure before replacing...
Anyway I was wrong..

Exactly how is she running when cold ?

As far as idling the car, I do, for about 3 to 8 seconds, sometimes for a minute if the traffic is heavy. She runs nigh perfectly all of the time.....
 
#23 ·
Ok lets start form the top.....what are your symptoms?

Car starts OK but after a couple of seconds it cuts out? How does it idle when warm? How does it start when warm?

Have you checked the automatic idle control (AIC)....I believe that your car has one? It will limit the amount of air so that the car runs rich.
 
#25 ·
Tweek's Turbos said:
I let the car warm up so the engine and block have time to absorb the heat and expand properly before go anyplace. 100k miles of me doing this and no sludge, everything works fine.
I had big time fuel dilution in my oil by doing this. Now I let the car sit for 30 secs tops and go. Latest UOA's show no fuel dilution. I would be careful with sitting for so long.
 
#26 ·
Ok,

So this problem is happening about 90% of the time, and seemingly only when cold. It does not happen when the car is restarted after being warmed up, and happens less if not at all after when the temp is over 50 degress outside. It seems that the engine needs to get all the cold before it will reoccur.

I start the car and it will run smooth for about 5-10 seconds, then it will start idling rough, the check engine light begins to flash while the "misfiring" is happening and then stays on. The rough running will continue for 1-2 minutes approximately, then it smooths out and runs fine. The normal codes to be shown are random multiple misfire and sometimes 1 and 3 cylendars.
I can sometimes stop it from happening if I drive away immediately, getting the rpms up so that the car doesn't idle. But this does not always work.

I replaced the ECU sensor under the intake manifold, not the gauge sensor. Thanks for the sugestion about that sensor earthworm, I had nothing to lose by replacing it. It was a cheap part.

As another note, this has happened before during the summer, but that time my plug wires were all corroded away, replacing them fixed the problem. Now its back, but my wires are all in good shape, I regapped the plugs and cleaned the contacts inside the distributor cap. If it is somehow related to this again, what would the engine temp have to do with it? The distributor assembly is fairly new also and I i replaced the vacuum hoses about a year ago or so. also upstream O2 sensor has been replaced.

The intermitency of this is what makes it so hard for me to undestand. since it goes away relatively quickly after start, makes it seem like it only takes a smidge of heat to solve the problem, what could be that sensative?

Thanks for all the brain storming,
Mike
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top