Engine: 2.5: Pinking

[Vic Clarke]

I have a pinking problem once the engine is warm. I have had a new cam belt fitted, timing has been checked. Engine light comes on for a couple of days, then goes off, no faults show on the comp. Any ideas any one.

[capt jack]

Pinking - pre-ignition - means a timing problem. In the days of of distributors and vacuum advances a bit of guestimation and a timing light would probably get you sorted. If only life were still that simple!

Depending on which engine and management system your car has, there will be a whole mass of sensors sending info to the ECU, which in turn computes the most appropriate advance setting, according to engine speed, load, coolant and air temperatures etc etc etc.

At a guess, one of your sensors ain't sensing, with the knock sensors or perhaps the camshaft sensor being prime candidates. If it's temperature related I guess it might be the coolant sensor. Is the temp gauge working OK?

Did this start after the cambelt was changed? How are you checking the timing? If so, whoever did the belt ought to be having a look.

Start by looking for loose and/or mssing connectors to the various sensors. Haynes will help to locate the various sensors. The local library will have a copy if you didn't want to shell out for your own. If you can't see anything obvious then it's possible one of the sensors is faulty.

The engine management light must be coming on for a reason, and when it is on there should be a readable fault code. What code reader are you using? Not all of them will work properly with your Volvo. The ones used by the RAC for example are as much use as a chocolate teapot.

Ignoring the problem is going to wreck your engine, so if you can't see an obvious fault then a trip to a main dealer to have the codes read is probably your only option.

Good luck

Jack

[Jod T5]

Originally Posted by Vic Clarke

I have a pinking problem once the engine is warm. I have had a new cam belt fitted, timing has been checked. Engine light comes on for a couple of days, then goes off, no faults show on the comp. Any ideas any one.

It is unlikely a EFI engine will suffer from pinking.....How have you checked your Lambda light codes...?...if you are suffering from some juddering under acceleration i would expect you to have a fuel trim issue, probably a air leak on the vaccum hoses or a over fueling due to a dodgy coolant temprature sensor..How does you temperature gauge behave?....
Cheers
Jod

[ShadeTek]

Originally Posted by Vic Clarke

I have had a new cam belt fitted, timing has been checked.

I would check the timing one last time.

[Vic Clarke]

Hi Thanks for your reply. Had the engine checked by the main dealer in Nottingham, no faults show. The light stays on for a while, then goes off. Once I took the oil filler cap off and the light went out. Could this point to a emission problem, i.e. pressure build up, could a sensor be reading this. Could I have blocked pipes do you think.

[Vic Clarke]

Hi, My temp. is good. After a run to Cornwall 2 weeks ago, no problems, Over a 1000 miles in the week. Back home a day later, drove about 4 miles, light came on, stayed on for a day, went off. Baffled.