Miss at Idle, seems like bad news...
06-20-13, 08:53 AM
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Miss at Idle, seems like bad news...
Hey guys,
I did a search, and found similar things, but generally running problems that cropped up after doing various things to the engine (mods / tunes, etc.). And it's been a loooong time since I've posted, because I took a new job and have been super-busy. To the car...
The car was running fine, I took my son up to my parents' house and we drove the FD. Love the car on shorter road trips. 140 miles each way. Car was running great.
Saw a newish 911 turbo (pretty sure it's faster than my car), and ran him down in traffic, and he was moving good. I followed him for a while and we played around, and then eventually the traffic thinned out. I got up beside him and tried to coax him into a run. He sissed out, and wouldn't run me. So I showed him what I had, and tried to coax him again. And he even shook his head NO at that point. I must have blown a flame out and scared him.
He was a cool dude anyway, and gave me a thumbs up to my car.
So anyway I did only one other small pull then exited later. Car ran great the whole time, and I had both fans running manually and never got over about 92°C the whole time (usually lower).
But at the stop light at the end of the exit ramp it almost stalled, and then idled with a miss. Sounded like 1 chamber of one rotor would not light-off at idle.
But once back up to road speed it ran smoothly and still had power. The rest of that weekend the same thing. Missing at idle but running good down the road.
Ran great the whole way back home on the interstate and surface streets, but I took it easy on the car just in case.
I'm thinking I'm losing a apex seal. Losing enough compression that at idle it will not fire, but the compression loss is not rapid enough to substantially effect combusting at higher rpms.
Does this sound about right?
Going to change the spark plugs and the oil and filter. All that stuff is due now anyway. Hoping I have a weak plug, but I doubt it as that would affect the whole rotor, not just 1 chamber. Looking for some advice from you experts. Thanks.
JyRO
I did a search, and found similar things, but generally running problems that cropped up after doing various things to the engine (mods / tunes, etc.). And it's been a loooong time since I've posted, because I took a new job and have been super-busy. To the car...
The car was running fine, I took my son up to my parents' house and we drove the FD. Love the car on shorter road trips. 140 miles each way. Car was running great.
Saw a newish 911 turbo (pretty sure it's faster than my car), and ran him down in traffic, and he was moving good. I followed him for a while and we played around, and then eventually the traffic thinned out. I got up beside him and tried to coax him into a run. He sissed out, and wouldn't run me. So I showed him what I had, and tried to coax him again. And he even shook his head NO at that point. I must have blown a flame out and scared him.
He was a cool dude anyway, and gave me a thumbs up to my car.So anyway I did only one other small pull then exited later. Car ran great the whole time, and I had both fans running manually and never got over about 92°C the whole time (usually lower).
But at the stop light at the end of the exit ramp it almost stalled, and then idled with a miss. Sounded like 1 chamber of one rotor would not light-off at idle.
But once back up to road speed it ran smoothly and still had power. The rest of that weekend the same thing. Missing at idle but running good down the road.
Ran great the whole way back home on the interstate and surface streets, but I took it easy on the car just in case.
I'm thinking I'm losing a apex seal. Losing enough compression that at idle it will not fire, but the compression loss is not rapid enough to substantially effect combusting at higher rpms.
Does this sound about right?
Going to change the spark plugs and the oil and filter. All that stuff is due now anyway. Hoping I have a weak plug, but I doubt it as that would affect the whole rotor, not just 1 chamber. Looking for some advice from you experts. Thanks.
JyRO
06-20-13, 09:58 AM
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I meant to add that the car is running a Pettit intake, Power-FC with commander on the default tune, wide-open exhaust, no cat. Most everything else is stock (rebuilt engine) as far as I know.
06-20-13, 11:04 AM
#3
Base map or Base mod map?
Stock fuel pump?
Fuel pump rewired?
What boost are you seeing?
Wideband?
Sounds like you have been skating pretty close to the map and fuel limits of the car, especially with an original "base map". First things first, do a compression test. It is not beyond the possibility of injuring the engine due to your mods, but you could have other issues.
Stock fuel pump?
Fuel pump rewired?
What boost are you seeing?
Wideband?
Sounds like you have been skating pretty close to the map and fuel limits of the car, especially with an original "base map". First things first, do a compression test. It is not beyond the possibility of injuring the engine due to your mods, but you could have other issues.
06-21-13, 04:20 PM
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See below.
Base map or Base mod map? Base map of the PowerFC. I say that because I've never heard the term Base mod map before.
Stock fuel pump? Yes, as far as I know.
Fuel pump rewired? No, as far as I know not rewired.
What boost are you seeing? 12 psi, it might squeek out 13 psi.
Wideband? No.
Sounds like you have been skating pretty close to the map and fuel limits of the car, especially with an original "base map". First things first, do a compression test. It is not beyond the possibility of injuring the engine due to your mods, but you could have other issues.
Stock fuel pump? Yes, as far as I know.
Fuel pump rewired? No, as far as I know not rewired.
What boost are you seeing? 12 psi, it might squeek out 13 psi.
Wideband? No.
Sounds like you have been skating pretty close to the map and fuel limits of the car, especially with an original "base map". First things first, do a compression test. It is not beyond the possibility of injuring the engine due to your mods, but you could have other issues.
06-21-13, 05:18 PM
#6
Wide open exhaust? Is your waste-gate ported...I doubt it?
Stock pump, stock injectors, stock wastegate, and simply an ECU upgrade is not going to save you from nor prevent the boost creep up top. I was seeing 13-14psi creep with open exhaust w/ out porting my wastegate on my stock twins. Make sure you do a compression check asap before messing around with things like spark plugs etc....I hate to say it, but its very possible that you blew the motor from overboosting and running lean.
Stock pump, stock injectors, stock wastegate, and simply an ECU upgrade is not going to save you from nor prevent the boost creep up top. I was seeing 13-14psi creep with open exhaust w/ out porting my wastegate on my stock twins. Make sure you do a compression check asap before messing around with things like spark plugs etc....I hate to say it, but its very possible that you blew the motor from overboosting and running lean.
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