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veloster running rich

10K views 11 replies 7 participants last post by  Nav14carvan 
#1 ·
my vt has 123K miles on it, now it's running too rich and burn oil, it doesn't burn, but too much gas wash off engine head. large and thick black scoot on the tail pipe. There is no cel on. I was thinking maybe bad maf and o2 sensor could send wrong info to ecm and cause too much gas dump into engine. There is no maf on all vt, it's map and ait senor instead, should I replace map or ait senor. don't know if those senor are still working because no code pop up. 2nd, there are another 2 sensor in my mind as well, fuel pressure sensor and fuel injector regulator. How should I start with, OBD scanner doesn't say anything, there is no code at all, normal air fuel is ratio is 13-14, mine maybe is 10, need help, 3 sensors, map/ait, fuel pressure sensor or fuel injector regulator or maybe o2 sensor, I don't know which one goes bad due to non code, all those senors cost $40-60 each, thanks. Tom
 
#2 · (Edited)
Get the upstream O2 sensor, clean the MAP sensors with some MAF sensor cleaner and take off the intake manifold to clean the carbon buildup on the valves with throttle body cleaner. Don't forget to change the plugs, if you haven't already. I'm not sure what maintenance you have done but you should also look into replacing your PCV valve too.
 
#5 ·
thanks guys, usually if ecm dump too much fuel, maf and o2 sensor are the 1st thing to check. Everyone knows that all vt doesn't have maf, it's map and ait sensor, so I don't know where to start. I've change downstream o2 sensor because cel on before, never touch upstream. Let's be clear, I think my vt running rich due to fuel system issue. ECM should let more air in to offset extra fuel or ECM should control fuel consumption. Now more fuel or much more gas sucked in with less air mix. ECM think should have more air come in, but it's not, so ecm is fooled by something or some bad sensor. If any sensor goes bad, cel should be on, but it's not. Also, the engine stalled few times when I stopped at traffic lights. We have to find which part going bad that fool ECM dump more gas to the motor, thanks.
 
#6 · (Edited)
Running rich can be caused by much more than a fueling issue. Clean the valves, MAP sensors, replace the upstream O2, and replace the spark plugs. You will have to take the intake manifold off to get to the valves. The sensors could still be getting a read that the ECU thinks is good, but it might not be accurate. The O2 sensor is cheap anyways so what's the harm in replacing it?
 
#7 ·
All this, because you see soot on the exhaust tips. If the mpg figures are descending, then a problem could be indicated. The best test then would be a compression test. Especially so, since you say it burns oil. Check your air filter, it can cause a multitude of problems. Trying to get relief by replacing parts is folly and can be expensive, yielding nothing but a lighter wallet.

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#8 · (Edited)
He described black soot coming out of the exhaust pipe, not white smoke. It's not burning oil. Replacing the O2 sensor isn't "folly". It's a maintenance deal and he has 123k miles so it probably needs to be replaced anyways. I've already had to replace mine at 44k miles because it was running lean and the sensor wasn't reading the AFRs quite right when I would let off the gas.
 
#10 ·
with highway and local driving, 50-50, 1 tank drive about 300 miles or little less, is this fair mpg, like what I said now my vt is 123K miles, I'll look for another car when my vt hit 150K, it's about a year, should I threw money to replace all parts. I'm not saying HY and KIA is bad, 150K is about the life cycle. My Kia before retired at 190K miles. Another possible bad part to look at maybe fuel injector, I clean it along with oil change. Now some times, car is hard to start, I have to hold key for 5-10 sec to start, not right away, also engine stalled few times on the road. So some parts on the fuel rail has some problem, but it's hard to find. loosing oil because running too rich. HY and Kia makes good cars, but on veloster, it's fair, thanks. Tom
 
#11 ·
123kon your veloster? What year is it cause that's a lot of miles. Don't mean to get off topic but I'm curious. My V is a 2013 with 31k on it. But ya sorry to hear about your car troubles and I hope the said suggestions will help solve the issue.
 
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