reset the trims, unplug the MAF and fire it up . If it idles without getting rough then likely an ECU or sensor problem. If it goes rough could be fuel system/pump related.
If it idles ok then I'd plug the MAF in, unplug the lambda sensor and check the voltage with a multimeter. If the voltage is somewhere near 500mv and it continues to idle smoothly for an extended period i would lean towards a wiring or ECU problem. Beyond that id need to have a bigger think!

 

highest i seen the first O2 sensor go up to was about 230mv range, it flucuates between 78 and 230~ mv in opcom. but read time is slow. i will pojke at the sensor tomorrow with meter and retry a run with the MAF off too,

memory a bit fuzzy but i remember it doing the exact same with the MAF off. but that was before replacing the bad injector,


Will report back tomorrow. it dark here now again

 

My reason for disconnecting the MAF is the ECU should go into limp mode and ignore the MAF (obviously) and the lambda. But I don't think the ECU should be going into closed loop and fuel trimming within ten seconds of a cold start.

 

Coolant 70c from a cold start?

 

Coolant 70c from a cold start?

might have been a picture 1 or 2 minutes after start. but i noticed the closed coolant loop does heat up really quickly,

Just drove 1km at 2k rpm in a straight line and it already was at 80c on the gauge,

reset the trims, unplug the MAF and fire it up . If it idles without getting rough then likely an ECU or sensor problem. If it goes rough could be fuel system/pump related.
If it idles ok then I'd plug the MAF in, unplug the lambda sensor and check the voltage with a multimeter. If the voltage is somewhere near 500mv and it continues to idle smoothly for an extended period i would lean towards a wiring or ECU problem. Beyond that id need to have a bigger think!

just did some more tests, aand great.... opcom keeps crashing when i try to log CSV's for some reason. so i got no readable data... ugh, i really need to get a MDI2.

driven the car for exactly 1km and noticed some odd issues,

1 the Traction control seemed to randomly kick in for a second when i turned right... atleast. i saw the light flash for a second despite barely accelrating,

before i got a alignment, it kept kicking Traction control on when i did normal right hand turns in 3rd gear too, odd...? i do have my 1.4's drive shafts on here which had NO ABS. but i think it has the Sensor ring....



2. the idling got even worse after 1km of driving at near dead steady 2k rpm on cruise, it now sounds like it has a fat cam installed... hmm.




unplugging the MAF then starting it makes it run identical, even if i leave it sit for a little bit.

but then if i plug the MAF back in while it is running, it does calm down a bit,

the only code in OP-COM that shows up is Missing EGR since valve gone, and P0170 exhaust lean.

the P0170 did not used to show up but now it pops up consistently even after TRIM resets..

here is a video from after the test drive,

I have unplugged and plugged the PCV valves incase it might be getting too much air from the crank case. but it idles exactly identical with both the pipes blocked off with my fingers,

No leaks from the tank EVAP line. cannot blow trough towards the tank with the valve closed and the lines are not leaking,

that idle is when i just pulled back in the car park. concerned me A LOT. because it sounds extremely voilent in the car, but when you stand outside. the engine barely shakes or moves. so not sure why it's so loud inside...

Then the 2nd part. i shut the car off. unplugged MAF. started car, same behaviour, plugged MAF in while car is running, and you can hear it calm down a hair, but not much.

I will swap back the og 210k km maf see if the KG/s values changes, but the MAF on here right now came off the astra that this engine came from. so 92.000km and running perfect,




I've just ordered a Simtech 71.1 ECU. it should work on the corsa C and be less prone to failure according to some users, we'll just wait for now. getting really pissed at this

 

Another thought, is this the engine that had the inlet manifold off for cleaning and a decat manifold fitted? if so are you absolutely sure there are no air leaks on either?

Also are you sure it has traction control? in the UK at least that was a rare extra cost option.

