2009 ZR1 Bank 1 stft issue

[blake-b]

2009 ZR1
GP Tuning stage 4 cam
Mamo AFR 260 heads
108mm TB
108+mm snout
Ported blower
2" headers; no cats
E85

At warm idle, I am having Bank 1 stfts that are positive while the Bank 2 stfts are hovering around zero. The ltfts were disabled when I got it and I left them that way other than using the scanner to play with them.

I bought this car last fall and it ran great and had ported LS9 heads on it. I knew (I think) I could squeeze a little more power out of it so I bought the AFR heads. They required longer pushrods with the exhaust needing longer than the intake. I found a thread on here about something having similar issues and they discovered one of the push rods was a couple hundredths longer than the others. I measured mine upon receiving them. All intakes were within .010 of each other as were the exhausts. Before starting the engine, I also verified I had the intakes and exhausts in the correct spots in the engine.

I used HPT to set the idle at 1200 rpms during at least one of the logs and there seems to be a hitch in it's giddyup but no codes. The only codes it has thrown is when I was unplugging the driver's side injectors one by one to see if anything changed. Each time, that side went lean and the stfts zeroed out until the injector was plugged back in.

The car is not tuned for the new heads. I am less than a novice at tuning so that might be the issue but I don't have the experience to know.

Things I have done to find the issue:
-switched O2s with no effect
-used a smoke machine to find vacuum leaks. I put it on a vacuum port on the snout and the only place smoke came out was the air filter. I am wondering if there is another place I should have used
-Switched the wideband from the passenger side to the driver's side.

Next time I get a chance I am going to pull the driver's side valve cover to see if anything obvious is going on there.

Idle log is with wideband on passenger side. Idle log2 is with it moved to the driver side (bank 1). It was during idle log2 I was unplugging injectors.

In summary, changed heads, longer pushrods, now having bank 1 stfts positive and bank 2 hover around zero once warmed up. All at idle. I have not driven the car due to weather and wanting to get it sorted out before I do.

What troubleshooting measures am I overlooking?

[Ben Charles]

Didn’t look at log... how much more positive is bank 1?

[blake-b]

Bank 1 is ranging from ~14.1 to ~16.4. (always positive)
Bank 2 is ranging from -6.3 to +4.7 (usually hovering a little less than zero)
Injector milliseconds are .2 to .5 higher on bank 1 than bank 2 if that matters. It just might be a symptom of the real issue though.

Prior to head change, both STFTs were negative (at warm idle) and usually very close to each other.

This morning, I checked torque on the headers and they were torqued so I am eliminating an exhaust leak there.

[Ben Charles]

How does it look driving???
Do they level out??

How is your catchcan routed?? Anything venting on bank 1?

[Pekka_Perkeles]

Did you remove headers during assembly?

Your O2 values are very strange at log 2. See the voltage. Suddenly other one goes up (900 mv or so) and then other one very low (100 mv or so).

Could your O2 wiring being crossed?

[blake-b]

Did you remove headers during assembly?

Your O2 values are very strange at log 2. See the voltage. Suddenly other one goes up (900 mv or so) and then other one very low (100 mv or so).

Could your O2 wiring being crossed?

Yes, the headers were removed and new GM OEM gaskets were used when reinstalled.

I noticed the voltage too.

Tomorrow, I am going to switch the O2 wiring to see if that makes a difference.

How does it look driving???
Do they level out??

How is your catchcan routed?? Anything venting on bank 1?

I haven't driven it since putting it back together. The roads here are snowy.
It is vented on bank 1 with the factory tube at rear of valve cover that goes over and connects to the passenger valve cover and a line going into the dry sump tank and the port down beside the tank. All that is factory. There is an extra line from an adapted oil fill cap with a long line that goes to a filter that is not one way (i.e. no checkvalve). I put a plastic bag on it and it puffed out, indicating to me it is venting and not pulling air in.

There is also a mighty mouse catch can. Top line connected to snout and bottom line connected to valley cover.

[gapd you]

Yes, the headers were removed and new GM OEM gaskets were used when reinstalled.

I noticed the voltage too.

Tomorrow, I am going to switch the O2 wiring to see if that makes a difference.



I haven't driven it since putting it back together. The roads here are snowy.
It is vented on bank 1 with the factory tube at rear of valve cover that goes over and connects to the passenger valve cover and a line going into the passenger fender. All that is factory. There is an extra line from an adapted oil fill cap with a long line that goes to a filter that is not one way (i.e. no checkvalve). I put a plastic bag on it and it puffed out, indicating to me it is venting and not pulling air in.

There is also a mighty mouse catch can. Top line connected to snout and bottom line connected to valley cover.

catch can routing is wrong. see mighty mouse website for correct routing. this could be a cause of your issue.

[blake-b]

catch can routing is wrong. see mighty mouse website for correct routing. this could be a cause of your issue.

I'm 99% sure I have it routed like this but I will double check. Also, I have a log from this morning, it appears they O2 sensors are in the correct location as the bank 1 sensor is reading lean and fuel is being added to bank 1. I'm having trouble attaching it at the moment.

[Ben Charles]

Bottom line of can should connect to valley (dirty side) and top (which is outlet and clean side on every catchcan I’ve ever dealt with is on the top

[Ben Charles]

Could cap can and bank 1 PCV just at idle and see if it clears up...

Also hate to tell it a real issue without driving it

[blake-b]

I will try capping things tomorrow.

[blake-b]

I think I found the problem...
After confirming again with a smoke machine there were no leaks. I unplugged the passenger side O2 sensor and it showed lean so the wiring was correct. I then went to swapping injectors, one at a time, bank to bank. I started with the #7 injector. Lo and behold, the tip (FIC 127s) was bent and the orings were less than stellar. I am the idiot who must have bent the tip when installing them. I swapped it to bank 2 and it was then adding fuel via STFT while bank 1 seemed normal.

I'm going to send the whole set in for a rebuild.

[Ben Charles]

Glad you found it