Ok i just got this car and im trying to figure out what is going on. When i floor it from a dead stop the car lags bad until i hit about 2500-3000 rpm then it kicks. Im trying to see if anyone else has this issue, here is the DL of the mods. It has stillen moddified cams, variable intake manifold, wheel well cold air intake, ported and polished exhaust manifold, aluminum underdrive pulley, And its chipped. If anyone has any idea's it would all be appreciated. I think im going to change the plugs but i dont think that plugs would cause that big of an issue. It almost feels like the car is getting more air then it knows what to do with.

 

do you have a CEL light on?

 

Sounds like you hit it on the head.

Most of those mods you listed (and I think it's safe to say most mods in general) tend to lose you some low end power. There isn't much out there that's gonna give you more power over the whole powerband. Usually you have to make sacrifices.

Try launching it at a higher rpm. If it's an automatic (which I assume it is by the way you described it), think about a high-stall torque converter. However, I don't if they make any for Maximas.

(Do I sense a knock sensor argument coming on?)

 

there are high stall converters mde for the maxima, they are just custom made rather than stocked on a shelf

 

yeah man you have got a lot of top end mods you are gunna dog off the line.

 

Some food for thought may include upgrading your injectors as well as a fuel pump. Have you checked your mass air sensor?

 

I thought about it and was curious if it would help. I haven't checked the mass air sensor yet, but it may be dirty maybe i will try cleaning it. I know i have all this air and top end power and i need to get more low end for the launch. so i guess i am going to have to do what you are all saying and fork out the money for bigger injectors, fuel pump, and a high stall converter. seems to be the only way i can get the low end back. Also i previously had a knock sensor code but it went away when i reset the ECU not to long ago. I didn't reset it because of this though i reset it for evap which there isn't anything wrong with. Thanks for all the help guys

 

ported and polished exhaust manifold???

 

Yeah rather then buying headers the previous owner had the stock exhaust manifold ported and polished..im with you on this one, cause it probably cost him more to do that...lol

 

It's because you have an automatic transmission. Only way to solve this is to do a 5-speed swap.

 

Some truth in here and some not so much maybe. lol

I agree that larger (300zx) injectors would help and a larger / more capable fule pump too. Plugs believe it or not can make a difference, especially off the line. And, yes the KS was mentioned too, so I must ask if you have tried to pull codes (even if the CEL is not on)? If you have a bad KS, it would show on a good OBDii reader. With all of your mods, you should have better performance under 2k rpm.

 

can knock sensors be bad without having a CEL i get bad gas mileage and i lag off the line

 

YES ... mine is bad and no CEL. I know it's bad cause I used our scanner at work to check it ... just playing around and I was suspisous anyway. Confirmed ... bad KS. Not cheap, even at cost and it's a PITA to install (unless you have a loving g/f with small hands FTW! lol)

 

cali spec.?

 

WOW. your car does NOT need any fuel upgrades.

Rip out this so called chip, and get it tuned with something proper like an EB or EU, or I suppose you could use a C-AFC

 

It's a ghost code on all 95++++ maxi's, but can also be caused by actual knock.

 

C-AFC? Sadly, no more SAFC or VAFC, only the Neo now...

Injector upgrades...

 

there you go, i lost a bunch of low end when i put mine on. make a short intake out of it, should improve the bottom.

 

Nope ...

 

Replace your knock sensor...its like $50 for an OEM one on ebay and go from there. If you notice no improvements, do what Kevin said and get rid of your "chip" and look into an EMU such as an EB or EU or an AFC from Apexi.

 

The C stands for crappy

 

I will get back to yall with the name of the chip i do however know you can set when the chip kicks in. Right now im under the assumption that it kicks at about 3000 rpm's. but i will look into that if the knock sensor doesn't work, although from what i am reading it should. So i do need bigger injectors and fuel pump or i don't, im getting mixed answers on this.

 

Kicks in? V-TAK FTW.

Anyway, no, you don't need aftermarket/larger injectors. If you want to look into it further, do a datalog of IDC on a WOT pull. I bet they'll be lower than, say, 80% @ redline.

 

So your check engine light does not have to be on for codes that could be flagging problems with my car? I'mma hit up autozone and see if I have any "hidden codes".

