Opel fuel trims is Fixed

I have a friend whose son bought an Opel Astra 1.6 L 2005 engine Z16XEP we were checking the engine mounts that seems bad and I noticed that the engine light did not light with the KOEO they have painted it black we pulled the code and it is P300 misfire with a fish bite at a lower speed short term fueltrim is -7 and longterm is + 17 at rpm 2500 fuel trim is close to zero at idle. it is a map engine only and someone has changed the coil cassette and done some work with the wiring to the ignition coil but I guess they could not fix the problem and painted the check engine light and sold the car. Opel seems impossible to find any wiring diagram so if anyone has some advice on what to check first.

I waiting on a real scanner so I will start to pull some 02 sensor data and fuel trim and I guess check MAP sensor voltage he will get laid off so I like to help him I feel this will get expensive at a garage.

So warmed up engine at idle is a consistent -7 on the STFT while the LTFT is +17? So total trim is around 10%.
A fish bite misfire can be tough sometimes. Good on you for pointing out this is a MAP engine. I was thinking classic vacuum leak with the fuel trim improvement with the throttle opened, but the speed density engines tend to NOT run lean at idle with a vacuum leak, though it does depend on where the leak is. I have absolutely seen in MAP engines a misfire from an intake runner leak on one cylinder. It may be worth doing the water test I've shown on locating vacuum leaks as a start.

Yes I try the water test I always liked it but I have forgotten it. The fuel trims at idle are close to Zero both long term and short term. At 2500 rpm longterm is +17 with short term correction at - 7 it is a little bit strange that it is only - 7 short term I guess it should have higher correction but it is steady LT 17 and ST -7.
I Have ordered a new Autel Autel MX808 scanner I will try that one the one I have now is a cheap Chinese UCANDAS VDM Wifi Scanner.

You'll find the respective diagrams in Autodata as well as in VIVID/Stahlgruber...,probably in Tolerance too.



I attached some screenshots,hope this will help you out. If you need something more visible let me know.

thanks, it helps a lot, European cars and wiring diagram is not easy to obtain for someone who does not work on cars full time. Now I just wait for the new scanner and it will be fun to try to fix the car

First a correction it was both MAP and MAF sensor engine. Did some test with my Autel scanner MAF was 2,2gr/sec idle and with snap 80gr engine is 1,6 L. Map was from 0.31 to 4.5 volt. The only thing I noticed 02 sensor 1 the heather was not active and the sensor still switching it seems to work I will test the heather circuit tomorrow with a test light. Still random misfire and running lean but not pegged lean. the car has bad engine mounts could a bad mount feels like fisbite misfire never heard about it. car runs great except when coasting at highway speed then the fishbite occurs. 02 sensor stays pegged 0.85 with full throttle and switches to lean when decel. Fuel trims great at idle.

The car had also a code P1300 misfire detected at a low fuel level?

On these Vauxhall-Opel engines if the EGR passages carboned up it can cause a P0300

P1300 isn't an issue you will always get it with a P0300 when the fuel level is below 1/4

Found where I got it The Independent Automotive Aftermarket Federation ( IAAF) --- from Hella tech info
www.iaaf.co.uk/news/hella-reveals-common...-vauxhall-engines-1/

Thanks, Andy great info for me.

The 02 heather circuit 18 ohms just been driving the car. I put a test light across the heather terminals and the test - light light up, but the Autel scanner showed heather circuit not active. I also tested the heather with amp clamp and it was 400ma. Sensor 2 pid for 02 heather showed active strange.
Had no bi-directional to test the 5 wire EGR did not have the guts to jump the ground to see if the engine stalled. I wish it was vacuum controlled .

I did energize the EGR solenoid and the car stalled. Did scope the ignition but found nothing but I guess this fault is intermittent. I will look into this further Next test is the fuel injector current ramp relative compression
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You can test fuel pressure and pump.

good point I will test fuel pressure I guess I try the water test also on intake.

Here's a wiring diagram.

Thanks paul6004 this is great..... can't work with the car so often but I am not giving up.

I have now long crank time and the same problem as before but I scoped the crank sensor it is not looking good almost like the scannerDanner video where he grinds of the synch notch, did I connect the right way I am sure I did one lead to signal the other to the battery ground.
The red trace is an injector

Here is the gap in the tone wheel I think it makes sense with the scope picture except for low amplitude will oil on the sensor and the wheel make a difference. This time I had both leads on the sensor. Pico file below

Got a picture of the tone wheel but it is too big 3 MB