danec020

Ok guys, I have searched and tweaked with the car for ahwile now and I can not get this 1500rpm pulsing to go away. I have a S4 TII with all emissions removed including BAC valvue. I have the TB MOD done as well. I checked for vacuum leaks, corrected timing, have a new and set TPS. I checked for vacuum leaks, corrected timing, have a new and set TPS and had the injectors cleaned.

Now that is out of the way, to the problem. The car starts fine, drives fine and looks good . But the problem lies at 1500rpm, when i slowly rev the car up to X rpm, when I go over the 1500rpm mark it bounces from 1500-1300rpm constantly. Pretty even pauses between drops. Once I pass 1500rpm it is fine and has no problem. You dont even notice it when driving but I am picky as hell. If anyone has any sugestions or had a similar problem and solved it, please let me know.

I have another problem that might or might not be related. I have just rebuilt the motor, and I believe something is wrong with the turbo setup. When I go WOT my boost slowly goes up to atmospheric pressure (and this is pedal to the floor), takes about 4 seconds for it to hit atmospheric. Once passed atmospheric it has a wierd feel, almost like a bog or as if it losing power. I have the twin scroll actuator hooked up, going to the green check valve then to the nipple on the front side of the throttle body. So I believe that is correct, what else could cause this? Still have all stock system. The turbo has been rebuilt as well, by me, so possable I might have made a common mistake? But I followed the write up to the T and had no problems and hear no chattering.

Anyhow, any help on either of these issues would be appreciated . The car has come a long way from when i got it, finally has 870miles on the new rebuild and starts everytime without a problem. Thanks for the help guys, couldnt have done it without ya!

Dane

Maca1ino

Did you change your fuel pulse regulator???? it runs 90 bucks....
Or it might also be the BAC valve

Maca1ino

On the Side of the BAC valve (loated on Passenger side Top of engine) there is a screw that you can turn by using a flathead screwdriver... Try adjusting that..

Maca1ino

to answer your 2nd question... get a fuel cutoff defender

danec020

Ok, as for the bac valvue stuff, I mentioned above it is removed and everything is capped . But for the fuel cutoffdefender, do you think I am getting my fuel cut off? I Thought the ecu could handle up to stock settings, right now everything is stock, so 7lbs. Thanks for the help, i will look into the defender.

Dane

slpin

iTrader: (9)

it pulses because you need to adjust your TPS
search for tps adjustment

iceblue

It could lie some in your TPS. Simple tests is unplugging it and then see if the problem persists. However 99% of hunting off of idle is caused from a lean condition.

If you wish to set the TPS use both methods the light diode and a multi meter :-) There can still be an intermittent flat spot in the TPS causing a hunt.

I will put my money on a lean condition.

danec020

Hmm, I can recheck the tps. I used a multi meter to check it and its right on the dot. Plus is it new so I know its in good condition . As for a lean spott, what could I do about that? I believe i am running rich right now, have walbro fuel pump, can smell the fuel and I have nice little pops from the backfire durring idle.

Also remember my idle is fine, it doesnt pulse, it is just when i get to exactly 1500 durring acceleration that it does this. If it is bellow or above it doesnt pulse at all. But a lean spot would sound somewhat correct but I dont know what I could do to check that... Time to search more! =P

Thanks guys.
Dane

RotaryEvolution

iTrader: (30)

good luck getting rid of it with the emissions removed, my suggestion is to not be picky and ignore it.

it is mainly due to the idle set in a different configuration than factory due to no BAC, accelerated warmup and various other factors. if it was at idle it would be the TPS adjustment but this not being the case refer to my original statement.

you could play with the idle set screw and readjusting the TPS but this could take a while and is a real pita being that it is a T2.

danec020

Thanks for the input Karack. I was wondering if it had to do with a side effect of the TB Mod and emissions removeal, it doesnt affect the driving in any way and really just an annoyance.

Thanks
Dane

HAILERS

You have a vacuum input going to some place that should be getting a air feed. That is why there is pulsing.

