Check Engine Light but no faults in Freescan

[fjmuurling]

Looks like oil temp sensor

 

There is a nice picture on the forum of an engine with all the sensors nicely marked. Found it but don't know how to put a link in the post. Maybe an IE thing??

 

[Qavion]

I think you're right. In the wiring diagrams it's shown as having a yellow/black wire. I earlier assumed it wasn't related to instrumentation as Bill didn't say he was having oil temperature problems.

Thanks!

Cheers

Ian

Edited August 17, 2015 by Qavion

[Qavion]

P.S. For info, the knock sensor is a little further forward (10cm?) and, of course, on the side of the engine (cylinder block).

[Qavion]

Well, folks, my orginal problem is back again. After warming up the car (up to closed loop mode), monitoring with Freescan, I took my car for a run. 5 minutes later, Freescan stopped communicating and the CEL light came back on. At this point, the engne starts stumbling. If I keep the car in a lower gear, with higher revs, it gets me back home without too many problems.The fans also come on, suggesting ECU failure. No faults are logged in Freescan. I've tried two different serial adaptors, so I assume it's not the adaptors which are blowing up the ECU.

 

I've changed the ECU and the alternator regulator since I originally started having this problem. Unrelated, but I've also changed the IAC and adjusted the TPS.

 

I'll order a new ECU, but the problem seems to  be too close to the original problem to be pure coincidence. Is there anything which would cause the ECU to fail like this? Could it possibly be the Memcal (ouch)? Even if I could afford one, I'm not sure where I could get one.

 

Thanks for any suggestions.

 

Cheers

Ian.

Edited August 21, 2015 by Qavion

[Qavion]

Does anyone know if a faulty fuel injector can damage an ECU (and cause nocomms on Freescan)?

I'm wondering if an earlier problem with my fuel pump fuse melting has triggered my current CEL problems.

Background: My car failed to start a few months ago, and I noticed that the fuel pump wasn't running. The fuse and fuse holder had melted. It looked like the fuse circuit had had a sustained high current flowing through it. I assumed a faulty pump had caused the problem and changed that (and the fuse/holder). Looking at the diagram, however, there are quite a few things attached to the fuel pump fuse:

Fuel pump relay, secondary injectors and secondary injector resistor, primary injectors. Could a fault with any of these cause the ECU to stop operating normally, but not generate a Freescan logged fault for these devices?

 

Thanks

Cheers

Ian.

 

 

[Barrykearley]

There has been more than one thread on here with guys having to replace an ecu more than once. You must disconnect the battery and leave for 30 minutes before changing. Esd precautions should also be taken. That said - I know lots of folks have done so ignoring all of this and have been fine. I know loads of folks who have never caught the clap as well....... Logic is the same!!

Seems very strange to me. Unless you have a doom and gloom issue and gremlins......the ecu provides power to sensors, they feedback voltage to the ecu, it changes stuff, does stuff and remeasures. I'm not sure there could be anyway of frying one unless there was a loom issue. I'm happy to stand corrected.....

The fuse issue I think is a little red herring that you lotus is using to throw you off course. Please bear in mind how old it now is. The contacts will be all oxidised and horrible, resistance of connections go up - pump carries on drawing lots of current - the joint gets warm and melts. Pull all the fuses and get some electrical contact cleaner into there. Then promise yourself to do the same next year!!!

[Escape]

The fuel pump has a separate ground, so high current through the pump can't affect the ECU.

The injectors are ground via the ECU, so if one of those has a short circuit, a lot of current will flow through the ECU as well. Until the fuse blows that is. If the fuse and holder have melted, there has been a highish current going through it for some time, rather than a very high current for a very short time, as this would only blow the fuse and not develop enough heat to affect the plastic holder.

 

As it happens, I had the same thing happen to me and strand me on the hard shoulder last Thursday... Suddenly lost power on the highway, managed to pull over (from the fast lane of course) and found the fuel pump wasn't running. So I checked the inertia switch and then fuses. The injector and fuel pump fuse was not blown, but had melted halfway through the fuse holder. So like you describe. I replaced the fuse, after some trouble getting the molten remnants of the old one out, taped it up and continued my drive. I checked the fuse this morning and found nothing out of the ordinary so will consider it a freak occurrence and keep driving the car... But reading your thread does have me worried...

 

Filip

[Barrykearley]

Forgive my ignorance.

But doesn't the ecu power the injectors??? If so I would have thought even if the injector went shortcircuit it wouldn't damage the ecu

[Qavion]

But doesn't the ecu power the injectors???

 

 

Looking at some of the diagrams in the manuals, the ECU is only providing switches for the current flow through the injectors. The positive terminal of the battery provides power to the fuel pump fuse, then the fuel pump relay, then the injectors, then to ECU internal "switches". The current flow continues through the ECU and back via the ECU plugs to an earth on the engine block.

 

In theory, the larger currents should be isolated from the ECU control circuits, but... who knows.

 

The fuel pump has a separate ground, so high current through the pump can't affect the ECU.

