Thanks, aode- good plans. Anyone concur with the Sea Foam reccommendation? I've heard it makes a black exhaust cloud big enough to scare the neighbors into calling the fire dept.

 

Only if you suck it into your engine via a vacuum line slowly while revving the engine, which I highly recommend you NOT DO, as some have lost valve seats purring in too much or had chunks of carbon come part and cause valve damage.


Make sure you are using premium gas as the car calls for,whenever you fill up,Jaguars like British Petroleum gas(BP) and 0w40 oil

 

Aside from changing the oil and filter - not needed yet - I did all this and finally sprung for a can of Sea-Foam in an empty tank before filling (always top-tier premium). The spark plugs had to be the originals at 131k miles- look at the image below! The coil packs seemed fine- especially the contact springs inside. I also replaced my air hose after finding that the bellows had cracked in one area on the bottom, and were electrical-taped over another area that had cracked before, letting God knows what into the engine. Then I noticed the throttle body was, for all intents and purposes, black. I don't think it had ever been cleaned before, so I spent a good couple of hours with CDC Throttle Body Cleaner spray and a rag getting that thing cleaned. There were several drops of oil on the bottom of the inner TB housing chamber that was concerning.

After seeing the condition of these systems, of all the easy 'tune-up' items, I started getting a bad feeling that despite the car's recent mechanic ownership history and having "a lot of stuff done to it", it may not have been a thorough as I had been trusting. Despite the lack of records because it was "all done at the shop with parts at cost"... This isn't holding water with me anymore. However, this was also 2 years ago and the car really has largely been very reliable and nearly a daily driver. Maybe the "if it ain't broke, don't fix it" school of thought was followed, which has some merit. But now I'm thinking the mere mention of 'tensioners' isn't good enough, and the car will mostly remain down for the next month or two while I can get that properly checked out, and I finish getting a new and solid baseline on this car.

Other than that, good progress! The CEL remains extinguished after a few dozen miles' worth of driving. It's got a slightly rougher idle for the first minute on a cold start, but the engine may still be recalibrating or getting the Sea-Foam through the system, not sure. But it smooths right out very shortly thereafter and runs as well as I ever remember it running.

All was looking up! Until the 'Engine Coolant Low' message came up. I got it home and let it cool. The coolant bottle later was still half-full (low?), but I obviously have a leak. I could very faintly smell coolant recently, and now can smell more of it- some hole in some hose has apparently gotten larger. Sure enough there's a very small puddle after turning it off too. Coming from the rear of the engine, so I'm thinking it's the octopus hose, as the two heater hoses in the valley under the SC were already changed several months ago with the same symptoms. Wonderful. But what was more concerning was that I've been using the Prestone GM DexCool orange coolant for two years now... and the coolant in the bottle is now green. WTF. An oil sample from the dipstick still looks and smells like 100% motor oil, so I don't think they're mixing somewhere... but is that what would cause that? This may need to be another thread.

I'm never going to get to the cats and exhaust at this rate...