[EverEv]

DTC codes P300 and P308. Live data shows misfire on cylinder 8 but only when starting. No issues at idle. While driving (in an empty car park) seeing almost continuous faults on cylinders 3 & 4 and intermittently on 1 & 2.
Clogged Catalytic? and is this 2 problems (one affecting #8 during startup and another affecting right bank cylinders while driving)?
Any additional diagnostic tests recommended?

Vehicle was recently purchased, sat for 6+ months previous and has 170k miles on it.
Work done to date (not necessarily to address the issue above but perhaps related)... plugs & wires; fuel pump & filter; trans fluid, filter, plug adapter & cleaned TCM of oil; water pump, thermostat, serpentine belt, idler pulley, tensioner

 

[Teutone]

DTC codes P300 and P308. Live data shows misfire on cylinder 8 but only when starting. No issues at idle. While driving (in an empty car park) seeing almost continuous faults on cylinders 3 & 4 and intermittently on 1 & 2.
Clogged Catalytic? and is this 2 problems (one affecting #8 during startup and another affecting right bank cylinders while driving)?
Any additional diagnostic tests recommended?

Vehicle was recently purchased, sat for 6+ months previous and has 170k miles on it.
Work done to date (not necessarily to address the issue above but perhaps related)... plugs & wires; fuel pump & filter; trans fluid, filter, plug adapter & cleaned TCM of oil; water pump, thermostat, serpentine belt, idler pulley, tensioner

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[tusabes]

Two obvious problems spring up to mind, bad coils and bad gas. You could either buy a new coils fairly cheaply, or swap the ones from the non-misfiring cylinders to see if the misfire changes and moves to the cylinders you swap to. Also put a can of HEET in the gas tank along with fresh gas and drive the car a long distance

 

[EverEv]

Two obvious problems spring up to mind, bad coils and bad gas. You could either buy a new coils fairly cheaply, or swap the ones from the non-misfiring cylinders to see if the misfire changes and moves to the cylinders you swap to. Also put a can of HEET in the gas tank along with fresh gas and drive the car a long distance

Thanks. Will explore those possibilities

 

[AtlantisVip]

Got a 06 S430 that keeps misfiring on random cylinders especially 3 5 and 8. It only happens when I hit about 5k rpms. Did plugs wires and coil packs already and no change. Going crazy.

 

[cowboyt]

If you've already done all that and are still having problem, then it's time to get that car on SDS.

 

[EverEv]

Got a 06 S430 that keeps misfiring on random cylinders especially 3 5 and 8. It only happens when I hit about 5k rpms. Did plugs wires and coil packs already and no change. Going crazy.

In my case, cleaning the Mass Airflow Flow sensor helped some (I'll be cleaning the Throttle Body soon). Also switched out the Crank Position Sensor (more for a warm start issue but seemed to help misfiring as well) however it still runs a little rough so continuing to diagnose as the winter weather permits...

 

[EverEv]

A thorough cleaning of the MAF seems to have solved the multiple misfire problem with cylinders 1-4. Cylinder 8 is still misfiring causing it to run rough but I'm treating that as a separate issue. Probably an injector related but I'll post it in another thread if necessary

 

[cowboyt]

An improvement is an improvement, and it sounds like you're on your way to getting this sorted out. Good deal.

 

[AtlantisVip]

I cleaned my MAF and made no difference. I managed to scan my car with Xentry Passthru and it advised me to add fuel to tank but it was already at 3/4 🙄

 

[EverEv]

Fuel pressure issue?

Also you could check the line running from the filter to the fuel rail for corrosion. Rust particles in the fuel rail will clog the injectors and cause misfiring. This is what caused my cylinder 8 misfire

 

[AtlantisVip]

In my case, cleaning the Mass Airflow Flow sensor helped some (I'll be cleaning the Throttle Body soon). Also switched out the Crank Position Sensor (more for a warm start issue but seemed to help misfiring as well) however it still runs a little rough so continuing to diagnose as the winter weather permits...

Did you do the crank sensor from the top or did you have to get under the car? I can't get to the damn thing. 🙄

 

[EverEv]

Did you do the crank sensor from the top or did you have to get under the car? I can't get to the damn thing. 🙄

From above but it was a real pain

 

[AtlantisVip]

Yea I'm noticing. An indy wants $150 to do the job. Says he has to get under the car and remove a bracket to get to it.