 

 

True, but the injector power does go through the ECU. Unfortunately, I just assumed the pump blew the fuse and changed it without checking the current flow through the various branches of the circuit (before the change).

 

Anyway, I might do more resistance checks before I install a new ECU. I'll also make sure the contacts on the Memcal and chip are ok. And I'll take Barry's advice on observing ESD precautions, although it seems like closing the door after the horse has bolted... Rockauto supply the ECU in non-ESD-safe bubble wrap !

 

It's frustrating when the ECU was behaving itself during the warm up, during the switchover to closed loop and for the first few minutes of the drive, then it decides to fail (like the old one did).

 

Thanks for the feedback

 

Cheers

Ian.

[fflyingdog]

On my S4s last year i had all sorts of problems car turned over wouldn't start ,loss of power for absolutely no reason (or as i thought at the time) until it was becoming a right royal pain.I troubleshot ALL my problems down to the relay tray on the r/h side behind r/h rear wheel,every single spade grip was loose causing the relays to become very intermittent. I ended up removing tray and tightening every one of the what is essentially a spade grip held in the tray via a tang ,one or two grips (as it happened the fuel relay was one of them) had obviously been chattering for some time and had been arching causing some plastic on the tray to become distorted.

 

Nick S4s

[Qavion]

Thanks, Nick. The fuel relay might be one relay which needs attention. It's probably had some high current flowing through it. I should have changed it anyway.

 

I was thinking about changing the ECU/ECM fuse, but would the CEL even illuminate if the ECM had no power (I guess it depends on the electronic switching in the ECM).

 

The wiring diagram for the fuel pump relay makes no sense at all. According to the diagram, if the fuel pump relay was energised, the pump and the secondary injectors would stop working. I've modified the diagram to how I think it should work (although the output may be on one contact, not two).

 

Edited August 23, 2015 by Qavion

[Qavion]

P.S. I've edited the diagram above to show the Fuel Pump Relay to have a single normally open output. I don't know where I got the dodgy initial diagram from. Hit your browser refresh button to see the latest version.

 

The relay has Lotus P/N C079M6141F which is a 5 pin, 30 amp (continuous) relay, but I'm sure an off-the-shelf Bosch relay will do (e.g. 0 332 019 150).

Edited August 23, 2015 by Qavion

[Escape]

P.S. I've edited the diagram above to show the Fuel Pump Relay to have a single normally open output. I don't know where I got the dodgy initial diagram from. Hit your browser refresh button to see the latest version.

 

The relay has Lotus P/N C079M6141F which is a 5 pin, 30 amp (continuous) relay, but I'm sure an off-the-shelf Bosch relay will do (e.g. 0 332 019 150).

 

For some reason, Lotus used 5-pin change-over relays when a normal 4-pin would do. The diagram you posted is the one I have in the S4/S4s manual. It is essentially the same as for the earlier cars, only drawn a bit differently and with more detail inside the relay. When not powered, the relay will connect the input (30) to output 87a. When powered, input to output 87. The physical layout of the relay (from top to bottom: 30, 87a and 87) does not correspond to the layout in the drawing. This makes it a bit confusing, but the drawing is correct.

So yes, a normal 4-pin relay will suffice, as the middle pin is not connected anyway.

 

Filip

 

PS: I can't see a difference between the 2 diagrams you posted, even after a refresh? I can't remember seeing something wrong with the relay when I first looked at the first diagram yesterday, but probably wasn't looking closely at the relay terminals anyway.

[Qavion]

I can't see a difference between the 2 diagrams you posted, even after a refresh?

 

 

The earliest versionof the diagram I posted had wires connected to both 87 and 87a. Now there is only one output at 87 (which now matches the manuals... apart from my added electric chargecooler pump)

[Escape]

The earliest versionof the diagram I posted had wires connected to both 87 and 87a. Now there is only one output at 87 (which now matches the manuals... apart from my added electric chargecooler pump)

 

I did miss that. I was looking for a difference between the first and second diagram.

[bogle]

I was able to shut off the Error 41 code (disabled it) thanks to help from WC Engineering.  Additionally, my ECM had an older code and now it's updated with an S4/S4s chipset.  However, the code 41 was replaced by code 65.  So I replaced the battery with a Optima brand yellow top.  Unfortunately, now it appears I need a new alternator.

 

My car was jumped at the auction I purchased it from twice or maybe 3x last year (one of those portable kits and not a vehicle).  I have a feeling my alternator might have been damaged at that time.  Right now the symptoms are driving 5 minutes or when cruising at above 50 mph for at least 1 to 2 minutes, then the CEL comes on.  After parking and shutting off the engine for a couple minutes, the CEL goes off.  The CEL continues to come on after 5 minutes of driving.

 

Just thought I would update you.

[Escape]

Unfortunately, now it appears I need a new alternator.

 

Easy to check: measure batteryvoltage with engine off (12-12.5V) and then with engine running (>13V). Using a jumper kit should not damage the alternator.

[fjmuurling]

Hi Bill

 

Did JW also change the VE tables in the new code. ? The S4(s) and the SE have different VE tables.

[Qavion]

If your alternator is causing the CEL, then you would simply change the alternator regulator (and brushes if required). You certainly wouldn't change the alternator as a first step.

 

This is what happens to some Lotus Esprit regulators in time.... That treacle/mud in the regulator should be solid shiny black potting compound.

 

 

The brushes can be accessed by removing two screws from the green assembly (although you may need to remove the red assembly above it to get it back in).

Replacing the brushes is tricky. It has tiny springs pushing the brushes onto the alternator slip-rings. When you unsolder the brushes, the springs could go flying off into space. Any auto electrician will be able to do it in a jiffy. You usually only need to replace the brushes if they have worn to the point where they don't touch the slip-rings properly.

 

Unfortunately, it's necessary to remove the inlet plenum to get to the regulator.

 

Cheers

Ian.

Edited August 25, 2015 by Qavion

[Qavion]

Looking at some of the diagrams in the manuals, the ECU is only providing switches for the current flow through the injectors.

 

 

re my problem, I see the current flow through the injectors is monitored by the ECM (in case of faults). The ECU will generate the CEL light if faults are detected. Curiously, however, only the primary injector circuits are monitored.

 

I guess if the secondary injectors are faulty or the ballast resistor is faulty, you could have engine problems at high rpms, but no CEL.

 

However, the code 41 was replaced by code 65.  So I replaced the battery with a Optima brand yellow top.

 

 

 

Isn't this code related to the primary injectors? According to the manual, the code will only appear if the battery voltage is above 9 volts. Not below 9 volts.

 

I'm sure your alternator is fine, but it's easy to check with a voltmeter.

[bogle]

My turbo isn't functioning and needs rebuilding - don't know if that would throw a code or not at the moment?  It's now throwing the code faster within one mile of the house.  There's no way I'm going to get through emissions until I clear this code.

 

Yes, the error 65 code points to the secondary injectors on my Free scan error.  I'll get the exact error later today. It starts with TIPS

 

Yes, the S4s code updated the VE tables to answer a question previously asked.

[bogle]

The code 65 exact phrasing is as follows:

 

65 - Fuel injector Circuit, low current

65 - TIP Check battery volts, is the alternator OK?

 

My prior battery was moving between 12.6 and 12.9 volts, but then moved to 12.9 to 13.1 volts after being at idle according to Free Scan.  Now my CEL is coming on within 30 to 45 seconds after starting up.

 

I'm noticing 1st gear has some hesitation and 2nd has little bit as well.  The higher RPMs are okay. 

[bogle]

I was incorrect to point out the Secondary injectors.  My Freescan logs indicate that the waste gate and secondary are zero values.

I inadvertently stated this due to my previous Freescan logs.  After reviewing the error codes listed above it's clear that it points to the primary injectors and I'm not sure what code if any would trigger a for the secondary injectors.

[Qavion]

65 - Fuel injector Circuit, low current

65 - TIP Check battery volts, is the alternator OK?

It seems that this is another case of Freescan disagreeing with the manual.

The manual seems to be saying that the injector current is low, but not because of low voltage supplied to the car as a whole (the ECU knows what the battery/alternator voltage is). The 9 volts is simply used as a message logic filter. The ECU is probably getting the voltage from a separate source as a reference value (not measuring the voltage across the injector circuit). Anyway, it wouldn't hurt to do another alternator check. Perhaps a direct reading off the battery would be more accurate (at various rpms and loads ... E.g. with headlights on).

Anyway, going back to basics, low current (through the injector circuit) can be caused by high resistances or low voltages (to this specific circuit). Can you see the diagram I posted on this page with the circuit for the primary injectors? Have you recently measured the resistances of the injectors? Cleaned the injector electrical plugs? Checked the fuel pump fuse holder? Have you changed the fuel pump relay? I'm about to do that on my car. I believe I had a fuel pump problem which melted the fuse and holder and which would cause sustained high current to flow through that relay (It's also the relay which provides power to the injectors). If the relay is offering a high resistance in your case, it may be the cause of "low current". Also, if the pump is not getting enough power, it may cause hesitation.

Of course, as you know, it gets expensive changing components on "theory". Perhaps you can find someone who can let you borrow a relay?

Hope this helps.

Cheers

Ian

Edited August 25, 2015 by Qavion

[Qavion]

My Freescan logs indicate that the waste gate and secondary are zero values.

 

 

Is this at all times? According to the manual, zero % shows when the car is at idle for both of these.

 

re my problem, I see the current flow through the injectors is monitored by the ECM (in case of faults). The ECU will generate the CEL light if faults are detected. Curiously, however, only the primary injector circuits are monitored.

 

 

I may have misunderstood what was written in the manual. The current flow is monitored in the primary injector driver circuits in the ECM for control. Current is not monitored in the secondary injector circuits for control. However, the ECU does monitor both primary and secondary injector circuits for fault purposes.

 

Secondary injector circuit faults will cause a "Category B" message (whatever that is).