Hesitation After Warming up
#1
Hesitation After Warming up
A) I know this is a re-post but I have a slightly different take on this now.
B) I also know I have an i35, but more people go to the Maxima pages than the Infiniti - figured I'd get more help here.
OK, so I think I found a connection to my own car's issue with uber-power when running cold and "blah" when engine is warmed up.
The system that loops exhaust is what I believe is the culprit. Before the car can warm up, the engine loops exhaust through the pre-cats. When the engine is at running temp, the loop is shut off and exhaust flows freely out the tailpipe. (If this is inaccurate, you only know this because you understand the concept I'm getting at.)
Point being, I had a serious oil leak from a gasket that was leaking into the spark-plugs and several other places in the engine. This has since been fixed (to the tune of $1200) but I'm wondering if this could have had an adverse effect on the catalytic converter should it have absorbed a significant amount of oil. Is it possible that is is clogging exhaust gas and not allowing the car to breathe properly when running at operating temp.
Could this also affect shifting? The car seems to not be breathing well, so could this be what's making the car not know when to shift?
Ultimate Question: Could the catalytic converter be the root of all evil here?
B) I also know I have an i35, but more people go to the Maxima pages than the Infiniti - figured I'd get more help here.
OK, so I think I found a connection to my own car's issue with uber-power when running cold and "blah" when engine is warmed up.
The system that loops exhaust is what I believe is the culprit. Before the car can warm up, the engine loops exhaust through the pre-cats. When the engine is at running temp, the loop is shut off and exhaust flows freely out the tailpipe. (If this is inaccurate, you only know this because you understand the concept I'm getting at.)
Point being, I had a serious oil leak from a gasket that was leaking into the spark-plugs and several other places in the engine. This has since been fixed (to the tune of $1200) but I'm wondering if this could have had an adverse effect on the catalytic converter should it have absorbed a significant amount of oil. Is it possible that is is clogging exhaust gas and not allowing the car to breathe properly when running at operating temp.
Could this also affect shifting? The car seems to not be breathing well, so could this be what's making the car not know when to shift?
Ultimate Question: Could the catalytic converter be the root of all evil here?
Last edited by ZGadson; 10-07-2009 at 07:07 PM.
#3
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A) I
The system that loops exhaust is what I believe is the culprit. Before the car can warm up, the engine loops exhaust through the pre-cats. When the engine is at running temp, the loop is shut off and exhaust flows freely out the tailpipe. (If this is inaccurate, you only know this because you understand the concept I'm getting at.)
The system that loops exhaust is what I believe is the culprit. Before the car can warm up, the engine loops exhaust through the pre-cats. When the engine is at running temp, the loop is shut off and exhaust flows freely out the tailpipe. (If this is inaccurate, you only know this because you understand the concept I'm getting at.)
#4
My car does the exact same thing. Although mine is a 6 speed, it still runs very sluggish when fully warmed up. Im not trying to hijack your post, but maybe if we are having the same issue we can figure this out.
#6
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Location: Middleboro/Carver, Ma
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The system that loops exhaust is what I believe is the culprit. Before the car can warm up, the engine loops exhaust through the pre-cats. When the engine is at running temp, the loop is shut off and exhaust flows freely out the tailpipe. (If this is inaccurate, you only know this because you understand the concept I'm getting at.)
#7
#10
What is your oil consumption like? If you are burning a quart more than every 2000 miles or so, I wouldn't be surprised if all three cats are at least partially clogged by now.
#11
Knock sensor?
(Yeah, I know i claim that in every other thread too haha)
When it's cold the engine is in closed loop so it's ignoring the 02s and KS. If the KS is dead/dying, your timing will be severely retarded once it enters open loop and goes into safe mode.
It doesn't throw a CEL, so you'll never know. Plus, if the V isn't out of range you won't get a code, anyway, but it could be telling your ECU it's knocking.
Just another stupid thing nissan did (no cel for safe mode).
(Yeah, I know i claim that in every other thread too haha)
When it's cold the engine is in closed loop so it's ignoring the 02s and KS. If the KS is dead/dying, your timing will be severely retarded once it enters open loop and goes into safe mode.
It doesn't throw a CEL, so you'll never know. Plus, if the V isn't out of range you won't get a code, anyway, but it could be telling your ECU it's knocking.
