Thread: Rough Idle, Strong exhaust smell.

I finally got my new coils sent to me, they cost me about $110 bucks delivered from the states. I also got new rocker cover gaskets, inlet manifold gasket, air filter and cleaned the MAF sensor. The job itself was a bit of a nightmare but I eventually managed it in around 4 hours over two nights. Oh...I also put a new set of ignition leads on it which I ended up getting from repco...they're the ones top gun supply and I was quoted $92 from supacheap and $199 from repco! (Repco eventually ended up matching SCA's price and getting them in sooner so i went with them!)
Anywho, the car runs fine...I think! I only finished it last night, so Ive only dont around 20ks in it since but it seems to run smoother and doesnt have the exhaust smell it used to have.
P.S the hero of the job was my magnetic picker upper thing which on many occasions went diving for small bolts I otherwise would have lost never to be seen again!

I'm a happy chappy today!


Got to the bottom of my crap running D2A V8.


I had replaced the plugs leads and coils and a new intake gasket while I'm at it but that didn't seem to make much difference. I had a bad O2 sensor according to the nanocom. I reckon it had killed one of my cat converters. I knocked the innards out of the bad cat and that seemed to improve things but the bad O2 remained.


Rather than just patching up the exhaust I decided to give it a bit of a going over. I fitted a set of hurricane headers, new cats, a new mid muffler and new O2 sensors. The result is it now runs a smooth as and feels great on the road. It was a bit of messing around but the result is good.


The headers are to suit D1 but fit OK. I welded put some new flanges on them and welded O2 bungs into the inlets of the cats. The system is still 2x 2" into 1x 2.5". I replaced the huge mid muffler with a smaller (about 2/3 size) glass pack straight through muffler and kept the rear resonator. Note is nice, deep but not obnoxious (still pretty quiet) and it's still quiet inside. Doesn't seem to drone.


Nanocom is happy too with no trouble codes reported.


Cheers


Michael

Good stuff Mick,
So what do you put it down to? Do you think it was a bung O2 sensor? I just took mine away for the Aussie Day weekend and while I think my car is better for the most part (it seems to not smell like rich exhaust anymore) it still has the occasional rough idle. At least one of my O2 sensors appears to be a bit oily from the leaky rocker covers...I heard that one of the reasons they get faulty is that they send some wrong signals after they get oily or have coolant leaked on them...were yours oily?
Ive fixed the leaky rocker covers with new gaskets...I also noticed the rocker cover bolts were a bit loose so they're all tight now. Did you buy bosch sensors?

My final diagnosis was a blocked cat converter probably caused by the rich running on the left bank (courtesy of the dead O2)

Yep, brand new bosch sensors same as the originals. I got them out of the US.

When I puled the plugs on the left bank they were black compared to the right. The O2 when i pulled it was black and sooty too. However I think this is a symptom of a dead O2 rather than the cause as I tried cleaning it up and re-installing it. No oil leaks and the sensors looked to be in good shape. I was getting a trouble code from my nanocom intermittently for a while and then it just stayed on solid.

Looking at the lambda numbers from it and it was just solid not changing values.

My Disco is on LPG so I don't know if that was a factor in the O2 demise.

All my trouble codes are clear now and it seems to be running very nice (It would bloody want to after all the work I put into it).

Cheers

Michael