mrjetskey

I am a retired Drilling supt. that has always been mechanic by hobby or professional. I can't find what is causing 2013 e-350 to feel like its missing when first started until warmed up. It has been to dealer in past by previos owner for this twice with nothing found. It runs great when warmed up, I did reset trans learning mode and that seemed to help as my wife and I drive totally different. car is 2013 with 59,000 miles.All service performed by dealer until I purchased it a year ago. Any ideas ? It runs great it just seems for first 1/4 mile its a tiny bit rough. If I manually shift its much better. Is this normal? seems like its worse when its not driven for 4 or 5 days. my wife doesn't notice it but it bugs me. Thanks in advance

KEY08

Have you had the transmission fluid changed? Plugs?

911st

I am having the same problem with my 2011 E350 with 60k miles. Rough from first start up at idle and when first drive till warmed up. Then is very smooth.

Runs great after warmed up so not the motor mounts. Replaced spark plugs and they all were perfict and no check engine warnings so probably not an injector. Ran a couple of tanks of Techtron through it. Did an oil change. Transmission fluid changed last year.

Does anyone know how long the O2 sensor runs in open loop? Help!

pb39374

Could it be vibration from bad engine/tranny mounts?

911st

Thank you for the reply!

I kinda thought that too for a while. However, it runs so smooth after warmed up I am not thinking so.

Last night I tried removing the ECU fuse overnight hoping it might reset the cold start system but that did not do anything.

Also thought might be an O2 sensor but I do not think they are in the loope on start up.

pb39374

ok, maybe try cleaning the MAF sensor?

911st

I will try that, thx.

911st

Cleaned the MAF with MAF cleaner and did not help at all. Also cleaned the elbo to the throttle body and the face of the throttle valve.

Ordered a new MAF because they are cheap and easy to replace.

I am not sure the MAF or O2's are used during cold start but was worth a try. Anyone know???

Mud

Cold starts (open loop) the ECU will run the engine in pre-programmed short term fuel control parameter until the O2 sensor elements heat up, usually within a minute or so. MAF is used in open loop so the ECU knows what the air inlet quantity is, along with other sensors, such as evap, crank/cam sensors, etc. Open loop typically refers to fuel control - when the O2 sensors are active the ECU shifts to closed loop (short term fuel control based on O2 sensor feedback/voltage).
When I hear about roughness at cold start that decreases or disappears, my first suspect is a vacuum leak somewhere. I look at live scan data even though short term fuel trim (STFT) is pending until closed loop, since it's the immediate response of the ECU to O2 sensor voltage. You should be able to see long term fuel trim (LTFT) strategy - it may be an indicator of a slightly lean condition. Lean condition will cause trims to go positive, engine is adding fuel. Rich condition will be the opposite with negative trims, engine is removing fuel. Trims can vary slightly from different engines, but generally 0 is perfect, with normal fluctuation of +/- 5%, sometimes a bit more. The ECU has a threshold programmed that will command the CEL if the mix goes too far either way.

You can also (if you have a decent scantool) look at misfire counts for each cylinder. Look at the cylinders/counts at cold start to see if any cylinder(s) are showing misfire that goes away or drastically decreases as the engine warms up. You can also check the data for misfiring at idle and say around 2500 rpm after the engine is at temp.

Next is carefully checking hoses, intake gasket, etc. - anything that has to do with intake vacuum. Sometimes it's obvious and other times it's more involved, smoke test or spraying cleaner around to see if engine speed changes. Intakes such as on GM LS engines are known for the cold (rough) to warm (smooth) transition. When the engine is cold, a slightly bad/leaking intake gasket will be contracted and allow a small air leak. As the engine warms, everything expands and seals up. You can also sometimes see an intake gasket issue even warm - the STFT will go positive (over 5-10%) at idle (meaning lean condition from vacuum leak excess air), then will go back to 0 or close when idle speed is increased. This is because the increased engine speed is now able to use that excess air).

I'm just making an observation here, but I would avoid buying parts until the engine can be inspected more closely and live scan data can be reviewed.
I've also found that some engines just seem to have a very slight idle roughness, even with all components at 100%. Drivability is excellent just that annoying very slight feel when at idle in park. Our 2011 Silverado 5.3 has been like that since we bought it.

911st

Great into! Thx!

Time for a close inspection and test for a vac leak. Maybe research into and investment in a scan tool.

911st

Mud,

Bought a scanner (iCarsoft II). No codes I could find. I had driven the car earlyer in the day so maybe not a cold start.

STFT seemed ballanced on start up ranged -5 to -1.6 for both sides.

LTFT did not seem ballanced!!!
Bank 1 was 9.4% and Bank 2 was 3.1%.

Any thought what might be up?

911st

Following up. I just finished putting in new motor/trans mounts and wide band O2 (air/fuel) sensors. Problem solved!!! Smooth as when new! It was probably the mounts.

I will check my fuel trims later to see if I still have a noticable varance between each bank. If the trims are now ballanced then I had a sensor our of spec.

Chasing this problem I replaced air filters & spark plugs, cleaned the MAF, pulled the fuse to the ECU over night, bought a new MAF, bought a scanner, and now new motor mounts & A/F sensors.

911st

Interesting, I now have perfect fuel trims!

I checked my total fuel trims today (short + long= Total). Before replacing my wide band O2's it was adding about +3% / +6%, Bank one/two, at idle/2500rpm. With new A/F sensors I am basically ballanced Bank 1 to Bank 2 and Trim Totals are near 0. If I understand correctly this should meen my car is runing as expected with no wear indicated. Seems my old Air/Fuel sensors were out of spec and adding fuel when not needed.

(I used the 'remove the mid exaust pipe' method so it only added maybe 15 min to change out the O2's (2 x $100 ea). Glad I bought the MB motor mount wrench.)

So, new motor mounts plus new A/F sensors made my car pur like a kitten (new). And I may have picked up some fuel mileage.

teksurv

Great news, thanks for the follow up for future reference.