Golf 4 1999 - Mis- and Backfires

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Golf 4 1999 - Mis- and Backfires

Postby terbo » Sun Dec 11, 2016 6:34 pm

Hi,

A friend dropped off his 99 Golf 4 1,6 AKL-Engine with AT.
He was with it in 8 different Garages, more $ then the Car could
ever been worth have been paid, many many Parts where thrown at this car.

4 different MAF-Sensors, 3 Ignitions Coils, 3 Sets of WIres and 2 Sets of Plugs.
Coolant Sensor, Thermostat, 2x Fuel Filter, 2x CAM-, 3x Crank Sensor,
Fuel Pump was swapped three times, Fuel Lines from Tank to Engine,1 used Engine ECU,
Ignition-Switch, 1 Fuel Pump Relay, 1x Lambdasensor, 3 Vaacuum Hoses,
1 Throttlebody, 4 Sealing rings (Intake), 2 Sealing rings elsewhere ,
and over 58 Hours of Work if i look through the repair orders he gave me.0

It was tested for Vaacuum-Leaks, it was tested for Headgasket, Ground points cleaned.
Wiring was dismanteld, checked and retaped...

Timing Belt was checked and replaced-

First many aftermarket things where built in and garage after garage
told him, they don´t wok right, he needs Original VAG parts....no help.

They all gave it up, or he picked up the car, because they wanted to
change things like the whole Wiring harness (~ 2000 Euros) or a new Engine
ECU (1000 Euros), or replace the Engine (totaly) or the Head.

And still its running crappy, sometimes its already mising at least 1 Cylinder
at idle, Sometimes it clears up , then runs "o.k" at idle but hesitates and
bogs and misfires (sometimes BAD Banging Backfires) when you want to take off.
It worked here and there for 1 or two weeks and then came back.

Weekend was busy with other things and its raining all day, so not much time
so far for the Car, took a few Shots with the Pico on easy Things to access.

If someone has good ideas....open for anything.
Attachments
Volkswagen_Golf_1999_Petrol_20161211-0003.psdata
Lound Backfire Bang in Intake while WOT
(7.99 MiB) Downloaded 61 times
Volkswagen_Golf_1999_Petrol_20161211-0002.psdata
MAF+Injector+Intake
(10.51 MiB) Downloaded 45 times
Volkswagen_Golf_1999_Petrol_20161211-0005.psdata
Inj+Plug Wire Cyl. 1
(838.21 KiB) Downloaded 44 times
Volkswagen_Golf_1999_Petrol_20161211-0004.psdata
Inj+Plugwire 4 while misfiring badly at idle
(1 MiB) Downloaded 61 times
Volkswagen_Golf_1999_Petrol_20161211-0003.psdata
Injector Current at idle
(791.4 KiB) Downloaded 41 times
Volkswagen_Golf_1999_Petrol_20161211-0002.psdata
CAM+CRANK
(2.77 MiB) Downloaded 44 times
Volkswagen_Golf_1999_Petrol_20161211-0001.psdata
Fuel Pump current and Voltage, Key on and start
(1.28 MiB) Downloaded 40 times
terbo
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Re: Golf 4 1999 - Mis- and Backfires

Postby STC » Sun Dec 11, 2016 8:33 pm

If it is backfiring then the first place to look at is Valve Timing.

Timing Belt was checked and replaced-


That does not confirm that you don't have an issue, spun sprockets, keyways, lobes .... .... .... Can you get a pressure transducer in to the bores ???


Only other thing that I can see is :

Odd event Delete.jpg
Last edited by STC on Sun Dec 11, 2016 10:35 pm, edited 1 time in total.
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Re: Golf 4 1999 - Mis- and Backfires

Postby terbo » Sun Dec 11, 2016 9:18 pm

I could get it into Cyl.1 and 4 if you like.2+3 only with Intake-remove.
Compared with Cyl. Secondary with a spark-tester installed ? Or with CAM or CRK ?

CAM+CRK Signals look like 2 others found on the Pico-Libary and a Forum Post.
So nothing "obvious" there...

BTW , missed that in First Post - No Fault codes in ECU, Fuel Trims are at 0+-2%.
No Misfire Monitors in Scan Data present.

EDIT : Funny that you saw that "odd" Event, i noticed that as well, but i think it
is a sort of "Fuel enrichment", because its on all tested injectors and with every snap.

Here is a Picture of 3 Snaps with that "odd" Injector behaviour.
Attachments
Volkswagen_Golf_1999_Petrol_20161211-0004.psdata
3 Snaps with Injector 4
(8.25 MiB) Downloaded 48 times
terbo
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Re: Golf 4 1999 - Mis- and Backfires

Postby STC » Sun Dec 11, 2016 11:00 pm

I could get it into Cyl.1 and 4 if you like.2+3 only with Intake-remove.

Would be good to get it with Injector or Coil Primary (using Spark tester) for each cylinder.

If you don't find anything in 1 & 4 then you are possibly left with no choice but to look at 2 & 3 too. Is there a way to get in there without removing the manifold to get a Running Compression - Idle to WOT - Waveform ?

With so many components thrown at it already I am thinking someone has missed the basics.
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Re: Golf 4 1999 - Mis- and Backfires

Postby Tronic » Sun Dec 11, 2016 11:45 pm

I have always been impressed by those people that can read the spark burn voltage line and tell with accuracy ,as they claim,what could be wrong. This kind of holy knowledge, as seen by me as a novice in this kind of readouts, brought my mind back to a trace that pointed out turbulence derived from a worn cam lobe on the burn line. Looking at psdata.0004 there is exactly same kind of turbulence at the end of the burn line. Be kind when comment, it is just an idea I got at late Sunday evening :lol:
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Re: Golf 4 1999 - Mis- and Backfires

Postby terbo » Sun Dec 18, 2016 12:05 pm

The Car is fixed....thinking about it, it was simple.
As written before : Basic things.
What does a engine need ? Fuel, Air, Compression.
WHat was not changed ? The Injectors.
Pulled the Mainifold, cycled the key, put the OTC 3398 on the Injectors, looked
at the fuel Pressure gauge, and - NOT ONE was the same to the others.
Number 4 was sometimes spraying, sometimes only drippeling.
I did 3 Test-rounds through all 4 Injectors, and only Number 2 fell 3 times to the same
level.
Went to the Scrap Yard, pulled a Fuel Rail for 22 Bucks - put it in, tested, looked good,bolted it together,
Car runs without any Problems, drove 2 Hours yesterday, and not one hickup.
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Re: Golf 4 1999 - Mis- and Backfires

Postby Fat Freddy » Fri Jan 06, 2017 1:13 pm

EDIT : Funny that you saw that "odd" Event, i noticed that as well, but i think it
is a sort of "Fuel enrichment", because its on all tested injectors and with every snap.

Here is a Picture of 3 Snaps with that "odd" Injector behaviour.


Yep!. Very common on gasoline EFI on accel/high load like stalling. Nothing unusual.
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