Pinking

[Dave Meredith]

Had a quick search through the forum but no results for the last 2 years so I now bring this question to the fount of all knowledge :C

My 350i pinks when I put my foot down which spoils the fun a bit

It's done 97000 miles, burns no oil, leaves no oil on the garage floor,sounds great and will do well over 30mpg if I keep my slippers on. The timing is set to 4 degrees before TDC. I'm currently putting in Shell V-Power which from memory is 98 RON. My next move is to retard it further to zero degrees BTDC but I'm not expecting the pinking to go away.

I'm thinking of doing a de-coke because I'm wondering if a build up of deposits in the combustion chamber is giving rise to local hot spots. Has anyone else experienced this problem and am I likely to get rid of the pinking by cleaning the heads?

[pwd95]

Well worth taking it apart Dave. Give everything a good clean, surprising what builds up in there. My motor has only done about 30-40k & it was quite dirty. Theres a noticeable difference in response and power. I used the RPI composite gasket set. Go for it.

[rev-erend]

Dave

As has been said - the cure is a decoke.. it won't take that long..

I used acetone to remove the carbon on the heads and piston tops - as it's not abrasive.. need marigolds though.. and a few clean rags.

Don't know if others would recommend something else .. maybe petrol.

[Boosted LS1]

I'd have thought that a few good runs would dry up and blow out any deposits likely to cause pinking. What do your plugs look like with respect to deposits and colour and are they the right grade with good electrodes?

Boosted.

[tempus]

Give it a drop of octane booster and see what the response is and take it from there.Tempus

[GreenV8S]

I suggest you check the position of TDC mechanically, it may be that you're using an inaccurate reference for the timing. Also check the fuel pressure, consider flow testing the injectors, if you have access to a lambda sensor it would be good to check whether it's running lean under power.

[GV]

Before you start stripping the engine - I would do the basics first such as checking the timing, ensuring the distributor hasn't worked itself loose, an ecu test as they are the principal suspects.

The under bonnet temp if excessive will cause the engine to pink - if the timing's out that will also be a suspect. De-coking is the last resort but I wouldn't thought it to be necessary due to the use of unleaded etc.

RPi will be a great source of info and are always good to chat with about the RV8...

Hope you sus out the problem soon.

[Dave Meredith]

Thanks for the feedback chaps.

No 1 plug looks ok and in any case they were replaced (not by me) about 4000 miles ago. I will attempt to remove a few other plugs and check them out. Car does not run hot and the gauge reads between 60 and 80 deg C while on a run so I'm not expecting it to be running lean. Having said that the fuel consumption can be as high as 34mpg wearing aforementioned slippers

ECU, fuel injectors, fuel pump and regulator have all been replaced in the last 10,000 miles so while I'm not sure I can rule them out my gut instinct is that after 97000 miles it might be a build up of deposits in the head. I'll give RPI a ring and enquire about a price for a gasket set

Sorry to hear you are letting the wedge go Wynn. It sounded great on the occasions I was able to catch up with you on the way to BBWF2007 :

[TVRleigh_BBWR]

I think the main reason they stop pinking after a de-coke is they are 95% of the time fitted with compersit gaskets, which lower the compression ratio, as they will help stop the pinking.

but as said you should make sure your TDC is right buy using a pistion stop.

[Boosted LS1]

TVRleigh_BBWR said:

I think the main reason they stop pinking after a de-coke is they are 95% of the time fitted with compersit gaskets, which lower the compression ratio, as they will help stop the pinking.

I'd have thought that a thicker gasket was more likely to encourage pinking given the poorer squish effect. Unless the enines leaking oil down the guides a good drive should clear it out, imo. When I booted one of my cars hard I used to see brown soot behind me on occasions which was the carbon from the cylinders.

[350zwelgje]

My wedge did pink in the past, as was running a bit lean. Rising rate fuel pressure regulator fixed this (2.7 bar instead of standard 2.5). Economy is the same, except on a track.... Additional benefit is that the engine is more responsive and pulls stronger from 2000 rpm (compared to 3000-3500 rpm with stock regulator). Once put standard regulator back, and from time to time the engine would again pink!

Second reason it pinked, was when the fuel tanks were less than 1/4 full. It seemed under these circumstances the fuel pressure dropped. Now keeping more fuel in the tank, or do no full out accelaration runs until refuelled.

But would suspect the ignition as well, and would make certain that this was ok. Are the coil/leads still ok? And is the ECU and coolant temperature sensor ok? ECU difficult to check, but perhaps you can borrow a good one and check by swapping.

Rob

[GreenV8S]

Dave Meredith said:

ECU, fuel injectors, fuel pump and regulator have all been replaced in the last 10,000 miles

In that case I have to wonder why, and whether the resulting system is working correctly and delivering the right amount of fuel for that engine.

[honestjohntoo]

Dave Meredith said:

My 350i pinks when I put my foot down which spoils the fun a bit

It's done 97000 miles, burns no oil, leaves no oil on the garage floor,sounds great and will do well over 30mpg if I keep my slippers on. The timing is set to 4 degrees before TDC. I'm currently putting in Shell V-Power which from memory is 98 RON. My next move is to retard it further to zero degrees BTDC but I'm not expecting the pinking to go away.

With the combined effect of both unleaded fuel and lower octane since the Standard Rover SD1 Efi system was introduced to the world in 1982-6 and the normal BTDC setting was then typically 8 degrees we have now got a situation where the engine and system run much better, with no pinking, when the timing is retarded by at least 6 degrees. So the if basic ign system is now set to 2 or 0 degrees BTDC, the pinking will disappear as long as the rest of the system is set up correctly. Its dead easy to try.

[Dave Meredith]

Honestjohntoo

I've set the timing to 0 degrees and with Shell V Power fuel the pinking has disappeared. I know it will re-appear if I advance it back to 4 degrees so I will leave well alone. Glad I tried one last adjustment because
the next step was to get my spanners out

thanks to all who responded

[TVRleigh_BBWR]

If your using 0 degree's I'll get a pistion stop and double check your TDC on your pully wheel. as you may find it's out plus is a easy job.