Just another stupid thing nissan did (no cel for safe mode).
Last edited by Child_uv_KoRn; 10-08-2009 at 11:31 PM.
#12
B) Fuel injector cleaner never seems to do much of anything (in my opinion).
C) Is the knock sensor something that gradually goes bad?, or is it one of those things that is or is not working with no kind-of working of in between?
D) Thanks for your responses once again - I really do appreciate the help when it comes to getting Foxy to run better again.
#13
Now that I think about it (and have done some more research on pre-cats) I'm becoming more sure that the catalytic converter is our issue.
As stated on Wikipedia: What is a pre-cat?
To put it quite simply, the pre-cats sit before the main catalytic converter in the exhaust system and help to keep the harmful emissions as low as possible for a short period after you start the car up.
This leads me to believe that because the car runs best when using ONLY the pre-cats, that it actually is the main cat that needs to be replaced. Although pre-cats can be clogged by oil leaks, so can the main cat, hence the lack of power when the car is using the main cat. Am I correct in my thinking here?
As stated on Wikipedia: What is a pre-cat?
To put it quite simply, the pre-cats sit before the main catalytic converter in the exhaust system and help to keep the harmful emissions as low as possible for a short period after you start the car up.
This leads me to believe that because the car runs best when using ONLY the pre-cats, that it actually is the main cat that needs to be replaced. Although pre-cats can be clogged by oil leaks, so can the main cat, hence the lack of power when the car is using the main cat. Am I correct in my thinking here?
#14
If the main cat is clogged then i would think it would run bad all of the time because exhaust is running through it all of the time, not just when its warmed up. Im thinking possibly a knock sensor because i use premium fuel in mine and it still pings a little bit.
#15
I guess its not a bad idea to replace the knock sensor either way. It's bound to go at some point, but could the sensor really limit power that severely? I mean, on the highway, if I'm going faster than say, 60, I have NO top-end power for passing. Might as well be driving my mother's 1996 4cylinder Camry at this rate.
Also, the pre-cats reuse the exhaust until it burns up all the harmful emissions that build up when the engine is off - so yes, it always uses the main cat, but during the car's warm-up stage, not all of the exhaust is going out the tail pipe. What doesn't exit out the tailpipe is being constantly recirculated by the pre-cats (hence the "loop" I was referring to earlier). Meaning, there is more strain on the main cat once warmed up.
Also, the pre-cats reuse the exhaust until it burns up all the harmful emissions that build up when the engine is off - so yes, it always uses the main cat, but during the car's warm-up stage, not all of the exhaust is going out the tail pipe. What doesn't exit out the tailpipe is being constantly recirculated by the pre-cats (hence the "loop" I was referring to earlier). Meaning, there is more strain on the main cat once warmed up.
Last edited by ZGadson; 10-09-2009 at 09:56 AM.
#19
Hmmm... limp mode issue?... Naaw.
#22
#23
BTW, forgot to tell you to stick a 470K resistor into the KS connector. Just follow the wire that comes out between the "V" in the block (the crevice). If your power is instantly restored, then that's your issue. I run mine bypassed like that.
#24
Will a bad Knock sensor make it ping even tho i use 92+ octane? I notice it only pings after its been fully warmed up also, plus the hesitation... I have noticed i dont get as good gas milage than i used to. I used to get about 400 miles per tank. Now im lucky to get 300
#25
Will a bad Knock sensor make it ping even tho i use 92+ octane? I notice it only pings after its been fully warmed up also, plus the hesitation... I have noticed i dont get as good gas milage than i used to. I used to get about 400 miles per tank. Now im lucky to get 300
Korn - As far as the resistor goes, is your knock sensor connected at all? And did you just connect the resistor to the + and - wires that go to the sensor?
Last edited by ZGadson; 10-10-2009 at 07:27 AM.
#26
Sounds like both our cars have the same illness. When I got mine, it had 34k miles on it and was getting almost 450 per full tank even.
Korn - As far as the resistor goes, is your knock sensor connected at all? And did you just connect the resistor to the + and - wires that go to the sensor?
Korn - As far as the resistor goes, is your knock sensor connected at all? And did you just connect the resistor to the + and - wires that go to the sensor?
#31
I don't trust auto stores and especially not junkozone. They like to box up used parts.
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