Update on page 2, post 43


Lately my car has been feeling somewhat gutless so I cracked off some 0-60 runs the other night and the results were pretty miserable.

Data on the car:

1997 Maxima SE 5sp
Fairly new OEM clutch that was put it right before I bought the car
175,000 miles
Loaded with every option
Two 10 inch subs in the trunk
The only mods that might affect power so far is a cold air intake into the fenderwell and a warpspeed 2.5 inch mandrel bent b-pipe


Maintenance related to the engine:

All maintenance up to date and performed by me within the last 2000 miles including:

-Completely cleaned and rebuilt IACV
-Cleaned TB
-6 new NGK v-power copper spark plugs gapped to .40
-both front o2 sensors replaced
-fuel filter was replaced with a 300zx fuel filter
-all engine grounds have been cleaned, sanded and reinstalled
-New knock sensor
-ran fuel injector cleaner through the tank
-Fresh oil changes every 3K with castrol 5w30 and mobil 1 m110 oil filter
-EXTREMELY gently cleaned my MAF with a q-tip and 90 some odd percent isopropyl alchohol.

The engine has not had a compression test, but considering it does not burn any oil (or at least not an amount at which I can detect over 3000 miles), I am assuming it is still in great shape as far as compression goes.

The only codes stored in the ECM are those related to heaters on the oxygen sensors. For some reason my car keeps blowing the 15amp fuse that powers the heaters, thus that would explain why it is throwing those codes. Other than that, there are no codes in the ECM.

The 0-60 times:

The several 0-60 runs I did were with just me in the car and timing with a stop watch from launch to indicated 60 on the speedometer (my tires are factory size so there shouldn't be much inaccuracy.)

The times ranged from 8.2 seconds to 8.7 seconds.


The test conditions:

5800ft elevation
69 degrees ambient temp according to my climate control
about 20 percent humidity
Dry flat pavement
No wind however tests were done in both directions, so it was not the road I was on.
Driver weight- 145lbs

I don't think it was my driving, I have been driving stick since I was 14, I know how to shift. I launched at approx 2500 RPM and got a good launch all but one of the times (that time I ran 9 seconds to 60 so I didn't count that run), I didn't bog it but I didn't excessively spin either. First gear I shifted at redline, and second gear hits 60 mph at about 6000 RPM if I remember correctly, so I stayed in second through 60 and did not shift into third. For one run, I attempted to shift a bit earlier, like 5700rpm since the power drops off a bit up top, but that did not help my times.


Compensations and comparisons to factory spec:

According to magazine reviews done on the Maxima in 1995, 6.5 to 6.8 seconds 0-60 seemed about the norm for the five speed. Now, I am not expecting to be hitting those numbers because there are factors that make that not attainable with the limited engine mods.

Altitude:
From what I hear, a general rule of thumb is for every 1000 feet of elevation, you subtract .1 second in the quarter mile.

Despite the fact that it was quite cool, I will still subtract for 6000 feet of elevation just to be generous to the numbers, thus meaning I would take about .6 second off my 1/4 mile time. Since this is a 0-60 time, and not a 1/4 I will cut that in half. So -.3 seconds. Taking the average of my runs, 8.5 seconds approximately -.3 seconds, that puts me at 8.2 seconds approximately with altitude compensation.

Weight:
As a general rule of thumb I hear for every 100lbs you lose, you gain about .1 second in the quarter mile. So I will take into account for every 100lbs extra that my car is over what a 1995 base model 5sp maxima, I will take off .05 second off my time, the reason that is halved again is because this is a 0-60, not a 1/4 mile.

Since my car is loaded with heated power leather seats, moon roof, bose, auto climate, ABS, etc. they say all that weighs about 70-100lbs more than a gxe. Also, since my car is a 4.5 gen with added strengthening for crash worthiness over the 4th gen (like what was tested in the magazines), I hear that is another 70lbs. I weighed my subs, and those weigh 60lbs.

So, taking this into account, if I were trying to calculate this for a 1/4 mile run, I would say I have 210 pounds more than those test vehicles in 1995, so if I wanted to compare what the machine can do, I would take off .21 in a 1/4 mile, thus since this is a 0-60, ill take off half that, so ill take off .1 for the added weight.

Compensating for this weight puts me at 8.1 seconds 0-60 now. Through this compensation, I believe I have ruled out almost all the factors that would make my car differ from those magazine tests, thus making this a direct comparison.

