Hi everyone

My friend recently bought a very low mileage 2001 seicento mpi.
Everything had been perfect with it until it started idling up and down and occasionally wouldn't start. The fault was intermittent but got worse to the point where it was undriveable, badly misfiring and idling badly etc

A little history that I know about the car, it had its ecu replaced and possibly the throttle body due to it being jump started with the leads backwards which fried some stuff.

I plugged my scanner in and pulled a P505 idle circuit malfunction and a cylinder 4 misfire. My friend bought a known good throttle body although I was suspicious due to the previous problems with the car.

I installed the new throttle body and there was no change! I started going through the loom and found the 4 wires for the connectors were soldered together as if the connector was cut previously.. Although this did not worry me
I wiggled the loom at the ecu connector and the car began to idle perfectly again! When I moved it again it went bad.

I checked for codes again and found this:
P505, P105, P130, P225, U1600

So my question is do I have a bad loom or a bad ecu, bearing in mind the ecu has been replaced once before and possibly the throttle body.

Thanks for your help!

Chris

It sounds like a loose connecion, first thing to check for me would be every solder joint on the cut plug. I'd kick my soldering iron up and heat every joint so it melts the solder. Every joint should have the wires twisted together nice and solid and the solder should go very shiney.
Second thing id check is the conditions of the pins on the ecu and the plug. The fact that it all wirked normally when you wiggled the harnes means the ecu etc is fine. If you wanted it repaired right id price up a new engine loom with the plug still on.

Thanks for the reply!
I think we will just replace the loom if that is the case. Looks like this one had had a bad life! I cannot see any evidence of bad connections around the connector, the connector itself looks perfect.

Could you tell me if there is any other car that shares the same loom? My breakers has many mpi puntos but am unsure if it's the same ecu etc

Thanks

Chris

I REALLY know this problem well -spent many a 'happy' hour sorting out all the nicks on my old loom. Best way to check is look at the engine in the dark- mine was lit up like a Christmas tree.
Pretty sure the Mk2 1.2 8v Punto has the same connectors (inc same style of ECU) but the lengths might be different. Why not contact one of the many people stripping a MPI Sei on the forum, at least that way you know you have a direct replacement, & it's more likely have no faults than something from a yard or Flea-bay.
Check out the classified section -Cento Painter is currently stripping a 2001 MPI.

Ouby said:

Check out the classified section -Cento Painter is currently stripping a 2001 MPI.

Click to expand...

Yes i am, a 52 plate...................

I would jump at replacing the loom right away.. Clean the ecu plug and contacts properly and then how it goes for a bit.

New loom it is then! I'll let you know how I get on!

Thanks

Chris

i meant to write wouldn't.. :doh:

just try cleaning the connections up first

Nah . Buy the loom off of Cento Painter- I need the commission

TBH it's worth checking/cleaning the connections first before you start spending money (am I tight or what!).

Haha its okay blu, I have already checked the connector and socket, both look perfect and no change after I cleaned them.
Which part of the loom do I need as there are 2 connectors? I'm only having problems with the smaller one

well find the main earth leads, take them off and clean them (that means like some sand paper of similar abrasive if clean it off not just wiping with a cloth) and where they bolt to body. There is one near the ecu which is the main earth for that, clearly there is another over near the battery and from memory there is another big one down the back of the engine. Not messed with mine for ages, sure someone can be more specific than that. Is defo worth doing that before spending money and time on new loom.

I agree try and trace the problem first before jumping in, ill help as much as i can, but im not out to screw people........... unless they want to be.

Dirty beast :devil:
Bit worried about what you're going to offer me as commission now! Ahhhh

I meant ..............., oh never mind.......... do you like fruit shapes ? The price of work or parts for you Ouby....... i think will depend on the flip of a coin.

I vant to be paid in small furry kittens, Nea-ha-ha-ha :nutter:

Back to the plot....
Chris -there's a product called GT85, it's similar to WD40 but I found it a lot better
for dodgy connections. You might want to give it a go, esp with winter approaching.

that because GT85 is actually designed to aid dismantling stuff and loosen bolts, that is not what WD40 is for although that is one of the things it does do its really just meant to be a water disperser and thats what the WD stands for.

For cleaning electrical contacts i would still use WD, but in general yes the GT85 is a much better product.

Altogether now -"you take the WD & i'll take the 85, & i'll be in Scotland before ye...."
Found the GT85 excellent for curing intermittent wiring/connector faults, just use it like Brute (now that's really showing my age).

Always use penetrating oil for taking things apart, wouldn't even consider using WD.

lol, if you read what i wrote then we are in agreement lol.. I never said use WD for dismantling, just that people do.

Anyways, you keep your GT85 - Plusgas is the daddy of penetrating oil

Misfire on one cylinder will be plugs or leads (or, in exceptional circumstances, and if MPI, faulty injector or injector connector).

Replacing the harness is a prertty daft move at this point.

Okay guys, I tried gt85 as iv never used it before but no luck ill defineatly be keeping a can though, seems like good stuff! Anyway those connections are now super clean
The only way I can get the car to run right is moving the wires around until I find that sweet spot. But the second I move them it starts going crazy again!

Finger the car is misfiring randomly on every cylinder at some point. I am able to make the car run perfectly by moving the loom near the connector around which is why I suspect the loom is a problem.

Thanks everyone for you help so far. Is there anything else I should try? My scanner can do live data if that is of any use?

Chris