I'm trying to figure out why my times suck. or at least I THINK they do.

Any other SC'ed Auto 4th Gens out there?

Here they are:
R/T - .638
60 - 2.367
330 - 6.355
1/8 - 9.570
MPH 1/8 - 77.99
1000 - 12.339
1/4 - 14.711
MPH - 95.48

I'm running the following Mods:
MEVI
3.25" Pulley
Custom CAI
WSP Y-Pipe
Stillen B-Pipe
Cartech FMU, tuned to 12.1:1 across the band.
2 step colder NGK Plugs

Dyno numbers without MEVI - 231hp 204tq
Dyno numbers with SC - 267hp 214tq

Previous Owner of SC got 190hp to the wheels with a manual tranny.

I'll post my Dyno sheets if anyone would like to see them.

Symptoms:
Vacuum is only 15Hg at idle in "D". Many nights and days have been spent moving the vacuum system around and testing for leaks as well as listening and testing with carb cleaner. No leaks found.

Peak boost - 8.5PSI

Car occasionally sounds like it's backfiring when I rev the engine in park.

Can also hear a rattling sound (small exhaust leak it sounds like) when cruising next to a cement wall on the freeway.

Thanks ahead of time.

 

Man seems like one auto max with basic bolt ons, like y and intake with a 100 shot had a lot better time then that?

 

There is some member 'Gadledge' or something like that that had an auto SC

 

Jay has an auto sc as well...

 

Vic ran 15.3 with his SC Auto

if you got your 60ft down to 2.1 that 14.7 would be 14.3

 

I ran a bunch of 15.3's in my SC Auto with 3.33 pulley. But I later found out that my Vortech fuel pump was disconnected and the car was running really, really lean. Plus my 60 ft. times were in the 2.5 range so that didn't help.

 

Did you fix that boost leak completely? I would think an auto w/ S/C and even the most basic mods would be in the high 13s.
-Cyrus

 

An auto SCed on stock boost usually should run high 14's (roughly 14.7).

Considering you are also running the MEVI, you should be quicker then that. 2.3 60ft is pretty good for a auto. The best i have seen is 2.2 on an auto unless you are either spraying within the 60ft, running slicks, o rhave a High Sall TC.

I use to flash the TC on launch when i use to drag my auto. This has yielded me 2.2 60fts and low 2.3 60fts.

 

You should be faster than a 14.7 considering you are runnning a smaller pulley and the MEVI.


Irvine78 stated he has a friend with a SC auto Maxima that ran a 13.7, how he did it I don't know. It's possible I suppose.

 

maybe it was altitude corrected

SC Auto's as Jeff said.. should be running mid to high 14's..

lets not forget the shoot out at Maxus last year.. two fastest cars were Supercharged 5spds.. running low 14's

 

Thanks guys.

This is what is perplexing me however:

I Dynoed with the MEVI before I got the SC. 147hp. At that time I had a HAI and Y-Pipe (and the MEVI). From what I've heard, most Auto 4th Gens are at 165-170hp with these mods.

Then I Dynoed with the SC with a 3.25 Pulley and left the MEVI turned off. 231. I've observed most people with the 3.25" pulley and Auto get about 250hp at the wheel.

Then my boost gauge was never reading over 6PSI. I worked with it some, and bought a new gauge, and it now reads 8.5 peak on a cold morning.

I also hear slight "backfiring" noises sometiems when starting the car on a cold morning. And the exhaust leak mentioned in my first post.

And my vacuum is low.

Basically, I think my car is sick, but i can't imagine what could be wrong. Over the last year (tune-up and getting the SC and troubleshooting), I have done the following:

Replaced the plugs with NGK 2 step colder,
Replaced the Fuel Filter
Put in Synthetic Tranny Fluid
Have always used Synthetic oil
Replaced the PCV Valve
Checked belt regularly, tighten/loosen if needed.
Replaced all vacuum hoses in the SC System and re-routed them several different ways. Boost gauge always reads the same.
Replaced boost gauge.
Vacuum tested with 2 other diagnostic gauges.
Taken the car to 3 seperate mechanics looking for the mysterious "vacuum leak"
Gasket sealed the manifold and all SC piping
Re-seated and re-tightened the manifold
Dynoed with an A/F meter and tuned the FMU to 12.1:1 across the band.
Took Y-Pipe and Cat off and looked for clogged areas/bad flex section.

Hope that gives some ideas, because I can't think of anything else to even look at, much less do.

IanS

 

knock sensor? Would this affect his performance that much though?

 

That's a good point, but:
I have put the ECU in diagnostics mode many times, and never get the KS code.

Can the KS be retarding the timing and not telling me through the ECU (even when I pull the codes)??

IanS

 

Also note that I have a 3.25" pulley.

 

2 step colder spark plugs? I think you should be running the 1 step colder spark plugs. That's what I'm running, and I'm using the 3.125 pulley. I heard that the 2 step colder spark plugs are more for nitrous user. If you use that with the SC, you car will run like a dog. Again, that's what I heard, not sure if it's true or not.


Also, I'm running an 8:1 FMU disc.

 

I was instructed by people on this board to use 2 step colder.

I'll try and find the thread about it and post it here.

IanS

 

Ian you need to go down to 1 step colder plug. I dont know who told you 2 step colder plugs but thats not right, your only at 8.5 PSI, I hit 10PSI. 2 step is good if your EGTs are high but besides the point something is wrong for EGTs to be high. 2 step will drop the temp by 200 degrees celsius but your car will lose that quick pep. My times where not so impressive with 2 step colder plugz. Also is there a way you can bring your 60fts down to 2.2? , that would help your time drop down. Traction is our enemy!!

