Cold Start - Accelerate - Hiccup

[igerald]

I have Polo 6N - Mk4,AEE Engine, 1997, automatic transmission.

Whenever I accelerate there is a "hiccup"/intermittent power (Engine is cold in initial condition).

No hiccup when the engine is hot.

The RPM Gauge dropped (hiccup) when accelerate but then jumps back to where it was.

No Check Engine light on the dashboard.

Is there anybody can help and point out the area that should look at to rectify the hiccup?

Thank you.

[igerald]

I have Polo 6N - Mk4,AEE Engine, 1997, automatic transmission.

Whenever I accelerate there is a "hiccup"/intermittent power (Engine is cold in initial condition).

No hiccup when the engine is hot.

The RPM Gauge dropped (hiccup) when accelerate but then jumps back to where it was.

No Check Engine light on the dashboard.

Is there anybody can help and point out the area that should look at to rectify the hiccup?

Thank you.

After more google I found this information:

Hints and Tips : Volkswagon (http://www.bba-reman.com/vwfaults.htm)
INCREASED IDLE SPEED
AFFECTED MODELS: Model year 96 Magneti Marelli 1AV, 1.6L, AEE engine.
FAULT: Increased idle speed (max. 2,500 rpm) after starting the engine with a coolant temperature between
18deg.C and 29.5deg.C
CAUSE: Software problems lead to increased idle speed (max. 2,500 rpm) after starting the engine with a coolant
temperature between 18deg.C and 29.5deg.C. After approx. 40 seconds or after the first acceleration the idle
speed returns to normal.
SOLUTION: Install the modified control unit:
Polo - Part No. 032 906 030 E
Polo Automatic - Part No. 032 906 030 H
Golf - Part No. 032 906 030 K
The control unit must be adapted to the electronic immobiliser. Also carry out a basic setting of the ECU (adapting
it to the throttle valve control unit).

My question is: Is it expensive to install/upgrade my current ECU to the 032 906 030 H?

[jets]

My wife has a 6n2 1.4 16V AHW so not the same as yours. It would sometimes miss a beat while running. A new coolant temp switch cured the problem. I don't know if it will cure yours though.

[Umai Naa!!]

I would advise against replacing the ECU at this stage. It'll be a bit of a headache when the time comes to program it.

The coolant temp sensor would be a good, inexpensive place to start.

[Jmac]

Sounds like there is a few things needing to be checked before you jump to an ECU. Fitting an ECU to these isnt a drama if all goes well, its a case of erasing learnt values and adapting the engine ECU to the Immob unless its of an age where the immob is in the cluster, mainly around 99. Easy to check if you or whoever is looking at it goes into cluster the immob should show up there, if it does then it needs to be coded, if it doesnt then its an erase learnt values then all good after next ign cycle. Main drama on these for the DIY guy is if you have to replave the immob ecu, non cluster ones need dealer or good auto locksmith who has the keyreader.
I know of a couple of ECUs at the moment but im sure they would be sold with keys and immob as its a waste if the Engine ECU goes alone if that makes sense

Cheers
Jmac

[igerald]

Hi All,

Thank you for all the info.

I found the solution in another forums. I adjust/RECODE the Auto Transmission using a borrowed friend's VCDS.

RECODE the Auto transmission to "00022".

I think they call it "semi sporty" mode transmission.

At the moment the "hiccup" is gone - no more high rev above 3000 rpm before gear shifting.

I will be changing transmission fluid and coolant temp sensor housing soon, just as preventive action.

Thank you again for all the information.


Iwan