 

KS (P0325/0304) is the only code that can be set without illuminating the CEL.

You can check the codes yourself, just takes a few seconds and a screwdriver.

 

KS

FTW!!!

 

KS was my most expensive repair so far...

on the cali-spec car the sensor is a bit further under the intake then in other models, I was able to get it off... but had to tow to a shop to have the new one put back on .

 

ok so my plan is replace the KS cause i did have a CEL on but it was popped by the evap as far as i know, but the KS code came up with the EVAP Code so i do have a bad KS as far as i know, It could just be wiring though because we have some physco rabits out here and it got chewed up by them, i spent about 6 hours rewiring stuff when i got the car so the wiring may be chewed. I get the feeling that the KS is going to be a pain in the A**. Do i need to pull the intake manifold to get to it, if so i may as well change the plugs and clean the injectors while im at it. After i get all that done im going to take it to a buddie of mines friends shop(solid technologies if any one from ABQ is on here) and get it tuned and possible full exhaust put on it. How much will exhaust help with power in general??

 

The knock sensor is an easy change w/the right tools.

A long extension and one of those movable hinge adaptors....

just get someone else w/small hands to put the new one in until fairly snug... then just torque it down to the specified lbs.

May want to practice w/a torque bar first...

 

There is problem number one(torque wrench) but i will find a torque wrench..maybe i will get one from work. i use them everyday so that wont be an issue as for small hands i will have my wifey put it in for me, suprisingly she likes turning wrenches with me. Im going to pull the codes again tomorrow and see if i still have the KS code in the ECU memory if so then i know for sure that i need to replace it. Although i dont quite understand how it affects low end power, i hope it fixes my issue. The season at the dragstrip is over so i have plenty of time to get the car ready for next year..I'm hoping to be a mustang killer..lol but we will see. I got yanked by my buddies camaro not long ago, which is what brought this topic around. I HAVE TO GET MORE LOW END POWER!!

 

As far as i know to use a torque wrench the mani will have to be off. -1

 

That makes for alot more work. DANGIT i was hoping to not have to pull the intake, but oh well im sure my plugs could use changing and the injectors could use cleaning anyways.

 

be careful w/ the egr gasket when removing the intake, if you crimp it you will set off an evap code, also check the plinnum gasket while it is off, since it's dual metal and rubber it should still be good. oh, and larger injectors won't do anything if the chip won't bypass the setting they're at. make sure you reflash the chip to support the new injectors and pump, otherwise it'll be all for not.

 

You are a life saver i think you may have just solved my mysterious evap code problem and possibly my low power problem. i know the previous owner had the intake manifold off many times and the car has been popping evap codes like crazy, but as far as we can figure out there isn't a thing wrong with it till right now. I think you may have just figured it out for me. So even the slightest crimp or imperfection will cause this? Althought there is a very good possibility that it is more then a slight imperfection...

 

A blocked up EGR passage won't set an EVAP code. Two completely seperate systems.

UIM-LIM gasket is straight rubber, no metal involved. Then again, that's for the USIM; could be different with the MEVI or 00VI.

A pump change won't require any sort of reprogramming to this...'chip'. And he doesn't need injectors.

 

dangit i thought i had the evap ghost solved...I wish i knew the brand of this "chip" i probably sound like and idiot(its ok to tell me so), but thats all i was told. Alls i know about it is that some guy with a shop in the middle of no-where made it and i have a book to program my rpm ranges..in my opinion i need to find it and replace it with something more reputable and more lejit(spelling)

 

He 'made' it?

Can you post up a scan or pic of this instruction book? It would be very interesting to see.

What do you mean your 'rpm ranges'?

 

you can set the chip to kick in at different rpm ranges just by changing wiring configurations as far a i know. I will see if i can get a picture up or the book(actually a sheet of paper that came with it). Yeah i guess he is legit from what my buddy said, but i dont know, im going to feel really dumb if it is a legit company..lol

 

WTF is that? Sounds like some sort of adjustable ECU, but I don't really understand. How do you change the 'wiring'? Did you rewire the ECU somehow? Not really sure what you're talking about. Is this some sort of 'new boost' technologie?

 

that chip is worthless