Meaning, I am running 8.1ish seconds to 60 when my car really should be running 6.6ish.

If anyone can help me in diagnosing what is wrong with my car, that would be much appreciated! Thanks!

 

That seems close to me, my best time with the same mods minus the subs and only 400 feet elevation is 7.8 with a real small down hill in the begining and normaly its around 8 to 8.1. Mine is a fully load 99 auto with 140000 miles

 

elevation matters but you said the car feels slower than normal, at the same elevation probably right? maybe you should look into a compression test.

 

... 175K, normal wear, normal decline in performance. Might help to clean/change fuel pump and trap/screen, fuel injectors. Other than that i think you covered just about every other maintenance issue that would decrease performance

 

Ok, maybe I will do a compression test tomorrow. What should the compression be at on this engine?

 

Is the trap screen easy to get at or would I have to drop the tank and all of that?

 

Hmmm did you check your ignition coils/wires to see if they are good?
And are you sure the OEM clutch is not slipping?

 

Oh and what octane fuel are you using?

 

its under the rear seat

http://www.vqpower.com/v2/infusions/...?article_id=96

 

I am pretty sure the ignition coils are good, I am not getting any misfire or anything. Is there a certain way to test them?

The car runs on premium fuel only.

Thanks for the link B eaze, I will definitely look into that.

Oh, and no, the clutch is very solid, enough that I get a very slight chirp/wheel hop into 2nd gear. I don't know if its my imagination though, but I remember there being more power before cause it just doesnt seem like my tach swings up to redline as fast, nor is it as easy as it used to be to chirp 2nd gear.

What blows my mind is trying to figure out what could have happened recently to make it gradually lose power over the course of a few weeks.

Also, I know the o2 sensor heaters have nothing to do with anything, but the fact that they are tripping a CEL could that make the ECU go into some sort of a mode where it runs on reduced power?

 

1 Warm up engine
2 Turn ignition switch off
3 Release fuel pressure (remove fuel pump fuse and crank engine a few times)
4 Disconnect ignition coils
5 Remove all spark plugs
6 Disconnect all injector harness connectors
7 Attach a compression tester to Cyl 1
8 Depress accelerator pedal fully to keep throttle wide open (or rig at throttle body)
9 Crank engine and record highest gauge indication
10 Repeat for every other cylinder
11 If compression in one or more cylinders is low, pour a small amount of engine oil into the cylinders through the spark plug holes and re-test.

standard psi should be 185 and it really shouldnt be much lower than 150. and there shouldnt be more than 15 psi difference between them. good luck

 

i didnt notice u had codes, gotta clear them for max performance. if your throwing O2 codes (pre-cat) ur engine might be retarding timing making performance and mpg go way down. check your O2 sensor connections and wires, see if you can find why ur running thru fuses like that

 

my maxima does 8 sec 0-60 run and i think its all it can do... its a 5spd and bone stock....
190 hp can only go so far... and those magazine tests were probably going downhill while doing those 0-60 runs imo...

 

I hope these 0-60 runs were done on a track........

 

I was wondering that too. I'm not sure exactly how the ECU controls ignition timing but you very well could be stuck with "safe-mode" parameters since your car thinks there is a problem with your o2 sensor(s). I would work on fixing that issue first.

 

Well sorry to let you down but no they were not. They were on a rural road out in the middle of nowhere with a speed limit of 75mph. I didn't do anything illegal.

Just curious, how many times have you been to the track?

 

try and clear all the codes and maybe even reset the ecu than redo the test before te light comes back on. if worst comes to worst than do the compression test i gave you all the steps a couple posts up.

 

talk about some thorough analysis for that.

 

Won't the engine run worse right after an ECU reset as it has to figure out timings again?

 

it would run worse than an engine with no codes but not worse than one with O2 sensor codes, theoretically. I could be wrong

 

this is exactly what i was thinking after reading the OPs post.....

you might need an o2 sim to bypass the codes. its a cheap part and relatively easy to install.

if anything, just disconnect the battery for a good 30 mins and let the ECU reset itself.

