A few days ago I had reason to change the Head Gasket on a 120k Mile Cavalier Cd Auto 2Li. This cured the water usage and returned the cars performance. Unfortunately-- 'my fault, finger trouble'-- I adjusted the Idle Mixture screw and in doing so have lost its original setting. Is there any simplistic way of getting this adjustment approximately right with out the need for an Exhaust Gas analyser. For instance if one places the slider on the potentiometer about Midway along its resistance, would that do?
Or is there some other way of setting this device?
My concern is that occasionally the Engine Management Light comes on, it does not flash and the 'Paper Clip test Method' shows all '12's and no fault. The advice of an expert would be much appreciated. One other observation, the adjustmet seems to make little difference, it certainly does not affect performance!
Regards Nikki
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If you have access to a voltmeter you can approximate the correct position by setting the output to around 1-1.3 volts from memory. I will check and come back to you and also tell you which pin to measure it on.
Andrew
Simplicate and add lightness!
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Amdrew, Many thanks for your responce to my Cavalier idling problem. Yes I do have voltmeters available but I do not know on which points to conect same. I asume the measurement is between a specified pint & Earth? I would very much appreciate this information, does one make the connection inside the top cover of the Air Mass connection box over the air cleaner?
In truth the car seems to run much the same no matter were one places the 'multi turn potentiometer', but I would like to have it right. Incidentlly the poteniometer measures 1.2k Ohms, It also- ulike must pots: seems to have 4 not 3 connections?
I look for to hearing from you my Email is j.siddon@ntlworld.com
please accept my thanks in anticipation! Regards regards
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Roll back the rubber boot from the plug to the airflow meter and put the + probe against the second pin from the right (2) put the-probe to battery earth and set it to 0.3v. If the voltage wont change then the pot has failed or possibly the linkage between the pot and the adjusting screw has broken. Carefully prise the lid off the meter to check.
Hth
Andrew
Simplicate and add lightness!
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Andrew, Many thanks for your prompt responce about the Bosch Air Mass Unir adjustment. Working to instructions I found that no amount of adjustment altered the 0.112 to 0.114 volt reading on Pin No 2 under the rubber gasket. Your other idea that the pot: might have failed was also investigated, I took the lid off and checked the 10 turn 1000 ohm .pot: ( with 4 connections) it seems to be OK resistance wise, however because nothing I do seems to effect the running of the engine, which is sweet & has a stable tick over! I have set the blue pot at 310 ohms between it's pins 3 & 4 ( reading fron L to R)and left it until another time. Could it be that mine being one of the earliest Mark 111 Cavaliers 1998, is that I don't have a CO monitor? I certainly don't have a catalyst!
For this reason this particular pot; may perform no meaningful function? it was the head gasket that was using water I should have left the rest alone.
However the main reason for this note is to say thank you for your efforts on my behalf, they are much appreciated. Regards regards Nikki
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Mk3 Cavaliers didn't get catalyst / lamda sensor as standard until '92 Kreg although it was available as an option on some versions earlier.
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Sorry Nikki, total brain fade on this one, comes of trying to be too clever. pin 2 is the output from the airflow sensor, not the CO pot which is on pin 1. Mid-position should be about 2.4v. Turning the pot clockwise increases voltage and CO value. Sorry to mess you about. The pot should have a tangible effect especially on the idle quality when set to max lean. Remember though that the change in CO pot value takes about 10-15 seconds to start showing any effect at the tailpipe which in itself is quite leisurely so winding the screw in and out quickly wont show much change.
Andrew
Simplicate and add lightness!
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Andrew, My thanks for your revised set of instructions, these worked! The original voltage on Pin No 2 was 3.4 Volts now adjustd down to the 2.4 Volts you proposed. Alls well that ends well. Once again Thanks.
May I also acknowledge RoderL who confirmed the lack of a CO sensor on my early model Cavalier which I was about to change foe a top of the range executive 1.6L Auto Honda Civic, but having ridden in the Civic I have decide to keep the Cavalier at least for anothe 12 months since its ride is far superior.
Regards regards
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Blimey, the ride of the Civic must be really bad if you prefer the Cavalier. I've used Vauxhalls for two decades, mainly Cavaliers which had many strong features, but were never chosen for ride quality!
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I couldn't agree more! I love my Cavalier but its ride quality, even when brand new and especially now its getting on a bit must be one of the weakest features.
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