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Car was remapped and now won't start

## UPDATE ##

I have finally sussed out how to successfully get the car started everytime... so now I hope to be able to trouble shoot better.

All I have to do is Disconnect the LEFT plug that connects to the ECU for around 10> 30 seconds then reconnect and the car starts up.

Can anyone tell me what the LEFT plug does/connects to/controls?
 
The shorter plug is mainly for the injectors/coils/throttle body and all the other things (like sensors) which are mounted on the engine itself. The longer plug is for everything else, stuffs which are mounted on the chassis instead of the engine (f.eg lambda, throttle pedal, brake/clutch switches, relays, can & obd communications, etc...). The long one feeds the constant power supply in, too.
 
Sim said:
The shorter plug is mainly for the injectors/coils/throttle body and all the other things (like sensors) which are mounted on the engine itself. The longer plug is for everything else, stuffs which are mounted on the chassis instead of the engine (f.eg lambda, throttle pedal, brake/clutch switches, relays, can & obd communications, etc...). The long one feeds the constant power supply in, too.
Click to expand...

Awesome! Cheers Sim.

That makes sense about the power feed as removing it must do something to the ECU power wise.
 
Ok having a bit of a play around and found something strange.

If I turn the ignition to the first click then all the lights go on the dash and all go out apart from the battery light. Now I found that if I remove FUSE 2 and then plug it back in the EPC and engine Management lights come on and the fuel pump sounds like it primes.

I then try to turn it over, car is hesitant but it starts.

I also checked the voltage from FUSE 7 and 8 and it is only 2volts. Ibiza125 could you please check your fuse 7 and 8 with a multimeter to see what the voltage is?
 
Last edited:
kyle'87 said:
Ok having a bit of a play around and found something strange.

If I turn the ignition to the first click then all the lights go on the dash and all go out apart from the battery light. Now I found that if I remove FUSE 2 and then plug it back in the EPC and engine Management lights come on and the fuel pump sounds like it primes.

I then try to turn it over, car is hesitant but it starts.

I also checked the voltage from FUSE 7 and 8 and it is only 2volts. Ibiza125 could you please check your fuse 7 and 8 with a multimeter to see what the voltage is?
Click to expand...

Don't have access to one just now but will check it on Thursday.
 
Ibiza125 said:
Don't have access to one just now but will check it on Thursday.
Click to expand...

Cheers mate, if you could check for me that would be great.

Also if anyone else has access to a multimeter and thier fuse 7 and 8 to check the voltage going accross the fuse.

Also I think the car has hit the barrier now as I came out this morning, turned ignition to first click and the car showed all signs of starting up but failed to fired. Only was to get it to fire was remove the left ECU plug for 10 seconds then reconnect. Car started instantly.

Trying to think of it as a new 'Security' feature lol
 
Last edited:
Btw. do you have a vagcom? Can you access the ecu when it is playing up?

Also, all solenoids, injectors, coils, etc will get battery+ from the fuel pump relay. The fuel pump relay is activated only when priming fuel pump and while the crankshaft is rotating (cranking or running). When you just turn the ignition on but the engine is not revving, you wont find battery+ at the engine ant that is normal. Try to test fuses while cranking.
 
Sim said:
Btw. do you have a vagcom? Can you access the ecu when it is playing up?

Also, all solenoids, injectors, coils, etc will get battery+ from the fuel pump relay. The fuel pump relay is activated only when priming fuel pump and while the crankshaft is rotating (cranking or running). When you just turn the ignition on but the engine is not revving, you wont find battery+ at the engine ant that is normal. Try to test fuses while cranking.
Click to expand...

I have a friend who has VCDS lite and we can access the ECU. I have also had it on a 'Laucnher' machine which can access the ECU.

The fuel pump relay gets hot after a while of running, should this be happening?
 
Warm may be still ok, but definitely not hot. Maybe you could measure how many amps the pump and other devices draw. Get out fuse 7 and use a (good quality) multimeter which can measure at least 10A. Put the two probes of the meter into the fuse socket. Repeat with fuse, 8 too. The values should not be too high at idle.

Watch out you have to keep the circuit closed in order to keep the engine running, also this may trigger some codes too, but dont care about them.
 
Sim said:
Warm may be still ok, but definitely not hot. Maybe you could measure how many amps the pump and other devices draw. Get out fuse 7 and use a (good quality) multimeter which can measure at least 10A. Put the two probes of the meter into the fuse socket. Repeat with fuse, 8 too. The values should not be too high at idle.

Watch out you have to keep the circuit closed in order to keep the engine running, also this may trigger some codes too, but dont care about them.
Click to expand...

The relay is warm not hot.

I will check this out tonight Sim, I have a good multimeter that should handle the draw.

I'll update later tonight.

Cheers
 
I have been over sooooo many different options I am almost on the verge of burning the damn car.

I am still no closer to the problem however I am currently in the process of trying to apply my computer knowledge to my mechanical klnowledge.

Took out my ECU and took my heat gun to the ECU. Initially started with a low heat for a good few minutes and then let cool down on the warm radiator and then gave it a second blast with a heat range around 300Degrees and then let it cool down again on the radiator.

It's now back in the car, started first time everytime so I am leaving it for a few hours to see what happens as this is normally the case when it refuses to start.

Will update later on.

PS Glad yours is fixed mate! bet you are relieved lol
 
I think I owe everyone an update on this...

Since I tackled the ECU with a heat gun at the weekend the car has been, dare I say it, perfect!!!

What have I done???

Heated up the ECU with a heat gun with the following cycle

1. 150 degrees for 5 minutes
2. cool down on a warm radiator
3. 300 degrees for 5 minutes
4. cool down on a warm radiator
5. wrapped ECU in some 'Fragile' tape and sat back in location (Not in the bracket for now)

This seemed to have done the job.

Want to say thanks to everyone who offered their much needed advice, hopefully see a few of you at the big meet (If it doesn't break down before hand)
 
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