Carina Hunting Problem

[jhonf]

My wife has a 1996 Carina with the 1.6 litre engine. It has done about 70000 miles and is serviced regularly. It was last serviced about two months ago and was running well. However it developed a leaking water pump which my garage replaced. They are a local service station with a good reputation and I have used them for many years.

When they drove the car after replacing the pump, they found that the engine was hunting badly. When warm, exhaust readings showed that the mixture was extremely rich. On road test, the engine pinked noticeably and lacked power going uphill.

No engine error codes were detected either by the garage or by a specialist using more sophisticated equipment.

They have tried replacing the temperature sensor but this had no effect.

Any ideas would be gratefully received.

Thank you.

[gazza1286]

Replacing the water pump of itself should have no effect upon fuel mixture. Did they replace (or tamper with) the timing belt at the same time? The belt may have been installed one notch out of alinement.

The lambda sensor generally causes issues with running. If the problems occurred simultaniously the garage may have spilled coolant onto the sensor when filling (or topping up) the radiator. But if there are no engine faults registering this doesn't seem all that likely.

The 'pinking' effect may be a red herring. The same sound is produced when the alternator drive belt is tensioned incorrectly. The drive belt would have been removed to replace the water pump. This is a common issue. This sound usually occurs from cold but soon stops.

Let us know how you get on.

[jhonf]

Many thanks for your thoughts which I have passed on to the garage. Will let you know how it turns out after Christmas.

[jhonf]

Sadly no joybut thanks, Gazza, for your help.

The garage have tried everything they feel they can reasonably do, including further diagnostic sessions with their electrics specialist. They have tried changing components with the owner's own Carina but to no avail. They suspect the injectors but don't want to go down the path of buying those in just to try it.

They have suggested going to a Toyota dealer in the hope that they may have superior diagnostic kit that will find the problem.

I have driven the car again and the pinking does seem to have gone. It's behaviour can be summarised as:

From exhaust analysis, it is running very rich.

When started from cold, the engine hunts on tickover and this becomes much worse as it warms up. The engine may stall but can be restarted immediately.

Running at constant speed around 30mph is awful with the engine speed varying wildly. However, going up a long 1 in 10 hill at 30, it pulled well with no problems although it did sound a bit noiser than normal.

Some people elsewhere have written about Carina injector problems and trying cleaners have been suggested.

If you or anyone else has some further advice I will be very grateful.

Thanks