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Hi everyone, I am new here and hope you people would be able to help me out. I have a Liana 1.3 manual version. I recently did an engine swap to m16a from a Suzuki Swift Sports Assembly. Using the stock m13a manual ecu in my car. Once everything was fitted and in place, we started the engine and it fired up successfully and revved like an absolute dream. We let it idle for 10 minutes and it was working fine. After that when we went for a test run of the vehicle, it started misfiring after 3-4 minutes of running. Now the situation is that car starts up easily but engine dies down immediately if the throttle is not pressed. There is constant misfiring in all cyinders and car bogs down at around 4000RPM above.

We have tried replacing new spark plugs, new ignition coils and checked fuel pump, but all in vain. Everything seems fine, there is no error code present on ECU but the engine wont idle and keep misfiring continously, the plugs are coming out quite black and dark indicating extremely rich fuel mixture or unburnt fuel.

Can any expert here guide me what next step I can do to resolve this issue? Please help me I am really frustrated with this problem.

Thank You.
 

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You need the services of a LIVE DATA SCANNER, monitor the B1S1 and the MAF as a baseline... Check the ECU for Freeze Frame Data...

Not sure if the M13a ECU is capable... and stop chucking parts at it!
 

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Hi,

Sorry for late reply and Thank you for the prompt response @aquanaut20 . That engine itself was problematic. It had leaking valves issue and was returned to the seller for a replacement. Now I have put the replacement engine on my car. This m16a seems to be working good and no misfiring noticed yet. Even the m13a ECU seems to be controlling it nicely.

The only problem I am facing in this new replacement is that the engine keeps knocking above 2000 RPM. So I always have to up-shift before RPM crosses 2K. Hence, I am unable to realize the full power and potential of this engine. The old m13a never used to have knocking problem. This problem appears once the engine has reached its operating temperature (i.e Coolant temperature reaches 80 C+ ). So when the car is cold for like 5-10 minutes after a cold morning start, there is no knocking. But after 10 minutes, knocking problem appears.

This can be due to the plugs or the octane level of fuel since m16a is a high compression engine (11.1:1) in comparison to m13a. Or its also possible that this engine has already much used and kept in storage for long, so it might have lots of carbon deposits which are raising the temperature inside combustion chamber unnecessarily. So kindly recommend me three things please?
1-) What spark plugs would you suggest for my use? I am currently using NGK BKR6E-11 spark plugs.
2-) What fuel should I be using? What fuel does Suzuki swift sports is recommended? I am currently using Premium 92 octane fuel.
3-) Can you guide me what products can I use to burn carbon buildups on my engine?

Thank you once again.
 

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I strongly suspect you have pre-ignition knocking due to low octane fuel or insufficent fuel (lean-out at revs) because you will be using the 1.3 fuel injection maps on the 1.6 injectors.
Get some decent fuel in it first before you melt pistons or destroy the engine, then check mixtures by looking at fuel trims.
95 octane or better is a good rule of thumb in engines over 10.5:1, at 11:1 i'd be using 95 or 98 octane myself.
Plug heat range can be easily checked visually but the 6 range should be fine.
 

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I strongly suspect you have pre-ignition knocking due to low octane fuel or insufficent fuel (lean-out at revs) because you will be using the 1.3 fuel injection maps on the 1.6 injectors.
Get some decent fuel in it first before you melt pistons or destroy the engine, then check mixtures by looking at fuel trims.
95 octane or better is a good rule of thumb in engines over 10.5:1, at 11:1 i'd be using 95 or 98 octane myself.
Plug heat range can be easily checked visually but the 6 range should be fine.
I did one tank fill up of 95 octane fuel and the knocking was reduced by almost 70% but it was still there. What can I do now? 98 octane fuel not available here. Can't this be countered by going for heat range 7 or 8 plug?

