ASTRA F C16SE long time issue with no resolve. Please HELP!!

[svdwest]

Good day everybody.

I am at my witts end here and really need some input. From 2017 to 2019, I was driving 3000+ Km's every 2nd month. The very last trip I had to do in 2019 is where this issue started. The car was running fine up to the point where I arrived at my destination, where it was stuttering and shaking a lot out of the blue. As a result I replaced the following the day after:

MAP sensor
TPS sensor
ICV
Coil pack
Bougi cords
Plugs
I also did a service again which was the second service in a weeks time, just to be thorough.

The issue initially seemed to be fixed but one issue remained and persisted since 2019 and is still happening today. The engine dips. When cruising you feel it more prominently where you'll be cruising along and it has intermittent jerks/misfires. When stationary and just idling, it idles smooth at first and then you hear the dip in the engine. This happens hot/cold. The only time you don't feel it is when you floor it. Fuel consumption at 13km per liter which is very good. Compression on all cyl. 350psi

Since then I have rebuilt the engine 3x times and I'm currently 70thou oversized. The last rebuild I replaced EVERYTHING. Crank, cam, rockers, tensioners, pumps, lifters, belts etc. I am very confident that there are no mechanical faults unless the gearbox can cause it? I have opened up the gearbox and inspected all the gears individually, replaced all the seals and the gearbox works seemingly well. I have done the clutch kit multiple times. I have replace ALL sensors multiple times. This includes the temp sensors and knock sensor. I have replaced the fuel pump multiple times. I have replaced the Bosch Motronic ECU. I have replaced the injectors, albeit I did so using second hand ones as they are so bloody expensive here I just simply can't afford them. But I have checked the spray patterns and they all appear to be functioning accordingly.

Just last week Thursday, I opened up my wiring harness AGAIN. I disconnected every plug and tested each wire individually for continuity and also possible shorts. I have no doubt that the wiring is indeed good.

I have not replaced any relays but I have tested them each individually while in operation and they do not give any issues/ breaks.

What am I missing?

Just a note. As far as I understand, in South Africa, they never built in the cats and left out the lambda sensors. replaced by very specific resistors in the configuration of a voltage divider. I have tested these resistors and they are still giving the rated Ohms.

Edit:
Also The engine light does come on when this happens. Using the paperclip method I get error codes 73 and 74 at the same time which is Airflow senor High voltage and Airflow sensor low voltage. Because there is no airflow sensor it falls on the MAP sensor but I fail to understand how it can give high and low voltages at the same time. As mentioned before, I have replaced the MAP multiple times and checked the wiring multiple times.

 

[DavebGsi]

it never had a lambda sensor at all? Because the upstream one has nothing to do with emission and actually just regulated fueling.


also what engine code and what year

 

[svdwest]

it never had a lambda sensor at all? Because the upstream one has nothing to do with emission and actually just regulated fueling.


also what engine code and what year

Never had a lambda sensor at all. I'll post a photo later on in the day of the voltage divider configuration.


Engine code is the C16SE, and in South Africa it's a 1998 but I've come to understand through years of searching for manuals etc. that in UK it's the 1994 model. We South Africans love to be behind on tech XD.

I do also agree with the fueling regulation, I'll maybe just look into those specific wiring and resistances again.

 

[svdwest]

Good day,

Just earlier I removed my fuel relay and removed all plugs and did a compression test. I was in fact mistaken with the readings I gave in my original post, my memory failed me XD. The actual readings are cyl1 - 3 1350psi(13.5 bar) cyl 4 1450psi(14.5 bar) I'm not actually sure if the 1 bar oon cyl4 will cause this as this issue had been there when al 4 cylinders had equal compression prior to rebuild.

Also, here is the photo of the voltage divider I spoke of:

 

[Varnis9]

Good day,

Just earlier I removed my fuel relay and removed all plugs and did a compression test. I was in fact mistaken with the readings I gave in my original post, my memory failed me XD. The actual readings are cyl1 - 3 1350psi(13.5 bar) cyl 4 1450psi(14.5 bar) I'm not actually sure if the 1 bar oon cyl4 will cause this as this issue had been there when al 4 cylinders had equal compression prior to rebuild.

Also, here is the photo of the voltage divider I spoke of:
View attachment 27575

What about the fuel filter?

 

[svdwest]

What about the fuel filter?

