I wrote a while back about a similar problem. I thought it may have been bad gas, and other people thought maybe it was a bad Knock Sensor. But my gas mileage has been GREAT (25-27 mpg) so I am pretty sure it isn't that...

So my symptoms. When the car is cold, starting it up for the first time in a few hours or after sitting overnight, it runs great. Strong, smooth, etc. After maybe 5 minutes though it feels like it is lacking power. I have a 5 speed and at lower RPMs, esp if under 1500-2k in 2nd it will buck on occasion and you can feel it trying to get the power to the wheels, not as smooth as when the car was cold. I have been putting the 93 octane in it, so I know it isn't a result of 87 gas. And when the RPMs get higher I feel like there is hesitation in the motor as well. Any ideas??

The spark plugs were changed about 20 k ago, newer clutch, we just changed the fuel filter 3k ago, coil packs are good, and O2 sensors are good, like I said, I get 25 MPG plus. The car has 147 k on it now

 

Is the hesitation only when you punch the throttle, or does it hesitate even when you aren't moving the throttle pedal?

 

have you cleaned the MAF ever, or TB ???? I'd start there. my guess is that it's the TB cold temp sensor. once it warms up, it closes the circut and drops the RPMs via the ecu. at least that is how i understand it. hope this might help.

 

check your codes.

 

No codes. Checked those. And it idles just fine, it is when I put pressure on the pedal that the problems start to occur. Is the throttle body difficult to get at and clean?

 

no not at all clean it and see what happends.A dirty tb can kill a good amount of power.

 

Aside from cleaning the TB, might as well clean the IACV while you're in there. What sort of plugs are you running? After 20k you might want to double check the gap just to make sure it isn't off. Also it probably wouldn't hurt to run a bottle of injector cleaner on your next fuel up. Dirty injectors can have some dribbling which isn't so good for performance.

S

 

My car is doing the exact same thing - almost to the point where it isn't driveable. I'll watch this thread - hopefully your fix will fix mine, as well. I'm at 230k on my 96, however.

 

Someone mentioned checking the engine coolant temperature sensor in a thread I read. Even if the sensor is "working", apparently there could be corrosion at the terminals which lead to problems when the car warms up.

Let me know if cleaning it works for you

 

how do you know your coils are good? coz i did resistance tests on my coils and they all were within specs.....but i was missfiring and had similar symptoms....i changed coils anyways and fixed it....just a thought

 

You will know if you have a bad coil pack. Believe me! In addition to most likely throwing a code, it just won't sound smooth upon start up. When we changed the plugs, we broke one of the coil packs and WOW. 3rd gear at 45 MPH barely gave it enough juice to get around town. I will check all those things and report back. I toss injector cleaner in it once a month religiously. I am blaming it on that damn ethanol gas we have now. It has been destroying everything! I have the Hayne's Manual, does that give a good descript of cleaning the Throttle Body or is there somewhere on here that gives a good breakdown. I have read about people cleaning it and it doing wonders, and have been meaning to do it, now I guess I have that much more of a reason to get out there and clean it. Maybe this weekend I will get around to it and let you guys know.

 

And Joey, if your car is running as bad as you make it sound, I would def check the coilpacks because that is what it sounds like. When I had a bad one, I didn't want to even drive it down the street.

 

hey just throwing something out there. i got a bad knock sensor, but still get 24 mpg. and about cleaning the TB, i cleaned it and it helped a lot with my idle issue. but giving me more power? not really......recently, i reset my ECU, went out, was driving home for like 30min (car was up to full temp) and decided to mess around, my car flew like a butterfly....it pulled much better.....try reseting your ecu for now reason, and check it out.

 

The mechanic charges like 10 dollars to clean the TB. I have the same problem as you and the TB cleaning did nothing. Like I said, I was reading up on the issue and the engine coolant temp sensor seems like the culprit. I will get mine checked out once I get the chance.

 

all i have to say is 25mpg is not bad at all.
and i agree on at least checking the coolant sensor. if that is not working wouldnt it stay in closed loop?

 

dude i understand about what you're saying..but it doesnt throw a code necessarily, like i said i had a few bad coilpacks and it didnt throw a code...also it would run fine until it hit operating temperature..before that it would run smooth but after that it would run crappy..you could ask another org member to do a non permanent swap....just to check...btw i could be wrong but you can only use injector cleaners so much...they will break o2 sensors...

 

Alright, instead of starting a new post I found my old one to revive...

Update: Last weekend finally got some free time, cleaned out the TB and MAF (the TB had a good amount of gunk in there but not to the point where I feel it was resisting the air from getting in there). Anyways, unplugged the battery and let the car sit overnight to reset the ECU. Still having the same symptoms. When getting the car going first thing in the morning she pulls real hard. I feel like after 3-3.5k it just takes off like a jet. After its warmed up, it just doesn't have the power. 2nd gear is the most noticable I feel when I try to run it up to about 6k I feel it just takes so much time to get there I could put it in 3rd and it would be almost as quick. Any other suggestions of where to look next or is she just getting old on me??

 

Hmm when's the last time you changed your oil?

