I have a 2003 Lincoln LS with the 3.0L, Ran great 2 days ago.started it today and is running so rich that its blowing black smoke out of the exhaust. I tried to rev up the engine to clear it out, but it will not take any throttle. I had it towed to the nearest shop they told me that it has a PO303 code Cylinder #3 misfire. I had them repair it and it still runs the same way. it will not take any throttle it just seems to make it run worse. The mechanic thought it might be a clogged exhaust so he removed the O2 sensors to release any back pressure but that didn't help. there are no other codes. The mechanic stated that the coolant temp sensor is reading correctly. Any help would be appreciated. Thank you.
It can be as simple as a cracked vacuum hose that could cause this kind of problem.
You have vacuum hoses on the fuel pressure regulator and the MAP (manifold absolute pressure) sensor. A cracked or broken hose on these sensors may cause the engine to run very rich.
Check the air ducts from the MAF (mass air flow) sensor to the engine, a cracked or misaligned hose may also cause this problem.
I would go to another mechanic for a second opinion because if he was a qualified professional he would have been able to see some of these problems by just looking at the parameters of these sensors on the scanner.
These conditions may not set a code but the voltages that appear on the scanner to these sensors if they were out of specs would set up red flags to the mechanic to check these particular sensors for any wiring and vacuum hose problems.
A fuel pressure test can confirm if the fuel pressure regulator if not functioning properly.
Check on these few suggestions I gave you and get back to me when you can with the results.
Thank you for your response. The shop that has my vehicle has a very good reputation, however the lead tech has been on vacation. The other tech doesn't seem to know as much. We live in a very rural area and the next shop is 30 more miles away, that would be another tow bill. I told the tech about your reply, he stated that he has checked all of the vacuum lines and hose assembly to the MAF. The tech stated that the scanner recommended that the hose to the PCV is known to start leaking causing a rich running condition. He stated that he has checked it and it is OK, h stated that he has also checked the intake manifold for vacuum leaks. I don't think he has very much experience with computer controls. Any additional information would be helpful as the lead tech will not be back for another week. Thank you.
The question is did he check the fuel pressure?
If the fuel pressure regulator is faulty then you will have high fuel pressure which could cause a rich running condition.
He should also check all of the fuel injectors, if just one fuel injector is stuck in the open position by mechanical malfunction or electrical fault they could also cause a rich running condition.
Keep me informed on your progress; I'll help as much as I can.
Thank you for all of your help. The shop couldn't figure the car out so I had it towed home. I'm somewhat of a do it yourselfer so I purchased a used Matco scan tool and have recorded all of the sensor readings so here they are.
Manifold Absolute Pressure 29.23 inhg 14.36 psi, vehicle power volts 12.3 v, Mass Air Flow 0.00 g/s I'm assuming because the car was off with key on, Mass Air Flow 0.03 v, Map Sensor 4.28 v, VSS 0 mph, spark advance 10 deg, Barometric Press Frequency 156 Hz, Baro Press 29.40 inhg, Baro Press 14.44 psi, IAT volts 2.92 v, Engine oil temp volts 3.32 v, Eng Fuel Temp Volts B1 3.47v, Cyl Head Temp Low Volt 3.16 v, MAP Sensor 4.27 v,
App Sen 3 Volt 0.91 v, APP 2 Volt 1.51 v, App 1 Volt 4.00 v, VSS 0 mph, IAT 79.8 degF, Engine Oil Temp 59677
degF Could not locate sensor in oil pan seems high, CYL Head Temp Low 71 degree, Rear Fuel Trim Bank 2 0.00%,
Rear Fuel Trim Bank 1 0.00%, Variable Cam Time 2DC 0%, Variable Cam Time 1DC 0%, ST Fuel Trim B2 399.7%, ST Fuel Trim B1 399.7 %, LT Fuel Trim B2 0.0%, Bnk 1 0.0%, Calc Eng Load 59.2%, Knock Sensor 65535 seems high,
Baro Press Frequency 156 HZ, Baro Press 29.40 in hg, Manifold Absolute press 29.23 inhg, Eng Fuel Temp 140 degF,
ECT 73 degree F, IAT 79 degree, If you need anymore info let me know. The car will only start and will not rev up, smoking bad, I think I need to install new spark plugs.
Did the mechanic test the fuel pressure?
These readings are for the engine off and key on.
What are the readings with the key on engine running?
Before we go any further we need to know what the fuel pressure is with the engine running.
When you get the engine running concentrate on the fuel trim on both banks of the engine, 2.0 is a good running engine. Give me the reading with the engine warmed up and running.
Give me the updated information when you can.
Yes, you definitely need to check the fuel pressure before going any further, and at the same time check for fuel contamination.
Did the problem begin shortly after filling up the tank?