Speedtoys

My car has developed what feels like a huge amount of ignition missing, when I go from a light cruise, or idle.

Just tipping in it will start to shudder/shake.

But it can simply 100% go away too, or just as suddenly come back. But will usually go away if I step on it, and I can push through it. It will sometimes do this up to WOT, and then clear out, and runs great and strong.

I only have WBO2 number from one bank, but they never change, they remain stable where they should be..no change there.

Just because I didnt know the age of either, I changed fuel pump and filter last night, no change.

Plugs are 1mo old, wired 1yr old, caps and rotors 20k old, although Im headed out to get eyes on caps/rotors today and see what they look like.

drooman

MAF and connection? but maybe that would show up on the o2 readings..

Speedtoys

I would think so, as well.

Ah ya, NBO2 is...6mo old.

PorKen

Does it have a EZK-S chip? Try resetting it. (Pedal to floor at key on.)


I have noticed after a session of aggressive driving in hot traffic, for example, there may be a low rpm shudder feeling the next day when cool.

Speedtoys

Yes, it does NOT do this until warm...and I only have your S chip, yes.

I'll go do that first Ken, Thx..

Speedtoys

Ken:

This _seems_ to have resolved this..but this evening drive was short.

Whats up?

PorKen

Not sure yet. The fix is to reset the learning so I am not sure if it requires any coding changes.

It may a hot cylinder or two needing their timing pulled way down when hot making it run strangely when cool. Was not apparent in cooler weather. I've noticed it with my supercharged car at least once. One other person at least has noticed it as well.

Schocki

The other person was me. It did exactly what was described before. Felt like every cylinder firing was noticeable or the engine/transmission mounts collapsed and they made contact with the car.
Car ran extremely strong with no further issues.

Soft reset cured the problem instantly. I'm thinking to switch from 100 ROZ fuel to 98 again on my GTS.

Speedtoys

Bingo,it was so "even" that I could not work out what would affect every other position in the firing order as a common component.

One coil out, would not feel so even.

beran earms

I've been experiencing the same thing and I will give this a try. thank you.

zekgb

This is only an issue with the S4 chips and not the S3 chips correct? I had a weird episode last week where during a relatively warm day and an hour of highway cruising pulling to a stop light the car had a noticeable miss at idle and a bit of a stumble off the line. That condition persisted until we reached our destination but was perfect on restart after a 30 minute sit and did not reappear on the journey home at night when it was 25 degrees cooler.

PorKen

The S3 chips do not learn. Problems with S3 are going to be mechanical in nature.

This thread describes a symptom/feature of the S4 chips. My theory is the chip is correcting one or more cylinders for a specific (hot weather?) condition too much for general running. I may need to reduce the limits of the retard per cylinder or make higher levels temporary.

ador117

Bonjour,
I'm glad I found this thread because I was having had time with this issue : at idle, few minutes after hard reset (disconnecting the battery), the lambda fall from 1 to 0.70 with irregular RPM... And while accelerating a huge and long lean peak... and globally hesitating accelerations...
The rich idle happen only while the LH is working closed loop with the O2 sensor. If I run the car open loop, the idle is adjustable with the idle potentiometer and it stays good. But while accelerating the car was very lean like close loop.
As I had just removed the intake to correct a leak I had at idle (the Y on driver side has popping out so I was having a lean idle), I do not suspect an issue with the chip at all. I was focusing on a mistake I could have done while reassembling the intake or with the breather system modification I did... I was close to remove the intake again...

Reading this thread I just changed the chip and everything goes back to normal...
Here outside temperature is about 26 degrees Celsius, much below 35 degrees average temperature we usually have during summer time. And the issue happen only few miles around after a hard reset.
Maybe with ethanol the issue is happening sooner?
Raphaël

PorKen

Condition could not happen in a few minutes.

ador117

You may be right. I did so many things... and I don’t want to post something wrong. So I corrected my previous post. The few minutes where from start to observe the idle becoming rich.

however the issue stated with a 250km trip and then, after at least 2 hard reset (I was suspecting the idle valve), the issue comme back just driving around.

Raphael