Describe what you did with the fuel injector air bleed nipple. Where is the air feed hose coming off it going now?

Describe your arrangement of the twin scroll actuators vacuum feed. In detail.

At idle, when you remove the vacuum hose from the twin scroll actuators feed tube, what happens to the lever/rod on the twin scroll actuator?

What happens to the twin scroll actuators rod when you rev the engine over 2800 and are looking at it?

********have the twin scroll actuator hooked up, going to the green check valve then to the nipple on the front side of the throttle body. *********

Didn't we kinda, sorta leave out some parts here??????

There's a free download of the factory service manual online and for free.

Digi7ech

iTrader: (1)

Hmmm. I have my TPS dead on and it still does a 1500 bouce if I hold it near that rpm. So your saying that some nipple is getting vac when it shouldn't and when it does it can cause a pulsing idle?

I have the entire rats nest removed and none of the solenoids even hooked up.

What ports on the engine manifolds would require normal air reference? OR if unplugging one solenoid(twin scroll.etc) would this cause an error like this?

iceblue

^ same thing as you. I got 1.5k bounce as well when my motor was runing I chalked it all up to lean conditions.

HAILERS

IF the fuel injector airbleed nipple b/t the oil injectors is getting vacuum, you'll have and odd idle.

OMP spider gets air not vacuum. It's hard to mess this one up though.

danec020

My Primary air bleed is going to the first nipple from the bottom on the back side (pointing to firewall) of the UIM. I have several diagrams showing it to go there, so it should be right.

As for the twinscroll acuator, it could be hooked up wrong because what I stated is all I found about hooking it up. Is there more vacuum it needs to see, or should there be another nipple that needs to run somewhere?

I did notice that the vacuum that goes to the FPR is spose to have an orange check valvue. Is it necessary? I dont have that check valvue on mine, only one of my daigrams showed it.

Here are the two diagrams I still have that I found the most helpful when I was doing this. Please let me know what you think. My setup is exactly as the diagrams show unless I accidently missed something.

Last, I went and took the car for some serious runs last night to try and daignos the problem. I got it to 7krpm fine while driving and reved it to 8k durring idle fine so it isnt having problems with the secondaries I would say. Now if I give it 40% throttle to 50%throttle the boost will climb it's way up to about 30(hmg?) on the stock gauge. But past that which is usually right at 4krpm it has a loud whistle sound and just stays at that boost but will still gain speed but slowly. I noticed if i go WOT then it does the same thing but just as soon as I do it, doesnt matter if it hits 4krpm or not. So when i got home I inspected my turbo setup for leaks, well on the TID i see it has a crack in it right at the clamp, it is about 4-3inches long but looks like it is shut because the clamp is clamping it together... Does this sound like it could be that something pulling vacuum?

Anyhow, I really appreciate the help guys, I am going to pull the TID today to get a better look at it and try to duct tape it and take it for another run to just test the theory out.

Dane

danec020

Well I went out there to start tweaking with it a little but it started raining on me so I geuss it will have to wait. I watched the Actuator rod and didnt see it do anything when i had my friend rev it. I tried two different revs, a slow one and a 80% throttle rev to 4krpm and both times i noticed nothing. I am geussing it is spose to move? As for the UIM nipples, I forgot to mention that my firewall side had 4 nipples, if i remember correctly the 2 bottom ones were smaller and the third was a fat one and the top on was slightly smaller than the "Fat one". I cant really see where they are all going right now, but from memory I would have to say the bottom two small nipples are the ones I used for my injector bleeds, the third fat one i capped, and the top one I believe i used for the Twin scroll.

Does that sound right? And once again it isnt an idle issue for any of the new readers =P. It is purring like a cat right now idling fine, its just when I rev to the 1500mark.

