164Q4 ecu question

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Mitsos
Posts: 5
Joined: Tue Dec 27, 2016 6:25 pm

164Q4 ecu question

Post by Mitsos » Mon May 01, 2017 10:29 am

Hello everyone! I am using a modified Q4 engine in my 75 and I was wondering if anyone has experience/knowledge about the fuel cut-off rpm. In most other ecu's (any brand), during deceleration in gear, fuel delivery is restored at ~1400-1600rpm. In the 164Q4 ecu, fuel is restored at 3000rpm, which I believe is connected to the 4wd feature. Does anyone know if this is a matter of mapping or something that can be easily adjusted by changing some resistors (for example) on the ecu board? Thanks in advance for any answers.

Jim K.

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Alfan
Q4 owner
Posts: 1100
Joined: Thu Oct 22, 2009 8:20 pm
Location: Denmark

Re: 164Q4 ecu question

Post by Alfan » Wed May 03, 2017 7:33 pm

Well, my answer won't help you... But I would like to know where you found this information, as I find it very interesting?

My guess it that it would be difficult to modify using components, as I think you risk modifying other things as well, since RPM is a very critical part being monitored for many things.
1994 Alfa Romeo 164 Q4 Proteo Rosso 550.000km
1989 Lancia Thema 8.32 Verde Indy 265kkm
2001 Alfa Romeo Spider 3.0 24V Blue Lightning 55kkm
2011 Alfa Romeo Giulietta Multiair TCT Bianco Pastello 135kkm
2015 Alfa Romeo 4C Rosso Competizione 85kkm

Mitsos
Posts: 5
Joined: Tue Dec 27, 2016 6:25 pm

Re: 164Q4 ecu question

Post by Mitsos » Thu May 04, 2017 3:03 am

In my 75 3.2liter, I have installed an afr gauge. With this and a precision tachometer (Stack), it is very simple to see when fuel is cut off and restored on deceleration. 3000rpm is the magic number for the 164Q4 ecu. In contrast, in the Lancia Kappa 3liter 24v engine (fwd car) deceleration fuel is restored at ~1700rpm (from the factory manual). I believe the rpm difference from the 164Q4 engine has to do with the 4wd feature. Other differences between the two ecu's like the two lamda sensors of the Q4 vs one in the Lancia do not play a part in this cut-off feature.

Jim K.

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AlfaWhiz
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Joined: Thu Feb 06, 2014 1:15 pm

Re: 164Q4 ecu question

Post by AlfaWhiz » Thu May 04, 2017 5:14 am

I don't have an answer for you, but it's interesting to me: why do you want to modify it? Does it cause any unwanted behavior?

Mitsos
Posts: 5
Joined: Tue Dec 27, 2016 6:25 pm

Re: 164Q4 ecu question

Post by Mitsos » Thu May 04, 2017 6:04 am

The feel of the car when driving normally is different than what you would call 'normal'. Deceleration in gear is not as good as it could be (engine braking is less at 3krpm) and there is also the matter of higher fuel consumption... Don't laugh, 98RON gasoline costs ~1.80€ now here in Athens -the reason for 98RON is 11.5:1 compression ratio and many other engine mods.
I have a Lancia Kappa ecu (0261203482). When we figure out how to disable the immobilizer feature, I will try it on the Alfa and see what happens.

Jim K.

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