Any idea what could be causing this intermittent problem?
05-28-17, 02:24 AM
#1
Driver School Candidate
Thread Starter
Any idea what could be causing this intermittent problem?
As the title implies, my 1994 sc300 has been having an intermittent problem where it idles very rough, has very reduced power, wont rev past about 4500 and spews white smoke. As a bonus, today after idling for about 15-20 minutes (the car usually works the issue out by just running for awhile), I noticed smoke rising from around the shifter. The transmission tunnel was so hot it was burning the carpet or something, I poured some water on it and it sizzled. After sitting for several hours I started the car up again and it seemed to run normal, as per usual with this problem.
I think I know what my problem is but I'd like someone else's opinion, so here's some background to explain my reasoning. First, I had the ECU rebuilt awhile ago, so hopefully that can be eliminated as possible cause for my current woes, I also replaced the fuel pump and fuel pressure regulator recently. I had a leaking valve cover gasket that was allowing oil to pool above my plugs, I assumed that could be the issue so I replaced the valve cover gaskets, plugs, wires, cap, rotor and ignition pack. That was a couple weeks ago and the issue has still persisted, today was the worst instance of the problem that I've had yet. Before today I'd just let the car run for 10 minutes or so and the problem would go away and the car would run fine, now with so much heat coming from the transmission tunnel I need to get this fixed before it starts a fire.
Anyways, my theory is that the pooling oil above the spark plugs dripped into the cylinders and burned off causing the catalytic converters to go bad and the clogged cats are what's causing my current issue. Should I be looking at other things besides the cats? If it is the cats should I be replacing sensors or anything else simultaneously?
As a side note and probably unrelated, my car has a weird idling problem. When you first start it, it idles normally (around 600-800) but once you give it gas the idle will stay at around 1600-2200. The idle will drop back down a little if you bog the engine down with the clutch, but the most effective way to drop the idle is to rev the engine up to 5000+ and let off the gas, then it will typically drop below 1000. Most of the time if you stop and start the car the idle will also return to normal though sometimes it will return to a slightly elevated idle (about 1200-1500).
I think I know what my problem is but I'd like someone else's opinion, so here's some background to explain my reasoning. First, I had the ECU rebuilt awhile ago, so hopefully that can be eliminated as possible cause for my current woes, I also replaced the fuel pump and fuel pressure regulator recently. I had a leaking valve cover gasket that was allowing oil to pool above my plugs, I assumed that could be the issue so I replaced the valve cover gaskets, plugs, wires, cap, rotor and ignition pack. That was a couple weeks ago and the issue has still persisted, today was the worst instance of the problem that I've had yet. Before today I'd just let the car run for 10 minutes or so and the problem would go away and the car would run fine, now with so much heat coming from the transmission tunnel I need to get this fixed before it starts a fire.
Anyways, my theory is that the pooling oil above the spark plugs dripped into the cylinders and burned off causing the catalytic converters to go bad and the clogged cats are what's causing my current issue. Should I be looking at other things besides the cats? If it is the cats should I be replacing sensors or anything else simultaneously?
As a side note and probably unrelated, my car has a weird idling problem. When you first start it, it idles normally (around 600-800) but once you give it gas the idle will stay at around 1600-2200. The idle will drop back down a little if you bog the engine down with the clutch, but the most effective way to drop the idle is to rev the engine up to 5000+ and let off the gas, then it will typically drop below 1000. Most of the time if you stop and start the car the idle will also return to normal though sometimes it will return to a slightly elevated idle (about 1200-1500).
05-28-17, 07:05 AM
#2
You had these issues before the ECU rebuild? Sounds like your cats are clogged. Try replacing them or at least gut them to eliminate that issue. As for the smoke I thing iit could be oil burning off. clean the engine bay of all oil and fix any leaks to narrow down that problem.
Keep us posted on this situation. Good luck.
Keep us posted on this situation. Good luck.
Thread
Thread Starter
Forum
Replies
Last Post