2000 Cirrus P0300 System Lean V6 2.5L Fuel Injected

Egr valve would be the first thing I'd check on those cars for those symptons although it should never shut the car down, you should still have spark and fuel pressure! Why was the pump changed? For this issue or something else? How recent are all of these repairs? used distributor or reman?

jeff compton wrote: Egr valve would be the first thing I'd check on those cars for those symptons although it should never shut the car down, you should still have spark and fuel pressure! Why was the pump changed? For this issue or something else? How recent are all of these repairs? used distributor or reman? Fuel pump was changed due to an intermittent no start that was traced to fuel line pressure at startup. Repairs were done about 1 year ago. I should have noted the car didn't shutdown automatically on the highway. My daughter saw the Check Engine Light and pulled off the road and turned the car off for a while. When she tried to restart the car but it wouldn't restart (i.e. the engine didn't even turn-over). I believe the PCM wasn't getting the readings it wanted and wouldn't energize the ASD relay. That's making me somewhat suspicious of the Crankshaft Position sensor. Is there any diagosis (on-vehicle or off-vehicle) to verify an EGR or Crankshaft Position sensor is operating properly? Is 13.9in/Hg Intake Manifold Pressure normal for a car running at 2712 RPMs ? Discover more Spark plug Ram Pickup Ram Just trying not to throw random parts at the problem but diagnose the symptoms (as intermittent as they are). Thanks

the vaccum reading sounds okay, scoping the signals would verify the cam sensor and crank sensor signal! Crank sensors aren't as common as distributor failures but your is new right?

I hate to disagree, but I have to here. A leaking EGR won't cause the fuel trims to increase(add fuel) The reason is because exhaust gas is 99% inert, which means it's nonreactive and DISPLACES oxygen. So, when there's a EGR leaking inert ex. gas into the cylinder, it results is the O2 sensors reading a fuel/o2 ratio that requires less fuel. An o2 sensor doesn't read inert gas. As a result, a leaking EGR usually is accompanied by a leaning of the fuel mixture.

Assuming his fuel trim reading is correct! Doesn't leave much then!

Darkrooms wrote: I hate to disagree, but I have to here. A leaking EGR won't cause the fuel trims to increase(add fuel) The reason is because exhaust gas is 99% inert, which means it's nonreactive and DISPLACES oxygen. So, when there's a EGR leaking inert ex. gas into the cylinder, it results is the O2 sensors reading a fuel/o2 ratio that requires less fuel. An o2 sensor doesn't read inert gas. As a result, a leaking EGR usually is accompanied by a leaning of the fuel mixture. From my reading of Motor Magazine (Sep 2006) the following applies to positive fuel trim readings - "Positive fuel trim percentages indicate that the powertrain control module (PCM) is attempting to richen the fuel mixture, to compensate for a perceived lean condition." This seems to agree with my freeze frame readout on my Autoenginuity scan tool that says P0171 System Too Lean, followed by P0300, 0301 & 0305 (I've also seen a 0302, 0304 & 0306 on another occasion). With the freeze frame reading 24.18% on both Short-term and Long-term fuel trims it seems the PCM was trying to request excessively high levels of fuel add to richen the fuel/air mixture. I don't know if 24.18% is pegging the level (i.e. its the maximum reading) requested or some short-term event came along and either a) maxed the air or b) cutoff the fuel. If its a) - then EGR might be a suspect if it let too much recirculation back into the throttle - crankshaft or camshaft position sensor error that fouled up the event readings (although no other code was thrown) or b) - fuel pump didn't deliver the required fuel flow when requested (seems odd only at high speed) - injector signal shorted out temporairily (denying fuel flow) Seems it wouldn't be a coil failure as the mixture would have been too rich not too lean. Am I missing something or could there be other issues? hhmorgan I've added some graphs from a non-code setting run of the car to show operation of the 02 Sensors, short & long-term fuel trim, intake manifold levels vs engine RPM & speed for further info & observations. (see links below - NOTE ALL THESE GRAPHS ARE FOR THE SAME RUN AND NO CODES WERE SET) http://farm2.static.flickr.com/1409/763 ... f1aa_b.jpg http://farm2.static.flickr.com/1379/763 ... d341_b.jpg http://farm2.static.flickr.com/1425/763 ... 8f8f_b.jpg http://farm2.static.flickr.com/1375/763 ... 7138_b.jpg

Again, you're not paying attention to what Im saying. First what you said here: "Positive fuel trim percentages indicate that the powertrain control module (PCM) is attempting to richen the fuel mixture, to compensate for a perceived lean condition." Yes, that's correct understanding of fuel trim characteristics. but your next statement is false: "then EGR might be a suspect if it let too much recirculation back into the throttle." This is a typical misunderstanding that many technicians have about fuel trim and NOx readings that accompany an EGR leak. If you go back and re read my post you'll see that I already stated the chemistry of exhaust gas is nearly all inert gas(with some o2, hydrocarbons, and CO). Inert gas is non reactive. An o2 sensor reading the exhaust gas from the offending cylinder will misinterpret the data as too much fuel per o2 content and will remove fuel accordingly(NEGATIVE FUEL TRIMS, NOT POSITIVE) Using your own words the PCM is trying to "compensate for a PERCEIVED lean condition." (bold mine) rather than an actual lean condition. Again, I was posting this information as a possibility of contributing to your problem, not as the only possibility. I hope this clears it up for you. Also, anyone who contends that the above info is innacurate is an ignoramous with only a rudimentary knowlege of the sophisticated computer systems currently in use on modern autos.

Darkrooms wrote: Again, you're not paying attention to what Im saying. Darkrooms - I am now! The inert gas would not drive the system lean, it would drive the system rich by displacing O2. Thus it's not likely that a fault EGR is driving this problem. Now what could be driving the system this lean and setting misfires only at high speed operation? The car has been running now for several weeks without setting another code. But I don't want my daughter stranded on the highway in the future like she was the last time. On a MAF based system I would immediately suspect the MAF sensor in this problem. But the 2000 Cirrus V2.5L is a MAP based system. And if the freeze-frame intake manifold reading of 13.6lbs/Hg is ok then what else is left in the system to cause a problem? A basic question I have is even though the PCM is recording the system lean (i.e. LT & ST 24.18%) could the crankshaft or camshaft position sensors be responsible for collecting data at the wrong times (due to intermittment operation? Thanks

*ahem* for the last time: A egr leak would drive the ACTUAL engine condition rich, yes, but I was talking about FUEL TRIM READINGS. Using again, your own argument, the PCM would determine that the engine was running rich, yes, and then try to REMOVE fuel by shortening pulse width accordingly, not increase it. Your INCREASE in fuel trims doesnot point to an EGR leak. THAT is what I was saying. Im leaving the board now and returning to my lair.

intermittent lean code! likely a lower quality fuel pump or fuel pressure problem! Yes I know you already replaced it!

<-----wonders if the lair has pics of blondes or schematics on the wall

It's actually decorated with the hides of rookie techs who give bad advice because they're too arrogant to realize they don't know anything.

Should I send my "hide" to you!

No, Comp, wasn't directed at you, just humorous remark. Besides, you're no rookie.

Tahnks for that!