Low RPM Knock Retard

[mituc]

With LTFTs reset, using stock CX-7 partition breakpoints, the STFTs are around 10-12% at idle and they increase from there, maxing out up to 25% even under light acceleration.

Well, that is one reason why we use different fuel trims partitions, because the stock calibration assumes that a correction will be the same in both vacuum and boost (see the last partition). Which is totally wrong.

[zaclaw]

With LTFTs reset, using stock CX-7 partition breakpoints, the STFTs are around 10-12% at idle and they increase from there, maxing out up to 25% even under light acceleration.

Well, that is one reason why we use different fuel trims partitions, because the stock calibration assumes that a correction will be the same in both vacuum and boost (see the last partition). Which is totally wrong.

What are the recommended partitions then? STFTs are still crazy even without learned LTFTs.


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[mituc]

At this point it's a lot easier and practical to simply pressure test all the tubing, including exhaust, rather than trying to spend hours to make a tune around the current defect.

[zaclaw]

Found a significant leak at the turbo going to the manifold. Didn’t see the leak last time I smoke tested exhaust. Ordered new hardware kit from Corksport.

[mituc]

You can get them from a lot of places, no need to wait for these from CS... I'd go with the OEM ones to be honest if the ones currently there cannot be tightened properly.

[zaclaw]

Well, replaced the turbo gaskets and that fixed the exhaust leak. Engine still runs terribly though. It misfires almost all the time now. Before it was only really bad when engine was cold. Severe hesitation/lack of power at low RPMs, smooths out above 3k. Backfires a lot and engine vibrates. Fuel economy is trash.

Misfire moved to cylinder 1, seemingly after replacing cylinder 2 injector. Before it would alternate between cylinders 1 and 4. SP63 said my core’s inner filter had collapsed, preventing testing and refurbishing, and possibly clogging the nozzle. I suppose the next thing to do is replace the other 3 injectors but it’s a pain and ETA is 1-2 weeks. Cannot test fuel injectors with scan tool by commanding them to turn off when engine is running. It worked with the same scan tool on a gen2 MS3 the other day. I also tried to do it with FORScan, didn’t work. So without being able to test it, I’m stuck waiting for more parts to take another shot in the dark.

[mituc]

Ideally you should send all the injectors for servicing, and when you put them back in replace all the o-rings between the injectors and fuel rail as well as the injector seals if they are not reusable (the brass ones can be reused just fine as long as you do not damage them when you remove the injectors from the head or the seals themselves from the injectors).
Cause for random misfires was also the coil pack wiring. So since you take everything apart in that area just take a look at the harness and inspect it visually.
Also try to move the coils between cylinders and see if the misfire code migrates with the coil. The coils from these engines do not fail often but when they do the behavior is quite misleading.

[zaclaw]

I’ve moved coils around, no change. Replaced plugs. I’ll inspect the wiring again.