Freelander Intermittent Too Lean and Severe Loss of Power
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05-04-2014, 11:33 AM
Join Date: May 2014
Location: Stillwater MN
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Freelander Intermittent Too Lean and Severe Loss of Power
Hi, I have a 2003 2.5 gas Freelander that I picked up cheapand up until this point has beat all the odds. That is up until a month or so ago when it started exhibiting intermittentsevere losses of power. I have aninexpensive Blue Tooth code reader that I use with the Torque app on my smartphone. Various fault codes come upequating to one or both banks too lean then various misfires. When started from cold it starts up asnormal for the first 5 to 10 seconds (must be starting on some sort of predefinedrich starting mixture and control) then when it would normally back down toidle rpm it begins to run very rough and often dies. Pressing the accelerator during this dropoff has little or no effect. You canhear the extra air flow but the rpms don’t pick up and instead it either coughsand jumps or just dies. At this point ifyou try starting it multiple times and keep the rpms up during and after the 5 –10 second startup cycle it will eventually “clear itself” and run pretty normal- for a while.
Then using my code reader and having my son ride along andmonitor some of the engine parameters I’ve been able to test drive it and makea few observations: When it’s runningwell the short term fuel trim on both banks is up around 27%. Then for some reason these trims start steppingdown (he can watch them on a graph and they tend to move together in what lookslike a stair step pattern) and eventually go to zero. While this is happening the engine losespower and all but dies. Keeping the rpmsup can prevent or reverse the step down in trim and roughness. So it seems that higher rpms help thesituation but I’m not sure. Also, oncethe engine is warmed up, shutting it off and restarting always brings it backto normal for at least the first 5 – 10 seconds and often it will continue torun fine for up to 10 minutes or more (as long as it’s not just at idle).
I don’t know which is the cause and which is theeffect. The engine control unit seems tobe stepping the fuel mixture down to the point that it’s too lean to even runbut I don’t know what the root cause is. And keeping the rpms up either mitigates the underlying root cause orputs the engine control in some other control condition that automaticallytells it to call for a richer mixture.
I’ve tested the fuel pressure, looked at the spark plugs,monitored the O2 sensors, cleaned and monitored the mass airflow sensor, lookedfor vacuum leaks etc. but I’m not sure what to try next. Oh and by the way, I have had some troublewith the butterfly valves and motors in the plastic part of the intake manifoldso they could be acting up again but I’m assuming they couldn’t cause thesemore serious symptoms?
Anyone have any ideas?
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