Lazy shifts, erratic and un-commanded upshifts

'Microsquirt' Transmission Control development and support.

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SDCE
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Joined: Mon Jan 16, 2017 2:37 pm

Lazy shifts, erratic and un-commanded upshifts

Post by SDCE »

Hi Guys,

A little back history first, before getting to the car we're trying to get off our dyno!
While we're fairly new to MS3 and Microsquirt software, we have over 20 years experience with 4L80e transmissions and stand alone DFI and other brand tranny controllers in many fast street and strip cars. I Feel this is important to state so people understand this isn't my first rodeo.

Currently, we have 3 different customer's cars using microsquirt controllers. One is running a GM 4L60E and 2 are running 4L80E trannies. All 3 are displaying similarly weird issues.

With the first car, we'll call it 4L80E Nova, we noticed issues with 1-2 shifts, specifically how long they take. It seems we have to command the shift 1000-1500rpm's earlier to get it to happen when it's supposed to.

The second vehicle, 4L80E Dakota, everything initially worked fine and we sent the customer home. He DROVE it 1300 miles from our shop in RI to his house in Ill. He then started having random issues with shifting into second gear, similar to Nova.

Now we have 4L60E Camaro that we just started tuning on our dyno and it's showing similar and weirder issues. The 1-2 shift is very slow. And it shifts into 3rd 30 mph sooner than what is commanded. The data record is showing the controller is actually commanding the shift 30 mph earlier than commanded. The rpm shift is turned off and it's set at 7000 rpm's, so don't think that's a contributing factor.

Any assistance to help us while we get more familiar with Megasquirt products is much appreciated. And if anyone with experience with 4L60's and 4L80's and microsquirts/trans controllers wants to contact us directly off the forum, we'll gladly pay for your time.

Files for the 4L60E Camaro are attached.
Last edited by SDCE on Tue Jan 24, 2017 8:05 am, edited 1 time in total.
ashford
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Re: Lazy shifts, erratic and un-commanded upshifts

Post by ashford »

all your shifts appears to match up perfectly for the 70% throttle that the logs were showing. if actually you were wot then you need to calibrate the tps
SDCE
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Posts: 19
Joined: Mon Jan 16, 2017 2:37 pm

Re: Lazy shifts, erratic and un-commanded upshifts

Post by SDCE »

ashford wrote:all your shifts appears to match up perfectly for the 70% throttle that the logs were showing. if actually you were wot then you need to calibrate the tps
Sorry...attached the wrong log. Here's the correct log.

The engine was at full throttle for the previously sent logs and the one attached here...this log attached has the tps set correctly.
Last edited by SDCE on Tue Jan 24, 2017 8:05 am, edited 1 time in total.
ashford
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Re: Lazy shifts, erratic and un-commanded upshifts

Post by ashford »

looks like min shift time needs to be increased to .6 to .8( this is essentially a wait time before another shift command is issued).
SDCE
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Posts: 19
Joined: Mon Jan 16, 2017 2:37 pm

Re: Lazy shifts, erratic and un-commanded upshifts

Post by SDCE »

It should not have comanded it in the first place, right? if i move time out to .8 i am basically shifting on a timer not speedo .what if it spins the tires ? it will sit on rev limiter .8 before making a shift.
ashford
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Re: Lazy shifts, erratic and un-commanded upshifts

Post by ashford »

It should not have comanded it in the first place, right?
it commanded a 2-3 shift because you were at max rpm setting for 2nd gear and went straight to3rd after the wait time(min shift time) because the rpms didn't come down to below the set level because the trans had not completed the shift yet,there is a delay between when the solenoids are commanded and the hydralic/mechanical completes it. so some more time will fix this particular problem
if i move time out to .8 i am basically shifting on a timer not speedo .
the time is a hydralic/mechanical delay, shifts need to be anticipated roughly this amount of time, this is the case with any electronic trans some are faster than others. this is basically a wait time after a shift command before another can be done so the mechanical can keep up.


what if it spins the tires ? it will sit on rev limiter .8 before making a shift
almost correct, it will command 1 shift but there is still the mechanical delay , the other option with no wait time is to go directly to high gear which is even less desirable
SDCE
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Joined: Mon Jan 16, 2017 2:37 pm

Re: Lazy shifts, erratic and un-commanded upshifts

Post by SDCE »

That all makes sense to me but my max rpm were set to 7000 .my3rd gear comand was at 5700 and 30 mph early.
ashford
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Re: Lazy shifts, erratic and un-commanded upshifts

Post by ashford »

supply a matching msq and log
SDCE
MS/Extra Newbie
Posts: 19
Joined: Mon Jan 16, 2017 2:37 pm

Re: Lazy shifts, erratic and un-commanded upshifts

Post by SDCE »

I moved gnd wire from the back of cylinder head to body/battery location now it wot shifts as comanded :yeah!: :yeah!:
SDCE
MS/Extra Newbie
Posts: 19
Joined: Mon Jan 16, 2017 2:37 pm

Re: Lazy shifts, erratic and un-commanded upshifts

Post by SDCE »

ashford wrote:supply a matching msq and log
LSXCutty
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Re: Lazy shifts, erratic and un-commanded upshifts

Post by LSXCutty »

I new to the transmission control side of things. I just added a micro and 4l80 to my car but have not got it running yet. Looking at this log, it looks like the car shifted to 2nd gear then almost immediately shifted to third before rpm even dropped from the 2nd gear change.
jsmcortina
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Re: Lazy shifts, erratic and un-commanded upshifts

Post by jsmcortina »

LSXCutty wrote:I new to the transmission control side of things. I just added a micro and 4l80 to my car but have not got it running yet. Looking at this log, it looks like the car shifted to 2nd gear then almost immediately shifted to third before rpm even dropped from the 2nd gear change.
Hence the need for increasing the "shift time" setting as discussed above.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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