have the maxima low end Blues.

Everything i've been searching points to the Knock sensor. (i.e lacking power under 3k rpm).

The only other culprit is 70k mile oxygen sensors or an exhaust leak, but I doubt I have one. I DO have 1 bolt stripped off my y pipe where it meets the manifold, but it doesn't leak for ****. I stick my hand up there and don't feel any puffing or exhaust odors. I'm going to try seafoaming it to see if i can see any leaks before i buy oxygen sensors.



Its Stock manifolds/WS Y pipe/ 5th gen Cat / 22"x2.5" Magnaflow resonator / 2.5" mandrel bent cat back / 5th gen muffler.



Just replaced fuel filter today. Check that off the list.
Spark plugs are good.
Coil packs good.

 

honestly, its gotten to the point that with the Maxima's that theres a quick checklist to go down to diagnose them..


If you can confidently say that the below items are indeed in good working order than you should have healthy engine.

1. Mass Air Flow
2. 02 Sensors
3. Knock Sensor
4. Exhaust Leak Throwing a 02
5. Plugs
6. Coils
7. Intake Air Temperature Sensor
8. Injector
9. Random Misfire
10. Fuel Filter
11. Air Filter
12. Evaporative System Leak
13. Exhaust gas Re-Circulation System
14. Your Butt Dyno Is Out Of Wack

Self Explanatory: 1, 10, 11, 14
Should Illuminate CEL/SES: 1, 2, 7, 9, 12, 13
Require Further Diagnosis: 1, 3, 4, 5, 6, 8, 9
Not Your Issue: 5, 6, 10, 11, 13

My Recommendation is pull the codes if you haven't already, run some seafoam down the Brake Booster Line, if you have access to a Scanner monitor the 02's You want the Voltage to Spike pretty frequently. From around .06V to 1.56V IIRC ( dont quote me). Clean your Air Filter, Plug up the Exhaust with a Rag and see if theres a leak (only thing that makes the Highly unlikely is the simple fact that a leak would cause you to run LEAN rather than rich, you would actually see a power increase).

Otherwise, 02's and Knock Sensors. KS First than 02's Junk yards ones are fine.. Im running some Denso 02's i found at the yard work great!

Im sure im forgetting something but this is a great start.

If all else fails replace #14.

BTW, im curious what kind of Intake are you running? Intakes are notorious for dropping off Low End. And I Don't Care What Anyone Else Thinks So Don't Even Start In On It.

 

great post!

When I plug the muffler, what should I look out for? Any sound/fumes in particular? How much time maximum is safe when clogging the muffler?

-I'm running a 5th gen Intake.


-Only code I have is the rear o2 sensor (post-cat) which i deleted when installing my exhaust. My Wideband reads 14.6.15.1 at idle. When its warm its stables off to 14.7~. When I accelerate, as in gently and steadily holding the gas about 12-15% throttle, it will fluctuate from 13.5-15.5 but once its cruising, it settles down to 14's. Im guessing my o2's are just tired and lazy by 74k miles and the old rusted y pipe they rested in.

-Air filter is new. Bought about 2 months ago.

-Butt dyno is fine. Might just be the auto-trans laziness to downshift from 4th/3rd into 2nd but under 40mph, the car is just sluggish and giving it throttle does nothing. (I have to stay in closed-loop under 40% throttle because of the larger injectors and inability to tune that range. The VAFC2 doesn't serve low-throttle justice with its "interpolation")

-intake is sealed. check it today when replacing fuel filter.

-coil packs haven't misfired in a loooong time. I did some tweaking which included wrapping in electrical tape and cleaning the contacts inside the tube (easily oxidized). So it seems to have worked.

 

my first question is...did u first notice low end loss after completing the exhaust mods???

dude, U are running 3" exhaust pipe. Your exhaust velocity under 3k is prolly way too low. Up top prolly feels like a beast tho hehe.

If i were u, i wd put a stock 4th gen muffer back on to build up some resistance in the exhaust line.