Brand new with brand new fuel pump a couple of times. Also had the idea but from past experience it doesn't give symptoms of fuel starvation. That usually occurs when floor it when there's an increase of fuel pressure.yet I tried it anyways but the problem persists.

Actually fixed that problem on someones fiat last week.

 

[DavebGsi]

are you running an air filter and box that are standard, or are you running a cone filter?

 

[svdwest]

are you running an air filter and box that are standard, or are you running a cone filter?

Standard box and filter

 

[DavebGsi]

So the issue is just it jolts around mid throttle and mid load, fine below and above that?

 

[svdwest]

So the issue is just it jolts around mid throttle and mid load, fine below and above that?

Does it all round, idling, driving slow, heavy load, it's constant but erratic, there's no pattern

 

[Varnis9]

Did you do any smoke test to check for air leaks? Also check your grounds. Put your voltmeter in resistance mode and check between battery -ve to every ground point. Resisrance should 0.3 Ohms max. If more then you have an issue with grounds. Also check -ve to engine block or gearbox.

Edit: There is also a ground point which I think it is also used for the ecu, under the sill cover on the driver's side, so remove that as well.

 

[svdwest]

Did you do any smoke test to check for air leaks? Also check your grounds. Put your voltmeter in resistance mode and check between battery -ve to every ground point. Resisrance should 0.3 Ohms max. If more then you have an issue with grounds. Also check -ve to engine block or gearbox.

Edit: There is also a ground point which I think it is also used for the ecu, under the sill cover on the driver's side, so remove that as well.

Checked for air leaks yes, no air leaks.

I tested 3 ground points. Battery to body, gnd point under the sill cover and battery to engine. I cannot recall the readings so I'll do that again tomorrow and give feedback. Thinking about it I don't even think I really took note of any readings, I just quickly ran through for continuity but you make a good point regarding the resistances.

Will check and get back, thank you

 

[DavebGsi]

Yea don't forget a continuity only tell you if you are checking the correct wire, you could have 1 strand of wire still connected and the rest broken, and you will show good continuity.
volt drop is a much better test for actual condition of wiring

 

[svdwest]

Yea don't forget a continuity only tell you if you are checking the correct wire, you could have 1 strand of wire still connected and the rest broken, and you will show good continuity.
volt drop is a much better test for actual condition of wiring

True, I was actually testing to make sure there are no breaks or shorts in the wiring but you are preaching the truth.

I couldn't get to testing yesterday, work flooded in but am testing today

 

[Varnis9]

Checked for air leaks yes, no air leaks.

I tested 3 ground points. Battery to body, gnd point under the sill cover and battery to engine. I cannot recall the readings so I'll do that again tomorrow and give feedback. Thinking about it I don't even think I really took note of any readings, I just quickly ran through for continuity but you make a good point regarding the resistances.

Will check and get back, thank you

Continouity is pointless unless there is a cut wire. Measure for resistance and let us know of the readings.

 

[DavebGsi]

Continouity is pointless unless there is a cut wire. Measure for resistance and let us know of the readings.

but so is resistance, if you have 1 good wire, youll have good resistance.

You have to test for volt drop while the end consumer is being powered.

I had an alternator that was putting out 14 volts, cable fine, good resistance etc.
but when you loaded the car up you had 14v at the alternator and 12.3 volts at the battery. Turned out the alternator was putting out the voltage but not enough amps and the natural resistance of the cable was enough to steal all energy out of the charge being pushed along the cable.
Same idea as if you had a rotten cable or breaks in a loom, would do the same thing

 

[Varnis9]

but so is resistance, if you have 1 good wire, youll have good resistance.

You have to test for volt drop while the end consumer is being powered.

I had an alternator that was putting out 14 volts, cable fine, good resistance etc.
but when you loaded the car up you had 14v at the alternator and 12.3 volts at the battery. Turned out the alternator was putting out the voltage but not enough amps and the natural resistance of the cable was enough to steal all energy out of the charge being pushed along the cable.
Same idea as if you had a rotten cable or breaks in a loom, would do the same thing

Measuring for resistance is a quick first step in checking that everything is grounded correctly. Let's hope that he finds an issue

 

[svdwest]

Hi everybody,

apologies for the silence, I only managed to get to testing today so here goes:

I recently also replaced main battery cables to 35mm².