 

coils can be hard to tell if theyre bad. i replaced my alternator, plugs (to platinums), and bank 1 coils and it was like i gained 10 hp across the whole rpm band. that was 500$ worth of parts though. if i were you id have someone you know with new coils swap with you to see how it drives then, but i doubt if you have that opportunity

 

post 12 i call dibs on that.... jk

clear ECU with diagnostic tool or screw method

 

All of this O2 sensor talk is irrelevant, codes or not. WOT is open loop operation, relies on pre-determined ignition and fueling maps. Short of a faulty knock sensor, not many things will come into account here.

 

wait 75mph speed limit?

 

Your rule of thumb about elevation is inaccurate. Cars that run at Bandimere in Denver are generally about 1.5 seconds slower than they are at "normal" elevation tracks. Given your altitude and the extremely inaccurate timing method you're using, I think your car is running pretty normal.

 

I think I found the problems

 

They weigh about 60 pounds, I tried to take that into consideration in my timing.

Anyway, thanks for the info Nealoc187, I didn't know there was that much of a difference in the 1/4 mile. Perhaps it is just the altitude.

Either way, I have noticed my car doesn't stay put on a hill in gear nearly as well as any other cars I have owned, so maybe my compression is a little low. I am going to run that compression check once my engine cools down a little this afternoon.

Also, it has been a few months on that airfilter. Since it is in the fenderwell, it might be more prone to getting gunked up quickly. I'll check that out as well.

You are correct. A lot of interstates and some rural highways are 75 out here.

 

^^ yeah i remeber driving on i-25 in my brothers accord doing 90 to keep up with traffic lol.

but in contrast to the whole elevation thing. my brother used to own a 98se and lived in castle rock for years. and when he would bring it to minnesota he always said he seemed to run so much stronger out here. maybe i need to drive my maxi out to denver so i can compare and idk and maybe visit my brother and mess with his passat

 

do they not have 75 MPH rural roads where you live? they are here in TX too

 

its only 70 out here past the belt way. i know in CO it was 75 by the airport.

Sorry for the off topic but

Minnesota= no fun

no fireworks that go into the air
no alcohol sales besides bars on sundays or national holidays
50% tint

 

Thanks for all the help guys, I haven't gotten around to checking this out any further because I have been so busy, but I think the first thing i do is a compression test. I have noticed my car doesn't stay put on hills in gear well at all, and when I take my foot off the gas in a lower gear going down a hill the car doesn't engine brake well AT ALL. Maybe I just have really low compression.

Then again, the Density Altitude here has been between 7700-9500 feet lately too......

 

Modena,

It's your rebuild mate! Just kidding!

I would think elevation would play a huge part in your issues. It even affects cooking things too! lol Another thing to check is the air filter. It's possible that it is just needing a good cleaning or new cone.

.... driver weight #145 ?? and you did your trans by your self? Sweet!

Cheers mate!

 

Bwahahaha...um....lets just say I had some open wounds and some bruised ribs when that f!!!er came down on me.

Just for anyone who is like "wtf are they talking about?" JtzMax is the dude who spent a lot of time helping me over the forums when I decided to drop and rebuild my transmission having no experience doing it before ever. In a nutshell, Jtz is ****ing awesome!


Anyway, tomorrow I think I might do the compression test, check the airfilter in the fenderwell (its only about 4 months or so old, but you never know), and then I will let you all know what I find. I think it definitely is pulling timing though, because in the low end it feels exactly like it did before I replaced the knock sensor, yet I don't have a knock sensor code or anything.

 

Would you be able to post up a datalog of a WOT run? That'll show you what's going on with timing, AFR mixture (crudely, but possibly usable), air flow, etc.

 

Nope, I don't have any equipment that shows me those parameters. What would I need to be able to monitor that stuff and do you think I could rent it somewhere?


EDIT: One other thing I might check out, even though I don't want to mess with it too much since my multimeter is analog and from the 80's, is my throttle position sensor. Perhaps that could explain some of the poor engine braking and poor performance.

 

Any OBD-II scanner (not a code reader, an actual scanner) that can log to some form of storage media would work.

A ghetto way to do this would be a camcorder facing the OBD-II scanner. Seen it done before...

That or OBD-II software and a laptop, or a CONSULT cable and appropriate software and a laptop.

 

Awesome, I am looking into it right now. Unfortunately from what I hear OBD to USB cables don't work as well as OBD to serial? Unfortunately my laptop does not have a serial port. Also do you recomend I use Consult or OBD?

 

0-60 doesn't matter on a HWY as long as you do not spin the tires...you can get up to speed as you please

 

ecu take about 10-12 hours to fully reset itself