Secondly, can I find a Liana compatible 1.6 ECU that will also help in this situation? My friend has the same car and he is running m18a engine on his m13a ECM but he has no knock problem, his car seems to run fine on 92 octane fuel and he makes some decent power too
 

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the fact the knocking reduced on the higher octane fuel points to fuel grade, quantity and possible timing issues. Changing heat ranges to a colder plug may help but you shouldn't need to change from the standard heat range. I suspect theres an inherent problem in the way the 1.3 ECU is trying to run the 1.6 engine and the data the
ecu is getting from the sensors.. Time to diagnose this properly, start by looking at fuel trims and timing advance in real time and see what its doing..
 

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Discussion Starter #7
95550


Here is the screenshot of engine data at idle. I will try to record the video at the point when knocking starts occurring.
 

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Thats enough, the fuel trims say it all, its leaning out excessively at idle for a start, re check at 2000 and 3000 rpms no load and post the results as I describe below, run at least 30 seconds at these revs and watch what the trims are doing and note the results please. I think you are excessively lean and this is causing the detonation. No amount of fuel octane or colder plugs will help this. The fact higher octane has made a difference is its resisting detonation better

The total fuel trim figure should average to less than - or + 10 very worst case. outside this and the ECU is running a real risk of not being able to control mixture correctly. If it gets over 20 then you're in serious trouble and need to look at things before something dies.

If you can get your scanner to show graphs it will make things easier to determine whats going on if you can look at trims and lambda at the same time.

Humor me and unplug the MAF sensor and see what they do at idle and at 2000 rpm. That will force the ECU to use default values and default airflow. I'd be expecting more like 3.5 to 4 g/s on MAF which is making me suspicious. You will get codes but ignore them, might not idle nice but if it stops knocking and trims look better we know what were looking at. Check the intake very carefully from the air filter element to the throttle butterfly for any leaks between the MAF and the inlet manifold.

Lambda value looks suspect too, at stoic or correct mix, it should be about 0.45 V so thats showing very lean at 0.075V which confirms the fuel trim figures
Check its cycling between about 0.10 and 0.9 V as it detects changing mixture in the exhaust.
The ECU is thinking its running too rich at idle–High negative fuel trim corrections can be caused by MAF sensor problems, high fuel pressure, leaking fuel pressure regulator diaphragm, faulty evaporative emissions components, leaking injectors, defective O2 sensors, exhaust leaks/pinholes before the O2 sensor, coolant temp sensor problems, and base engine issues such as low compression and incorrect camshaft timing.

next test to do after the MAF test is note the fuel trims at idle and increase engine speed to 2000 RPM and hold.
If the STFT immediately decreases and moves to acceptable levels (+ - 2 ish at steady throttle) and the LTFT slowly starts to come back down, you have a vacuum leak somewhere.

I suspect (initially) that you may have a MAF issue as the cars seeing too much fuel for the airflow and is leaning it out at idle.



now, how fuel trims work....

Short Term Fuel Trim (STFT1 and STFT2 If you have a second FT) is the computer’s immediate response to adjust the air/fuel ratio. In positive corrections, fuel is added to adjust for a lean condition, while negative corrections respond to a rich condition. STFT corrections represent the current engine run cycle and react very quickly to O2 sensor input. If you were to create a large vacuum leak at Idle by disconnecting the PCV hose, the computer would immediately add positive fuel trim to balance the mixture. Blip the throttle and watch what it does. Short Term Fuel Trim is not stored in Keep Alive Memory (KAM) after shut down and automatically resets to 0 for the next start/run cycle.

Unlike STFT, Long Term Fuel Trim (LTFT1 and LTFT2) is learned over time while in closed loop operation. It is stored in the KAM and used for open loop fuel calculations (like start up and wide-open throttle). LTFT is a coarser adjustment and also works to keep STFT within specification.
LTFT may take 10 miles of steady state driving or so to stabilise, easiest way is to clear ECU memory and drive to get immediate LTFT results with current conditions.

