b18vteceg

a week or so ago i finished my 3.4l swap with a 1st gen sc on it. everything went well and i followed gadget's vac. diagrams. motor is strong and i have no CEL (and yes i tested to make sure it works)

no urd kit or anything just a stock setup. stock pulley, stock ecu, stock injectors.

run perfect and has nice sound and is strong but i have some small problems.

when its cold it idles at 2k and once warm it will drop to 1200 to 1500rpm.

i checked all vac lines and used plenty of cans of starter fluid to see if i could find a leak. none were found. replaced tb "O shaped" gasket and made sure it was on correct way.

that's the first issue i have and the second is what concerns me a little more.

after 4000 rpms the rpms still go up but its like the motor just stops making power. high octane fuel is used and filter was just changed. motor does not ping at all. sound perfect just you hear the intake suckin air like crazy but its like im not going anywhere.

i dunno maybe im used to my acura tl but i would think a sc v6 should have a little bigger power band than between 2k and 4k.

anyone have any ideas? i have no misfires or anything. runs smooth just lacks power.

thanks,

Daniel

Tragic Drive

HI Daniel, Did you try to pull the accelerator cable off the throttle body to see if that was pulling it open a little. You should also use a scanner and check for MAF position to see if its calling for more fuel.
On the second issue these supercharged motors should pull hard up to the rev limiter. Have you checked your fuel pressure ? Maybe your fuel pump isn't feeding the monster the way it should.
The first thing that popped into my mind when you stated loss of power above 4k rpm was the ECU is pulling ignition advance. Your Knock sensors work from 3K rpm and up and will advance timing until knock and then back off. However they will pop a code if the signal is bad/out of range.
How did you interface the computer to check codes? Do you have the OBD2 plug wired in?
Oh yeah one more thing, Get the fuel kit installed asap Injectors,FTC,thermostat,colder plugs etc. These boosted 3.4's run really lean without it and will cook your motor.

Good luck,
Thomas

b18vteceg

ya checked throttle cable not pullin on the butterfly at all.

and yes i have the obd2 connector wired in and i checked the codes there and i have 0 codes.

i still have stock fuel pump from my 3vze motor maybe i will try and hunt down a pump from a 5vze and see if that fixes it.....i cleaned my MAF and i do have extra knock sensors but i would think it would throw a code.....

i do have colder plugs in it but maybe they arnt correct.....what type are you running?

like i said tho this thing never pings not once....i can even be going 15 mph and put it in 5th and floor it....and it wont ping.....its wierd.....

and its very smooth just seems like im loosing power somewhere.....

b18vteceg

took it to the dunes this weekend and it did just fine but im still alot short on the top end.....i pulled a trailer with my 2 quads and it pulled just fine a HELL of alot better than with the 3vze but still i think im missing alot on the top end....after 4k you can hear the intake really start suckin air HARD.....but the power really doesnt go up....still no check engine light.....and still idling about 1400 rpms.....i might pull the charger off this next weekend and put the normal intake on and see if this problem is coming from the sc or its something else....when i bought the sc i really didnt know the history of it even tho its in great condition and sounds fine when it's running....

what plugs are you guys running with the 3.4 sc?

cadman

Did you have the high idle problem before the sc install? If you did, the IAC valve is probably covered with carbon/junk and is sticking. There is a writeup somewhere on YT to clean it.

b18vteceg

never had motor running with the normal manifold on.....when i put the 3.4 in the sc was already put on.....

i do have another complete throttle body i could try to swap those out.....

maybe ill try that today when i get home from work....

UKMyers

Do you have a boost gauge installed? The SC may be in need of a serious rebuild and may not even be making much boost. If that's the case it's basically a drag device like an alternator or AC pump. There are a lot of moving parts in those things that do wear out with time.

b18vteceg

i dont....that's a good idea....i do have a vac gauge i use for work....ill hook that up to the boost port and see what kinda of boost im creating.....ill get back to you guys with the results....

b18vteceg

alright hooked up the vac gauge i had from work and this is what i found at idle (1500rpms still cant figure out why its idling high will swap TB today) i have a vacuum of 22 in Hg which is approx 10.8 psi (that seems high to me) and when i rev it (i hope the video works) i actually lose all the vacuum and it turns to pressure....im pretty sure that it should always stay around 6 psi of vac on the boost port not pressure.....and you can see when i slowly rev it up the vac stays around 22 in Hg and then as soon as I open her up all my vac goes away.....is this a sign i need to send this bad boy to magnuson for a rebuild??? do i have seals blown or somethin inside the charger?

[YOUTUBE]http://www.youtube.com/watch?v=jH_mi0tKd9Q[/YOUTUBE]

Tragic Drive

At idle what you are seeing is the engine vacuum, not boost. This is normal. On a normally aspirated engine, this vacuum will approach zero as you go to wide open throttle. However, with a supercharger, which provides positive boost pressure at higher RPMS, you will go from a vacuum condition then pass through zero and continue into positive pressure indication( forced induction). Also, engine vacuum is typically expressed in inches of mercury or inHg, and 20 inHg is a fairly typical vacuum reading for an engine in good operating condition at idle. Once you pass through zero, boost pressures are typically expressed in pounds per square inch or psi.
Your supercharger sounds fine by listening to your video and your pressures look correct. However you did not keep it in boost for very long so I couldn’t see the MAX boost you have.
You asked about plugs I’m using Denso IK22 Iridium Spark Plugs. I dont remember the gap right now.
Another point I wanted to make was just because you’re not pinging when you are in boost doesn’t mean you are not damaging your motor. Your EGT’s (exhaust gas temps) are prolly sky high. You need some form of fuel management and spark control.
I ran my supercharged motor for a few months with no fuel management and I didn't ping as well. However, I sure could smell my exhaust cooking and it wasn't a normal catalytic converter smell
Good Luck,

b18vteceg

alright ill see what the max boost i get....in the (psi) area of my gauge.

