Help with 3800 xpz tuning.
 

Hey guys. What a nightmare. My monte has been gone over a year with building and repairing parts. Please don't ask lol. I need help with tuning. The basic power adders I have are as follows: ported gen 3 blower with 2.8 pulley. Northstar tb kit. 2 short stack inter coolers with 5 gallon reservoir in trunk. -8 fuel lines and -6 return line with a walbro 455 pump. I also have custom aeroforce fuel rails. I'm running e 85 and am on 60 lb injectors. I have pacesetter headers with 3 inch downpipe and an exhaust cutout on the downpipe. This leads to a 2.5 inch exhaust. My tuner says the 60 pound injectors are too small as the car leans out at 5200 Rpms. He ordered me 100 pound injectors so we can hit 6500 Rpms as I'm sure a this car can hit. It's on 24* timing and only hit 275 wheel and 300 Tq. He says the exhaust is too small and that I need 3.5 inch exhaust and my xpz cam is too big for the ported gen 3. When I did the original ssm90 kit from zzp with a single belt setup and 3.4 pulley, no heads or cam,I ran 276 wheel on 93 gas. How is this possible???? Can some one please help so I can tell my tuner what to do??? Thanks in advance

Any reason you skipped over the 80# injectors? Those seem to do pretty well on e85 builds but admittedly would be close to their upper limit on your setup. I just hope they're good injectors that he ordered, especially running e85.

You should be able to do over 6500 on an xpz cam once you get the fuel you need. Only running it out to 5200, you're definitely taking a hit on power.

That does seem extremely low. Is it the same dyno you used before? You're certainly low on power due to the rpm, but I don't see you picking up the 75+ whp you're missing in 1000 rpm.

To me, that's massive red flag #1 that says your tuner is making excuses and doesn't know anything. You have a cutout- the size of the catback is pretty much irrelevant at that point. Not to mention, how would you ever get 3.5" exhaust? The biggest header outlet for a 3800 is only 3" (unless you found some big dogs that were 4"). This one take 10 minutes to disprove - unbolt the catback and run again.

That's massive red flag #2 and would be a big enough flag to make me find a different tuner. The xpz was designed to maximize the m90, period. What does he expect you to install, a 4 liter whipple?!? I'm sure he's going to use the excuse and say you need a gen 5 which is BS. If your gen 3 was ported correctly, the flow difference is only minor different.

Here's what I would do:
1. Find a different tooner. This one clearly has no idea what he's talking about. A tuner can make or break a setup, especially one as modded as yours, he may be holding you back.

2. Get bigger injectors, 80s, 100s, 110s, whatever and make a pull to at least 6500. Then you can compare apples to apples with before and with everyone else out there.

3. At that point you'll be good on fuel, you're already beyond good on spark timing. If it still doesn't make power, id start verifying mechanicals- checking for valve float on the dyno chart / scan logs, check compression and compression variability, ensure you're getting wide open throttle, etc.


If you get to that point and still aren't making power, id sell it all and buy a turbo (or a different car platform), lol.

The gen 3 was ported only the outlet and lim by zzp and I took it to a shop to port the inlet to match the northstar tb. I had my heads re polished and valves redone and runners opened up a bit. It doesn't make sense

Also I'm not sure if this will be a factor but I had zzp flash my PCM becuAse my tuner was unable to access the 2 bar map. So I did that months ago and my tuner said that they deleted all the info he had in the PCM from 2 years ago and complained that he would have to take more time and more money to put everything back in and that it is easier to run the 1 bar map and the old PCM that already has the old
Info from the 93 tune which ran 330 wheel horse and 320 tq. I asked him if the bossy would be affected by doing this and he said no. I was running 15 psi on the 93 tune on a 3.1 pulley with half the mods 2 years ago and now I'm only at 13 pounds of boost on the 2.8 and e85. Does the 2 bar map need to be used? I will find out the a/f ratio and post it today. What do you think bumpin96??

