Renix Unit's

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mac
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Renix Unit's

Post by mac » 31 May 2006 12:56 pm

A subject to get yer teeth in !

The Renix (Bendix) electronic ignition system was used from the 1984 year model onwards replacing a conventional distributor (with contact points, mechanical advance etc.)

The Renix consists of an ECU and coil unit combined, a flywheel sensor, a toothed sensing ring built into the flywheel and a distributor which is a simple shaft turned by the camshaft with a rotor arm to distribute the spark to the dizzy cap contacts. The pic.below shows the main components.

Image

1 = Flywheel, 2 = flywheel sensor, 3 = distributor, 4 = ECU, 5 = engine vacuum sensor and 6 = coil.

The ECU has stored in an EPROM an optimum ignition setting for each combination of engine speed (from flywheel sensor) and engine load (from vacuum sensor) and will provide plug sparking as appropriate to driving conditions. This is known as mapped ignition. An example of an ignition map is shown below.
Image

The Renix unit looks like this,
Image

The 'works' of the ECU is sealed during manufacture and cannot be serviced, the EPROM cannot be re-programmed. ( over the years I have tried several times to find a way of disolving the sealant without harming the chips etc. - no luck so far).

The rear of the unit lloks like this,
Image

Under the resin it will look something like this (this shows a type D unit and Volvo 300's use type F but will be very similar),
Image

I will post this in stages - I don't want to crash and loose data part way through.

More soon.

Mac

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Post by mac » 31 May 2006 01:22 pm

Part 2.

The stored map differs from model to model and from year to year in some cases. The label on the ECU will give the code number that distinguishes the map. It is the 3 digit code in the second line of the label - not the larger 6 digit Renix part no.

Image

The code no's for various models Engine types) are listed here.

As far as servicing goes the distributor cap and rotor arm should be inspected and cleaned/replaced as with any car. In fact a very common cause of poor running/backfiring is failure of the rotor arm on B172K engines. Often replacing the rotor will transform the running of the car.

Another fairly common problem is a build up of corrosion on the coil connections. The coil can be removed (2x T20 torx machine screws) ans the blade contacts in the ECU and the pins on the coil can be carefully cleaned.

Image

note the unit may or may not have a suppression capacitor fitted.

Image

Image

Here endeth part 2.

Mac

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Renix part 3.

Post by mac » 31 May 2006 03:05 pm

Basic fault finding and testing.

Non starting can be caused by many problems but the Renix system is generally reliable (strange for French electrics). Obviously check the usual culprits - plugs, dizzy cap, rotor, fuel etc.

If you suspect the ignition a number of simple checks should give you a guilty or not guilty verdict.

1. Check that all HT leads are secure, and that the plugs in the top of the Renix are secure. etc. There will be 2 and possibly 3 plugs, A - a 3 pin plug on the top right. B - a 2 pin plug in the center and C - a 3 pin (but with 1,2,or 3 wires) on the top left.

Image

In plug A terminal 1 provides a speed signal for the Rev Counter, the Tachometric relay (in CVT cars) and for the over-run fuel shut off system if fitted (1986 0n).
Terminal 2 is to ground (earth)
Terminal 3 provides a 12v+ supply from the ignition switch (via the fuse box but not a fuse and the ignition relay).

Plug B has two wires and connects to the flywheel sensor (on the bellhousing).

Plug C normally is not fitted on UK cars but terminal 8 gives a signal to the gear change indicator (1985 only I think).

However - one tip - If you run an 84,85,or 86 year car with a Type 402 Renix and suffer pinking on unleaded fuel you can retard the ignition timing by 4 degrees by earthing terminal 7.

The first check is to ensure you have power to the ECU, Disconnect plug A
(and testing THE PLUG not the ECU) and with a test lamp or multimeter connect between terminal 3 and earth.
Ignition on and cranking the starter should give at least 9.5volts. (best to use a meter to measure this) Even with no faults you will not get 12v as the current draw by the starter motor will bring the voltage down.

If you do not have 12v - find out why.

Ensure that you have a good earth on terminal 2 of the plug (multimeter should give 0 ohms(no resistance) NOT infinity. (even auto electricians make that mistake).

To be continued).

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Renix testing continues

Post by mac » 31 May 2006 03:25 pm

Asuming that the power ans earths for the ECU are ok, the next thing is to check the flywheel sensor. Disconnect plug B from the ECU and using a multimeter measure the resistance across the plug terminal. Anything other than 220 ohms with a variance of 60 (160 - 280 ohns) condems the sensor.
(it is worth when removing the sensor (x2 bolts/nut) from the bellhousing, checking for magnetic debris on the end).

