Re: Citreon C5 HPI 2.0 2001.Excessive lean mixture Archived Message
Posted by Trevor Grigg on October 22, 2008, 6:49 pm, in reply to "Re: Citreon C5 HPI 2.0 2001.Excessive lean mixture"
Hello all. Just need to explain the very first problem encountered with this vehicle in early october. During the early stages of exploratory tests we noticed a bad engine noise from the valve train area,but would dissapear for a while then return.At the time a vacuum gauge was connected which indicated an abrubt drop and irregular change in inlet manifold vacuum,And recovery coincided with a demise in engine noise.This having a direct influence on the map sensor.I must add that this engine could have been mistaken for a 300,000 mile diesel engine,a similar comment made by Nigel. The fault was traced to a worn vvt hub,the component was causing a backlash affecting the vacuum level and the camshaft/ valve train. After renewing the hub the engine sounded completely different,And the vacuum reading good and consistant.I think at this point is where we fell down a little.After this repair we failed to take the vehicle for a test run,Had we have done we would have appreciated the vast improvement in the driveability of the car,instead after start up we connected the gas aynalyser only to observe very high lambda,low co2 and high oxygen,based on the fact that traditionaly readings like this are indictive of major faults we sailed into further testing as previously posted.To some extent we persued a condition that fooled us into thinking we had a further fault.At the time of undertaking this job we were not conversant with the technical operation of statified and homogenous combustion and its associated gas aynalser readings.After a couple of weeks on this thing,And informative posts from members and a talk from Dave Garrat on monday we have learned a great deal.Misgivings aside,it has emerged that this vehicle does have inherent faults. Even though this car now sounds and runs much better, I can at times under light load conditions detect what i would describe as a weak mixture misfire.Twenty years ago i would have run the car on the dyno and selected a different idle and main jet,IF ONLY.But its gone,Wiser and lessons learned,but a bit poorer for the time spent. Many thanks to all who posted and praise to the site. Best wishes Trevor.
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