Ok, so I've been experiencing some unusual power loss, an occasional stall out and some noticeable engine shudder at 55mph.

I hooked the car up to my laptop and I started graphing (a) coolant temperature, (b) MAF air temperature, (c) throttle position and I forget, something else.

I was basically trying to determine whether or not the TPS, or the CTS, or the MAF sensor was flaking out on me. When I drove in to work, of course everything seemed fine. I ran an errand midday and of course, everything was still fine. But on the way home from work is when the magic started.

The graph on the throttle position started to flake out. I would be keeping a steady gas pedal but i started seeing peaks and valleys. The other three screens were all smooth.

It must be the TPS, right? Is there anything else worth checking? Anything else that can be causing this?

I do want to add that I removed the throttle body and gave it a thorough cleaning, on both sides of the butterfly, so I know that is clean.

Thanks!

 

Assuming a 6cyl 4ltr here?.

The cleaning of the throttle body is good.

The TPS flaky is NO good.

Maybe some cleaning fluid go past the small seal and entered the TPS, dunno. At the age of these items now, a new one will do no harm.

 

Apologies, it is the 4.0 AJ16.

I did find oil in three of the spark plug wells. Planning on replacing the cylinder gaskets this weekend. I don't have to replace the camcover gasket, do I?

I replaced both about a year ago...guess I didn't do a very good job.

 

Have a CAREFUL look at the actual camcover itself.

Pay particular attention to the spigots that form the spark plug tubes. There has been reports of that section being porous, and no amount of seals etc will stop the ingress of oil into the wells.

Have a read/search on the X300 section, as that is where I reckon I read it.

The consensus seems to pount at teh Magnesium in teh casting reacting with the ignition coils "field" or something.

My X300 is very rough inside those tubes, but not porous at all.

 

Thanks Grant, I don't recall anything looking particularly porous or rough in there.

I wonder if theres any kind of sealant I can add in there to help the gaskets along? Hylomar, Hylosil, whatever the sealant that the half moons require perhaps?

 

I use Hi-Temp Red RTV as a dressing on BOTH sides of the cover gasket, AND the spark plug seals.

 

That is good to know Grant. I have never used that stuff before. I never had gasket problems.

I'm going to use Permetex 85420, Permashield Fuel Resistant Gasket Dressing and Sealer. Apparently it's supposed to be the closest thing to Hylomar this side of the pond.