Vibrations at 2k

[jd96969]

Vibrations at 2k on 90 q45. finally got to pull out ecu. getting 2 error codes 21 and 53 . Please point me in the right direction.

[wlong]

Codes:

21 Ignition Signal Circuit 53 EGR Temperature Sensor (LH)

First: Check for any obvious problems (in order of cost), anything that could be loose or disconnected, vacuum leaks, loose wires, low fuel pressure (weak pump - I had this problem). I also had a vibration problem (2250 rpm) caused by a bad transmission mount. Apparently motor mounts can cause similar vibrations.

Second: Address codes - suggest EGR first.

W. Long96 Q45

[Q451990]

Code 53 is the Exhaust Gas Sensor (commonly known as an oxygen sensor) on the right bank. The Early Qs don't have an EGR temp. sensor unless they're set up for California Emissions. I'd replace both O2 sensors first and see what happens. This is something you want to address quickly, because you run the risk of melting your pre-cats if the fuel mixture is too rich. It's unusual to have an outright failure of the O2 sensors, but they'll typically get sluggish by 60-100K.

For 21, be sure to check your connections at the transistor packs on each bank, the CAS connections, etc.

Good luck!

Heath

[elwesso]

I got an intermittant code 21, and it didnt affect anything..... I wouldnt worry about it, but check your connections, and maybe unplug/plug all the connections, as doing this helps to clean them to a certain degree.

[jd96969]

today I pulled right side plugs # 8 was coated in a dark "oil" on the chamber side of the plug. oil changed last w/e new plugs 2 weeks ago. cleanned up and reinstalled. still vibs. I will pull again tomorrow and check status and swap plugs and coils. ????

[elwesso]

You should have vibrations at idle if you have a bad coil..

[DAEDALUS]

By "oil" you mean a heavy carbon buildup? If it's really motor oil you may have a bad valve stem seal. Was the plug wet with fuel? Most likely either no spark or leaking injector. If you have a timing light and a spare plug wire lying around you can check for spark on #8.