Air/fuel ratio too rich

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Jimmy Turcotte
Québec

Jun 29, 2017
Air/fuel ratio too rich

Hi guys, I have a pulsar with a VET, forged pistons and a lot of stuff. The engine was freshly rebuilt when I bought it. I drove it around 1k kilometers without a problem, altough it was burning a little too much gas (saw it on the wideband). Suddently, from one day to another, it began burning way too much gas, the air fuel ratio was stuck between 10:1 and 11:1, no matter if I was driving or on idle. (it happened on a rainy day, it rained for 2 days before and I haven't drove the car for 3 days). So it happened last september and since then I haven't drove the car because I don't want to ruin my 6k$ engine setup. I changed the MAF and the O2 sensor, but it didn't solve the problem. I'm about to dyno-tune it but since the shop is at 300kms from the car I want to check every possibility before. Can someone help ? Thanks.

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Regina

Feb 6, 2010

What engine management are you using?  Any check engine light?

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Jimmy Turcotte
Québec

Jun 29, 2017

By engine management you mean ECU? It's a nistune that was tuned 4 years ago with the same setup.
There is no check engine lights.
I checked behind the ecu to see if the red light close when the engine starts and it did. So the ecu is fine.
In fact I called the guy that tuned the car 4 years ago and he said that it's probably fine and he is going to fix it on the dyno.
I still think there is something broken, could be complicated to fix right on the spot.

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Regina

Feb 6, 2010

Good luck.  I have nismotronic and it started being pegged at 10:1.  Turns out a connection on the daughter board was coming loose.  Resoldered the board and all works again.  Are you able to datalog nistune?

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Jimmy Turcotte
Québec

Jun 29, 2017

I can't datalog.
I checked inside the ecu and I saw that one tiny wire of the circuit looks like it overheated. Turns out that this wire is for the MAF sensor...I may have found the problem.
I will solder it tomorrow and update. Thanks for the help.

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Jimmy Turcotte
Québec

Jun 29, 2017

I soldered it and it didn't changed anything. My roomate who's a mecanics think that my ecu is probably the problem. Something must have overheated inside so I will replace it.