ZHP NA Project - More Power

[Newjack]

I put back the stock headers because at the moment i am trying to find the issue that causes:

1. At 1500 rpm when in 4 5 6 gear and i fully press the gas pedal the car jerks for about 1-3 secpnds and then accelerates
2. When accrlerating at 4 gear i can hardly reach 6000 rpm and i. 5 gear i cannot go past 5000 rpm no power
3. When i redline at neutral it misfires in the muffler
4. At idle when i turn ac on the car starts jerking


My assumptions

1. Fuel pump
2. Coil
3. Injectors


It must be either of these what do you think ?

P.S. ebay headers are a must mod !

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Coils and plugs would show symptoms at idle or low RPM's right?

Maybe fuel pump/filter if its old or a failing injector?

[Vas]

MAF sensor...

[Newjack]

MAF sensor...

[BerDz3nA]

Coils and plugs would show symptoms at idle or low RPM's right?

Maybe fuel pump/filter if its old or a failing injector?

Plugs are brand new and i have tested two different sets of them to eliminate plugs.
Coils are next to test and fuel pump.

Fuel filter is brand new.

[Sockethead]

Did you scan for codes? Not all codes will trigger SES light

[BerDz3nA]

Greetings,
Long time no post. I have removed the headers because it messed up with my AFR, providing that I ordered from ebay, the post cat banks didn’t clear so I relocated them to another spot, and I also had to seal the pre cat bank one because it hit the other header and I was unable to mount the cat sensor, so I had to drill another hole to fit it. Unfortunately drilling another hole that was not the same height and was positioned not similarly to the other pre cat sensor messed with my AFR and the car couldn’t rev post 6000 rpm in 5th gear, there was just not enough power.
Note that pre cat sensors are in charge/reponsible for fuel/air mixture
I know I could have drilled another hole, a proper one this time but I decided to sell the headers and buy factory drilled in the future.



I also went and dynoed the resulted with K&N intake. I wanted to compare before and after K&N gains, which by the way were impressive. Before I installed the K&N my car showed 235 HP at the crank. With K&N the car showed 248 HP ! A big gain of 13HP at the crank, So the K&N air filters really work. The torque was 297 lb/ft and now is 328 lb/ft this is a massive gain for torque, but i think decated manifold with K&N really brought up the power + ZHP cams
At the moment my car specs are:
1. Decatted exhaust manifold
2. K&N filter + Custom Intake





As you can see from the dyno AFR results from 2300rpm – 4000rpm the AFR stays between 14 ratio which is lean. From 4000rpm – 64000rpm stays at 13.5 which is normal. Because the filter induces more air the DME needs tuning to keep the 13.5 ration constant. After I install the headers I will get it tuned.

As for the problem at 1500 rpm i think it is due to the AFR needing tuning, if i unmount the MAF cable it solves itself, when unmounting the dme provides rich mixture that is why it stops the problem. As i said earlier i will tune the dme after i install the headers.

[ZHPizza]

Wow for a second there I glanced over the decatted bit and thought you got that power boost from the intake. I'm betting almost all of that power came from removing the cats, but damn that's a nice gain on the stock exhaust manifolds!

[kakashi169]

so the headers was too much of a headache and thats why you sold them??

i was expecting a happy ending with the modded header story

[BerDz3nA]

Wow for a second there I glanced over the decatted bit and thought you got that power boost from the intake. I'm betting almost all of that power came from removing the cats, but damn that's a nice gain on the stock exhaust manifolds!

I don't even know what you are saying but if you looked at my previous posts you would see i was already decated when my car ran 235 hp everything else stock after i installed the k&n then i gained additional 13 hp so there is no need of betting and wondering it is clearly due to the intake.

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[BerDz3nA]

so the headers was too much of a headache and thats why you sold them??

i was expecting a happy ending with the modded header story

The china ebay headers was too much headache for me i will buy locally the one that will not cause that much problems. Headers is still on top of my must mods for a zhp.

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