Hi All

Been struggling a long time to tune my AEB 1.8T, posted similar questions a few months back but gave up for awhile and now want to try again.  Problem is that I have large timing corrections on stock ECU settings.  To me, everything looks okay for A/F ratios that I get by using a wideband install; so no longer sure what else it could be except maybe my intake air temps are too high?  Only way I seem to get rid of these CF is if I run some e E85 mixed into my 93 octane fuel.

Wondering if something is wrong with my stock inter-cooler or if everyone that tunes when hot outside (90 degrees F days) have to use upgraded FMIC setups. Take a look at my log, did this in the morning so temp outside when I did this log was about 75 F.  Do you think IAT of 35+ C could cause the type of timing corrections factors I see?  Seems I have been asking a lot of new questions lately so thanks for whatever help you can provide.

Thanks Mocke,  think these IATs are typical for a stock IC?   I already checked it and is clean w/o oil accumulation.

I can see the same behaviour on my Passat 1.8t.
Stock engine and software. IATs at 30-50degC.
Timing retard up too -8 deg on 95 RON

I can second Mocke's experience, only with a 2002 Jetta. Really hot IATs like you are seeing in the summer with the associated CF corrections. I 'upgraded' to possibly the cheapest Ebay front mount. I did it to get quantitative data on how bad they are for a forum disagreement. I ended up being pleasantly surprised by the performance. For $200 it was a worthwhile mod.

Here is a graph of stock SMIC vs Ebay FMIC (8x3x22 IIRC):



Both runs were done two days apart on the same piece of road following a 'warm up routine' of driving to temp through my neighbourhood. Low load, no stopping to avoid heatsoak, until coolant is 90* then hit the freeway on-ramp (at the edge of the 'hood) for a pull. Both runs fell short of redline due traffic. Ambient at both times was 9*C if IIRC.

As you can see it made a decent difference. I don't have my car laptop at hand for the logs, but I believe I went from -4.5 CF to -3.0 CF with the same timing map. Just for your consideration... Even a super crappy FMIC beats the stock SMIC hands down.

That is better than I hoped.  I think there is a map that retards timing based upon IAT such that i pre-corrects what we see in CF in the logs, so your FMIC may actualy be doing even better than what appears in the logs for reducing CFs.

Probably will upgrade to an FMIC when I no longer can resist the temptation but gonna screw around for awhile first with different E85 blends, sometthing between 50/50 and 25/75 : E85/Reg_87 to see just how much I need to really tune up the timing before seeing a CF.  I think 25/75 should give me a 93-95 oct value.  I know at high E85%, you never see timing corrections.

Edit- NVMND, I see your plot is not CF but actual timing.  Still better than I would have thought.

Edit Edit - Geez, i need to go to bed, those are temps

Your stock Lamba is 1, but as you get into knock pretty quickly it is folowing MKR fueling ands up with BTS fueling due to high EGTs.

Well just when I think I'm starting to understand things...,  So my lambda starts out at 1,then due to knock, lambda drops like shown in my logs, after which my lambda then becomes controlled by exhaust gas temps?  I was thinking CF changes timing, did not realize it controls fuel too. Had no idea about EGT.  Thanks for the tutoring lesson.

Edit:  DD posted when writing this.  I'm running M5.9.2.  Does CF change fueling on this ECU? don't think I have EGT monitoring capabilities.

I have seen similar knock CF like your log indicate. Those seems to be more or less normal for 90°F (32°C) ambient temps inclusive with 95RON octane fuel. Take in account CF retard table starts around IAT @ 40°C with some few degrees.