C stekker Renix

@AvdAkker, the info from the Renault 5 GTT that timing is advanced when knock is heard is curious?

@setsunakaede, knock, pinking, pinging detonation are all different phenomena and get lost in translation (even between English and American-English).

Overall though the octane phenomena is the mixture burning too fast once lit.

The higher the octane rate, the higher the resistance of the fuel to temperature and pressure before it self ignites. So, if knocking occurs you need to retard ignition (spark is later, piston closer to top of travel)

For a higher octane fuel, it can handle being a more compressed even as the flame begins.

@antiekeradio Very interesting information.

Going to need to look up some info in the UK B14 volvo green book before I come back to you?.

Here's the info from Mac for UK cars

1984 (begins with A reg.not B reg), 402 unit, mapped for 98 octane - suitable for unleaded but likely to pink on 95 octane. can be retarded 4deg. by earthing 'C' pin 7. (socket 'C' sealed from factory).

I have never seen a 300 series Renix without the 'C' socket - doesn't mean it doesn't exist though.

1985, 402 unit, socket 'C' pin 8 triggers gear change light on dash., mapped for 98 octane, can be retarded 4 deg.by earthing 'C; pin 7. Volvo brings out wiring kit to convert, and begins to fit kit in production.

1986, 402 unit, same map, socket 'C' pin 7 earthed at factory. Gear change light discontinued.

1987 on, 412 unit, pin 7 earthed at factory for car to run on 95 octane unleaded. I do not know how different the actual map is from a 402 but pin 7 still gives retard 4deg.

Catalyser cars I believe also have a further 2deg. retard by earthing pin 6 as well.

Earthing pin 7 was Volvo conversion for LOWER OCTANE fuel - whether leaded or unleaded.

Shimon-

[edit]the UK only got the B14 4E, no 4S here.

Hi Wouter

Re your comment

"the B14.4 cars sold in NL market with 402 Renix and no wires connected to the C-plug had a compression ratio of 9.25 to 1.

these required RON 96 , not RON98"

Is that the B14 4S or 4E?

In the UK, the 402 has a map for 98 octane and by earthing pin 7, a map for 95 octane.

Different 402 for UK and Holland (and other markets?)

If you can earth the c plug to adavnce the timing then that would be very usfull with cars running LPG to make use of the octane.

Ignore my last post as I'd not read page two.

I can't find any referance to 96 ron petrol only 95. Wouter could it be the 86 MON equivelant that you were thinking of?

nope, its all RON i'm talking about.

It could be that, before lead free "euro 95" was introduced in the mid-eighties the premium/super/extra fuel that was replaced by lead free "euro 98" had a minimum spec of RON96, or different manufacturers had different grades of leaded fuel.

I never saw it happening because the first times I can remember my parents going to a fueling station and picking fuel type, was already in the ninetees when there was only one type of leaded fuel left.

First time I read the 96 RON I was also surprised, but seen it in lots of different places. (instruction manuals, "Volvo Service Data" booklet, etc)

one important technical bulletin is the one where Volvo specified which engines could run on lead free and with what adaptations.

hi there,

the intrigue continues.

I've also found some references to RON 96 in the technical specifications in the owners manual from 1988. Ill try to scan than and upload.

Also, in what appears to be one of the latest editions of the service manual green book for engine, various engine types, compression ratios, minimum octane etc are listed. There are also ignition timing and octane rating listed.

Curiously, octane is listed as 86 (seems that's MON rather than RON) and all engines from the B14 1E are 9.25:1. True, a low compression 8.9:1 type also listed. B14 4E are 9.25:1. Also one Ive not heard of call a B14 4ED. Ignition timing is listed as different for manual cars and CVTs. CVTs seem to run more advanced maps - due to lower load than manuals?

RON 96 could be the lowest octane rating for the engine with original Renix settings i.e. a more advanced map (so far referred to as the '98 octane map') could in fact be good down to 96 octane (just!).

By earthing pin 7 as per Mac's article, we get a 3 or 4 degree (volvo green books suggest 3 degree) retardation which makes a map suitable for 95 octane.

Given the CVTs have a more advanced map (curiously!), then if volvodspec / AvdAkker's B14 running a 402 with no plug C or pin 7 earthing, then that does seem to make sense given the info in the volvo green books.

So, it seems the CVTs can run the more advanced map hence run a 402 (or 412) with no C plug earthing. For a manual car, you need to earth pin 7 to get a more retarded map.

But.....why do CVTs run more advanced maps on 95 octane (pos also on 98 octane, need to check).

I'll try to upload some pics of data.

It seems that we are approaching the point where everybody knows they know nothing.. which is a good starting point for gaining new knowledge

offtopic: @ foreigners, do you think this forum needs an english section?
just curious.

antiekeradio;118007 schreef : It seems that we are approaching the point where everybody knows they know nothing..

too bad the actual ignition curves are practically impossible to get hold of, we have the drawing numbers but that's about it..