I am trying to diagnose what the issue is here, any input would be very helpful! I am one for one with this forum so I would love to hear what you guys have to say. I purchased this vehicle less that a month ago. The check engine light was on throwing code 4 which after a ton of different testing ended up to be a faulty ECU. Engine light is gone and it is now out of limp mode (revs above 3500 rpm)

The car is misfiring bad and a ton of white or possibly blue smoke is coming from the tailpipe. I changed the plugs which were all pretty bad, the wires, the distributor, the ECT sensor and air filter so far just to give you a heads up. I pulled the new plugs back out after the car started to run terrible again and they were black, the tip where there is spark on 2 of them looked like oil had gotten on them.

After some due diligence on line reading a few other posts, I determined that it could be a head gasket or possibly the rings? FYI there didn't seem to be coolant in the oil or any oil in the coolant and no oil on plug wires or plugs other than at the tip and partially on the threads of the two I mentioned. I think I ruled out valve cover gasket or the seals that are in the valve cover? Please help!

 

Start with checking the compression in each of the cyl's. What are the numbers.

 

Sorry it took me a few days to get back, I had to rent a compression gauge. The numbers are as follows. Cyl 1: 155, Cyl 2: 145, Cyl 3: 155 Cyl 4: 155. Seems as if compression is ok, It almost seems as if it is running very rich possibly, I believe the white/grey smoke may very well be raw gas as it smells like gasoline, almost like a snowmobile or motorcycle. I thought maybe one of the injectors was stuck open so I disassembled the fuel system, cleaned the injectors and fuel rail. All of the gaskets/o rings seem to be in tact and look decent. I cleaned the plugs up because they're brand new, put everything back together and it started right back up. Didn't seem to run as rough but still idled poorly and their was still smoke coming from the exhaust. Is it possible the cat might be clogged? Any other suggestions would be greatly appreciated.

 

With the engine cold, start the engine, let it idle for a couple of minutes, stop the engine and pull the plugs. Look and smell for excess gas. If it is too rich the timing could be off, the ignitor could be weak, the fuel injector resistor may be bad, etc. It should not be related to the cat. FYI, the injector resistor is located near the under hood up top near the fire wall. it is made of aluminum and has vented ribs cast into it. I believe it is about five inches long and around three inches wide. If you have a friend who's car runs fine from the same generation you can try swapping them and see if your problem goes away or simply go to a salvage yard. They don't go bad that often but it is not unheard of.

 

Your compression seems low, I'd check the lower limit spec. Also the valve stem seals may be gone, do you get a puff of smoke when you first start engine?

 

The compressions are on the low side but OK. Lower service limit is 135 psi, nominal 178 psi, maximum 200 psi and all are w/i 28 psi (max variation) high-low.

Suspect a combination of engine wear and valve stem seals may be leading to oil fouling. A leak down test can be performed to ID where loss of compression is occurring; rings, valves, or gaskets unless head cracked. Following is one example of leak down test.


good luck

 

Started it cold and pulled plugs, they do smell like excessive gas and they're quite dark again almost black after I just cleaned them. Its not so much a puff of smoke when started but almost as if its steady smoke like unburned fuel very rich smell. Do you mean ignition timing or the timing belt?

 

After a closer look, I don't think there were oil on the plugs I think it might have been carbon deposit from raw fuel?

 

blue smoke is OIL
white smoke that does NOT dissipate quickly and smells sweet = antifreeze
bad rings will show up as excessive blow-by and a SOS showing excessive hydrocarbons on your oil sample
valve seals will result in misfire

 

Thanks, I am aware that blue smoke is oil and white is likely a head gasket, but the smoke is more of a white/grey and has a strong fuel smell to it. It is constant, not just on start up. I really think it is running rich due to a fuel system failure. The plugs have a strong scent of raw gas and the oil even has a hint of a gas smell. Just not sure what could cause the problem and how to troubleshoot. I appreciate any input and the responses that every one has given thus far.