1991 Zx Avantage 1.6 Mis-fire At Low Revs

[Guest Larry & Jill Kuiper]

We have an Avantage 1.6 petrol with single point fuel injection system. The car suddenly started banging and farting at low revs. If you keep the revs up and change down a gear you can pull through the problem. Town driving is therefore a nightmare. It obviously uses more fuel as well when these conditions prevail.

We have had the MAP sensor replaced at a cost of £93.25 including labour. According to the mechanic the plug leads appeared to be fine, but we have ordered a set and will fit them in any case. Can anyone suggest a cure to this problem (short of getting rid of the car that is, It is my wifes pride and joy and any mention of selling invokes the wrath of hades)

[kfk]

Many years ago had problems with one of these......thought it was manifold pressure sensor but turned out it was cambelt had stripped 4 teeth and the valve timing was out.

 

Considering the constant roadtesting that was carried out in trying to diagnose the problem it was suprising we didnt wreck a set of valves......but you can say these things with hindsight.

 

So...........question iwould ask is why did the manifold sensor get replaced and when they replaced it did it give the reading they then expected?.......i'd get the valve timing checked.

 

Missfires & poor running......suprising how many people jump into the engine management system without checking that everything is mechanically ok.

[ArticFox]

Always start with the basics - spark plugs, HT leads (inc coil lead), distributor cap & rotor arm. Check for damage, signs of tracking/dampness, and if you're competent, check for a spark at each plug - remember the ignition is a high voltage circuit ;) One of the inline spark checker tools is handy for this - it plugs into the HT lead between the lead and the plug and a lamp illuminates when a spark is fired.

 

MOST running problems are either igntion or electrical based - so check all electrical connections for cleanliness and security.

 

Next, check the timing of the engine as a previous correspondent suggested - bad timing will cause poor running. Remember to check whether you need to have the timing set with the distributor vacuum line connected or not. (I'm not familiar with your engine so can't offer you specific info I'm afraid).

 

Next check for security of all vacuum lines and breather hoses - a leaky vacuum line can cause poor running too.

 

Have a go with tha for now, and write back if you're still having problems.

 

Cheers,

AF

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[Guest 105ps]

check your spark plugs