Running rich at high RPM

[olopezm]

Hi Tom,

Good finding, probably it was the cause of your problem.

I wonder if your scanner is capable of showing the BARO PID. If it does, you can compare that reading to your local barometric pressure (don't rely on weather stations as those normally show a compensated value), if you don't have a barometer, you can subtract 1in.HG per 1000 feet in elevation from the sea level, from the atmospheric pressure at sea level (29,9in.HG).

That's:
Pressure at sea level= 29.9 in.HG
Greensburg, Pa Elevation (according to Wikipedia) = 1017ft = 1 in.HG
Approximate pressure at Greensburg, PA = 29.9-1= 28.9in.HG

So your BARO PID should read 28.9 in.HG; If not, it's probably that either the MAF or the O2 sensors are bad. We can rule out mechanical, fuel delivery and vacuum problems as you already checked that.

If you have access to an exhaust gas analyzer (like those from emissions tests) we can use those value to see if your engine is running rich or lean (even when the fuel trims show it's rich) and rule out O2 sensor problems. Another proper test for O2 sensors is to look at them with a digital oscilloscope to see their switching rate and min/max voltage.

Oscar.

[tomj76]

My scan tool (Actron 9185) doesn't report the barometric pressure from the PCM. I also don't know where I could get access to a gas analyzer, but I have a oscilloscope that I could use.

[olopezm]

Originally Posted by tomj76

My scan tool (Actron 9185) doesn't report the barometric pressure from the PCM. I also don't know where I could get access to a gas analyzer, but I have a oscilloscope that I could use.

That's weird, isn't that an enhanced data capable scanner? Anyway... Maybe a good shop would have an exhaust gas analyzer but it's unlikely as not many people put attention to them. An emissions testing facility WILL surely have one

With such a high oil consumption problem, it's also likely that the O2 sensors are fouled.

Oscar.

PS I made a mistake, the BARO PID will only confirm the MAF sensor, not the O2 sensors.

[olopezm]

I wonder if your scanner can record live data. If so, you could record the MAF, IAT and RPM's at WOT from a stand still until the shift from first gear, and post them here. With such info I could try and figure out if the engine is breathing properly, at least it will confirm if the MAF is OK.

Another quick test, after googling a little, is to check the signal (sig return) from the MAF sensor while snapping the throttle. The signal should produce at least 3.8v and a visible spike without glitches in it. Make sure the voltage for the MAF is 5v between both grounds (battery and PCM) and ref voltage at the connector on the sensor.

I'll update if something else comes to my mind.

Oscar.

[tomj76]

Yes, it records live data. I can do that once I complete the engine rebuild. I've a few more parts to procure and a several preparation steps to do before I start to reassemble it.

[tomj76]

I've now honed the cylinders, installed my new pistons & rings, installed the timing set, installed the new main bearings, and installed the new rod bearings. Next on the list is to prepare the remaining sealing surfaces by adding a filling and smoothing any blemishes on the mating surfaces, and a final cleaning. I need to put the block back in before I assemble too much, since the complete engine assembly can't be installed through the hood.

I takes about 15-20 ft-lbs to turn the crankshaft, much more than before this rebuild. Hopefully that is a sign that everything is now high and tight.

[MarPac]

Haven't read through this thread but have you checked the CMP sensor's position? I had quite same issue, oxygen sensors were OK, mass air sensor as well and still one bank was too rich. The issue was in CMP sensor which was set to wrong cylinder's TDC (one rotate of engine later so no. 4 cyl at TDC).

Engine was going fine no codes in PCM during long time. I found this when trying to set LPG on my van. The thing is fuel is prepared based on camshaft pos. sensor timing while ignition is detected based on crankshaft pos. sensor.

Fuel was prepared in front of the closed valve. There had to wait one rotate of engine when it should be sucked. Normaly fuel is injected into the sucked air and is not waiting there.
Fuel comming in front of the closed cylinder's valve was partly sucked by other cylinder. Especialy No. 1 cyl was sucked by no. 4th one.

Check Camshaft pos. sensor. Place No. 1 cyl to TDC. Than rotate clockwise 2 tooth. CMP sensors signal must fall down to 0 volts in this pos. There is Ford's Tsb showing correct timing which might be checked better than with alingment tool.