Sounds like the blower was done as good as you could really get it.

You mention having the heads redone, where were they ported? If theu werent ported by a 3800 shop, did they provide flow numbers showing an increase? Not that I think that's the key to the problem, just trying to understand.

My tuner brought the heads to his shop he always uses. I asked for the flow numbers
But he didn't get them from the porter. He said the runners were only opened slightly more than they were. I know it's unclear but at this point i don't know what to believe. What about the 2 bar map? Could that have any affect?

That's red flag #3. What tuner doesn't save their previous tune files? Of course zzp didn't try to figure out what tables he tuned to transfer them over, they probably just reflashed it as a stock l67 and sent it back. Once the pcm was unlocked (assuming that was the issue), your tuner would just have to open both files at the same time and copy the non map tables over to it.

Ok, now we're getting somewhere. At some point you were making reasonable power. What mods are different from then to now? That may help us figure out what went wrong.

I'll also ask it again because it's very important - are all these figures from the same dyno? If theyre not, then a comparison is worthless.

Dont get caught up in boost numbers. Most mods (other than a smaller supercharger pulley) make boost go down. The engine will make more power, but boost won't be as high. A big cam will also usually knock boost down a good bit.

The only thing you should be looking at boost for is it see if it falls off up top from belt slip.

"Need", no not necessarily. I don't see why you wouldn't though. They're dirt cheap, and if you start off with an l67 pcm file, it'll already have that data in there for it to work.

Honestly, I don't think the air fuel from this last run would help us much. With the setup you've got you should be shooting for high 300 whp and 60# injectors would never support that on e85. So it won't be surprising to see the fueling start going lean up top as you run out of fuel.

I guess we could look at the rest of the pull, but at this point it doesn't matter anymore. You're going to get new injectors and will need to be retuned for them, so that's what is important to see.


I'll still reiterate, it's time to ditch this tuner. Too many red flags IMO. May not be your only problem here, but it is clear that he doesn't know what he's doing with 3800s.

Why didn't you have the heads ported by a normal 3800 shop? With how much money you've got in this thing, id want them done by someone that knows what they're doing.

I'd also be pretty irritated that they didn't flow them to show improvement, especially if you asked for it. They could've made the heads worse and you'd never know. Again, unless the shop is really bad, I don't think this is the key to your problem, I just would've went the route of a major 3800 vendor doing them since you really seem to be going for a big m90 build.

As I mentioned in my other reply, I don't know why you wouldn't just switch over to a 2 bar. Just swap it out and have the tuner upload the proper tables when you go to swap injectors. I don't see any reason not to run it.

I wanted to run the 2 bar with the flashed PCM but he said it would be a more expensive tune and take longer to tune. I emailed Zoomer and he said either the cam is installed wrong or the timing is way off and I should be making 100 hp more

The only other power mods I have added since last time was an exhaust cutout, removed the high flow cat, e85, -8 fuel lines -6 return lines, 2.8 pulley , ported sc inlet, northstar tb kit, a second short stack inter cooler and a 5 gal coolant res. I forgot to
Mention last time I was using an xp hot cam. I just hot off the phone with my tuner and I mentioned what you were saying and Zoomer from zzp and he sticks by his head shop who has ported heads for 3800s a lot. Also he claimed the cam is installed correctly which I believe it is as well and the timing was not done wrong because I already had the double roller installed with my xp hot cam. He said the af ratio was 13 at 5200 Rpms wot and he was letting out. He said it should
Have been 11 and we should be hitting 6500 Rpms with the 100'pound injectors. He is saying it will gain power from the bigger injectors but I can't see 100 like Zoomer said missing out on with my build. It's aggravating. I've spent too much with add ons and e85 to make less power. It doesn't make sense even Zoomer said it's hard to make less power even with a lot of error and with my mods especially. I don't know what to do. If the cam was installed wrong, wouldn't the car be undrivable?