Everytime there is a downshift I get 40 degrees retard. it seems that as soon as i downshift I get a spike of like 90* advance from the maf. I am out of ideas on how to fix it. My friend and I have been buring chips left and right and no change. from 0-60 run i get about 4 degrees knock but nothing major. any ideas on how to fix this?

 

I take it this is your '89 350 w/an auto? Not really sure what to tell you as my car does the same on a downshift. Not the same exact car but non-the-less it does rack up the knock retard. Others here have reported the same thing. My feeling is that it is due to tranny noise triggering the sensor.

I've increased the knock retard decay rate to eliminate the retard quicker. Other then that, _shrugs shoulders_.

RBob.

 

As long as you do not get retard on heavy acceleration,or excessive retard on acceleration then try to limit amount of retard
that ecm allows to like 3-5 degrees. That way it still puts you in safe zone and does not hurt performance that much.
If you are really sure you are safe then limit it to less,but first make sure you don't have total advance set to anything higher than 38 degrees and dist. is set same as prom constants is.

 

The other post, the guy was getting spark knock when shifting to a higher gear.

Seems like if there was some kind of patch added like...

delta RPM vs spark retard

figure out what your approximate RPM change during a shift. load up a table (constant?, register?, heck, I'm just getting into the language) that sets KR to 0, make sure you are already at a high RPM (i.e. to prevent it from enabling when you flash your tires), have a timer that kicks out of the routine a half second after the shift, etc.

 

I think I missed something the first time I read your post. . . Are you saying as you mash the go-pedal and the trans downshifts you get a sudden increase of SA to 90 deg? Which then drops off?

Any chance you have a cable driven speedometer (I don't think that you do though)? I've seen the cable wrap up and do strange stuff like this.

If you happen to have a datalog of this occurrence can you post it?

RBob.

 

If i'm going 35 MPH and nail it i get a spike of 90* advance and a max retard of whatever I set it to be which is 40*. At that moment the car screams and has 0 power. I do not have a cable driven speedo. Also I am getting 36* knock retard at a cruise of 70 MPH with no load and max timing at 35*. only between 68-72 MPH. THAT really confuses me. The car will shake and studder unless I give it half throttle and more load then the counts go to 0

 

Post your bin.

 

Almost sounds like you have a *0* entry where a value is needed. Some of the timing calculations puke if you use a really small number.

might look at your burst knock retard stuff

 

http://www.cecoatings.com/images/misc/mkos1980/

 

Knock is now up to 67 Counts retard

 

ttt,

Hope ya get it figured out matt. Was deff. a weird situation. Let me know when ya have another day off or something I'l bring my laptop down again and try and get some more logs.

Hopefully by then You could have had your buddy do a few diff. chip mods and go form there again..