 

this is the Corsa C GSI with a replaced engine. the old engine had burned exhaust valves.

this is the inlet manifold of the original broken engine since the inlet was different for corsa/astra Z18XE.

i have used new gaskets for block and throttle body and exhaust.

i've just did some more testing. emptied a bottle of brake cleaner and there is zero intake leaks.

no response from throttle body/evap lines/brake boost lines/PCV lines/intake hose to MAF.

sprayed up and down the block around the intake to block too and nothing either.

even checked the valve for the fuel evap.


Also. yes i have Traction control. i have done a clutch dump before and it very much cuts engine,

i took a right turn at 5-10mph and the light just briefly flashed on, seems odd.

 

You say with the engine off, ignition on the lambda reported 400mv , was the lambda hot or cold?

 

it was still a little warm from the test drive a hour or 2 before it. the MAF also reported 30C intake temps until it started and sucked it down to 20c which was ambient.


i just checked again. not ran all day. both O2 sensors read 412mv and opcom labels it as RICH.


i messed about with the ecu today took it out. checked pins. all good. put it back. and it actually ran even worse. 3 cylinders and actual sad.

for the first time it was running rich for just a split second and then went right to leaning out and actively dying... odd..

checked opcom logs. ECU was reset so no trims. sensor 1 was stuck at 400~ mv range. at rich condition the entire time.

but sensor 2 this time was fluctuating between 400 and900 ranges. and towards the end of the test, was settled at 118mv. lean condition.

while sensor 1 was still stuck at 412mv.


this is doing the exact opposite it did before where sensor 1 was fine and 2 froze... wtf

 

That looks like a faulty lambda sensor or bad wiring or ECU problem. 400mv is on the lean side of the range but without the engine running there should be plenty of oxygen in the exhaust and give a very lean reading, assuming the heaters have got it up to temperature and if it isn't up to temperature there should be no voltage at all. Can you unplug the lambda,start the engine and get a reading with a volt meter? Also, I know you stated it was a genuine sensor, but, when we needed to replace the lambda on my brother's z18xe we had to go through three brands one of which was Bosch as they were being supplied with the correct part number but the plug wired incorrectly .

 

Ignition on engine off.

ECU TO SENSOR with sensor unplugged
TOP TO BOTTOM
Pin1 ground
Pin 2 battery voltage
Pin 3 0.40v
Pin 4 3.79v

 

What I think you should have is,
Pin 1 brown/blue, this will be earth if the ECU has the lambda heaters turned on otherwise is likely to be open circuit.
Pin 3 Red/white, battery voltage
Pin 2 brown/white,
Pin 4 brown/black, these two are the tricky ones as I dont know if the signal is ground isolated but if you measure between them I wouldn't expect to see a significant voltage, I will try and measure one over the weekend.

 

Got the ECU in and programmed and seems like something was wrong with the lambda circuit on the old ECU?


Instead of the first O2 sensor freezing up to 412mv or other values,

it now seems to sit at between 0 and 50mv at idle. and goes up to 7 to 900mv when i rev it, better than just the signal freezing, but i think that means the sensor is at fault?

opcom also seems to lag less when reading the live data now with this ECU, the updates is atleast double the speed.


Here's the O2 sensor plug with the sensor plugged in. it is upside down compared to last time so pin 1 is 4 in this image.

 

Sounds like you have a vacuum leak or a leak before the first o2 sensor to me?
Which exhaust manifold do you have?
There still are a number of 02 sensors out there that are not wired correct for Vauxhall/Opels even top brand ones. This was a big, well know issue back in the late 90's early 2000's.

