Thread: Charisma.
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Old 06-11-2021, 08:23 PM   #180
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Jerd's Avatar
Join Date: Mar 2008
Location: Vancouver WA

M47 has been pretty noisy but yesterday on my way home from work after a few pulls it got super noisy and started puking ATF out of somewhere. Good thing I bought a backup. So looks like I'm doing a transmission swap and locker install this Sunday.

I'm trying to get this thing in as good of condition as I can afford by the 24th. So if anyone has any ideas on what to check for the AFR swings, please let me know. AFR swings from 13:1 to 16.5:1 about 5 times in 10 seconds only in closed loop. On cold start the car idles stable and at a decent afr. If the o2 sensor is unplugged the warm idle is stable at about 15:1 and the car seems to actually drive better. Low load afr is about right and it richens up with boost on set and runs about 11:1 at wot in boost.

I do have a CEL for low EGR flow. Because removed all the EGR stuff. I did this after the +T and after first noticing the afr swings.

Made an air hose adapter and pressurized the intake. Found and fixed 2 big boost leaks. One of them being the EGR pipe at the intake manifold and the other being the MAF cover pushing up and blowing air out. After the repairs the only thing that changed was idle vac increased from about 15inHg to 17-18.

Cleaned the MAF, no change. Swapped the MAF, no change.

I checked the o2 sensor voltage swing at idle and at elevated rpm and the cycle rate was a little slower than some say it should be. About 5 cycles in 10 seconds instead of the stated ideal 8 cycles in 10 seconds. The wide band afr swing closely matches the narrowband swing. This is a brand new bosch o2 sensor it was swapped in an attempt to resolve this problem. I have noted there are a couple of small exhaust leaks. None major but they might add up to being a problem. Ordered some gaskets for the turbo, and I may consider moving the o2 sensor up stream of the 2.5" vband.

I pinched off the IAC hose and idle drops to about 600rpm. Unpluging power from the IAC results in a high rpm idle that fluctuates several hundred rpm approximately once a second.

I have verified the throttle switch clicks just off idle and the car is cutting fuel on decel.

I have pulled all the vac lines from the manifold one by one and no noticeable change was made.

The FPR does not smell of fuel.

Replacing plug wires, cap, and rotor this weekend as well.

Last edited by Jerd; 06-14-2021 at 10:13 AM..
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