 

what mods do you have?

i have an open intake and sometimes if you dont have a good heat shield you can get heat soak ...and the engine can reach around 200 degrees normally operating temp and the lack of power can be from an open filter sucking up hot air...that was my prob for a while

 

WOW guys this is exactly what my car does. Its really fast when its cold, like the first 2 minutes or so. The car will spin through 1st and just rip. After its warmed up it takes sooo much longer to wind first gear out and its slow again. Its so noticeable. I almost lost to a v6 mustang with an automatic(won by one car length). If my car was cold he would have been raped. I was gonna ask this question but thought nobody else had my symptoms.

 

Mmm cold air intakeeee

 

Could it be my MAF? I don't mean to hijack, but it seems we are having the same issue. I use 93 octane also, along with Eneos Fully synthetic oil and oem Nissan oil filters. Oxygen sensors possibly, Cant be my plugs they are new oem, has to be some sensor that screws with my ecu telling it to be slow.

 

Check the MAF
Check the TPS
Make sure your cat isn't clogged
PCV working ok?
Is your air filter dirty?

 

Oil is changed every 3k, (was last changed 2 months ago around 1500 mi ago), air filter was cleaned over the summer (K&N), where would I check to see if the PCV is working ok? It isn't throwing any codes. Plugs should still be good, and if the other guy has new plugs with similar symptoms there must be somewhere else to look. Fuel filter was changed over the summer too, and always 93 octane in it.

 

Redwagon, I have the "exact" same symptoms as you. Go to autozone and have them run the OBD II scanner. Chances are that you have an P0325 knock sensor code. And no, your CEL will not be on.

I run 93 and recently did a full tune-up but the symptoms persist. BTW, just because you are getting good mileage does not mean you don't have a KS code. I am running 23+ mpg with the code.

Go get your ECM scanned and get back to us.

 

I will go get my ECM scanned to see if I'm pushing any "hidden codes". This is just one of those things that is really annoying and depressing I hate seeing my car run like this.

 

How about the knock sensor?

 

How about a cracker? jk lol.

I hope for his sake it is not because I already had mine replaced and so have others in the same position as us and the problems remain.

Redwagon, if you get a chance, have the engine coolant temperature sensor looked at as well. I was reading through the 3d gen section and they had these exact symptoms and they were linked to it.

Good luck. Keep us posted.

 

the engine light is on for my knock sensor and ive still got all 200 horse so dont thinks its that

 

fuel injector problem?

 

or even fuel pump?

 

You didn't have 200 horsies with a working KS.
You certainly don't have 200 with a bad one.

 

lol I wish i could give some of you .org members a ride, you would be like wow your flooring it, NO YOUR NOT! YES I AM I SWEAR!!

 

I have a question, check out my vid of my max, all i have is intake and exhaust in this vid - does it look like i'm lacking power, i've only been in one other maxima and itw as an automatic with a UDP CAI and exhaust cat back... so i'm cuirous, oh but when i had my automatic, i had a bad knock sensor and when i replaced it, it made a large difference in torque...

http://www.youtube.com/watch?v=xu3iJebcrl0

 

No dude, your car is how mine runs when its cold, it RIPS! When my car is up to operating temperature, its sooo much slower. Your car is how I wish mine ran.

 

Well got my codes read, and what do you know It read "P0325 Knock Sensor Malfunction Bank 1 Sensor 1". Yet my engine light wasn't on? Should I replace Knock sensor?

 

You have two things going on.
1 - The KS.
2 - Bank one sensor one - thats an O2.

Replace that O2 first, clear the ECU. Check for the KS code about a week or so later.
A faulty O2 will also trip the KS code.

Makes sense that the lack of power is only when the engine is up to operating temp, thats when it's using the signals from the O2 sensors to control fuel trim.

 

Ah. I took mine to Advanced Auto yesterday and had my codes read as well with a P0325 popping up. I thought that just meant the knock sensor. So is there a good chance that replacing the O2 sensor will cure my problem? I would have thought the O2 sensor would've had a dedicated trouble code that would get set off if that were the case? And is this O2 sensor easier to get at than the KS? Good thing I didn't already buy the KS if that may not be the problem, that thing ain't cheap

 

It only read P0325, there's no oxygen sensor code there. CEL would've been lit if there was codes other than the KS. Different readers will say different things about P0325, sometimes they'll just say knock sensor, other readers knock sensor circuit 1, etc.

In this case, it displayed P0325 as circuit 1, bank one; more commonly referred to as B1S1.

Also, WOT lack of power wouldn't be a symptom of a bad oxygen sensor; their input isn't taken into account in open loop.

 

Thanks for that clarification. That's what I figured, but I saw that and got a little confused. I'm going to tackle the sensor on Sunday I hope, I've been reading posts with the instructions of how to get at it without taking apart the intake manifold (really don't want to spend a full day of Sunday football doing that and with my luck I'll put something back together wrong or lose a piece somewhere and be screwed.

I was reading in some posts that getting at it in a 5spd is a lil more of a b*tch cuz of added tubes. Anyone have suggestions or advice before taking on this endeavor?