Thread: 160whp dyno run with mods... whats wrong!

My car is a 2005 GP GT. My car ran fine stock but I wanted to get a little more out of it and make it fun to drive. About 6 months ago I added my first real mod to the car. I installed ZZP Headers and 3" exhaust with a catted downpipe. Which is where all my trouble begins. My car seemed very boggy under load and low rpm. I drove the car like this for a few months. The car is insanely loud even with a resonator and i figured it is very rich due to how boggy it drives. The next thing I did was add the HV3 intake and the ZZP PCM in hopes it would help with my car running rich and make it run like it should. The PCM did not help me in any way.

About 3 weeks ago I took my car to the performance shop in my town which is very well known for tuning and upgrading and does a fantastic job. I was getting my water pump replaced that day and I told him about my car running like hell and he hooked up his scanner. He could not pull any codes and I have never had any CEL,SES lights in my car. He did get the MAF fuel trims on his scanner and it was commanding -10% fuel at idle and -14% under a slight load. I then decided that I would let them have a go at tuning my car and getting it good to go.

My dyno tune was today and I was not actually there during the dyno runs because I had to work. I did get a call from the shop owner and he gave me some very confusing news. First that my car made only 160whp which I thought was a little low. Second that fuel injectors were maxed out at 4500 rpm. But my AF was very good in both the O2 and the MAF. He stated the AF was 15:1 at idle and 13:1 under power. the MAF was also within 5% of 0. All of this made no sense because I know that simple headers and intake insert will not max out stock injectors at only 4500 rpm, that seems very insane.

I am going to pick up my car tomorrow morning and I will have an in person conversation on what all was going on. I suspect that the values he was reading were the commanded values and not the actual values. I will be able to add more information on this tomorrow after I get my car .

I think 160whp for NA is pretty normal, cant really comment on the injectors unless ZZP just has it tuned THAT rich to make sure your kr is low as possible.

Did he actually do any tuning, like make changes to the ZZP tune? Or just look at what was already there?

I was talking with him in chat and he said his pcm is locked so they didn't make any changes. 160whp for a n/a with a HV3 headers and a downpipe seems kinda low to me.

You're running way rich that's why it's low. He doesn't seem to know what he's doing with tuning. Try putting a rear o2 in it and see if it helps

The guy at the Performance shop could not get into the PCM with his HP Tuner because for some reason the PCM was locked from ZZP. All of these numbers came from my base pull. I am probably going to look into the rear O2 because it seems like the most likely cause right now. I just don't know how much more money I can throw at it just hoping it works. I am not getting any CEL SES lights or codes to give me any guidance.

I emailed ZZP about the PCM just now. I dont think it is a PCM issue since my car ran bad with the stock pcm as well as this one. I am going to head to the Dyno shop now and go pick up my car. I will know more later tonight.

160whp is the power of a stock n/a 3800. headers and hv3 you should be higher, by how much im not sure.
id be interested to see a good dyno as i have pretty much the same mods as you do, and as for the tune not helping that's very weird cause I got a overkill tune and that was the biggest gain I noticed. and I got the tune before I got headers.

I got my dyno chart back from the shop.


He confirmed with my injectors were at 100% flow at 4500 rpm and strangely my AF lined stayed pretty flat. He did say that the That it was a calculation from HP Tuners and might not be accurate. And since he can not get into my PCM to check the adjust trims, he is at a loss.

Right and that is what's bothering me. Stock L26 injectors should not max out at 4500 rpm and only produce 164hp. I should be over 200hp to max stock injectors.

Why not just use your stock PCM and get it tuned

So the duty cycle was over 100% on that run??

Seems really odd for such a high afr.

Originally Posted by Fivefingerdeathpunch

So the duty cycle was over 100% on that run??

Seems really odd for such a high afr.

yes my duty cycle was 117% is what the owner said.

Originally Posted by 91parkave

Why not just use your stock PCM and get it tuned

This I wouldn't even got a zzp PCM
If I coulda got a custom tune

Originally Posted by Theaceofspades

This I wouldn't even got a zzp PCM
If I coulda got a custom tune

Looking back this would have been the way to go and been waaaaayy cheaper.
When i first got the ZZP PCM it was cheaper to go that way but all the fuss it gave me with the install made it pretty expensive.

they don't do a whole lot of tuning of the wbodies there at LMT.

All of the numbers were comming from hpt when he had it on the dyno.