question about the cold start lever

[dyoungen]

I have a 1985 Jetta Diesel and have no idea why to use the cold start lever. What is the purpose of it? The temprature the last few weeks was in the low 20's to high 30's and didn't have any trouble starting the Jetta. Am I missing something?

[maxfax]

It advances the timing to aid in cold starting and running.. I personally have never had to use mine either... IF everything is healthy, and depending on what your pump timing is set at you may have no need for it...  ALthough in extremely cold sub zero temps it does help....

[vanbcguy]

Jezebel will start without her cold start, but it's not a pretty start.  She blows a little blue smoke as she catches and often needs a second cycle of the glowplugs to really go, at least when it's cold out.

With the cold start however she fires right up on the first crank!

[8v-of-fury]

Depending on how much you know about the fuel pump and its timing procedure, the cold start lever is used to manually advance the injection of fuel 3-5 degrees relative to the position of the cylinders to top dead center.

Say you have your pump timed to 0.95mm pulling the lever will make the pump think it is timed to 0.98-1.00mm. more advanced over stock is usually better for cold starts, performance and less smoke at idle. However there is a significant amount more of NoX being let in to the atmosphere with the more advanced you go.

[ldeikis]

While we're on the topic...

On a car that needs/wants the CS lever pulled to start, how long is it meant to be kept out?  Should you push it back in immediately, if possible?  Is it better to use the throttle to maintain a high idle and push the CS back in (in a situation where the car would stall if allowed to drop back to idle without the CS out)?  And, last--if your pump was timed a little too retarded and you left the CS out, how is it different from if the pump were just correctly timed a few degrees more advanced?  I've read a couple different pages about how the ve pumps work, but I'm still having trouble wrapping my head around exactly how the cold start advances the inject... and, I guess, how the pump actually manages to advance injection timing.

Thanks.  All of this may be moot practically for me,as I've got the head off and will be timing it for the first time, with no knowledge of where it "used" to be, but I'm interested in understanding more about how the pump works.

Luke

[vanbcguy]

The cold start handle pushes the timing piston over a touch - it essentially moves where the lower stop for the timing piston is.  However as soon as the pump is making any pressure it will still move the timing piston like normal.

As soon as the engine is spinning to about 1500 RPM or so it's running in its normal timing range regardless of the cold start position.  It's only at idle speeds that it really has any effect.  So if you were to time the pump advanced by a few mm then it would be advanced a few mm through the entire RPM range while the cold start only advances it from 0 RPM - 1500 RPM or so.

Yes, you can definitely time the pump a tad more advanced if you find your car needs the cold start a lot of the time.  I'm actually thinking I'm going to move Jezebel from 1.00 to about 1.03 or so to see if she's happier as she doesn't like starting without the cold start when it's cold out.  But you don't want to over-advance your timing or you're really not going to get good mileage, have a turbo that spins up slow and a NOISY engine.

Clear as mud?

[vako]

i have one question about colt start lever too.   i have swapped 1.9td to suzuki vitara. so i don't have original wv cold start lever. i'm using lada samara lever instead. so i'm interested how much should I pull the lever to completely a advance the pump to cold start position. it feels like after pulling the lever 1-1.2 inches, it doesn't want to do more. but on the pump itself the lever could be pulled way further than that..


so my question is..... is 1-1.3 inches enough for the pump to be advanced completely  ?


vako 

[8v-of-fury]

Hmm, Vanbcguy I might have to disagree a bit only on a slight hindrance i noticed.. Last night I went out and started my 1.6 N/a that hasn't been started in about 1.5 weeks. Now I have my pump timed to 1.04mm so I know my cold start (prior to starting) will have adverse affects on engine starting.. so I cycle my plugs, start the car, and then pull the CS out. Now this results in the car running perfectly! HOWEVER! push the CS back in before the engine has had an adequate warm up and it gets rough idle and rough revving. IF I rev the engine up with the cold start out (being smart and not letting the throttle off so the timing piston gets slammed in the pump) to above 1500rpm and push the cold start in and out it still has an affect on engine noise, speed, and quality of running.

