no spark on 2 & 3

[fuzzynuts]

I am posting for a friend so I don't have all of the information. I have searched but have not found anything that matches this situation exactly.

The car is a 2nd gen Tsi that loses spark on the 2 and 3 cylinders after 10 seconds of running. We have removed the plug wires and actually seen the spark disappear.

So far he has put in a donor ECU, swapped the coils and transistor and checked both the CAS and CPS as per testing instructions; they all check out.

He did a test with the transistor. He hooked a multimeter to a wire going from the ECU to the transistor. When all cylinders were firings he had a steady voltage pattern (the voltage would spike, drop, spike drop...he explained it to me like a heart monitor in a hospital). When 2 and 3 lost spark the voltage in the wire stopped fluctuating and stayed at 11.3 (he said it was like a flatline).

does this sound like a bad connection between the ECU and the transistor?

any help would be appreciated guys!

thanks

p.s The tach is not working...i don't know if it's relevant but from other posts on the topic seems like it could be.

 

[da_golden1]

sounds like a bad coils or wires

 

[luv2rallye]

The signal he's testing sounds like the tach signal (white wire) which goes from the power transistor (PT) to the ECU (and a few other places). This is the "OR" of the 2 PT outputs which should always be pulsing as long as the PT's are firing (half frequency if only one is firing) and the coil primaries are good and ECU to PT control signals are good. So you could have either a bad coil, bad PT, bad ECU, bad CAS/CPS (these tell ECU when to fire PT), or an intermittent wiring connection. Since you say you have flatline yet cyls 1 & 4 still fire, I would lean first to a bad PT. The PT may be temperature sensitive to failure. Try heating it with a hairdryer to see if it then always fails.

 

[fuzzynuts]

thanks guys,

he replaced the PT with one from his car which runs fine and it still does the same thing. As I said, he has done the testing on the CAS/CPS and they check out. He swapped the coils from his other car and the problem persists. He swapped in the ECU from his other car (both are eprom?) and the problem persists. We are both beginning to conclude that there is a short in a wire going from the ECU to the PT...especially since the tach isn't working.

is there any special transistors or relays we should look out for?

thanks again!

 

[Boomer420s]

Sounds like coils to me. What's the resistance value on the coils? To me, sounds like the coils are heating up after ten minutes and the resistance from the heat is getting too much. That's just my two cents.

 

[fuzzynuts]

Sounds like coils to me. What's the resistance value on the coils? To me, sounds like the coils are heating up after ten minutes and the resistance from the heat is getting too much. That's just my two cents.

that is what i thought at first but multiple coil packs have been tried, all from working cars and with no change.

 

[fuzzynuts]

ok, I think he is at the point where he is going to send it to an electric specialist....no point wasting so many hours when the specialist could find it quickly. If we resolve the problem I will post what it was.

 

[xhackerekx]

i have 95 GST just park car and next day no start no spark on 1 and 4 cylinder replaced coil and power transistor clean conectors still have same problem any idea WTF ????

 

[92AWDHX40]

IS the coil pack new or used?

 

[Tyeler18]

also try the transistor pack? i believe i heard something about that going out on here last night also

 

[GRAVEDIGGER]

You might have to check the wiring to the power transistor. You should have an on off signal from the ecu to the power transistor to fire the coil.

 

[xhackerekx]

coil pack removed from my buddy eclipse for check and power transistor .

 

[xhackerekx]

i remove ECU and check capacitors everything look ok .
now i try search dealer manual for checking wires.

 

[xhackerekx]

find code on ECU P0340 Camshaft Position Sensor "A" Circuit
i change sensor today and engine back to life

 

[Whitetal]

Ok what happend and what solved your problem? All I see is ECU P0340, Camshaft position sensor. The letter A and Circuit you changed. What about A and what circuit and what sensor did you changed?

I replaced a head gasket and started the car up. Started up and ran good but found the head was cracked. Took me a month to find a head. I redid installing the new head. Started it up but now something's wrong. There's no spark in 1&4. Really sick of this car and need to get it fixed.

 

[dsm_guru_tsi]

check this out:
http://members.cox.net/50reasons/J722TModule.pdf

that was my problem cause my 1&4 fired but not 2&3, the PT

 

[dsm_guru_tsi]

check this out:
http://members.cox.net/50reasons/J722TModule.pdf

that was my problem cause my 1&4 fired but not 2&3, the PT