| Author | Message | |||
     Bill Hart Experienced User Username: bill_hart Post Number: 23 Registered: 6-2015 |
Well, just when I was congratulating myself for fixing all the issues on my new {to me} Turbo R, up pops the "check engine" light.The Owner's Manual makes vague reference to the emission control system and recommends that I take the car to a dealer. Even if I wanted to do that, which I don't, the nearest dealer is 100 miles away. Is there a plug-in for an OBD reader? I can't find it if there is. Any suggestions, anybody? All help appreciated.} | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1694 Registered: 6-2009 |
Bill, What model year is your car and what is the SZ Chassis Number Derivation from VIN? If your car has the Zytek Engine Management System I can help you out. If it's an earlier example with Bosch there's not much I can do for you as far as OBD-II goes. Definitely have a read through the thread on this forum entitled, Mastercheck Port & OBD-II - What do we collectively know?, for lots of collective wisdom on this. Brian | |||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 562 Registered: 5-2015 |
Wiggle test the fuel injection loom on the engine. Including the exhaust oxygen sensor. A lot can be tested with a simple DIGITAL multimeter. Injection systems in general all makes have 5v sensing circuits. Often a sensor will have 3 wires. 5v negative and the signal or output. So at each plug there should be 5v and negative. Usually the outer 2. The signal voltage varys and is usually the middle one. So by checking between 1 outside terminal and the middle terminal ohms can be measured or volts by back probing. If the volts vary then the sensor is working. Usually sensors work fine or they don't. Back probing. This is done with the sensors connected. Use 2 sharp needles through the wire plastic covering. The oxygen sensor has 3 wires or 4 wires. The 3 wire version is earthed through the body. The 4 wire version has a separate earth and hence the extra wire. The supply voltage is battery voltage which is the heater element. The other 2 wires are variable voltage produced from comparing the atmosphere oxygen with the exhaust oxygen. The voltage is between 1v and zero. When the voltage is SAY 0.5 volt the muxture is correct and when SAY 0.2 volts the mixture is weak and when SAY the volts are 0.8 volts the mixture is rich. An added complication is some systems are back to front and more volts means weak mixture. The oxygen sensor is only obeyed when at a constant throttle and the throttle is being moved not a lot. The oxygen sensor has authority. When hooning around the oxygen sensor is ignored and the fueling map is used. The map has authority and the oxygen sensor has no authority. Quite a few cars I have fixed turned out to be dodgy injection looms and or plugs. Sensors are sealed and generally reliable. If the engine runs as it should and has a rock solid idle.Then the sensors are ok. But if the oxygen sensor in the exhaust pipe is faulty the ECU defaults to fuelling map and lights the check light. The engine runs fine. The above is very very general and I suggest reading up about the finer points of this particular system. Not necessarily a Bentley book just a book on this particular system. OB2 readers are available about 100 quid Gunson do one. Never not never no how on pain of blowing the ECU ever use test bulbs or analogue multimeters. The low impedance or resistance will overload something. Never drive injectors independently of the ECU the injector coils will overheat and be damaged. Also most injectors have 2 wires earth which is common to all the injectors and live. The ECU switches the live side. Often injectors are fired in batches. Say 4 pairs for a V8 and 2 pairs for a 4 pot engine. It actually doesn't matter which injectors are paired. Usually the next door one for wiring convenience. Some injection systems such as my Jeep fire each injector the same as the spark plugs. This is fully sequential. Absolutely no advantage in sequential injection for reasons I won't explain here unless somone wants to know. Especially turbo charged cars. | |||
| Bill Hart Experienced User Username: bill_hart Post Number: 24 Registered: 6-2015 |
Thanks for the response,Brian. I used to be fairly mechanically self sufficient back in the days when cars had carburetors, but all the new electronics are way beyond my skill level. My Turbo R was manufactured in October 1994. VIN: SCX55371 | |||
| Bill Hart Experienced User Username: bill_hart Post Number: 25 Registered: 6-2015 |
