No throttle blip when starting...normal?

B6/7 S4/RS4
#18

The vids were so short I blinked and missed the first one lol.

Not sure why there is a difference upon start-up. Usually, on stock calibrated ECU’s the idle rate is based on a combination of things like ambient temp and how quicly the SAI can get the pre-cats to an “emissions acceptable” temp. Maybe the tune is the cause but either way I don’t think it’s an actual problem or causing any type of damage. Not sure if the S4 has the SAI like the RS4 but the initial high idle on most OBII cars is usually emissions related.

#19

Axel

Its just the start over shoot. Its normal but it dosn’t happen every time. Its ok for this to not happen. Stock you get a blast of air to help get the car motor started. To do this the ECU gives extra RPM. You have a blower so chances are when you start there is a blast of air from the blower making this less needed.

I wouldn’t look at this as something that is an issue. So yes this is normal. Also the fact that your car will do it sometimes and then not others just says your car is doing it when it needs it.

Being a Audi tech Ive seen this happen ALL The time. Some cars blip the RPM’s to 1800 on start. Some other cars never get past 1000. Just depends on that cycle start and what the requirements are at that start.

#20

who said computers couldn’t think for themselves, its terminators all over again

#21

Ok, that makes sense BUT today, it finally got to the point where it started and then died. Had to start the car again. Also, earlier today as well, I turned the car on and the rpms got stuck at around 300/400 and it seemed like it was about to die so I gave it a slight throttle blip myself and it came alive. This behaviour is all new and started happening about 10 days ago (more or less). I’ve had the supercharger for much longer.

#22

Axel its called a shallow start. They are more prone to come up in the cold weither. This may speak of why you have just started seeing this. Lots of the points are valid in this post. Temp plays a major… Being a Audi tech like carlos I can tell you this is something that many members can say has happened to them. We would see this more and more in the colder months.

I would say we look at how this continues to play out. When the car starts on blip cycle its called for. When the car starts on shallow cycel its called for as well. Carlos was correct that the range of RPM on start up is called for in the ECU.

At this point if your not getting a code for a VAC leak or fuel pressure two low. I wouldn’t say this is abnormal. Why now are you seeing this more then you might have in the past. I can’t say. I can say that this shallow and blip start is normal to jump between several start up RPM selections.

#23

Ok, but it’s happened at my work’s underground garage where it’s 20c (70F) as well as my own underground garage where it’s 15c (60F). That’s not really cold weather. And all of last winter, it never happened and the car was parked outside in freezing temps…

#24

And I would say thats normal. I would suggest that this has happened more then you might have noticed. Shallow starts seem to be more pronounced when its cold enough to still call for a shallow start but its also cold enough to require blip starts.

Just like the throttle hang on shifts Thread I posted in. ECUs will have there own strategy for stuff like this. The New B7 ECU has more strategy and more maps calling for stuff like a shallow start. Keep in mind a shallow start isn’t bad and its not a sign that there is anything going bad.

As for exactly whats calling for a shallow start. I can’t say what all the operators in the ECU that are calling for this. I can just say there temp related. Not just outside temp. Im also talking coolant,oil and outside temps.

While I can’t tell you exactly what is the trigger. I can tell you from 20years of Audi Certified tech experience its normal.

#25

I’m sorry, no offense here but

  1. it hasn’t happened “more than I might have noticed”. I noticed it the first time it ever happened and it caught me off guard as I didn’t expect it at all. It’s NEVER happened before. Please don’t assume “I just haven’t noticed it”.

  2. I have difficulty believing a car dying on startup as normal behaviour. Call me crazy…
    I can just imagine some joe schmoe going to the dealer and telling them the car sometimes dies when starting it and the service manager responding “Oh, that’s normal” (on any car, not just an Audi). Yeah…ok…

#26

I apologize then there is nothing more I can do to help you. Its something that happens and you don’t want to hear this. SO I’m sorry.

Is it normal, yes, is it something that happens more then you probably notice, yes. Sorry.

If you wish to think there is something wrong with your car best of luck to you. You asked a question and as a Audi Tech that sees thousands of Audis, This is something that happens. Your not the first person that thought this.

I can only give you my honest assessment of what is going on. Whats going on is a shallow start, We do and we have seen as Audi techs several people thinking there is something wrong on a dry restart or shallow start. There are terms for these things due to there happening and end users thinking there is something wrong.

Best of luck to you. To be brief No throttle blip when starting…normal? Yes, nothing you should be too worried about. If you see codes, list them. As it is, A shallow start is normal, A dry start isn’t uncommon. There both related to emissions.

Regardless of what your saying It wasn’t an attempt on my side to insult you. Still, My response will still be. Its probably happened several times in the past and you just haven’t noticed it before.

#27

Ok, but you’re also saying a car that stalls right away when starting is also normal?

#28

I didn’t know there was a term but if it helps my car did this today… the shallow start thing

I’ve never seen it before

I do know that the start rpm is different by the outside temps from what I’ve seen.

#29

Axel

Short starts are ok. Stalling or incomplete starts just after a short or shallow start are not completely unheard of.

Generally what you see on a short or shallow start. Is the cars will turn over and then stumble and not start or to start for a quick second and then die. So I can say that a shallow start is normal. I can say from time to time shallow starts result in stalled starts

I’ve been told this is for emmisions and reduced ware on start up. I also know some people have seen this with weak fuel pressure

I can’t say this is ok I can’t say this is what your experiencing. The only thing I can comment on is that this is not un normal. I also obviously can’t say if you have had this happen before.

#30

I don’t know if its helpful but I’ve cought my car shallow starting several times. I haven’t been able to track down exactly when and why it happens

#31

Yup, seems completely random.
I’ve owned many cars (like most of us), most of them old pieces of shit (like some of us) and I’ve never had any of them stall when starting as a normal thing. I have difficulty believing that when an Audi S4 does it, that it’s considered normal. Just saying…

#32

My s4 did it last night. It just went straight to a 800 rpm idle. The car is in a heated garage though. Scanned it And perfectly normal.

#33

I’m not so worried about the “shallow start” as it seems to be called. I’m more worried about stalling.

#34

I’d see about installing a fuel pressure gauge to make sure thats alright. You could put it inline in the rubber fuel line once it gets in the engine bay. Not sure thats something you want to mess around with or not though.

I had my car die right after startup before, turns out the ecu chip was loose in the socket. The car died while driving a few days later. I hadnt reinstalled the chip right when I swapped it months earlier.

#35

Interesting about the ECU. Mine has never died while driving though, only at start-up.
As for the fuel pressure…hmm…something to consider down the road I guess.

#36

yeah I didnt have issues with the shallow starts except on warm start ups (like coolant at temp). It always started like a cannon.

When you start yours up, how long do you key it on before cranking? I always give mine like 2-3 seconds at the last click before cranking, then I crank it. Maybe give that a shot and see if anything changes. If the fuel pump is struggling then the extra time may let it build some pressure up.

#37

If the chip isn’t on right, you’ll notice your epc light won’t come on when the key is in the on position. Just an FYI for Anyone experiencing problems down the road