4500rpm limiter?

[3800 cavalier]

I was tuning a car the other day and it went fine. I got all the fueling diled in perfect. car ran much smother and had more tip in response and was very crisp. So we went to the dyno for some numbers and to finish off the top of the maf curve and teh car would not go over 4500rpm. it was like it hit some torque management and droped the spark off like hitting a wall. but the fuel injector never fell off and the spark never droped. so we took it off teh dyno and on the street and it wont go past 4500 on the street when driving to the dyno it was fine. theres no bad plugs or missifire checked that and the cam and crank sensors are good.it runs and drives perfect but wont go past 450orpm. any ideas?
also i will mention the car has a manual 5spd conversion but all automatic tranny functions have been removed. like i said it drove fine all day and weeks prior to that.

[Phantom]

Have you tried to run the last tune before this happened to see if it still happens? Also post the current tune.

[Isaak]

I am the owner of said car... I did try a recent file and it seemed fine but I am not 100% sure as it hit knock for some reason and I backed out of it, to see if would disappear and it did and I got back into it for a very short period of time, I will try again but with someone with me to keep an eye on the gauges, just a little safer that way!

Alittle more info, we compared files, the one I showed up with before it was tuned, and the new file that is tuned, only major differences were the tuning aspect of it, Maf, VE, high/low octane, etc, no trans/torque changes.

I will post up the files tomorrow, I do not have them with me.

[Isaak]

Here is the new tune........ I think I have found the issue, but need to speak to 3800cavalier first before I assume.

[Phantom]

I would make several changes to your tune set the Part throttle, full throttle shift/rpm speed back to normal or closer to stock. Currently it should not shift from first to second till it reaches 256mph and 8000rpm and the same for each gear.

For full throttle shifts you might want to set the mph to 0 and the rpm to 500rpm less than you want it to shift at since it needs to meet both settings. For normal driving you will want to set the shift speeds at stock for atlest 50% tps and lower or even lower the shift mph.

Also I would take all the torque reduction changes you made and place them atleast 50% between current and stock.

Make both those changes and report back.
If you want do the changes separately and report on both.

[3800 cavalier]

I would make several changes to your tune set the Part throttle, full throttle shift/rpm speed back to normal or closer to stock. Currently it should not shift from first to second till it reaches 256mph and 8000rpm and the same for each gear.

For full throttle shifts you might want to set the mph to 0 and the rpm to 500rpm less than you want it to shift at since it needs to meet both settings. For normal driving you will want to set the shift speeds at stock for atlest 50% tps and lower or even lower the shift mph.

Also I would take all the torque reduction changes you made and place them atleast 50% between current and stock.

Make both those changes and report back.
If you want do the changes separately and report on both.

I was eliminating all posibilities as to thinking that the pcm was using any automatic tables for some reason even as the automatic functions are removed. the car is running a 5spd manual so the automatic table are usless.

I may have found the isssue which is good news. well see tomorrow. i used my tune in my car as a base and isaak has 1 small differance then me i forgot! sorry dude!!!

[Phantom]

Make sure to post what the issue was and keep us updated. Sorry I forgot that you had a manual in the car I should not respond to posts late at night after drinking.

[Mobile Chassis Dyno]

What is going on with your maf curve? That has to be fixed!!!!!!!!!!!!!!1



So what was the issue?

On a side note I would zero your P/E vs Time and flatline your IFR table as well.


I do not not mean to step on anyones toes but that tune is in need of a lot of work still regardless of the 4500 rpm limiter.

[bilemke]

Guessing you are using some L67 PCM. You have a scan of when this occurs? In particular, is it showing an injector pulsewidth drop or a timing advance drop when it occurs?

[Isaak]

Found the problem in the maf....... car runs like a bat out of hell once again, even more so now that it has some personal tune time and more timing under its belt, going back to the dyno to try once again.

[3800 cavalier]

the maf curve was not finished. I know theres work on it to do. The pe and injector tables are like that for a reason not going into that now. Also as i said the injector pw and timing advance stay consistant they do not drop at all.

With that being said i just uploaded a bin file to my car and now have the same issue. i changed nothing at all in the tune from when the car ran perfectly fine. except i changed the base pe from 11.9-11.8. this is the second car i have flashed with the beta 2.23 version so im wondering if theres a glitch in the beta. anyone using bata that could confirm this?

[Isaak]

Guessing you are using some L67 PCM. You have a scan of when this occurs? In particular, is it showing an injector pulsewidth drop or a timing advance drop when it occurs?

Just to add to what 3800cavalier said... I am using a 99 GP PCM, I have scans but it shows nothing out of the ordinary except at 4500 it just stops, like a limiter. Timing does not drop of at all, only time it drops off is if I hit knock, and I had zero knock on that tune.

[bilemke]

If timing doesnt drop and and injector pulse width doesnt drop, it should keep going.. That is the only two things the pcm could take away to slow your acceleration down.. Short of shutting off an injector or two (even though pulse width stays the same).

[3800 cavalier]

If timing doesnt drop and and injector pulse width doesnt drop, it should keep going.. That is the only two things the pcm could take away to slow your acceleration down.. Short of shutting off an injector or two (even though pulse width stays the same).

exactly thats why im confused right now!

[Shane Hewitt]

the maf curve was not finished. I know theres work on it to do. The pe and injector tables are like that for a reason not going into that now. Also as i said the injector pw and timing advance stay consistant they do not drop at all.

With that being said i just uploaded a bin file to my car and now have the same issue. i changed nothing at all in the tune from when the car ran perfectly fine. except i changed the base pe from 11.9-11.8. this is the second car i have flashed with the beta 2.23 version so im wondering if theres a glitch in the beta. anyone using bata that could confirm this?

I've used the newest BETA to flash my GTP numerous times without this issue.

[Isaak]

Even when he sends me a tune with his beta, it will not open in my software, it used to!

[bilemke]

Hmm. No problems like that with the beta for me..

Only other thing I could think of, if you are not scanning it, would be misfires..

[3800 cavalier]

Hmm. No problems like that with the beta for me..

Only other thing I could think of, if you are not scanning it, would be misfires..

equal # of misfires at idle due to the cam but only 8-12 counts which is ok for the vs cam in isaaks car

[bilemke]

equal # of misfires at idle due to the cam but only 8-12 counts which is ok for the vs cam in isaaks car

And if they are only occurring at idle, shouldnt matter.

Well, I doubt it is a software problem.. But, who knows.. Got a spare PCM to try?

[Isaak]

I have a different pcm in the car now, same issue when I load the tune.