Matt's Tune Thread

Last scan of Matts we saw KR at WOT

With this issue existing, he will never be able to up his timing and make more HP.

Shouldnt have sold that 3.5", bro!

You should be running 0 KR with stock timing and then start bumping your timing until you see KR or see if you can get to around 19-20* @ WOT with 0 KR. Only when you are getting 20* timing @ WOT should you consider dropping pulley size, IMO.

But im just a noob still learning so dont mind me.


I never made it to the track this summer but I wanted to test my 3.4" tune vs my 3.25" tune in the quarter mile.

Everything I've read says timing > pulley torque in the quarter mile, though.

Back to what I said.....

You can't get 20* timing out of a near-stock 3800. Period. You are going to see KR on it. So unless you de-tune a stock engine, it isn't going to happen. Even if he were to drop back to a stock pulley with the mods he has, you aren't getting 20* of timing. A bone stock 3800 WILL get ~5* (+/- 2*) KR in higher gears. That's my point.
We all understand what you're getting at, but just please quit with the timing advance. Until Matt gets a Cam, some Rockers or an Intercooler, we aren't touching the timing.

I have a tune from Overkill (getoverkilled.ca) that I acquired. It's for a BONE stock '97 Riv. The timing tables aren't anywhere near where you think they should be. Some of the timing curve is actually RETARDED, not advanced. They have a max 16* advance at WOT ~5000rpms. Just sayin.

Here's today's scan:

https://www.dropbox.com/s/2yxlzrwknc4b0r7/10-28-14.csv?dl=0

It looks like the knock is pretty much gone, minus the knock on lines 797-810 which I think was just a fluke. What happened was I shifted into first manually and gunned it, but I repeated that a few times and didn't see it again so I figured it was just a one time thing. Any other knock is still when the A/F drops below 13.7.

I'll have a look at it later. I've got quite a few big jobs to get done today.

I haven't forgotten about you man. It was a busy weekend....

No worries, I've been busy too.

Just posting here to keep a log as to what's been changed.

-Deleted P0140 CEL codes
-Messed with shift points - did not raise WOT shift points above what they were, only for 80%-99% TP

Matt, are you still running any of the tune we flashed when you visited? If so, your part throttle shift values should have been raised, I think.

It's similar to it, pretty sure they're the same shift points that we set. Just changed it so that 80% and up shifted near/at WOT points

96v7 - MAF tables are pretty well down, just have to mess with WOT a bit. Bumped up the in gear idle a bit because it was having trouble idling without giving a bit of gas to keep it at ~1k RPM.

If it's having trouble idling at factory spec, there's something wrong.....
Without a cam, it should idle perfectly at ~750rpms. Is it running too rich at idle?

matt270avian wrote:

Bumped up the in gear idle a bit because it was having trouble idling without giving a bit of gas to keep it at ~1k RPM.

what does it idle at once it reaches operating temperature? You have to give it gas when you first start the car cold?

Does it choke or anything?

Haven't looked at the fuel trims for idle, but it's only when it's at cold start. It didn't do it when it was warm out (~60*), it only started when it dropped down to ~30*. When it's all warmed up it idles alright.

Well it still doesn't like to idle even after I bumped up the idle RPM. I'll upload the bin and scans when I get home for you all to review. I think abaddon is right about the idle fueling being weird.

https://www.dropbox.com/sh/mbldmi92dyzzwcn/AADhpt6f2FCOTSeNSwT1EjH6a?dl=0

Current tune and today's scans. Car will not idle without giving it some gas when cold. When fully warmed up it will idle, but a little roughly.

So wait now it doesn't want to idle? What's been changed that it's not idling? It was idling ok since you installed the northstar setup? Those LTFT's on your latest scan there are quite rich. The PCM is commanding a pretty pig rich AFR during a cold start in the first place so if it's got a very rich tendency and those compound, it'll be drowning in gas until warmed up. It just doesn't want to idle even after warmup though? I thought I saw you installed the new O2 and the signal does look spunkier than before so what all went wrong that it doesn't idle? You wouldn't wanna just add some big multiplier to the maf table without having evidence to say it needs it. Need stock maf table and reset FT's and read what the fresh o2 says.
Btw my fuel trims are almost as rich as yours are there right now. I'm suspecting my gas station snuck in a winter blend of e85 that has more gas but the car starts, idles, and drives like before without any of my intervention so I just have a suspicion you still have something going on besides an AFR issue.

So you just want me to go back to the tune I had before the N* install and see what everything says? I did install a new O2 in the manifold the other day.

Went back to old tune as Codith recommended. Already idles much better even after a fresh fuel trim reset. Did 2 long drives with 2 restarts, so I'll go get a scan tomorrow or Monday.

Computer crashed while flashing a tune. Car won't start. DHP can't read pretty much anything from the PCM. Should I just go out and buy a new PCM?

Ouch! Did you just try to re-flash the cal? Or DHP can't even connect to the PCM? If that's the case, it's toast.

It can connect, but it won't read any of the information on it.

Yep. If it won't let you upload a cal to it, I'm afraid you're going top need a new PCM. I don't see why it won't let you just re-flash it though. We have programming errors all the time in the shop. 9 times out of 10 we can just start the program over again. It's that 1 other time where the module actually has to be replaced...

bricked. If the computer goes down mid-write you basically need a new PCM. What year is your car?

It's a '96. I got SUUPER lucky and the local JY had one out of a '96 Riviera supercharged. Only difference is the OSID. Mine is 16238447 while the new one is 16211539. Will this cause any issues? I'm also assuming I'll have to do a security relearn by turning the ignition to accessory for 10 minutes, off for 5 seconds, and repeat 2 more times. Do I have to do a CASE learn, and if so how do I do it?

I also have another one coming from eBay with the same OSID as the "new" one.

There's a separate Theft Deterrent Module that controls the Security functions, so you should be ok there. Normally, we have to upload the PCM file via GM's database to a TechII, then load the file to the new PCM. Now, we can do it wireless via an MDI and GM software.

I think that in your case, you might be able to just flash the new PCM with your .bin from DHP. It should be the same thing, as you'll be burning the VIN and everything right to it. I'm not exactly sure though. I've never had to deal with it outside of work.

If/when it works, the only thing you'll have to do is a Crank Variation Learn, which is an option on DHP every time you flash.

New on top (just realized it's a reman), old on bottom.