Xoutpost.com - Throttle tip-in issue/stumble (3.0 5-speed)

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Quote:

Originally Posted by paramax55 (Post 1244971)

You can do a search for e53… that will keep you up past your bedtime.

Oh man.. How many times have I been here! LoL… :yawn:

E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Quote:

Originally Posted by paramax55 (Post 1244929)

My X5 5-speed does the exact same thing. I've never tried to fix it because I know the cause and I've just never felt it worth the trouble to fix it. It's the off idle tip-in map.

I've had two e30s that did this exact same thing in the past. The first car was just an eta and it drove me crazy. I figured it was just an old car and running bad. When it was wrecked, I bought an "i" car and used the tranny from the eta to make the newer one a 5-speed. It had the same off-idle problem so I knew it was a BMW thing. I turbo'd it and put in big injectors, so I was forced to remap it. I used a Moates eeprom emulator and free software (I don't remember the name). But the definition file called the map "throttle enrichment" or something like that. Once I fixed that map, it was smooth as silk.

Any recollection what the table name was? Now that i'm in TunerPro there are approximately 5 billion tables, many without good descriptions or titles. Did you end up just increasing the values in the table incrementally to smooth it out?

Edit: Are they these tables? These are for warm engine. There are three additional for cold engine.

ip_tco_2_pl_ivvt_1__n__maf (Injection time used for bank 1 during part load. Warm engine)
ip_tco_2_pl_ivvt_2__n__maf (Injection time used for bank 2 during part load. Warm engine)
ip_ti_tco_2_is_ivvt__n__maf (Injection time used during idle. Warm engine)

These also sound possible:

ip_tib__n__maf (Basic injection time)
ip_ti_wup__n__maf (Warm up correction for injection time)

Edit 2: Found some documentation on the MS4X website about "Tip-In Enrichment / Cylinder Rewetting" with the note at the end, "Applying 5% steps to the whole table ip_ti_pvs__pvs__n in either direction shows good results". I'm probably going to try tweaking this table and see what happens.

I also got a copy of TSB B 12 39 06 (which supercedes B12 204 04) and it only applies to production dates 10/3 - 10/4. Mine was built 09/3 and therefore the bulletin doesn't apply.

Here goes the rabbit hole...found another thing that might do it:

Anti-jerk "_AJ_" retards ignition during rapid throttle opening to smooth out torque (can be removed by increasing c_tco_min_aj to 142.5C).

I was surprised how easy it was to upload the new maps to the car using MS4X. Was expecting some errors and troubleshooting but it worked right away.

For the record, I did go ahead and replace the fuel pump with a new Carter unit. It seems "somewhat better" (although I've learned that when a problem isn't totally fixed, any improvement is usually a placebo).

Does the pressure stay the same when hitting the throttle? After i replaced FPR the rail pressure was constant no matter what.

Quote:

Originally Posted by andrewwynn (Post 1245076)

Does the pressure stay the same when hitting the throttle? After i replaced FPR the rail pressure was constant no matter what.

Yes, I did check it after the FPR was replaced and it was completely steady.

Another work around you could try is to pull up/down with a resistor the air charge temp sensor in the intake to make it look like the air is a bit cooler than it really is. The DME looks at that for "tip in" fuel amount. That being said I finally got my temp gauge problem fixed by cleaning the connector in the E-box, I might be imagining it but my tip-in throttle response seems better too!

Just to follow up on this - it's hard to tell if it's 100% "fixed" because I don't know what it was designed to feel like when new, but it feels about 80% better and overall I'm happy with it.

To recap:

The elusive TSB didn't actually apply to my build date, so no luck there.
In addition to the maintenance items throughout this thread, I increased the throttle tip-in fuel map "ip_ti_pvs__pvs__n" by 10% across the low-throttle regime <= 2200 RPM and 5% across the mid- to high-throttle regime <= 2200 RPM using TunerPro (the tuning software) and MS43X (the software to transfer the data back and forth to the car's DME). I intended to do an adjustment of 5% only, but the minimum increment is larger than this (something to do with the table entries being stored as 8-bit values).
I also disabled the anti-jerk feature, which retards timing on throttle tip-in to supposedly smooth things out, by setting c_tco_min_aj to 142.5C. This means at any engine temp below 142.5C, the feature is turned off (and the engine would never reach this temperature without self-destruction).

It seems a bit ridiculous to resort to tuning to solve an issue like this on a 100% stock BMW but it was easy enough to try and seems to help. The only rationale that makes sense to me is what is explained on the MS43X wiki: The throttle tip-in fuel is extra fuel designed to wet the cylinder surfaces.
With age and carbon build up the surface area of the cylinder may have increased. :dunno:

I think what you are describing as "throttle tip-in" I have referred to as "throttle pumps," which is when you dump a bit of extra fuel in when the throttle is being opened rapidly. I don't think it is for wetting the cylinder (indeed that sounds like something which is undesirable) but rather because the air mass flow meter doesn't measure as quickly as the air starts moving, so you have to add in some fuel before the airflow meter is really telling you that it needs it. I might be wrong here, I am not an expert.

Quote:

Originally Posted by Masospaghetti (Post 1245639)

It seems a bit ridiculous to resort to tuning

Pretty rad we have an E53 tuner on the forum. :2thumbs:

E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Quote:

Originally Posted by Bdc101 (Post 1245645)

I'm also not an expert by any means, but before you could atomize the fuel you'd have to wet the surfaces, right? i.e. there's a certain amount of fuel that condenses on the cylinder walls and piston top and doesn't contribute to the A/F of the ignitable mixture?