REVscene - Vancouver Automotive Forum

noventa · 01-19-2011, 11:25 AM

hey guys, I have this problem with my car that maybe you guys could help me with. my engine is an s13 sr20det blacktop with a microtech ecu tuned by forcefed.

The last time i drove her was in early 2009 before her aircare expired. Back then she ran fine. After the aircare in early 2009 I had her park until around recently. Now I am driving the car and I have noticed that a lot of time she will sputter and stall, sometimes shaking violently, when am in neutral at a stop light. Also, I have noticed that she is running very rich (rich fuel odour and backfiring) and the mileage has gone way down (240 km/tank vs. 380 km/tank). Power-wise, my buttdyno says it is a bit slower than before, but not by much. The funny thing is, sometimes the car will run fine all afternoon driving around the city in stop and go traffic. But then if I turn it off and turn it back on, it may run like crap.

The car was retuned in 2009 to pass aircare. From what I gathered from the mechanic/tech guy who worked on my car, it took a few attempts because one of the injectors was stuck and that somehow affects the emissions. It was eventually fixed and my car passed. In the last month I have changed my spark plugs (properly gapped), fuel filter, oil filter and oil. The mileage has improved slightly but I am still getting the idling issue.

So I am thinking maybe a vacuum leak? bad o2 sensor? no spark? Could one of my cylinders not be firing?

What kind of ideas do you guys have?

thanks for the help!

Qmx323 · 01-19-2011, 11:48 AM

check your fuel injector wiring. mine had an issue where the corrosion was cutting the connection in and out to an injector.

could also be a vacuum leak

noventa · 01-19-2011, 06:14 PM

thanks qmx323.

I looked around the engine bay today and to my surprise I can see that the o2 sensor on the exhaust is not plugged into anything. I've been looking around for the other end of the sensor but have not yet found it. I thought it was a requirement to have my car running but I think I don't understand the entire situation.

Nechako87 · 01-19-2011, 06:19 PM

did you take your car thru aircare, or did marko?

because of the cold weather, you may have to adjust your cold start on your ecu

noventa · 01-19-2011, 06:48 PM

marko did it. Could it be possible that he forgot to plug my o2 sensor back in? I've driven it before in the winter and it was fine.

Nechako87 · 01-19-2011, 06:59 PM

he probably unplugged it so that he can stick his air pump in there, or to put his on O2 sensor in.

without the dongle, you cannot diagnose your car thru the ECU. If you don't have one you can buy one through microtech.

Qmx323 · 01-19-2011, 07:02 PM

Quote:

Originally Posted by noventa

thanks qmx323.

I looked around the engine bay today and to my surprise I can see that the o2 sensor on the exhaust is not plugged into anything. I've been looking around for the other end of the sensor but have not yet found it. I thought it was a requirement to have my car running but I think I don't understand the entire situation.

not having ur 02 sensor plugged in i bet is why your mileage is suffering

as for the stalling though no idea lol

noventa · 01-21-2011, 10:04 AM

apparently the microtech works on a closed loop system making the o2 sensor not needed.