ROUGH RUNNING

[D813YBB]

When starting the car from cold on fast idle, the engine is running very rough – i.e chugging with some puffs of bluish coloured smoke emitting from the exhaust. This is accompanied by excessive vibration from the engine. The car pulls as it should and once upto temperature seems to drive as normal without further vibration. I can hear the auto choke probe operating correctly before start up. The engine fires up straight away with the roughness starting within about 20 seconds. Viton O rings were put in about 2 years ago. Smoke stops on reaching normal running temperature as far as I can see from the rear view mirror.

Oil has been in for about 5000 miles, spark plugs were renewed about 2 month ago.

[Guest]

I have the same problem

Hi

I have exactly the same problem... I have a 1988 Maestro Mayfair which gurgles on first start of a morning - basically sounds like the engine is about to cut out but never does. Once up to temperature it works absolutely fine.

It did have a stupidly fast idle for a good 15 minutes (2k+ revs) which after quite a few people looked at it couldn't get it down at all. Since it's come back after being thrashed by the thieves (this is the one that was stolen 2 weeks ago) it seems to have stopped the really fast idle and will sit quite happily at 800-1100 revs once at temperature which generally doesn't take that long.

But as I say - the first few minutes are a bit harey as I keep expecting it to cut out!

Sorry that wasn't a solution, but just to let you know you're not alone in this!

Carol

[G Force]

Hi have you repaired the split vacuum pipe yet? as that could be causing the main of the problem.

I would check the vacuum switch diaphragm is ok, by removing the vac switch and try to suck air through the single vacuum connection, if you can suck air through it then it is faulty and needs renewing.

The smoke could be just general engine wear or the engine running rich, but if the vacuum switch is faulty it can actualy dilute the engine oil over time, so I would recomend another oil change once the vacuum switch has been renewed.

Gary

[G51 NAV]

This is exactly the same problem I reported on A658 OWL: basically the car seems to overfuel on choke, giving rise to the "chugging" you describe and virtually unburnt petrol dripping out of the exhaust. Gary gave me the same (excellent) pointers but none have worked for me. Hopefully they will work for you.

There doesn't seem to be any easy way to reduce purely the choke enrichment on these SU carbs I know you can reduce the overall mixture: I can make A658 run brilliantly on choke by turning the mixture-screw anti-clockwise by two full turns, but then when the car warms up it is so obviously underfuelling and hunts terribly. It's no wonder people give up and fit aftermarket manual choke conversions. Like your car, my car's autochoke unit is working perfectly fine, it's just throwing too much petrol in.

[E_T_V]

When fitting the viton O rings did you move the brass cylinders in relation to each other? If so then that alters the amount of choke enrichment that the stepper motor provides I believe.

[D813YBB]

I haven't fixed the split vacuum elbow connector yet, however I've just bought a new one from Rimmer Bros for £3.75. I'll put this on when it arrives and see if there's any difference.

This problem only occurred at the weekend so I'm not sure it could be a problem with the o rings which have been on almost 2 years. The rings were a straight swop for the old ones. No other adjustments were made while the stepper motor was out of its housing.

Rimmer Bros also have the vacuum switch on the shelf, but I'll wait for the results of the new connector first.

[Guest]

I get exactly the same problem when the vaccum line comes off mine, But it happens so often I can just stop and deal with it now. This morning one of the connectors finally snapped off, so I stuck it back together with electrical tape, and it seems to have come right now.

[Guest]

It's finally given up

Well, this morning I get to the end of our road and my Mayfair gave up. I mentioned in the forum about it being a bit harey on cold starts until it gets up to temperature...well it started first thing - pulled it out of the drive, it drove fine until I got to the junction at the end of our road and I watched the revs drop down from 500 to 0. It just chugged out almost as if it had run out of petrol. I then tried to restart it which it managed to catch once or twice but just didn't seem to have enough revs to get going. It ended up in a quick tow home.

It was running a bit rough on first start (chugging, strong emissions out the back ) but I'm just wondering what has happened.

I'm going to try turning the screw tonight to try and bring the revs up and see if I can get it steady, but it's just there's quite a few problems when running. Like I mentioned in the other post about occasionally there being a strong petrol smell inside, the temperature only getting to normal when stuck in traffic (generally only gets up to a quarter) and the electronic choke being more than a little tempramental!

The rubber T piece vacuum pipe split last year - it's currently taped - could it have anything to do with this? or could it be a combination of a few parts that may need replacing to get the car running correctly?
Is there maybe a list or something I could run through to make sure all the bits are in clean and working order? I really don't mind spending the time and money replacing whatever needs doing to get her running again - I love my car!

Thanks for any help!!

[G Force]

D813YBB Hope that the vacuum elbow has arrived and not been held up in the postal dispute. Has it cured the problem?

L824SMA It is very important that you dont have any leaks in the vacuum pipes or breather hoses, so make sure you fix properly any problems of this nature first.

Check the vacuum switch diaphragm is ok, by removing the vac switch and try to suck air through the single vacuum connection, if you can suck air through it then it is faulty and needs renewing.

Check the ORFCO valve is not sticking open. If you look in the FAQ section under tuning the S series there are instructions how to do this. You could also try working through the checks and tuning procedure,in this section to fix your problem.

The temp gauge showing a quarter could be caused by the thermostat sticking open (especially if the heater performance is poor), or a poor connection, open circiut, in the coolant temperature sensor wiring, or a fault with the sensor.

Cheers Gary

[Guest]

Pipes and thermostat

Thanks Gary! I'm going to try it all out tonight. Thank you for all your help and advice - you really know your stuff!

[D813YBB]

Hi Gary

I think the elbow connector is lying at the bottom of a big pile of unsorted mail some where. The car's still chugging merrily along, patiently waiting for it to arrive.

Martin

[D813YBB]

Good news

The elbow connector from Rimmer Bros eventually arrived and fixed the cold start problems. Its been on over a week now without any re-occurrence.

Thanks due again to G Force, I now have a reliable Maestro again.

[G Force]

Hi glad you got it sorted, hopefully things will be ok for a while now, fingers crossed.:laugh: