Hi all

Have done a search through the forum for this idling problem with EF and EL falcons. Has anyone covered the problem with the dead capacitors in the ECU unit? If its been covered I won’t bother posting the fix but if not everyone let me know and I will post more info.

I found two electrolytic capacitors faulty in the ECU and it made my EF Fairmont run heaps better down low – cheap and easy fix if its your problem.

I will post in this in the ECU section too…

Scooter

Post it up. I don't think it has been covered before.

id be interested to know as im having idling issues, post it.

Hi all

If you remove the ECU unit from the vehicle, remove the covers and you should be looking at the pic I have shown below. Note C7 is on the right and C2 is on the left. C7 is a 47uF (pronounced 47 micro farads) 10Volt Electrolytic capacitor and C2 is a 3.3uF 63V Electrolytic capacitor. To check them you really need an ESR meter, which checks the capacitors AC resistance under load. A normal multimeter may have a capacitor check function but it only checks the DC capacity and most of the time they will check OK under this test. What I just told you is irrelevant anyway because they are cheap as chips so I recommend you just chuck ‘em and replace them. C2 in my ECU was a bit leaky while C7 had a leg rotted right off it!

When replacing (you should be able to get them from D. Smith, Jaycar or other electronic retailers) C7, get a higher voltage value unit than 10V. Use 35Volt or 63Volt units – it won’t affect the performance. The temperature rating is printed on the side of the capacitor too, try and get 105 degree jobs. Oh, and one more thing – Electrolytic capacitors are polarity sensitive. If you put them in back to front they go BANG and disintegrate! Have I scared anyone off yet? All you have to do is take note of the markings on the cap and put the new one back in the same way.

I would recommend that if you aren’t too handy with a soldering iron to get a mate who is. The negative lead of C7 is soldered to an earth ground plane and you need a fair bit of heat to get the solder out of the hole. Not too much though because you may damage the board.

I will be interested to see how other people go with this…It fixed the irritating surging and stalling problem I had with my EF Fairmont. This was after I put a new ICV valve on it which made very little difference.

Scooterxf

 

 

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Nice one Scooterxf!

I've been working my way around the car trying to resolve the rough idle and might have found it (had a gearbox guy hook it to his diag machine today after a service and came up cam angle sensor) but I'll be doing this on spec anyway.

It's a bit strange only putting a 10V cap in if the circuit is being run from 12V. Maybe it's only on a 5V rail or something. I can't imagine they would be that stupid...

Hi Falcondave

I didnt get any feedback from my diag results - they displayed "no fault" . Im not sure if you can see from my pic but C7 is near a heap of ICs that drive the large driver ICs along the edge of the ECU. There would only be 5V around here, but even so a 10V rating is still too low. You see this all the time with domestic electronics though.

Scooter

make 5 billion ECU's and save 5 cents on each cap (which will work for many years) and calculate the difference. big bux!

Might be advisable to get some flux/resin spray to protect the components.
no doubt people will remove half of the wax to get the the pcb. =D

I dunno how many ppl notice this, but very early in the morning and more in the eastern states the ECU almost ices up! and is prolly the main cause of the capacitors failing.

Not to be too negative, but i doubt the cap replacement will play a major part in the idle performance. however the relearn sequence will smoothen it out better!

These big six's just hate low rpm!

But I can be wrong!

Nice to have you on board Scooterxf..... welcome mate!!!!!

Thanks for the welcome slick…

And now to Krytox

Ok, not to be too negative but I will correct you on a few things you have said in your post that may mislead people;

Flux/resin spray; Flux/resin is used with or, in multi-core solders case, in the solder to clean the copper or material you intend to solder. It is very corrosive to the base material but only at the solder melt temperature. So this is not what you want to use to protect the PCB after repairing. A rubber silicone compound like what’s already on the ECU PCB would be the go but its not really in a bad environment chemically so I wont bother.

Electrolytic capacitors fail because they have an oil-like electrolyte impregnated paper used as the dielectric between the two electrode plates of the capacitor. Under heavy load, poor rating selection during development or mechanical damage, the capacitor heats up, the case warps, the oil escapes, the paper dries out and the capacitor loses its rated capacity. Or in my case the chemicals in the electrolyte attack the coper legs of the cap and it fails to even connect to the PCB. Cold temperatures, as long as it isn’t under its min. rating, wont effect Electrolytic capacitors. The worst ones are rated at –24 deg C while most are –40 to –50. Eastern states can get cold but not that cold! At –50 you have more to worry about than caps in your ECU – like the oil in your sump!

If capacitors fail you get ripple voltage on power rails to ICs and you cant predict the results. I’m not saying that this fix is a be all and end all to the EF/EL idling problem, we have seen from other posts that people have fixed it in other ways or even had multiple faults…all I am saying is that if you have tried everything else and you don’t want to spring for a new ECU give it a try – it DID fix my EF…

By the way, I dont accept your last statement "These big six's just hate low rpm!" - they ran great when they were new and if they dont run right now then there is a fault somewhere - you need to fix it!

Scooter

Well done scooter, will look into replacing my caps soon. Another way to test is with freeze spray and a hair dryer as caps change with temp if faulty. To pin point with heat simply use the tip of a soldering iron on the top of the cap and if any change theres the faulty cap.
The older Samsung VCR's had huge problems with caps on the power reg with drying out and failing when power was turned off for a period of time then powered up again. Originals were 85 deg and had to be raplaced with 105 deg caps. Again thank you for your input to a very common problem with the EF's and EL's.

Wow!

Scooter this could be a significant breakthrough in terms of poor E series 6 cylinder idling.

Should get in touch with Greg (aka Happy) and have this information posted as a technical document.

Great work and welcome!

In reply to joolz;

Sounds like you’re a domestic repair tech eh? I was once too…where would we be without electrolytic capacitors and dry joints?

Most switch mode power supplies have a “bootstrapâ€￾ cap on the primary (mains) side of the supply. These caps are usually low value (.1 – 1uF but are high volts – over 250V) and get hot due to their location and dry out. The VCR works fine until you turn it off or a thunderstorm knocks out your mains (and you all thought that the lightning strike took out your VCR or telly – WRONG! – telly fix it man strikes again! – now where is my hidden camera!) and the switch mode cant start up again…most VCRs have this problem.

There are a whole heap of other areas in domestic stuff where these things fail. TVs, Faxes, Copiers, PCs, LCDs, CDs, Amps, stereos, you name it, they die…I have even done network hubs with dead electros – when will they stop using these things!

If anyone out there is into tinkering with electronics, get yourself an ESR meter…they will pay for themselves in a day if you are a full time tech and maybe a couple of months if you do the odd job. D. Smith sell a kit for $50 (cat.# K7204) which is what I use and it was one of the most handy bits of gear I have.

Regards

Scooter

An easier way to check the caps is to check the top of them. If there is a slight bulge or bubble feel its dead. These often go into computer components and often will stop a motherboard from starting up probably and even running smoothly.

Cheers

yes u r correct about the electro's they are they very prone to fail especially where extreme temperature change occur

the best case and probably the most expensive and problematic was a few years ago when a s**t load of computer motherboards had catastrophic failures due do faulty caps being fitted - the caps were manufactured with an incorrect electrolite formula making them unstable and overheat and burst - and most of the motherboard manufactures refused to admit there was even a problem

anyway just for interest sake the ones you removed were the rated at 85'c or 105'c

i always/only buy 105'c and low impedance caps - they cost a few cents more but are less prone to failure

Yeh, or you can now buy these metal caps that most motherboard maf are using now. They are 100% guaranteed not to explode or malfunction