Lean problem when cruising

[Juan AR155Q4]

Last weekend I´ve been traveling about 1000km, so I had chance to "play" with the car.
I´ve noticed a strange behavior of the car when cruising.
Until 150 km/h (94 m/h) the injection system goes in closed loop, but if I want to crusie at 160 km/h (100 m/h) it doesn´t operate in closed loop and goes lean.
So I had to travel at 150 km/h or floor it a little more and cuise at 180 km/h (110 m/h) but in that moment it was at open loop and with rich mixture.

What are the condition that are required to go on open loop?
Is my chip (evocars) badly configured at the begining of the open loop (can´t remmeber pressure value, but I think it wasn´t positive)??

[Juan AR155Q4]

Wolf? Nick?
Come on chips specialist!!!

[Stuntz]

Wolf is on holiday sorry :)

[markgq4]

not too sure on the specifics Juan,

but i do remember Barry used to sell the chips as
"running lean on light throttle, to improve cruising fuel economy"

[arjunior45]

I knew that Evocars chip slightly undefuel at 2300 - 2500 rpm, especially with Tipo inlet cam. But, according to late B.W. it was something not to worry to - not dangerous.
150 kmh should be arround 2300 rpm, am I wrong?
What AFR did you had at 160 km? Did you measure it?

Regards

Nick

[Juan AR155Q4]

not too sure on the specifics Juan,

but i do remember Barry used to sell the chips as
"running lean on light throttle, to improve cruising fuel economy"


I knew that Evocars chip slightly undefuel at 2300 - 2500 rpm, especially with Tipo inlet cam. But, according to late B.W. it was something not to worry to - not dangerous.
150 kmh should be arround 2300 rpm, am I wrong?
What AFR did you had at 160 km? Did you measure it?

Regards

Nick

I haven't connected the wideband yet (more than a year that I have it....:doh:). Surely that will be the next thing I do. Also I'll be measuring EGT, so in a lean condition I'd have to see highs EGTs. I they are not to high, that economy-lean condition wouldn't be a problem.

PS: first Multiquote I do, great thing!!!

[arjunior45]

Evocars chip, at least for the 16V, were made to have less consumption from the OEM one! Even the 4-maps eprom for the 16V had identical fuel-ignition maps and only the boost related maps were different.
I bet that fuel economy is something that we all want, at least in light throttle. And according to my infos even the "fastroad" chip for Evo2 - 155 Q4 was more economic in light throttle than the OEM one.
Install the oxygen sensor first and then press the engine to higher boost levels! I've seen too too many broken engines due to lean mixture.

regards

Nick

[Xti]

OMG !
What if my Q4 engine does not have the proper mixture? What would be the simptoms in that case? (Sounds like a begginer, doesn't it ? But won't last forever...)
I don't even want to think ... I have some plans and I'd be very sad to do this to "him" right now (I'm trying hard to learn as much I can about Q4...I wouldn't sell him in this life. EVER.

Thanks, Cris.