Batt to Body - 0.0Ω

Batt to Engine - 0.0Ω( Interesting note as I'm not sure if this is normal: When engine is off, ignition on and off Batt to engine gives 0.0Ω, when I start the the engine it jumps up to around 50Ω and then gradually drops and stabilizes around 5-6Ω, jumping to 7Ω every now and again and dropping again. The interesting thing about this is that Batt to body does not do the same yet they are effectively on the same 'line'. 2 x 35mm² cables connected to the battery, one going straight to body one going straight to engine.)

I unplugged all the sensors and plugs and ecu, so measurements are from plug end to ecu plug end.

MAP - gnd - 0.1Ω
- ref - 0.0Ω
- sig - 0.1Ω
TPS - gnd - 0.2Ω
- ref - 0.1Ω
- sig - 0.1Ω
The ICV pos/neg could be inverted. I noted how high the resistance is here however I have no issues with idling unless this is my problem here which I couldn't imagine as when the throttle is open for cruising that shouldn't make that big of a difference.
ICV - UP pos - 35.5Ω
UP neg - 0.1Ω
DOWN pos - 34.8Ω
DOWN neg - 0.1Ω

Injectors - Gnd - 0.1Ω
- Feed - 22.1Ω/22.1Ω/0.1Ω (On the ECU plug the feed wires from injectors 1 - 4 has 3 contact points so I'm just giving the readings of each pin on the ecu plug side. All 4 injector plugs read exactly the same on gnd & feed. The 22Ω corresponds to the voltage divider configuration values of the resistors.)

Coil - Black - 0.1Ω
GND - 0.3Ω
GRN - 0.0Ω
GRN2- 0.0Ω

Intake air temp - GND - 0.1Ω
Sig - 0.1Ω

Head Temp(under coil) - GND - 0.2Ω
sig - 0.2Ω

I hope everything makes sense.

 

[Varnis9]

Hi everybody,

apologies for the silence, I only managed to get to testing today so here goes:

I recently also replaced main battery cables to 35mm².

Batt to Body - 0.0Ω

Batt to Engine - 0.0Ω( Interesting note as I'm not sure if this is normal: When engine is off, ignition on and off Batt to engine gives 0.0Ω, when I start the the engine it jumps up to around 50Ω and then gradually drops and stabilizes around 5-6Ω, jumping to 7Ω every now and again and dropping again. The interesting thing about this is that Batt to body does not do the same yet they are effectively on the same 'line'. 2 x 35mm² cables connected to the battery, one going straight to body one going straight to engine.)

I unplugged all the sensors and plugs and ecu, so measurements are from plug end to ecu plug end.

MAP - gnd - 0.1Ω
- ref - 0.0Ω
- sig - 0.1Ω
TPS - gnd - 0.2Ω
- ref - 0.1Ω
- sig - 0.1Ω
The ICV pos/neg could be inverted. I noted how high the resistance is here however I have no issues with idling unless this is my problem here which I couldn't imagine as when the throttle is open for cruising that shouldn't make that big of a difference.
ICV - UP pos - 35.5Ω
UP neg - 0.1Ω
DOWN pos - 34.8Ω
DOWN neg - 0.1Ω

Injectors - Gnd - 0.1Ω
- Feed - 22.1Ω/22.1Ω/0.1Ω (On the ECU plug the feed wires from injectors 1 - 4 has 3 contact points so I'm just giving the readings of each pin on the ecu plug side. All 4 injector plugs read exactly the same on gnd & feed. The 22Ω corresponds to the voltage divider configuration values of the resistors.)

Coil - Black - 0.1Ω
GND - 0.3Ω
GRN - 0.0Ω
GRN2- 0.0Ω

Intake air temp - GND - 0.1Ω
Sig - 0.1Ω

Head Temp(under coil) - GND - 0.2Ω
sig - 0.2Ω

I hope everything makes sense.

0 ohms means open circuit. It has to have some resistance. Engine off, ignition off, put your voltmeter in resistance mode and measure again. From every ground point to battery -ve.

 

[svdwest]

0 ohms means open circuit. It has to have some resistance. Engine off, ignition off, put your voltmeter in resistance mode and measure again. From every ground point to battery -ve.

Hi Varnis9,

Thank you for your input.

I'll do the test as you described anyways as I've been struggling with this for very long and will do and redo everything and anything just to get this figured out but I respectfully disagree with your statement. My multimeter was set in resistance mode but when there is an open circuit my multimeter indicates so with "OL" (open line) 0 ohms on my multimeter just means the resistance is less than what it can display, doesn't mean it's absolutely 0, so the change from OL to 000.0 when touching the probes means it is reading something, just can't display the value.