U can try to replace KS, but i doubt it will help. 3" pipe is for F/I.

 

Whoops. I've misinformed you. I have 2.5".

 

When I first got my i30, I thought something was wrong but I figured out that it was a combo of being an AT and being a fairly small v6.

The problem have been remedied though

 

I don't think you should be trying to smell fumes to diagnose a problem; just saying.

 

are you saying the car used to have more power and now it feels sluggish?If you are does it feel slower at full throttle and did you check the a/f ratio at full throttle?Could also be your MAF going bad.It's my understanding when the o2 sensor starts to go bad the car usually runs rich.15.5 is definitely on the lean side.

 

Car hauls *** in open loop. (full throttle).

 

Pic: Beautiful.

02's sound like their the issue.. IIRC the ECU is only supposed to lean out to 14.5:1 - 14.7:1~ at cruise.

Don't have to really worry about a time frame for plugging the exhaust, eventually it'll pop out of it if its sealed up good.. But you should be looking for visible leaks and if you can smell any exhaust fumes well.. yeah.

Glad to hear that shes sealed up tight, i recently found my accordion section to be WAY loose.. i was irate.

good to hear you keep your filters clean.

Your VI cup JB'ed? That thought just graced my mind that maybe shes stuck on the longer runners?

BTW your 2.5" exhaust is nothing to worry about isn't that stock size?

Also something im interested in is what do you have your Open Loop AFR at?

 

2.25 is stock i believe.

open loop is from 13.6-12.9...pesky vafc

Vi is jb welded fine.

 

stock is 2". My boy has the same problem- he did exhaust 2.25" from headers all the way back on a 4cyl and lost low end torque. Of course u gain high end, which is all that matters cuz when u race u up top anyways like kevlo said.

 

4 Banger's Specifically Honda's dont take well to anything bigger than 2 well.

Also Honda's dont make **** for Trq in any range really... That and you gotta Rev the **** outta them. 7X00 RPM stock rev Limiter? Jebus.

We on the other hand have 3 Liter Rich burning VQ's. I Highly Doubt 2.25-2.5 would cause him to lose a bazillion ponies below 3K.

Like i said, His Buttdyno's broke-dededed.

 

I've concluded its just the stupid transmission taking itself to 3rd/4th gear when cruising under 40mph. I really loves to stay in the high gears once you let off the gas. The loss of power was just the engine trying to force 3rd/4th gear @ 20mph.

 

I remember the first time i drove a honda. It was an 1999 accord LX MT. Not a bad car in any sense but it was Revy as shyt. Its fun because the u engage the gears frequently to keep in good power band, but dammit mph-wise i wd only be doin like 30 or 40mph. I was like wtf. I imagine it felt like a maxi that had both a fidanza and UDP on it, minus 2 cylinders of course lol.

I remember test driving a 1998 camry 4 cyl MT, and it was not revy like that. CAmry had more a linear acceleration and velocity, more of what im used to with other cars.

 

Back on course, replace the KS, I just did mine 2 days ago. Cost me $25 for an ebay one + a few cuts/burns.

 

I'm guessing it worked? I've bought an ebay knock sensor before and it didnt work. Can you post a link fromm where you got yours from?

 

i got 470k resistors and it makes no difference. Knock sensor reads good.

 

aint that the truth...i still got the scars from replacing KS

 

Thats what i am running right now.

 

running 93 octane right?

 

Link:
http://cgi.ebay.com/ebaymotors/1998-...item45f348115e

I would run 93, but CA only goes into 91 where I live, so I get that.

 

this^ cali is only 91

 

How bad is the low end? Could it just be that the 00vi pulls so hard up top that it just seems like the car has no guts below 3k? I have a somewhat similar setup to you except a 5speed and I don't really feel that much power come on till I get the revs over 3k either. I mean, I can keep up with slow traffic just fine with light throttle and shifting at 2000-2500rpm, but it definitely doesn't feel like the power starts to come on strong until 3000, and then 4000-6500 is just absolutely amazing with the 00vi.