cruise control adjustment on 03 m45

[saeedakobiakov]

Hello,Is there way to adjust the cruise control for better accuracy?Thanks,CAug.14.1 @100.05

[Sentientbydesign]

What do you mean by better accuracy? You want it to "stick" to the MPH that you set and not deviate?...Drive on level ground lol. But seriously, what are you referring to?

[Q45tech]

In top gear there is not enough torque to instantly correct for the major differences going up and down inclines create.

The only way would be to cruise in a lower gear which would wreck MPG. The system tries to avoid a transmission downshift unless abosolutely necessary.

http://ocw.mit.edu/NR/rdonlyre...c.pdf

http://www.ictct.org/workshops...n.pdf

[saeedakobiakov]

that is corect, stick to the speeds i set it at..there are two different pully things that connected to the throatle body. i was thinking of messing around with the one that not conneted to the gas pedal.

p.s.grounding wires on your car, what do you think?should i get them for my car?would you get it again for your next car?ARE THEY WORTH THE MONEY?THANKS,CAUG.

[Q451990]

I wouldn't start messing around with the throttle body. How much variance do you have at cruise? I would say +/- 3 MPH from your setpoint is about normal... My mom used to have an '88 Maxima that would downshift on almost every hill... trust me, the way Nissan does it now is much better.

Heath

[Q45tech]

If you set transmission in 4th gear instead of overdrive you will see a narrowing in speed deviation as the lower gearing increases torque by 20%.Remember overdrive actually decreases rear wheel torque.

[Sentientbydesign]

p.s.grounding wires on your car, what do you think?should i get them for my car?would you get it again for your next car?ARE THEY WORTH THE MONEY?THANKS,CAUG.

I sell the kits, so I'm a bad person to ask hahaha.

I personally think my kit is worth every penny (And the kit I have installed on my car is lower in quality and higher in price than what I actually make and sell). I built my kit (with tons of research) as a project. I later realized that I over paid for my supplies and could have used better materials (which I do now).

The engine revs faster, my audio sounds cleaner (which has temporarily put off my need to upgrade). On the automatics, they shift faster and smoother.

Get me an M member in SoCal and I'll build a kit for your cars

[texasoil]

The Q45a cruise control has a long 'integral' interval in the 'proportional,integral, derivative (PID) controller logic. The 'P' adjusts throttle opening proportionally to the error, the I accumulates the error 'amount * time' and adjusts P to zero out the accumulation, and the 'D' senses how fast the error is increasing or decreasing and moderates the throttle opening to smoothly approach the set speed (zero error).

While this smooths out sudden throttle moves, it does allow speed to droop or swell a bit as you go up and down grades. It you notice--it will droop 3-4 MPH and then get back to set speed in about 6-8 sec. Same reaction going downhill. IMHO, not worth fooling with.

[SteveTheTech]

that is corect, stick to the speeds i set it at..there are two different pully things that connected to the throatle body. i was thinking of messing around with the one that not conneted to the gas pedal..

That is not really advisable don't adjust the lines there, you may run into a problem when your driving(stuck throttle) or throw off you closed throttle position sensor, base idle depending on the extent of "adjustment" you perform. I didn't see you mention whether you had Intelligent Cruise or not?

[szh]

Similar answers in this earlier thread too : zerothread/354261.

Z