im assuming i should be around 6 or so?

also i will try and check fuel pressure....

this might be a dumb question but dont these motors run well without fuel management? like in a stock 2000 runner?

so why am i having issues? what is different?

also another stupid question.

i know gadget knows what he is doing but how does it make sense to run my stock fpr off of the boost port? dont you always want the fpr to have vac not boost? just some questions i have im headin outside to swap TB in a few mins

thanks for your help

b18vteceg

alright took some videos of me driving and kinda half assed hooked the gauge so you can see my rpms and gauge at sametime....


This is Normal Driving. I was at stop (notice high idle) then shifted 1 to 2 to 3 shifting at 4k. Also notice it never goes into the positive range.

[YOUTUBE]http://www.youtube.com/watch?v=XNrWxHHZTcA[/YOUTUBE]

Alright this is wide open I was at stop (again high idle) then shifted 1 to 2 and watch how long it takes for rpms to climb you can literally see it has no power and again not alot of boost. seems like the boost fades off even with wide open throttle

[YOUTUBE]http://www.youtube.com/watch?v=k_OUEcbOfeg[/YOUTUBE]

And this is just a random thing i happen to see....when i push on throttle should that thing move up and down? and shouldnt the little black valve deal sorta stay open while im in the throttle? instead of closing right away? you can see in the last throttle up the rpms were still going up but when this little tube deal moved up the black valve thing closed....am i losing the boost?

[YOUTUBE]http://www.youtube.com/watch?v=8s9l7u_95OI[/YOUTUBE]



any more pics or vids you guys need ill be happy to get them.....also this is with the new tb on.....same high idle issue.....

thanks

b18vteceg

had this thread moved to here hoping for some extra input

skrassow

Well I just installed a SC on my 3.4l so Ill try and help out if I can. There are a few more guys on here WAY more qualified than me, hopefully they will see this too.

First, no these motors dont run well supercharged without fuel management. You really need to get the 7th injector kit. At the very least I would get a wideband AFR sensor and see what your AFR looks like as is.

Your vacuum at idle looks fine, thats where it should be in the 20-22in hg range. With this SC you can drive all day long and never hit boost, even if you rev to redline, if you drive like you did in that first video. Granny driving will never get boost. The harder you get on the gas, the more boost youll get into. If I push the skinny pedal through the floor I get about 8.5psi, but I have the smaller pulley. With the stock pulley I think somehwhere between 6-7psi is expected. With that in mind it looks like maybe your belt is slipping in the higher range, maybe thats why your losing boost.

The "little black thing" in the last video I believe is part of the bypass valve. Im not really sure how and when its supposed to open, maybe TA, or speedy can explain that. But I know that many of us have notices vacuum leaks coming from around the bypass vavle. Looks like your maybe doing it too. Check around the unpainted area nearest the SC. Use some high temp RTV to seal it if its leaking.

With regards to the FPR, those are not just Gadgets instructions, but the TRD instructions do that as well. Again Im not sure on the operation of it, but I know it works!


I know its not a lot, but I hope that helps some. Good luck!

b18vteceg

i understand the whole 7th injector thing and i will get to that. but im not going to upgrade the motor until i can get what i have running correctly.

somethin is wrong because in that wide open video i am pedal thru the floorboard and i cannot even hit rev limiter....again no vac leaks and no check engine light. im working on getting some software for my laptop so i can get some more accurate info but there is something a little off.

granny shifting all day motor is cherry. wide open and i dont go anywhere.....the motor makes alot of noise but i actually think i go slower than if i would have shifted at 4k.

mastacox

Thre is definitely somehing wrong with your supercharger. When accelerating at full throttle, you should be pushing 6psi of boost all the way to the redline, but yours drops down and is back in vacuum by the time you pass 4k rpms. Looks like you need to get the charger checked out, you're either losing boost somewhere or your bypass valve is not working properly.

b18vteceg

that is kinda what im thinkin....i cannot hold a boost ever....no matter what i do....maybe i have an internal leak? if that makes any sense....

okie81

Is the gauge hooked up correctly? It should be holding steady, as mastacox explained, but there's no reason why it would gradually drop psi at full throttle; that doesn't sound right.

You've done a few modifications/tweaks, have you pulled the fuse to reset the ECU?

b18vteceg

well....not to sounds like a smartass....but i dunno how i could hook it up wrong....

the fpr goes to the boost port and i have a vac tee in that line and that is where the gauge is hooked up.

and to answer your other question ya i have reset the ecu many times. the amount of power i am missing i dont think its going to be solved by a "sensor" im really starting to push toward a sc issue.

this weekend im going to pull the charger off and put the normal intake manifold on and see if the problems go away. that will atleast answer some questions.

but yea i agree i should be holding steady and im not at all. that last video i showed i really dont think that thing is supposed to moved up and down....i think i might be getting blow by on that seal right there because you can see when i throttle up the bypass valve moves....and then slowly backs off even when i am still in the throttle.

mastacox

All of the symptoms you're having point to a problem with the supercharger. You're going to have to take it off and send it in for service from the sound of it.