NefMoto

Hello me again, there is a guy in our 20vt group whose car has been sitting still for well over 3 months now (due to the issue and turbo build)

He can't resolve the problem and it isn't tune related, so i was hoping some expert could chime in on what could possibly be wrong with this car.

The problem is it runs like shit on idle, don't even think about driving it. Codes stored are P1358 and P1364. It also isn't tune related, as it does this on a simple stage 1 tune and also on different ECU's. List of replacements;

Coil packs, spark plugs, engine loom, ECU, injectors, camshaft sensor.

Anyone perhaps have an idea on what might be going on? The codes seem very clear, but i can't make sense of them after the loom, ECU and packs have been replaced but it keeps coming on.

Year make model engine code. Description of the P codes so we dont have to look it up. I am wondering if the car has a power output stage for the coils. Those things used to go bad all the time on the cars with bolt down coils.

Sorry my bad!

2002 Leon with 1.8T AUQ engine

Cylinder 4 Ignition Circuit: Open Circuit
Cylinder 2 Ignition Circuit: Open Circuit

They aren't the bolt down style ones, they are of the newer type. I am also quite sure these AUQ/AUM engines don't use power output stages sadly.

It just doesn't make sense to me, the ECU is changed, the engine loom and the coil packs. What else is in between this wiring that could possibly cause issues on just these two coil packs?

Replace the main ecu relay it wont provide power to coils if its failing, not an open circuit but its worth to do anyway. 2 of my Audis both suffered from the same problem, just always replace these when you get a new VAG group 1.8t etc car, infact if you havent already, go ahead and do it now, get Kracker(VEMO etc.) as they are the OEM supplier.

You have to track down service manual to see when does it throw the open circuit code but I would assume its for the signal wire.

Thanks for the suggestion we'll get straight to it

Try an oscilloscope you can Scope the signals coming from the ecu.  Buzz out the wiring with a multimeter end to end.  It’s possible you have a defective wiring loom. Or the old loom killed the new ecu.  Shorts are only nice when hot chics at the beach are wearing them.

The car has seen three wiring looms and two ECU's I can't imagine the problem persisting through these changes. But I'll tell him anyway, thanks.

On my car(Audi tt) it don’t seem that complicated.  2 pins per coil (2 &4)go to ground. Pin 1 of each coil makes its way to the ecu relay and a single pin to the ecu.  Then the other 4 (pin 3 of each coil) are the signal wires from the ecu.  But since all these wires are run with the whole loom it sounds like a giant pain to replace the entire loom.  Best to buzz them out with a meter.

ECU and fuel pump relay swapped, still doesn't work.

Any ideas?

Are you 100 percent positive the coil packs you replaced with are good? Can you swap 1 & 2 around?  Open circuit means exactly that.  Either wiring is disconnected somewhere or blown resistor in the coil pack.

He has tried two sets of packs and also swapped in any direction. Fault stays on #2 and #4 so i'd say it's unrelated to the packs. (OEM redtops, original packs etc)

I'm not too sure about the wiring about the coils though. The engine loom is replaced, but the coils are powered through a relay in the car. Wouldn't this mean there is more wiring involved that could cause issues? I also read something about wiring under/near the battery. We'll have to do some more digging, i was hoping someone has seen this strange behavior before.

Noteworthy: problems arose after he replaced turbochargers, i can't see how this is related but that's how it went.

Did it happens on a stock file?

Good one, it happened on his old "generic" stage 1 which was fine before.

After which i supplied him with a base file for his hardware adjustments (440cc, 4 bar, deletes etc etc) so he could drive the car before getting it tuned at some tuner with dyno.

Stock file not tested, but i can't imagine my file and both a generic stage 1 to be at fault for this.

I do not have access to Seat wiring diagrams. However looking at the diagrams for my GTi it looks like the ignition coil wiring is part of the body wiring harness and not the removable engine wiring harness. There is also a 14 pin connector by the battery on the GTi. Maybe seat uses this too?? I think a pin to pin overlay is in order.

Not really.  There is power from the ecu relay.  But it’s all joined to pin one of the coils.  If there were no power from the ecu relay coil pack 1 and 3 wouldn’t be working either.  On mine it’s violet and black.  If you continuity check between 1 on each coil plug they should all be joined.  Is there a ground wire on the valve cover on yours?  Maybe that’s dirty.

This is some really good info - we'll get to it. Thanks.

There is, but that's not the issue as the entire engine loom was replaced.

Did you try another ecu? 

Also check the grounds under the battery tray. Beetles with 1.8t used to set all kinds of weird faults from corrosion on those grounds. ECM disabled intermittently if I remember correctly. Which I know is a seemingly unrelated thing, but if the ECM was being disabled by poor grounds there it stands to reason its possible it could be causing your issue as well.

Did this ever get fixed???

Sadly, it has not. Relays were changed, wiring was checked but to no solution.

It's not my car nor have I worked on it, but it's for a good friend who lives 300km away. Car has been stranded for a good amount of time now.