95551
 

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Discussion Starter #9
Thats enough, the fuel trims say it all, its leaning out excessively at idle for a start, re check at 2000 and 3000 rpms no load and post the results as I describe below, run at least 30 seconds at these revs and watch what the trims are doing and note the results please. I think you are excessively lean and this is causing the detonation. No amount of fuel octane or colder plugs will help this. The fact higher octane has made a difference is its resisting detonation better

The total fuel trim figure should average to less than - or + 10 very worst case. outside this and the ECU is running a real risk of not being able to control mixture correctly. If it gets over 20 then you're in serious trouble and need to look at things before something dies.

Humor me and unplug the MAF sensor and see what they do at idle and at 2000 rpm. That will force the ECU to use default values and default airflow. I'd be expecting more like 3.5 to 4 g/s on MAF which is making me suspicious. You will get codes but ignore them, might not idle nice but if it stops knocking and trims look better we know what were looking at. Check the intake very carefully from the air filter element to the throttle butterfly for any leaks between the MAF and the inlet manifold.

The ECU is thinking its running too rich at idle–High negative fuel trim corrections can be caused by MAF sensor problems, high fuel pressure, leaking fuel pressure regulator diaphragm, faulty evaporative emissions components, leaking injectors, defective O2 sensors, exhaust leaks/pinholes before the O2 sensor, coolant temp sensor problems, and base engine issues such as low compression and incorrect camshaft timing.

next test to do after the MAF test is note the fuel trims at idle and increase engine speed to 2000 RPM and hold.
If the STFT immediately decreases and moves to acceptable levels (+ - 2 ish at steady throttle) and the LTFT slowly starts to come back down, you have a vacuum leak somewhere.

I suspect (initially) that you may have a MAF issue as the cars seeing too much fuel for the airflow and is leaning it out at idle.



now, how fuel trims work....

Short Term Fuel Trim (STFT1 and STFT2 If you have a second FT) is the computer’s immediate response to adjust the air/fuel ratio. In positive corrections, fuel is added to adjust for a lean condition, while negative corrections respond to a rich condition. STFT corrections represent the current engine run cycle and react very quickly to O2 sensor input. If you were to create a large vacuum leak at Idle by disconnecting the PCV hose, the computer would immediately add positive fuel trim to balance the mixture. Blip the throttle and watch what it does. Short Term Fuel Trim is not stored in Keep Alive Memory (KAM) after shut down and automatically resets to 0 for the next start/run cycle.

Unlike STFT, Long Term Fuel Trim (LTFT1 and LTFT2) is learned over time while in closed loop operation. It is stored in the KAM and used for open loop fuel calculations (like start up and wide-open throttle). LTFT is a coarser adjustment and also works to keep STFT within specification.
LTFT may take 10 miles of steady state driving or so to stabilise, easiest way is to clear ECU memory and drive to get immediate LTFT results with current conditions.

View attachment 95551
Thanks for the detailed reply. I will do the tests as you have suggested and post back the results, but there is however one thing I donot understand. In the beginning of your post, you have mentioned that "its leaning out excessively at idle" and near the end of the post you have mentioned that "The ECU is thinking its running too rich at idle". These both points are reciprocal of each other? I am confused.
Secondly, this car doesn't come with a MAF but a MAP sensor, so you want me to unplug that?
 

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Sorry for the confusion, its probably the way I describe things.
The ECU thinks the car is running rich, this is usually caused by a faulty input to the ECU, so its possibly either a faulty sensor, or incorrect data coming from somewhere.
To compensate for what the ECU is perceiving as an over rich exhaust, the ECU is removing fuel from the engine to try and balance it to the correct air / fuel ratio, which is making the engine actually run "lean" causing detonation.

As I don't know exactly what sensors you have used from the original engine, or whether the cam / crank sensors will function correctly with the ECU you have I can only suggest places to look. Injectors could also be another item that could be causing this. The fact its missing and stumbling around at idle as well as having reduced power points to either a mixture issue or a timing issue.

What does the timing advance do at steady revs?

you have a MAF sensor somewhere, where is the 1.26 g/s air rate coming from? it may be combined with the MAP sensor.
 
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