Runs very rich during cold startup...
#1
Runs very rich during cold startup...
Mostly stock car. Brand new engine with about 1500 miles on it. Everything new; housings, irons, seals. Pre cat was removed in favor of a downpipe and an RX7 Store mid-pipe with cat was installed. Air pump is hooked up to the cat. RB catback. New Mazda O2 sensor was installed with the new engine. Other than that it's bone stock.
On cold startup when the temp is below about 45* it runs very rich and smokes. It's definetly fuel rich smoke and not oil or coolant smoke. Idling at 10:1 or less. Once the car reaches operating temp it doesn't smoke at all and the mixture leans out as it should. If the temp is fairly warm, say 60*+, there is no smoking at startup. To me it seems the smoking with cold ambient temps is related to a combination of the O2 sensor and the now fairly distant single cat taking a good while to heat up and start doing their thing. Just wondering if others have noticed this with similar setups or if I need to start looking into something else causing the problem like a bad coolant temp sensor.
On cold startup when the temp is below about 45* it runs very rich and smokes. It's definetly fuel rich smoke and not oil or coolant smoke. Idling at 10:1 or less. Once the car reaches operating temp it doesn't smoke at all and the mixture leans out as it should. If the temp is fairly warm, say 60*+, there is no smoking at startup. To me it seems the smoking with cold ambient temps is related to a combination of the O2 sensor and the now fairly distant single cat taking a good while to heat up and start doing their thing. Just wondering if others have noticed this with similar setups or if I need to start looking into something else causing the problem like a bad coolant temp sensor.
#2
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every one i've seen does it, been 30 here and i get a little fuel smoke and runs a tiny bit rough (not really a miss though)
jumper ten/gnd in the diagnostic connector and turn the key to on, see if it blinks any codes at you
prolly normal behavior though, i know mine's fine and it does it
rotary+8bit pos ecu+old car(old emissions standards and execution)=extremely unclean cold starts
jumper ten/gnd in the diagnostic connector and turn the key to on, see if it blinks any codes at you
prolly normal behavior though, i know mine's fine and it does it
rotary+8bit pos ecu+old car(old emissions standards and execution)=extremely unclean cold starts
#3
Tequila? ..it's like beer
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It's not your O2 sensor. There's no closed loop on warmup. The stock ECU does run super rich on startup when it's cold though so it could be very close to normal behavior. It's trying to heat up the pre-cat that doesn't exist any more. It also sounds like the coolant sensor is okay, as it seems to respond (car gets warm and leans out.. no issues above 60*) It couldn't hurt to swap it out or at least go over connections.. but I doubt it will make much difference.
The easiest resolution would probably be to toss in an ECU and lean out the warmup.
The easiest resolution would probably be to toss in an ECU and lean out the warmup.
#5
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Originally Posted by NewbernD
It's not your O2 sensor. There's no closed loop on warmup. The stock ECU does run super rich on startup when it's cold though so it could be very close to normal behavior.
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#9
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The stock ecu and PFC also retard timing another 15 degrees below 60C water temp which does not help either. With the PFC and DL, this can be changed to 0 which also helps cold starting, and a smoother idle.
I assume Mazda did it to warm up the pre-cat faster.
I assume Mazda did it to warm up the pre-cat faster.
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Mine does this too. After cold starting, at idle it feels like it is missing - especially between 2300 and 2500 rpm. If smooths out very quickly above 2500RPM though, but still smokes. Do the secondary injectors kick in at 2500RPM at idle in neutral?
#13
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My car does the exact same thing on start up, the engine has about 1200 miles on it. For the first 5 minutes or so it blows a light white colour smoke that has a fairly strong gas smell, once it warms up the smoke and smell disappear. At first I wondered if it was a coolant seal problem but have never experience a loss in coolant. My old engine didn't do this though. Ludwig if you could get video of your car doing this it would be nice to see if it is similar to what I am experiencing
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I forgot to mention my engine only has 1500mi on it and I have much less restrictive intake, exhaust and intercooler. (I won't boost until I put my upgraded computer in and get tuned.)
Ihor, I noticed my tires are 245 somethings. Is this the correct size to stay in the right class for Auto X? I have a few other misc questions. PM me your phone number if you want.
Ihor, I noticed my tires are 245 somethings. Is this the correct size to stay in the right class for Auto X? I have a few other misc questions. PM me your phone number if you want.
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