Rough running

[A26B]

Originally Posted by Billy Mild

My o2's were replaced when I put the headers on late last year. The o2 sensors were "Standard Motor Products" brand from RockAuto. I did use a O2 extension harness on the passenger side header. I have the o2 extension harness wrapped in wire loom and DEI high temp reflective tape to help prevent it from melting.

So I should be looking at a leak possibly on the passenger side of the exhaust or maybe the O2 on the left side is lose maybe? I will try and jack up the car and see if there are exhaust leaks.

Check the plug connector on the passenger side O2 extension to insure there is no moisture. An O2 signal short will cause problems in closed loop only. In particular, if the elec connector is under the HVAC condensate drain, water can drip on the connector. (actual experience encountered on my ZR-1)

[XfireZ51]

Since the left (driver's) side appears to be leaner than the passenger, I would check that first. I would also swap the O2's for AC Delco units.
Finally, make sure the O2's or the wires are not covered by anything. The way the O2 works is to compare ambient air to the mixture coming down from the exhaust. So air needs to move freely into the sensor itself.

[Billy Mild]

Originally Posted by XfireZ51

Since the left (driver's) side appears to be leaner than the passenger, I would check that first. I would also swap the O2's for AC Delco units.
Finally, make sure the O2's or the wires are not covered by anything. The way the O2 works is to compare ambient air to the mixture coming down from the exhaust. So air needs to move freely into the sensor itself.

The O2 sensor and wiring is how it is from the box. The O2 extension harness from SW is covered with wireloom and DEI high temp tape.

[Billy Mild]

I swapped the O2's from side to side. There was no difference in how the car ran. It had the same issue of Left INT going to 64 or so.

The O2 readings seemed about the same as well on ALDLDroid. I looked over the exhaust and there is no black soot at all on the outside or at the flanges for the exhaust. I did notice when I swapped the O2 sensors that the driver side had a lot less soot on it. The passenger side had a lot of soot.

Any other ideas?

[XfireZ51]

It doesn't need to be a large leak. May not see any exhaust trail. Remember what could be happening is fresh air being sucked in and going by the O2 sensor.
What does the O2 voltage look like side by side during the time this is occurring?

[Billy Mild]

I held my hand around the flange at the header and didn't feel any air movement.

It appears that that left side mV 800-900, right side mV . 200-300 while decel. Now right when I start to get back on the throttle it appears my car right side the O2 sensor goes up and down. The left side seems to stay more steady while the stumbling happens. I will do a datalog with the swapped O2 sensors. I assume this will make no difference.

[Billy Mild]

http://zr1.net/forum/showthread.php?...highlight=DFCO

http://zr1.net/forum/showthread.php?...ht=DFCO&page=3

There are a ton of these posts, but no resolution. Same thing, mods, custom calibration from Marc, then stumble after decel.

I'm getting a stock PROM to see if that cleans it up at all or makes it worse.

[jss06c6]

Billy,

Trying to recall if you have deleted the secondaries. If not, and you have not tuned your VE tables, your fueling will be "close" but not where it should be. In addition, you can edit the DFCO sequence to allow more fuel during deceleration which may help with your stumble upon acceleration. However, you'll need to get your fueling right with your VE tables first.. I've had to make some pretty good changes to mine after adding headers and high flow exhaust. Once you change spark, you'll need to go back to the VE tables and adjust again. It's an iterative process. Marc will get you close, but each engine and setup is unique enough to require fine tune to get the engine into it's happy zone..

Remember as well, that Marc typically installed a "piggyback" chip which works in concert with your stock PROM. We can get the stock BIN file and burn a new EPROM to replace the Haibeck chip, but I don't believe this will be the issue (certainly can be wrong here).

Steve

Sent from my XT1585 using ZR-1 Net Registry mobile app

[jss06c6]

You can also change the point at which your secondaries are commanded open..

Sent from my XT1585 using ZR-1 Net Registry mobile app

[Billy Mild]

I'm not a tuning expert and honestly have no idea how to change the tune on a FI car.

DFCO should be turned off on my car per my tune. I may try and switch out my O2 sensors again with a different brand to see if that helps. My car looks to try and really richen up the mixture on the left side of the engine. I'm wondering if it is loading up on fuel and thats why it hesitates when tipping in the throttle again.