 

Matt is using 2 steps because i think he is using boost and NOS..

i have one step colder.. one step should be good for you

 

Ian, if you want to experiment with the 1 step colder (instead of 2), I have a set that I used for less than 15k miles and pulled recently because they purported diminish performance... me being N/A. Although purely subjective, I think the proper heat range made a small difference for me. ...yours if you want 'em (free, of course).

As for the knock sensor, many here have questioned what would happen if the KS was detected by the ECU as in working order but erroneously putting out detected knock. From what I gather from reports, a bad KS can cut peformance down by 15+%. Still, you don't want to go swapping parts in and out at random just because you think it may be faulty... If your car is old enough and you have enough miles on it, I wouldn't feel guilty buying a new one though. Certainly though, the KS is not responsible for low vacuum.

 

Well, I went over to mtrai760's work and he hooked up the OBDII (or is it ODBII?) for me.

(Thanks again, mtrai)

Here's what we got. I'd been driving around for about an hour and the car had been idling for 7-10 minutes:

(All recordings are at idle)

MIL Codes - None
Intake Air Temp - 141 degrees
Engine Load Value - 17%
Short Term Fuel Trim - 11.7%
Long Term Fuel Trim - 9.3%
Short Term Fuel Trim 2 - 12.5% (not sure why there's 2...maybe Left and Right banks?)
MAP Sensor Vacuum - 9in Hg
Fuel System - Open Loop
Idle - Fluctuating between 700-730
Ignition Timing - Advanced 11-15 fluctuating, mostly at 15
Air Flow Rate - .37lb/min
O2 Reading Section 1, Sensor 1 - .05
O2 Reading Section 1, Sensor 2 - Varied - .1 - .5
Fuel System 1 & 2 (Once agian, Left and Right banks, I think) - Open Loop
Coolant Temp - 200 degrees


Maybe that will give some people some ideas.

IanS

 

The knock sensor is ignored by the factory ECU in closed loop (wide open throttle) operation.

I am back to one step colder now that I have the J&S.

 

Well, that tells me alone it's probably not having anything to do with the KS.

IanS

 

I beat ya I beat ya!!! sorry, so it was two missed shifts, I had to get that out of my system! Anyway, I have some 1 step colder plugs if you want to try those out. They only have about 20k miles on them, just let me know. I would suggest getting some more gauges to see what your car is doing as well, at least an EGT. Ebaymotors, most go for $80... you can install it at my shop after we close, takes about 15 minutes...

 

you guys raced ? 15.2 beat a 14.7 ?


i would also suggest suggest additional gauges such as a/f, egt or a apexi safc.

that way you can weed out any problems using measurments from the gauges that everybody is a little more familiar(sp) with.

 

No, I ran a 15.4 that run, but he accidently shifted from 'D' to 'N' and screwed up his run= my win...

 

Ian-

There is definately something wrong with your vacuum. You could be loosing a lot of power through the leak when coming on boost. 16 Hg is way too low. After installing my VI, my vacuum was at a steady 21 Hg at idle. I'd think yours should be no less. When reading the gauge, does your vacuum jump around at all? Vacuum should slowly increase as you slowly open the throttle and it should drop like an anvil when you quickly open the throttle. Does yours do this?

Did you replace the EGR, IACV, and throttle body gaskets? These MUST be replaced when changing out your VI.


Dave

 

Yep. It's dead steady at 16, and when I floor it and release, it drops to about 23, then pops back to 16. It slowly increases when slowly hitting the gas also. On the freeway, at cruising speed (65-70mph), it's usually around 20-22Hg.

I've replaced all gaskets, but have ordered an extra VI gasket from my supplier to replace that again as well, just in case. Nothing can be heard whatsoever as far as boost leak goes.

This was tested while on the Dyno at full boost by 2 mechanics at the Dyno shop for 5 seperate runs. There's just nothing to be heard.

I also tried disconnecting the vacuum system for the MEVI completely while on the Dyno, so as to make sure there wasn't any leaks in that system that was causing it.

I've also tried 3 seperate gauges and they all read the same, connected to various locations, including directly to the manifold.

 

Actually, I forgot I was manually shifting, hit redline in 1st, then over-reactd and dropped it into D insted of 2nd, then when I hit the end of 2nd, I shifted into N thinking I was already in 2nd.

That was by far my worst run of the night.

 

yup. trash that freaken stock vortech fuel regulator... its a pos
but i did end up fixing it
Vic

 

Ummm...I don't havea Vortech FMU.

I have a Cartech adjustable FMU.

IanS

 

I ran a 14.3 on a Gtech not like that matters but once I put my 3.25 pulley on I will dyno my car and see what happens

 

 

Thought you were going to sell your car.

 

I'm not trying to start anything, but are most supercharged autos in the 14s?

 

no he was going to sell his blower to buy a bike right before winter

 

man without you here to keep everything straight I would be lost

 

So anyone else have any ideas?

Basically, no vacuum leak can be found but I am reding low vacuum.

Otherwise, the car appears to be running perfectly.

But I Dynoed 20-30hp less than I should have, and about .5-.8 seconds slow on the track.

IanS

 

yea I was going to but instead im going to keep the boost and save for the bike and buy one this winter(because its cheaper), but thanks for know my plans anyways Doug

 

winter is primary bike sale season.. the prices don't change i know.. i watched it last year..

 

so are you going to arrange my scedual for me now