Now this could be a thing only my pump has wrong I know the CS is only for idle adjustment to the timing.. but clearly it goes a wee-bit higher than 1500.

Also since this thread is about this topic :p like I said earlier my CS prior to starting will cause the slower sluggish starts associated with too much advance.. But the car loves the CS to be pulled after starting.. could it stand for a little bit more Advance?

so my question is..... is 1-1.3 inches enough for the pump to be advanced completely?

I do believe on the back of the pump where the Cold Start mechanism is, there is a stop there.. so as long as the lever is being pulled to its stop, then that is where it needs to be.

[vako]

i think you are right. in this pic the pump seems to be in cold start position... but when i pull my lever out 1-1.2 iches it doesn't get to this position. so i'll adjust it

 thank you for reply 

[Vincent Waldon]

The cold-starting sweet spot for my 94 AAZ was just enough static advance that the car actually cranked *slower* on cold mornings with the cold start handle pulled out.

So... handle in, crank till she catches, pull out the handle... nice smooth cold idle with very little smoke.

My theory.. such as it is... is that there's a tipping point where two much advance actually fights the engine as it's turning over at a couple hundred RPM... yet it's appropriate for smooth cold running once the car is up around 1000 RPM.

[RabbitJockey]

i don't use mine unless it idles poorly, and i push it back in as soon as i drive a block or 2, just makes the car smoother and more drivable before it actually warms up, alot of the time its not needed

[Rabbit TD]

I've noticed on my 1.6 T/D when starting at even around 25 degrees F. if I just run my boost pump for a few seconds and cycle the plugs it starts just as good with the advance in as it does out. 

[vanbcguy]

Hmm, Vanbcguy I might have to disagree a bit only on a slight hindrance i noticed.. Last night I went out and started my 1.6 N/a that hasn't been started in about 1.5 weeks. Now I have my pump timed to 1.04mm so I know my cold start (prior to starting) will have adverse affects on engine starting.. so I cycle my plugs, start the car, and then pull the CS out. Now this results in the car running perfectly! HOWEVER! push the CS back in before the engine has had an adequate warm up and it gets rough idle and rough revving. IF I rev the engine up with the cold start out (being smart and not letting the throttle off so the timing piston gets slammed in the pump) to above 1500rpm and push the cold start in and out it still has an affect on engine noise, speed, and quality of running.

Now this could be a thing only my pump has wrong I know the CS is only for idle adjustment to the timing.. but clearly it goes a wee-bit higher than 1500.

Also since this thread is about this topic :p like I said earlier my CS prior to starting will cause the slower sluggish starts associated with too much advance.. But the car loves the CS to be pulled after starting.. could it stand for a little bit more Advance?

so my question is..... is 1-1.3 inches enough for the pump to be advanced completely?

I do believe on the back of the pump where the Cold Start mechanism is, there is a stop there.. so as long as the lever is being pulled to its stop, then that is where it needs to be.

If your pump has low internal pressure, it won't advance properly. If your cold start lever has an effect on how your engine is running past 1500 to 2000 RPM then in all likelihood you will find the advance mechanism in your pump isn't functioning.  If you are finding you need a ton of static advance to get good performance then that is definitely something to check! I believe there is a posting in the FAQ.

[damac]

It only gets into the teens/twenties around here.  I have noticed how nice that lever is in the colder climates

On mine I start the car, then pull it out right away.  It helps smooth things out as the engine warms up.  So I can let it sit like that and warm up for a few minutes, then drive off and a few minutes after that I can push it back in.

I don't really notice any difference in the car when driving around normally so I have to remember to push the lever back in

Also pulling the lever seems to help things run smoother I would say during warmup over raising the idle.

I have a resealed pump on my car right now actually and just got some rebuilt/tested injectors and plan on tuning the injection pump the same way be ear because it seems this is what the car likes.

[R.O.R-2.0]

my car has to have the lever pulled out to start if its super cold. and it will still sit there and buck a little till you give it some rpm.

and my cold start lever makes the engine more rattly only at idle, the second you give it some gas, the cold start advance doesnt do anything..

but i know my pump to be >10k mi rebuild..