 

[EverEv]

Probably easier to do it that way if you have a lift but since I don't have one, I'd rather not work under the car while lying on my back if I don't have to. If the bracket wasn't there it would've been easy but eventually I was able to get the bolt in. Either way $150 sounds ridiculous for what should be a 5 minute job

 

[AtlantisVip]

Agreed.

 

[wallyp]

Too late to help you, but changing the V-8 crankshaft position sensor is a ten-minute job standing by the car.

Buy, borrow or steal a 1/4" drive 10mm socket, ratchet and 16" extension. Tape the socket to the extension so that it won't fall off.

Lift the hood. Find the small tab on the right hood hinge, press it and carefully push the hood a bit more open. This should hold the tab in the depressed position. Go to the left hinge, press that tab and lift the hood to the vertical and locked position.

Stand by the left fender. Use a flashlight to look down behind the engine to the bellhousing just off center and find the CPS (Crank Position Sensor) and its wire harness.

Carefully work the 10mm socket onto the retaining bolt. Partially loosen the bolt, then start pulling gently up on the wire harness as you remove the bolt. Continuing to pull up gently on the wire harness and pushing down gently on the socket, bolt and sensor, pull the CPS up and out.

Unplug the faulty sensor and plug in the replacement.

Fold a small piece of tape over the head of the bolt and push it into the socket. The goal is to have the bolt where it won't fall out of the socket, but can be easily pulled out of the taped-on socket.

Put the bolt into the CPS. Holding up gently on the wire harness, work the CPS, bolt, socket and extension down into position, start the bolt and screw it in. Pull the extension and socket off of the bolt and out.

Start the engine to make sure that all is well.

Push back on the left side of the hood and release the hinge tab to unlock the hood. The right side should unlock.

Job done.

Most of the time, the CPS failure mode is that the engine won't start when hot, but will when cold. Folks have been known to dump a cup of ice water on the sensor to get home. After a couple of experiences, I keep an inexpensive socket, extension, ratchet and the intermittently failing CPS in the spare tire well.

Hopefully, you will never need these tips again...

 

[EverEv]

Too late to help you, but changing the V-8 crankshaft position sensor is a ten-minute job standing by the car.

Buy, borrow or steal a 1/4" drive 10mm socket, ratchet and 16" extension. Tape the socket to the extension so that it won't fall off.

Lift the hood. Find the small tab on the right hood hinge, press it and carefully push the hood a bit more open. This should hold the tab in the depressed position. Go to the left hinge, press that tab and lift the hood to the vertical and locked position.

Stand by the left fender. Use a flashlight to look down behind the engine to the bellhousing just off center and find the CPS (Crank Position Sensor) and its wire harness.

Carefully work the 10mm socket onto the retaining bolt. Partially loosen the bolt, then start pulling gently up on the wire harness as you remove the bolt. Continuing to pull up gently on the wire harness and pushing down gently on the socket, bolt and sensor, pull the CPS up and out.

Unplug the faulty sensor and plug in the replacement.

Fold a small piece of tape over the head of the bolt and push it into the socket. The goal is to have the bolt where it won't fall out of the socket, but can be easily pulled out of the taped-on socket.

Put the bolt into the CPS. Holding up gently on the wire harness, work the CPS, bolt, socket and extension down into position, start the bolt and screw it in. Pull the extension and socket off of the bolt and out.

Start the engine to make sure that all is well.

Push back on the left side of the hood and release the hinge tab to unlock the hood. The right side should unlock.

Job done.

Most of the time, the CPS failure mode is that the engine won't start when hot, but will when cold. Folks have been known to dump a cup of ice water on the sensor to get home. After a couple of experiences, I keep an inexpensive socket, extension, ratchet and the intermittently failing CPS in the spare tire well.

Hopefully, you will never need these tips again...

Not sure which engine these instructions are for but I can say on mine it's an E8 socket and I found a straight 16" extension too long. I used two smaller extensions with a u-joint in between. Also I had to disconnect the wiring first as it was in the way because the bracket beside the CPS left very little space to access the bolt. A magnetic pickup tool with lighted mirror came in handy. The real challenge was getting the bolt back in which took patience. Torque spec for the bolt is 10Nm

 

[tim687]

The real challenge was getting the bolt back in which took patience

This!

I've done mine too and this was very frustrating to do so on a V12.

Back to the topic; how is the engine running now?

 

[EverEv]

Back to the topic; how is the engine running now?

Better but not great. #8 injector was badly clogged so I replaced the injectors. However I believe I have a vacuum leak(s) that I'm trying to chase down by constructing my own smoke machine.