Bubble---

When I got my Strups installed my idle was choppy but I didn't notice any difference in RPMs while driving.

My butt dyno def felt a harder pull in the mid range.

2 weeks later got the Unichip installed and tuned.... We took a look underneath and one of the bolts rattled loose on the right header.

Since then everything has been good.... 252hp/239tq

Didn't you say you were getting a Unichip?

 

my idle was fine. Below 1K mark just like before. Ted blames STRUP made the pipe bigger; therefore, it results in the RPM increase. I find that hard to believe since NO ONE has this problem before. Somehow i just have a feeling that the header is not installed correctly but i can't prove it. hehehe

 

Your rpm's are dictated by your tranny, gearing and tires. Installing headers should not have changed your rpm's. Now why is your car reading the incorrect rpm's? I don't know. I am positive it has nothing to do with the headers.

 

I'm sorry but this statement is completely and totally wrong. Yes the ECU will adjust idle speed sometimes and make the engine idle higher, BUT that is ONLY when the transmission is in neutral or the clutch is disengaged.

When the transmission is in gear, and the clutch is fully engaged, there is a direct mechanical link between engine rpm and wheel speed. This link is perfectly finite and can not change unless the final drive ratio, or tire/wheel ratio is changed. If his car remained completely identical from prior the header install, to after, the engine rpm is exactly the same afterwards as it was before at the same engine speed.

Bubble, the only possible answer to your question is it has to be an issue with the tachometer. The servo controlling the tach must be off for some reason. But I guarantee you that the engine rpm at 80mph in 6th gear is identical to the engine rpm before the header install.

-Acree

 

that is what i thought. Damn it, i just hate when this happen. However, when they plug in the scan reader, it shows the tachometer is off by 200. So they blame the header.

 

HAHAHHA. your statement of rpm and speed always in perfect sync is completely absurd! haven't you gone up hill at lower gears? You mean to tell me your car cruises at the exact same rpm at certain speeds? anything can throw this balance out of wack dude.



your rpm can reach higher levels when the engine take significant heat. take out your raidator.. you'll be cruising at 60 and see your rpm hit redline before you head gasket blows up. pucture some holes in your exhaust, headers and intake. you can be cruising at 40mph, 6k rpm in 5 gear (figuratively speaking)

 

YOU ARE COMPLETELY IGNORANT.
It is a direct mechanical link!!!!!!! I don't know how many times I can say this. I don't care what the conditions are, the engine RPM remains the same at a given MPH with the same final gear and wheel ratio. Even if you take the heads off the block, and push the car down the at exactly 80mph, the crank will rotate at exactly 3000rpm. Not 3200rpm. I don't know where you got your knowledge of mechanics, but it sucks.

-Acree

 

Acree,

so the machanic lied to me ???

 

Well, I wouldn't say he intentionally lied, but yes I personally believe he is wrong. I don't see how a bigger header pipe would lead to an increase in engine rpm. Bigger header piping equals more exhaust flow. Yes, this leads to torque loss but also a gain in horsepower. As I said before, engine rpm is a FINITE ratio with the wheel speed. It does not change unless a component of the driveline changes aka wheel size, tire size, final gear ratio, transmission gear ratios.

-Acree

 

and how are we going to explain about the tachometer being off? The scan reader showing it off by 200. I tested it myself. At idle, like .6, the scan show around 600. However, at 3K on my tachometer, it showed only 2800 in the scan reader and so one (3200 in car compare to 3000 from the scanner). This is the thing i can't argue with him since he said the tachometer being off.

i just can't link the header with tachometer being off.

 

I understand on a M/T if the clutch is not slipping then YES there is a direct mechanical linkage between engine speed and wheel speed. 80mph in 6th gear will always be the same (unless your clutch is slipping).

However bubble has A/T, which has a torque converter. Forgive my ignorance, because I only know the BASICS of how torque converters work (never cared much for them anyways ) but doesn't that mean for an A/T there could be the possibility of a disagreement between engine speed and wheel speed? I mean, this is how you do a brake torque launch right? Engine speed = high, torque converter speed = high, tire speed = zero (until you let go of the brakes) ?

In all possibility I think it's much more likely that the tach is just "off" and needs to be fixed. The engine itself is probably fine. Bubble where does your rev limiter hit?

 

what you said makes a lotta sense.

Bubble: why dont you bring your car into nissan for service and ask them why your tach is reading a little off? At the same time get an oil change. Even though they might not fix/want to fix it they can certainly tell you what is wrong and the good part is you got an oil change and both parties are happy. Yes i know your car's warrenty is voided but a lot of mechanics will still trouble shoot your problem.

 

i would change the trans fluid, and filter if there is one. dirty old fluid plays havoc with the various modulators and check valves in the trans.especially if the car is modded and you drive it like it was meant to be driven. if the fluid gets too old i have had other auto trans cars ive owned rev higher to maintain the same speed.im not familiar with the 350's auto trans, but if you can i would change the torque convertor fluid as well.i dont know how many miles are on your car, or how many were aggressively driven but its cheap insurance.just use good synthetic, ive had good luck with neo-gen but it's a bit pricey.good luck

 

Acree, you're absolutley correct. I know i didn't have to tell you that but when i read what Cannysage wrote (it was sooooo way off) i just didn't know how to reply, lol. Well said though.

Abdulla

 

Thanks Kudos, atleast someone with mechanical knowledge is backing me up.

Bubble, I didn't catch the part about you having an automatic transmission. But that still shouldn't cause the engine to constantly rev higher, especially since you didn't have any work done to the transmission. I'm not an auto tranny expert, but the torque converter acts as a clutch. It releases when the transmission speed needs to vary from the engine speed, example at a stop light, or shifting gears. But, when you are cruising on the highway, both of the speeds are matched, so the torque converter shouldn't be affecting anything.

You said you were looking for some way to tie the header install to the tach being off. I hate to tell you but there is nothing that will tie those two together unless it was an issue with the installation. The issue is, your tachometer is not reading the correct engine rpm. You and the tech confirmed this with the scanner. The only logical explanation is it has to be something that occured during installation. You have verified the actual engine rpm is the same. You need to speak with the tech about the tach, not as a result of the header itself, but as the result of the installation. You should tell him, "Look man, my car worked the correct way before I brought it to your shop. I want it to work the same after it leaves your shop." The only problem is, I can't think of a single thing that could have happened during the installation to make the tach read funny.

-Acree

 

lolz..he said put back your stock header then problem solve.

 

Bubble you still didn't answer, what does your tach read when you hit the rev limiter?

If it reads high, then it's probably a stupid offset problem with the tach. But if it reads normal 6600rpm, then you might have other issues.

Just an idea, I hope this helps.

 

I'll try that next week. I'll have my AT tranny oil change this weekend. Let see if that help.

 

lol, just don't listen to acree, cuz he's got air coming out of his *** and you'll never get your car fixed... stating the obvious, such as.. .uhhh.. The only logical explanation is it has to be something that occured during installation... no duhhh.. next thing he'll tell you is to stick potatos in your exhaust.

 

Dude, just because you're a mechanical moron (which has been confirmed by other forums members in this very thread) doesn't mean you should be a d!ck. I'm trying to help the guy fix his car by supplying correct mechanical knowledge and helping eliminate possibilities. Why don't you go find some other thread to troll. I'm just trying to help the guy. Thanks.

-Acree