Car is running like crap!
 

Good news is that the odometer turned 340k miles (with 128k on Mazda reman engine).

Bad news is that the car just recently started running like crap. Runs like it's dragging an anchor. I'm getting rotten egg exhaust smell and gas mileage seems to be down. However, idle is good and steady.

I pulled trouble codes. I'm getting 17 (feedback system), 32 (solenoid valve - switch) and 41 (solenoid valve - VDI). I just changed the O2 sensor a few weeks ago. Only had 30k miles on the old O2 sensor. I replaced my defective PS pump about a week ago with a used pump. I might have bumped the solenoid cluster behind the pump during the install, but nothing got damaged.

I'll check voltages and switch operation tomorrow. Seems odd that two of these solenoid valves would go bad at the same time. Why am I getting code 17 after replacing the O2 sensor? Any insight here? What does solenoid valve switch do? Seems odd that two solenoids would go bad at the same time.

Looks like I've got my work cutout for me.

Happy New Year!

rotten egg smell?
Coolant seals have let go..you need a rebuild.

Really?
First thing I thought of was catalytic converter.

I agree, take the cat off first or punch it out and see how it runs. I can't believe it would need a rebuild

Btw Styx, you can't fix certain things, stinky feet that smells like rotten eggs like yours are NOT rebuildable lol

What year is it?

Have the following been changed?
Fuel Pump
Fuel Filter
Catalytic converters(Main and Pre)

It's a 1990 GXL.

I have changed the fuel pump about 12 years ago.

I changed the fuel filter about two weeks ago.

I'm running the Bonez High-Flow cat with pre-silencer. That was installed about 12 years ago. The cat might be going bad because I get a really rich exhaust smell. I've noticed that rotten egg smell only happens occasionally and mainly on start-up.

I don't think so. The engine has -- until a couple days ago -- been running very strong. Besides, I'm not loosing ant coolant.

FC's always run rich, I would be suspect of the cat and fuel pump based on the info you provided. The smell is probably from the cat but it is not something that would entirely clog the exhaust and bog the engine suddenly unless it collapsed.

I would rule out the fuel pump first; pull out the air filter and start the car, push on the throttle linkage to rev the car while spraying starting fluid. Does it rev fast and smooth with the starting fluid? If yes: Check fuel pressure/ replace the pump and filter. If No: Pull the Bonez pipe off and start the car and rev it. If it's fixed then punch the cat or replace it. If it still runs like crap test the CAS, MAF, and TPS per the FSM.

Your OMP also could have gone bad and may not be throwing a code. I forgot to mention it earlier but it will cause similar symptoms to what you described, fine idle but it will go into limp mode when attempting to accelerate and flash the CEL. If your OMP has never been replaced it could be the culprit, if you replace it I suggest getting a used ECU with no burned resistors and a good used OMP. A known good matching set is less of a gamble.

Burning coolant has a sweet smell...or at least in the United States, what kind of coolant do you guys run in Canada Styx? :p

Sulphur smell is usually the cat getting really hot due to clogging and it starts igniting sulphur deposits. Sulphur in gasoline here in Texas is highly regulated, so usually the cat just glows, melts, falls apart, or the engine won't run.

Easy test is to unbolt the cat, jack up the exhaust and take it off (the studs make it hard, but its doable if you pull some exhaust hanger doughnuts off) and run it without the catback exhaust and see what it does.

Usually a clogged cat will exhibit all the signs you mentioned, like idling normally but running like shit during load. A fuel problem wouldnt smell gassy.

Which is exactly what happened to me last June.
I went from driving fine to "what the hell?" in the space of 50 feet.

Just pull your cat and see what happens.

Hmm..Ok then the OP needs to check the cat..(but I'll stick on my assumption until otherwise just to be old and stubborn)
Iduley: My butt recently broke in half..2 perfect halves...It revealed a nice Xmas gift for ya!.:nod:..

Awesome, i love doughnut holes

Update...

Went to pull fault codes again this morning and got 25 (Solenoid, Pressure Regulator Control) and 41 (Solenoid, Variable Dynamic Effect Intake - VDI).

Whereas yesterday afternoon, I got 17 (Feedback System (poss O2 sensor) ), 32 (Solenoid, Switch Valve) and 41 (Solenoid, Variable Dynamic Effect Intake - VDI).

WTF? I'm getting a new code (25) and one of yesterday's codes (17) didn't display today.

These solenoid switches are mounted just in front of the oil filler tube on upper LHS of engine. The S5 NA has a total of 5 solenoids with 2 on top row and 3 just below on bottom row. Each has an electrical connector with two wires. So, I went to check these solenoids as per shop manual. Initially, I went to check the voltages. I disconnected the electrical connector for the VDI solenoid (top row, LHS) and noticed that the connectors (brass male spades) on the solenoid were all corroded. So, I took a piece of sandpaper and cleaned them off the best I could. I cleaned the connectors with sandpaper for all 5 solenoid switches (total of 10 terminals). They were all badly corroded.

Disconnected the battery to clear the codes, and then started the car and let run about 15 or so minutes. Went to check fault codes again and there were NONE!

PROBLEM SOLVED!

I think I'm going to make cleaning these connectors a regular maintenance item.

Thanks for everyone's feedback and happy new year to all!

Np need for that- clean the terminals, pack with dielectric grease and reconnect.
Done, for now and forever.

Congrats on tracking down the codes but how did any of that result in the rotten egg smell?

Didn't notice any rotten egg odor after the fix. It didn't do it all the time either. Maybe because all those solenoids were working only intermittently, the port air injection in the exhaust manifold wasn't working. Honestly, I don't know. The Bonez converter that's on the car is 12+ years old and has seen better days. I bought new Bonez replacement that's waiting to be put on. It's not a high priority item on my list since I'm no longer required to have an emissions test. Once my car turned 25 y.o., VA no longer requires bi-annual emission test to register the car.