Engine Ticking

[XfireZ51]

Originally Posted by Dmod81

I have not, but I just got a can of the stuff that you can spray into the intake. It has the long straw with the bend in it.

Originally Posted by XfireZ51

Yep!

I also removed one of the oil tube hoses and sprayed it through the the airborne opening. Just need to keep motor running.

[Dmod81]

The bog after coasting is back (well, actually, when I thought it was gone, I wasn't off of the throttle enough for it to appear, still have a rough idle as well). It bogs if I let off the throttle and for more than about 3 seconds.

I finally got some time to datalog the car. What I think (because I have no clue how to really interpret the graphs) I'm seeing is that when I go off throttle, the O2s either go erratic, or low or high, and the integrators start dropping sharply. Then when I get back on throttle, the RPMs don't increase until the integrators start coming up some. Also at cruise, the O2s are cycling only about once per second (thanks to Marc for pointing that out).

(Integrators, RPM and TPS % on top, and O2 voltages and map on bottom)

Bog 1:


Integrators dropping further the longer I'm off throttle:


Everytime you see the throttle being depressed here, the car was bogging until the integrators got back up to normal and the O2s started cycling again:


Cruise:

[XfireZ51]

So you ported the top end, what changes were made to the calibration?

[Dmod81]

I have Marcs normal BPPAG4 cal with custom settings:
Add fuel for headers
Fuel for cats
Enable anti-backfire mode
Add Fuel for top end porting
Secondaries removed
750 rpm idle
7200 rpm rev limit

[Bearly Flying]

Just a shot in the dark..What brand of O2 sensors are you running?

My car, after porting it, did exactly the same thing.

There is a thread on the forum about the recommended O2 sensors, I put those in and no more problem.

[Dmod81]

They are new densos. I had the same issue with the old ones that were in there too, but I'm not sure which brand those were.

[Dmod81]

OK, so I replaced the O2 sensors with OE type AC Delcos and also tightened the header bolts. Several were slightly loose. This seemed to have helped the problems a lot, but was not a 100% fix. It stumbled only once on the test drive, and there was no ticking or missing to be heard.

Unfortunately, on the next drive, everything was back to how it was before. So I seafoamed again and noticed a small amount of smoke was coming up next to the engine on the passenger side. So I took a look and noticed the header flange at #6 is dirty and wet:


Sorry for the poor quality, I was using a cheap snake camera hooked to my phone. For comparison, here's #4 and #1:



So its really only # 6 that is wet. Is it possible that after I tightened the bolts they loosened up again/ or the gasket is now damaged? Could a leak there cause a miss and stumble after getting on the throttle after coasting? I find it interesting that that cylinder is the one that had the original dead miss.