Just got your response, Bob. Good stuff. As I noted, I'm not good at electronics, but I know some mechanics who are. With your info I can probably keep them honest. Thank you. | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1695 Registered: 6-2009 |
Bill, I am presuming yours is likely a 1995 model year car, but what I'm attaching applies to 1994 or 1995. Your car would have a derived chassis number of either RBR-55371 if it's a 1994 model year or RBS-55371 if it's a 1995. The 10th character of your full VIN will give you the answer as to which model year this car belongs to, but given that it was made late in the year I'd suspect the following year's model year. I am attaching what I was able to determine regarding the 1994-1995 MasterCheck port as far as mapping pins to standard OBD-II pins. I believe those cars still had the Bosch engine management system and I do not know of anyone who's attempted to attach a scavenged OBD-II port to try to interrogate the EMS. Were you to try this you'd be in the avant garde and could be the one to definitively answer whether it can be interrogated via the OBD-II standard code readers. Brian
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| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 569 Registered: 5-2015 |
Bill Hart, I am also not very good with electronics but have gleened enough knowledge by reading stuff. I am all right until the maths. I usually end up with the decimal point in the wrong place and cooked transistors. | |||
| Bill Hart Experienced User Username: bill_hart Post Number: 34 Registered: 6-2015 |
As previously noted, my car is SCX 55371, manufactured in 10/94. Can someone please tell me whether it has the Motronic or Zytec Engine Management System? I'm hoping for Motronic because I have located the method for reading the "blinks" on that system. | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1704 Registered: 6-2009 |
Bill, Your full VIN is SCBZR03C6SCX55371, which means your derived "chassis" number is RBS-55371. The "CX" part of the last 8 characters tells nothing useful and the S is actually the 10th character of the VIN, which tells you the model year. The 5th character R, gives you the model, Turbo R, and the 3rd character B, tells you it's a Bentley. You have a 1995 Turbo R with Bosch engine management. Zytek came in for the 1996 model year at chassis 57001. Brian | |||
| Bill Hart Experienced User Username: bill_hart Post Number: 35 Registered: 6-2015 |
Thanks Brian. I'm relieved to hear "Bosch", which I assume means Motronic. I hear bad things about Zytec. After having owned several of these cars over the years, it's surprising how much I don't know about them. | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1705 Registered: 6-2009 |
Bill, You need to take a look at this page on the RROC-Australia Post-War Technical Library. I believe the cars from 1989 through 1995 all used the Bosch KE3-Jetronic with K-Motronic Control system, but since I haven't owned one I can't be absolutely certain. I'm sure someone will chime in regarding exactly which Bosch system is used on your car if that one wasn't carried through to "the end of that era." Brian | |||
| Lluís Gimeno-Fabra Grand Master Username: lluís Post Number: 404 Registered: 8-2007 |
Hello all, It would be a Motronic 3.3 as in BMW V8 of the period... I am silent but I still exists. Car doing great and me too. A bit busy. | |||
| Brian Vogel Grand Master Username: guyslp Post Number: 1708 Registered: 6-2009 |
Anyone want to help me create a table of fuel injection/engine management for the SZ cars by model and year? If it's already documented somewhere I have yet to see it. Lluís, thanks for that detail and glad to hear you're still alive, happy, and busy with life. Brian | |||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 614 Registered: 5-2015 |
Google Bosch injection. I read some stuff that gave what cars were fitted with what system starting in 1978 with the constant injection system which was the first injection system RR/B used. That system is really hydraulic/mechanical and has no electronics. One step up from carbs it was not a bad system and quite reliable. Fuel pump and relay are known failure points. The relay didn't like the ignition being left on without engine running and the pump didn't like low fuel level due to lubrication and cooling. As Jetronic developed the years that they were introduced on all makes of cars should roughly line up with the years of RR/B cars. Hunt house will know because they have the build sheets. |
1994-1995 MasterCheck to OBD-II pin mapping