Tach Learning - Remote Start

Okay, this should apply to just about any r/s that uses a tach input, but so you know, I have a "factory" Mopar remote starter in my 2005 Chrysler 300, which I installed myself.  Everything works fine, but on extremely cold days (this morning it was 14 degrees), it keeps dying.  I know the r/s transponder is programmed correctly into the SKREEM because it has started the previous two days since installing, and then again today when it was a little warmer out (25 degrees... break out the sunglasses and tanning lotion).

As many of you probably know, the problem is that when it is THAT cold out, the engine revs quite high when starting.  The installation instructions for the r/s say to set the tach when it is at a low idle.  That is around 650 RPM or so when warmed up.  The r/s shuts down at 3X that.  That gives me a limit of about 1950 RPM.  When I started it this morning manually after the r/s didn't work, I noticed the RPMs went over 2000 when it initially fired up.  After work I reprogrammed the tach to 900 RPM, which should allow me up to 2700 RPM.

Now for my questions/ concerns:  Why do these r/s manuals say to program the tach at a "low idle", when they know that 3X that will stall the engine, and that when it is very cold, the engine revs pretty high?  The instructions say that if set too high, it could cause "overcranking".  This sounds like such poor design.  Anyway, it should be about as cold tomorrow morning as it was this morning, so I will see if my new tach setting will work better.

Also, anyone know what the "Diagnostic Tach Mode" is on the Mopar r/s?  Will that disable the 3X revving limit thing?  Because that's what I'd like to do.  Come summer, when I use the r/s to run the A/C and cool the car down, the tach setting will be much too high, which I've heard can also cause the r/s to detect as a "problem"- such as thinking the idle is below normal, and shutting down to prevent battery drain.

Any installers that install these Mopar starters (I know there a few here... ), in climates where it gets down to around 5 or 10 degrees, what do you recommend to set the tach at?  Also, does the tach learning only remember the "idle" RPM, or does it also remember the RPM when it started?  I ask because it says to enter learning mode first, then start the car and wait for low idle before "setting" it.  If so, I could just rev the engine when starting the car to learn the tach signal.  Then it may see 2000+ RPM at starting as being acceptable.

Sorry so long!

-Kevin

I don't have the wiring diagram for the remote starter, but the harness was pre-wired, and simply plugged into the back of the ignition switch.  I don't know if that second starter wire is powered with the r/s or not.  Wouldn't that have more to do with cranking though?  It starts fine, it's just the higher RPMs during a very cold start that were making it shut down due to over-revving.

By the way, after I changed the tach setting to 900 RPM yesterday, it started and stayed running fine this morning, although it wasn't quite as cold as the other day.  20 degrees today, 15 yesterday.  Never thought I'd say this, but I hope we have a really cold morning tomorrow!    I'd like to make sure the tach change I made fixed it.

-Kevin

i think that you just have to relearn the tach at 1000rpm i don't know why mopar says that you have to lear the tach at low rpms, the second start is done don't worry about it  

It sounds like you install these Mopar units, Dare?  It is odd that apparently all r/s instructions say to set the tach at a low, normal idle.  This isn't a big deal, but if there is a 3X rev limit like on the Mopar one, it doesn't make any sense.  Do you typically set them at 1000 when installing?  I'll probably stick with the 900 I have programmed into it for now, unless I have another problem next time it is very cold out.

My only other complaint is that the Mopar r/s powers up the stereo.  I've installed two remote starters on previous cars (Bulldog), and they didn't.  I know I can just turn the stereo off, but I like to leave it on.  The problem is that I usually listen to CDs, so if I don't turn it off, by the time I get out to the car after remote starting it I have missed a few songs since I last got out of the car.  I will just have to learn to turn the stereo off, I suppose.

Thanks,

The Mopar factory remote starter PARTS (for 300 and Magnum) are $299 plus tax.  The local dealer wanted $530 installed.  I found another dealer through the internet and they had 10% off your first order with free shipping and no tax.  I ended up getting the parts for $269.10.

To update my problems... Once again this morning it would start and die.  I repeated this 3 times and said "screw it".  That is the odd thing about my problem.  It might work fine for two days, then I have problems.  It would always start, but would die.  Sometimes a couple seconds later, sometimes 30 seconds later, sometimes after a few minutes.  I got a chance to look at it today after work, and I think I found the culprit.  One of the guys here had warned me that the hood tilt switch is cheap and could be problematic.  I played around with it, and I found that to be very true.  At one time, I remote started the car with the hood down and gently pounded on the hood right above the switch.  The car died.  I also noticed that with the hood "popped", but not up, it would sometimes start, and sometimes not start.  I concluded that the switch is very finicky, and not very reliable.   Hmmmm.... sounds like the remote starter!  Anyway, I temporarily bypassed it for now.  I will give it a week, and if I have no more problems, I will go to an ectronic parts store and find a better switch.  Believe me, I am not going to leave it bypassed!!!  I work on my cars myself, too.  I just want to be sure I have isolated the problem.

-Kevin