Remove the coil (2x T20 torx screws) and measure the resistance between the coil contact blades. There should be no resistance (0 ohms).

Image

Next refit plugs A and B and connect a test lamp of at least 4w across the coil blades.

Image

Cranking the engine should cause the test lamp to flash (indicating that the coil is being powered).

Turning our attention to the coil iself, firstly measure the coil primary windings resistance - should be 0,4 - 0,8 ohms.

Image

To be continued.

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last part

Post by mac » 31 May 2006 03:49 pm

Next measure the coil secondary windings. This measurement should be between 2500 and 5500 ohms.

Image


Any values outside the given ranges condems the coil.

A final check (asuming the engine now runs) is to ensure that the vacuum sensor on the ECU is working. Disconnect the vacuum pipe from the Renix and run the engine at about 2400 - 2600 rpm, re-fit the vac.pipe and enging revs should rise indicating that iignition advance is taking place. If you suspect a fault with the vac.sensor DO NOT attempt to remove it (yes I know there are 2 screws on the back of the Renix) it is connected to the ECU electronics by two fine wires with no slack and you won't be able to replace it ( at least I never have - and I've tried).

I think that about covers all you can do sevice wise - I if anyone thinks I've left anything out or got anything wrong please shout !!

Sorry I split this post into bit but we are suffering random power cut here in deepest rural Suffolk and I didn't want to loose it all about 2 seconds before posting.

All the best everyone, Mac.

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Post by pettaw » 31 May 2006 08:21 pm

Erm, I think you just about covered it Mac :P

Just one other quickie thing you can do, the rev counter is directly connected to the coil primary so if you get a non-start, you can tell if the Renix ECU is working/triggering the coil, if the needle flicks gently up and down as you crank the engine over. That means you can isolate the fault to the HT part of the circuit (including the coil itself) rather than the Renix ECU.

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Post by classicswede » 03 Jun 2006 11:20 am

Wow this is some good info.
Mac do you happen to know the different maps for the renix units?
I'm looking for a map that will give more advance on the 1.7 unit.
Dai

Please email me directly on dai@classicswede.co.uk

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phone/text 07824887160

Web shop http://www.classicswede.co.uk/

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Post by pettaw » 03 Jun 2006 12:01 pm

Dai, I've not got the full maps, but I've got numbers for the advance at 900 and 3000 RPMs, with the vacuum advance hose disconnected.

The early B172K unit will give 2 degrees more at 3000, is that enough. Otherwise the 1.4 units give 6 degrees more at 3000, but no change at idle, so what shape the curves are is anybody's guess ;)

The B200 units all are more advanced but probably have completely different curves.

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Post by mac » 03 Jun 2006 12:29 pm

Hello 'classic',

I don't have too much I'm afraid - what I do have I have typed up and I post below - hope it helps !

Image

I never have been able to get full maps but managed to get the 401/402/404 stuff from Renix direct, some years ago.

All the best Mac.

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Post by 340cbr » 03 Jun 2006 08:42 pm

Does anyone know what is the reference of the renix in a B18K Volvo 440?


I have a '90 B172K with the correct renix (415), and I have a spare one that I took of a 440 B18K, and today I see and it is a 402..

So.. will it be a B14 renix? Or the B18K in the 440 have this Renix?
| 92' 965 Turbo 16v | B204FT - 190hp |

Had: 90' 340 GL + Turbo | B18 FT | Koni's | Alpina White |

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Re: ignition components and servicing

Post by Chris_C » 27 Dec 2009 01:03 am

I was just looking for this "early Mac guide" and realised it wasn't stickied or rescued anywhere. I've taken the thread, pruned out all the dross (which probably means it now doesn't make sense as I'm nearly asleep!) and placed it here.

We never managed to answer 340cbr's question about 400 renix's and lots of Renaults had them too, so I've left that there. Answers on a postcard.
'89(F) 340 GL F7R (ex B172k) - Fake -> SBKV 300 Runner Up 08, 12 - NASLR Time 15.7secs
'03 S60 D5 SE, '91 (J) MX5
Ex:
'91(H) 340 GL B14.4E - Kar; '88(F) 360 GLT B200E - Jet -> BKV 300 Runner Up 09; '89(G) 360 GLT B200E - Beast

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