cold start shifting lag

[RConrad]

does anyone know of a fix(chip change,etc.) to over ride the cold shifting of the xmission on the SL-320 . I guess all MB's are setup this way(an emissions thing when cold). I know you can disconnect the abs and they will shift normal when cold, but I'd rather not do it that way if possible. May be an insurance problem if in an accident..This car has to be(HOT) before it starts to shift out of second.. Thanks for any info, Ron

[Kebowers]

Some MBZ models have an 'upshift delay' feature that keeps the car in 2nd a little longer before it upshifts to 3rd. It DOES NOT prevent upshifting, merely moves shift speed up a little higher. This is supposed to heat up the catalyst mufflers faster and improve cold start emissions. If your sl320 will not shift up to 3rd at all--its not the upshift delay feature. BTW, the MIL (check engine light) will go on if the upshift delay feature is not working (activating).

[RConrad]

I talked with MB re-the s-320, they say it is a (design) situation to heat up the cc as you said. the problem is you must let it idle and heat up BEFORE it will shift from 2nd AT ALL...I've not asked about the SL as yet, but it is the same engine, so I assume It's the same situation. I'am guessing there may be a chip which can be (removed)changed to defete this. They can't do It because it would be illegle for them, but I could do it on the sly if I knew which/what it was. Thanks for your input...Ron

[LeaUK]

My '93 also does this. On cold mornings I have to rev to around 3500RPM to shift to 3rd (only once) - I thought this was due to the automatic fluid viscosity but to hear it's by design is interesting news...Thanks

Lea

[David Langsam]

My '88 560sl does this as well. On cold mornings, it will hold 2nd gear for a long time. But only once, after the first shift, it will shift normally. Kind of annoying, and as I drive down my quiet street in the early morning, I always feel embarassed because the car is revving so high. I was told long ago it's by design. Luckily, most of the year it's not that cold here.

[RConrad]

Thanks for all your inputs on this. I know if you rev It up past 3-3500 it will shift, I just can't rev a cold engine that high and feel worm and fuzzy about It. Long time ago at a tech seminar the fella said NEVER rev a cold engine over about 2-2500, thats when 90% of the wear takes place. I'am going for longivity on these two vehicles....

[LeaUK]

That's good advice, I never rev her just to change gear, I tend to wait 3 minutes or so and she naturally warms by then.

One thing I reported incorrectly; the rev range which forces a 2 to 3 shift, on my car its 2500 exactly - not 3500 as originally posted.