[Diy_efi] Problem with TPS on aftermarket ecu

Fri Mar 30 05:30:46 UTC 2007

I can say that in the 25 years since I have been exposed to all sorts of
wiring on industrial and automotive I have seen similar issues on about
such 5 occasions on multistrand wires.

The most common is corrosion of the (multi strand) wire  without much
evidence externally except perhaps an almost imperceptible bulge. Breaks
in telecoms single strand are far more common however, I have lost
count of those.

I am guessing that the PVC polymer may not be totally homogenous and
during the moulding process some monomer may be trapped inside the
wire, the presence of heat, especially in automotives, might well cause the
vinyl chloride to release chlorine, attacking the wire forming Copper Chloride
and either higher resistance or a complete loss of continuity.

On older cars the PVC insulation hardens and cracks and in the engine
bay the corrosion seems to be sulphate based, I have seen a couple of
light blue dust from sharp edges of cables where it has cracked, I am guessing
that long exposure to battery gassing might have caused this,

So not so uncommon me thinks,

rgds

mike

At 02:55 AM 3/30/07, you wrote:
>Damian,
>Mostly I lurk and learn on this group, but on this subject I may have some relevant experience, since you are looking for a non-obvious answer (having covered all of those already, heh.)  A few years ago I was trouble-shooting some intermittent sensor wiring, and got it down to one wire.  Connectors were good on both ends, but still no continuity.  Frustrated, I broke that wire out of the bundle, expecting to find a hidden break, but nothing visible, argh!  Knowing that I was going to replace it anyway, I began cutting into it in segments and testing each section, until I reduced the non-continuous run to a span of a foot or so.  Then I stripped that section inch by inch - to find a clean break in the solid copper strand, a perfectly square cut, no damage visible even under magnification.  Meaning that it had been mfgd that way, difficult as it seems that would have been.  I can imagine that as-new continuity testing would have passed, since the ends touched.
>
>Anyway, I send this not as a likelihood, but merely as citation of a very rare example.  So weird that I must proclaim my own present sanity [:oj and restate the factual nature of the tale; I was an instrumentation tech at Edwards AFB, so, while not an engineer by any stretch, I've got a pretty good grasp of the basics.  Meaning that I know how unusual such a discontinuity is.  But it did happen at least once.  Meaning that it could happen again, even tho I've never heard of anyone else finding such an anamoly:  Bad splices, loose crimps, hidden corrosion, yes, but never a clean square shear INSIDE undamaged & unmarked insulation.
>
>Ernie B.
>
>
>
>
>----- Original Message ----- From: "Damian Long" <bigcow_610 at yahoo.com.au>
>To: <diy_efi at diy-efi.org>
>Sent: Thursday, March 29, 2007 2:58 AM
>Subject: [Diy_efi] Problem with TPS on aftermarket ecu
>
>
>>Hello,
>>
>>gee its quiet in here.
>>
>>I have a problem with my TPS and I'm running out of ideas. Perhaps someone else on here knows whats going on.
>>
>>The TPS is not reading correctly in the ecu. The ecu is a Walbro BIKE400. Probably haven't heard of it but thats not real important as it uses basically the same principals as most ecu's when it comes to TPS.
>>
>>I have wired the TPS correctly. It is a standard GMH 3 wire TPS. +5v, GND, TPSsig.
>>
>>The throttle movement is correct. I could calibrate the opening 0% and 100% without problems. In the datalogging software, the throttle movement works correctly. WOT logs 100% throttle etc. The problem is that the 'dthrottle' value does not change. It remains at 0 with the occasional movement to 1 or so. Just like little blips of interference (noise). Basically the ecu thinks that, although the throttle is moving, there is no change. The result is no accellerator enrichment.
>>
>>If anyone knows why it is doing this, it would be a great help.
>>
>>thank you
>>
>>Damian
>>
>>Send instant messages to your online friends http://au.messenger.yahoo.com
>>_______________________________________________
>>Diy_efi mailing list
>>Diy_efi at diy-efi.org
>>Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>Main WWW page:  http://www.diy-efi.org/diy_efi
>>
>>
>>-- 
>>No virus found in this incoming message.
>>Checked by AVG Free Edition.
>>Version: 7.5.446 / Virus Database: 268.18.20/736 - Release Date: 3/27/2007 4:38 PM
>>
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
>Main WWW page:  http://www.diy-efi.org/diy_efi

Regards from

Mike
Perth, Western Australia
VK/VL Commodore Fuse Rail panel that wont warp, twist or melt, guaranteed  !
Twin tyres for most sedans, trikes and motorcycle sidecars
http://niche.iinet.net.au