 

STAINLESS EXHAUST MANIFOLD DE CAT DECAT FOR VAUXHALL OPEL ASTRA G MK4 1.8 Z18XE | eBay this is the manifold. no leaks that i can find, a first for me with exhausts. i can run my fingers along where the exhaust ports are and feel nothing,

The intake. i have sprayed brake clean everywhere, even on the fuel tank lines under the rear seats, but no response to anything.

only place i have not checked is spraying it where the clutch/brake pedal is. someone suggested me to try there since if the brake booster leaks it's internal from cabin.


anyway.. i did put my ECU in the oven and this time the engine ran better with maf unplugged LMAO.


picked up this 13k mile tigra ECU, this came from a car that was bought in 2005. and crashed in the same year, and then sat till crushed earlier this year. what a story lol.

got it reflashed to GSI firmware. should be the stock expected firmware, which should cut out all the vague question marks...

going to program it in later today and see if it runs happier,

i have been told by the dude who programmed the firmware for me, that -50 fuel trim means.. positive or something like that, he said it's quite counterintuitive to read,

so it could still be a fuel pressure issue. but ordered a pressure testing kit anyhow,

 

Love reading these stories , but sorry you are having issues .
Amazing the time effort and money you are obviously pouring into this project .
Hope you solve all the problems and get a perfect motor .
Sorry I can't help on any technical knowledge , but cheering you on in the background .
Andrew

 

Love reading these stories , but sorry you are having issues .
Amazing the time effort and money you are obviously pouring into this project .
Hope you solve all the problems and get a perfect motor .
Sorry I can't help on any technical knowledge , but cheering you on in the background .
Andrew

the one perk is. i won't have to replace anything on the front end for the next 10 years

 

i wonder, the 2nd O2 sensor is from the donor car where the engine came from.

i have not taken the sensor off since it came pre attached to the flexi-part, i assumed it would've been fine so just left it on,

but it could be a mismatched sensor, someone just suggested me that having a mismatched set of Pre and Post o2 Sensors can cause issues,


since i only ordered 1 new Pre cat O2 sensor. it might be related perhaps, i've also ordered a new post cat sensor from same brand and price class (bosch sells 40 and 90 bucks sensors and each have different design)

Anyways, have not installed new parts yet, but i noticed whenever i start the car now, you can smell from the exhaust that it switches between running rich to running lean, it definitely did not before on the old ECU.

Tomorrow the 2nd O2 sensor should arrive and then i'll kwak them both on, my fuel pressure and vacuum testing gauges have arrived so more testing tomorrow,


\/ old sensor has holes in the stem. new more expensive sensor only has holes in the tip,

 

another set of O2 sensors installed. also replaced the 2nd bank o2 sensor for the same expensive sensor (correct pre and post cat)

and now idles fine, seems like the OLD ecu was also frying the O2 Sensor possibly.

 

Glad you have sorted your tickover running issues
Amazing knowledge on the ECU changeover and programming hope it wasn't too costly or has the budget gone overboard recently .
At least it has fixed the issues and not been parts darts with no results
Well done 👍

 

Glad you have sorted your tickover running issues
Amazing knowledge on the ECU changeover and programming hope it wasn't too costly or has the budget gone overboard recently .
At least it has fixed the issues and not been parts darts with no results
Well done 👍

hmm. the ECU was 175. getting it programmed to factory GSI software was 80. then 20-25 for the opcom dongle. i did not need the original security code. or have it "reset" reflashing it trough proper tools will wipe it regardless,

then 100+90 for 2 lambda sensors,


besides that i did throw bunch of money on new injectors (old ones still tested bad, so eh not a waste) and a new MAF (yeah i ordered brand new one incase the one from the good running engine was bad. but imma just slap it on,

i intend to keep this car for a long forseeable future, it's rust free on bottom so atleast no more sensor issue for the next few years,

 

Great as a long term investment good job you can do the labour yourself you have yourself a lovely motor

 

driven 110km today, zero issues.

the fuel trims are at literary 0%. if i rev it up down hard. at most it will show -1 to +1% figures.



So case closed. fault ended up being ECU+O2 sensor fault.

Advise to replace 71.0 ecu for 71.1 version ecu if anyone else get's in the same situation . tigra's usually have them,