Weak orange spark 1995 850 2,0 10V

Kokonradus · Post by **Kokonradus** » 09 Jul 2023, 14:09

Hello, I am testing spark and on every cylinder the spark is bit weak, like on the photo:

: Snímka obrazovky 2023-07-09 215516.png (447.05 KiB) Viewed 470 times

Changed spark plgus, wires, cap and rotor, ignition coil, but the spark stays the same. (all the parts replaced have proper OEM number, all are Bosch brand).

What should I check next? Maybe a relay under the fuse box, or wiring connections? I suppose there is problem somwhere in power supply to the coil. Has anyone else problem like this?

Thank you a lot for help

Post by **scot850** » 09 Jul 2023, 16:38

Does the car start and run, or is that the problem and why you are asking about the spark color?

Neil.

Kokonradus · Post by **Kokonradus** » 10 Jul 2023, 01:51

Yes, the car starts and idles. But performance is not as it should be, there are some misfires and unburnt gas in exhaust and oil. Bad fuel economy of course. Sometimes the lambda light turns on and code 1-1-3 is thrown (short term fuel mixture is too weak).

Car had this code all the time and had bad backfires - replaced O2 sensor - backfires and permanent lambda light disappeared
Car had really bad long and painfull starting - changed fuel pump and FPR - now it starts right up
Car smoked like old TDI with rich mixture - changed ECT sensor, problem presists - changed ECT sensor connector - problems are gone
Car still had a rough idle - replaced whole PCV system and detected and fixed all vacuum leaks

With all these problems the car barelly starts and runs at all.

Anyway these side stuff has nothing to do with spark and ignition. Maybe I should mention I´ve replaced crank position sensor and cam position sensor and the spark remained like this. Also I tried three other types of spark plugs I found but the spark stays the same weak and orange yellowish...

Yesterday I studied 1995 fenix 5,2 electrical diagrams and It seems the + circuit goes from key ignition through the 40A fuse to Overload relay +15 (the middle 106 relay). Finally it goes to ignition power stage and coil 15 contact. Frequency of spark seems to be controlled with ground leading directly from ECU to power stage. Simillar as on the fuel injectors.

Post by **abscate** » 10 Jul 2023, 03:25

That is a weak looking spark but you seem to have covered all the suspects. Are you trying three prong plugs for the 10V

xanthefin · Post by **xanthefin** » 10 Jul 2023, 04:26

How is compression test results? Or did i miss it...

Kokonradus · Post by **Kokonradus** » 10 Jul 2023, 06:08

No I have not tried the three prong plugs. But I tested the spark on a four prong plugs, here is result:

: Snímka obrazovky 2023-07-10 140156.png (1.11 MiB) Viewed 407 times

Compression numbers are 155-175psi (should be 180-210 for N/A models)
Wet compression test is 210 on all cylinders (worn out piston rings)

Which spark plugs would you recommand for this cars?

I am working on it right now and I changed overload relay 15+ and 40A fuse, cleaned all the contacts on connector to power stage but the spark is remaining the same. Actually don´t know what to do now

mystery...

Kokonradus · Post by **Kokonradus** » 10 Jul 2023, 07:19

Is there a tool that measures relevant numbers of ignition coil output? Really have no clue now how to continue with solving this spark issue.

xanthefin · Post by **xanthefin** » 10 Jul 2023, 10:54

As there was fuel pump problems.. Does injectors spray okay or any leaking one?

Kokonradus · Post by **Kokonradus** » 10 Jul 2023, 12:50

Yes injectors are working fine.

Post by **jreed** » 10 Jul 2023, 16:33

If you haven't already, it might be a helpful to measure the voltage on the primary (low voltage) side of the coil to see if it's good. I would expect it to be > 12.6V with the car running.
Also, it would be a good idea to check the engine grounds and battery ground cables are good, with low voltage drop (< 0.1 to 0.2 V) across them with the car running.