Hey guys, i'm having a problem with my car having low power after the car warms up. Some history with my car includes, 8k mile old injectors and brand new knock sensor with working coilpacks. I've tested each coilpack individually by unplugging them, listening for change in engine spark. I've put in a resistor to trick the ecu that i have a "working" knock sensor. power is good when its cold, but after around 20 minutes of driving i feel like the car is severely heat soaked. I have a stock air box with the resonator removed and plugged with the air box opened up. houston, tx has recently gotten to summer temperatures but i never experienced this power drop before. Any suggestions? Thanks in advance

 

leak somewere?

 

Could it be the cts? What kind of leak? I changed all my vaccum lines

 

Hah no it hasn't yet. Wait until July and August. Texas heat torture!

 

How modded is the car? My blue VE project that I just got going suffers from a similar seemingly constant lack of power. It has a new KS, KS harness, CTS, etc.

At ~15 deg. it's REALLY sluggish. The only way I can get it to NOT be incredibly sluggish is by advancing the timing pretty far (not sure the exact degree, but judging by the CPS it's pretty far advanced), but it's still sluggish, and nowhere near as powerful as it should be considering it's fully modded.

When I first start it up and drive it, it's decently powerful (albeit not nearly as much as it should be - compared to my black VE when I had all the bolt-ons on it), but after driving around for a while it seems to be severely lacking power.

The engine is a JDM with new VTC's, so it's been opened up before. A few months ago I was thinking maybe the timing chain is off a bit and thus causing my timing issue(s). But, seeing as when it's cold the car is ALMOST as powerful as I feel it "should" be, then I don't think the timing chain is off. Plus, it passed Texas emissions with flying colors over the weekend, and if the timing was that far off I'm not sure it would pass.

I really don't know where to go from this point either. I'm leery of doing a resistor KS "trick" since I'm not really sure what my timing is at. Like I said, my KS and CTS are both brand new. The engine runs fantastic, idle is perfect, all injectors test great, no misses, etc. It just DRIVES sluggish.

Do you have Aaron's spacers? That's the only thing I can think of on mine that might be causing this issue. Not that his spacers cause this issue, but maybe I used too much RTV and it pushed out the sides and into the intake runners and causing problems with airflow. But seeing as there's no RTV pushed outwards of the IM (where I can see it), I doubt much got pushed inwards. So I don't know

 

I don't know if this is how they work on the Maxima BUT:

o2 sensors usually do not give a reading to the ecu when the car is cold, because they need to warm up to work properly. So when your car warms up, the o2 sensor circuit starts giving a signal. So I have heard that sometimes if your o2(s) are bad the car will run like crap/lose power when it warms up.

I don't know that this pertains to the Maxima so someone who knows for sure would have to back this up.

Good luck though!

 

i went with the resistor trick again and the power is back.. apparently either my KS harness is gone or the KS is gone again.. what might cause a bad KS? .. i realllly dont wanna replace it again.. cuz that was a pain.. i only did it cuz i replaced all 6 injectors at once. maybe its the KS harness? james.. i would do the KS trick, just get a timing gun. if you were in houston i'd let u borrow mine..can't tell if i have enough room to undo the knock sensor harness without taking off the ITM.. i guess i'll find out.

 

You don't I tried that already. You have to remove IM, fuel rail, and water pipe.

 

I do have a timing gun. I checked all codes this morning (55, all clear) and reset the timing per the FSM with undoing the throttle sensor and aac harness and whatnot. I'm nearly certain it's at 15 deg. right now (plus, judging by the relative position of the CPS as it's drawn in the FSM as well as how it's positioned on my other VE, I'm pretty sure I'm in good shape)

The car feels like the timing is extremely retarded, just absolutely sluggish, especially between about 1500 and 4500 rpm. The thing is, even when I advance it far enough that it drives okay, it's still sluggish with respect to how it SHOULD be considering it's fully modded.

Maybe I'll try the resistor trick now that I'm pretty confident with the timing.

nickdoof... I'm not sure if that pertains to the Maxima as well. Considering how trashed/bad condition everything else in this car was, it wouldn't surprise me if the 02 sensor is bad. But I'm not sure I remember reading/hearing if the 02 sensor does anything driveability wise other than terrible MPG?

 

Wow, am I pissed.

I just ran to Radio Shack and got a 470k resistor. Stuck that sucker in while still in the parking lot, and the car instantly feels like a new car. It pulls like a ****, and FINALLY "feels" like a fully modded VE 5 should feel.

And to think I was getting to the point of potentially pulling the timing covers to try to **** around with seeing if the timing chain was off, etc.

This is beyond infuriating. The knock sensor AND harness are both BRAND NEW.

 

 

Congrats James I think I'll be relocating the knock sensor on to the front head for a while.. I think matt93se did this for his ve from what I read from a previous post.. It's just too much a pain to get to the knock sensor.

 

How's this resistor trick done?

 

buy a 470-550kohm resistor from radio shack or any electronic place.. put the resistor into the knock sensor plug connected towards the ecu.. and you're done!

 

So you have to access the knock sensor to do this? I think I'm confused on where the resistor goes exactly

 

The resistance between the two pins on a good KS is approximately 470K so by inserting a 470K resistor into connector that goes to the KS you're essentially tricking the ECU into thinking that we have a properly functioning KS in place on the engine.

 

Ehhh... Low to mid range is good for stomping around town racing a GT-R from stop light to stop light. If you want real speed, real power that can compete.. VE my friend.

 

I'll give you the benefit of the doubt and assume you aren't insinuating that a VE can compete with a GT-R. Both would get smoked. And no, a VG isn't good from stop light to stop light with that car either, like I said, I got DESTROYED, and that's an understatement

Initial post deleted to avoid an engine debate, those don't lead anywhere.

 

I'll still have to do remove water pipe, manifolds, etc.

 

:metalmax:

 

http://www.4dsc.com/articles/drivetr...k_sensor.shtml

 

Thanks!