Thanks again guys
Dane

iceblue

The large nipple is for the OMP bleeder. This is hard to mess up b/c the hose coming from the spider is larger then evry other hose.

danec020

I was looking at my friends UIM we took off his S4 a few weeks back. His bottom nipple of the four had the green check valve but it is attatched to the thermowax on the TB. So I am geussing that the bottom nipple isnt for any of the injector air bleeds, so I believe I might have this one wrong. So to sum it up, I should have:


------------FIREWALL SIDE-----------------------------------------FRONT SIDE-------------

Top Nipple => Secondary Air Bleed-----------------------Top Nipple => Twin Scroll
Second Nipple => Primary Air Bleed----------------- Second Nipple => Capped
Third Nipple => Capped----------------------------------- Third Nipple => Capped
Fourth Nipple => Thermowax or capped if using TB MOD

HAILERS

There is no Secondary air bleed.

Top nipple gets capped.

Next nipple goes to the fuel injector air bleed nipple located b/t the two oil injectors on the intake manifold.

Third nipple is for the oil injector spider.

Fourth nipple is for the green/white check valve for the water thermo valve.


There is only ONE nipple of the four that is a vacuum. That is the BOTTOM one.

The twin scroll actuator gets a vacuum from a solenoid. The solenoid is green in color. With a vacuum on the actuator, the rod is pulled into the actuator. If you pull the vacuum line off the metal feed tube to the actuator, the rod extends. The same thing happens when you rev over 2800 rpm. The solenoid cuts off vacuum and the rod goes to full extension.

You have to have the vaccum for the actuator coming from the twin scroll solenoid. For it to work as it was designed.

NONE of the four nipples on the back of the intake were meant for the twin scroll actuator. Three out of the four are NOT vacuum.

If you do not feed a vacuum to the twin scroll actuator, it will be spring loaded to the FULL OPEN position and the turbo will spool up just a touch later than a NORMAL setup.

danec020

Ok. Thanks a bunch for the explanation. Very concise . Sorry forgot that S4s dont have secondary air bleeds. Thanks HAILERS, you have been awesome with the info. I apprectiate the help and will make sure to check my setupd and let you guys know if my problem gets fixed to let you know what to do with yours.

Thanks again,
Dane

Digi7ech

iTrader: (1)

lol. I made this diagram.

It's how I remember WTF I did when I installed this motor. The only change I did was remove the FPR solenoid. I have a S4 block but with S5 manifolds so I do have the secondary air injector nipples.

Now if the OMP and second nipple do not get vacuum. Where do they get air????? I did not see an open port anywhere and if so why would they incorporate it into the TB unless they just use it as a distribution block to share a common source of non vac air?


Dane-- The orange solenoid is the fuel pressure regulator solenoid. It's meant to override the vacuum refernce temporarily during startup if I remember right. It's suppose to help solve hotstart problems. I found that it did nothing to help ym hotstarts so I removed it.

danec020

Sorry for the long delay in responses, my fiancee was in town and I haven't seen her in a year so I ended up spending time with her . Anyhow, I checked the UIM Nipples on the firewall side, and I believe they are all ok. I have the top nipple capped, the second to top is for the primary air bleed, the middle was the omp line so i capped it since it was removed and the bottom one that was vacuum for the double throttle i am using as the twin scroll actuator line.

Can the bottom nipple be used for the twin scroll line or is this not an efficient amount of vacuum to be using?

For those who don't want to read the first post, basically I have a stock series 4 with emissions removed. When I boost I get 30mm*hg of boost and no higher, and once I hit 3700rpm i feel a power loss and can barely accelerate. Not a bog, just a drop in power. But if I give it only 20% throttle i can ride it up to X RPM without a problem. I tested it in neutral and can bring it to 8krpm with no problems. On top of this problem, my idle is sitting at 1450, and when if it decided to go up to 1500rpm idle it starts bouncing, but over or under 1500 it is fine.

A new issue arrived too, when i boost the car, when it comes back down sometimes my idle stays at 1krpm, this is where I would like it but it is randomly doing this. I hope this helps shed light on the other problem. The TPS is new and set to 1kohm... Someone please figure this out, I would like to see my highend power.

I am thinking maybe the ECU is cutting fuel? Any suggestions would help.

Dane


EDIT****** The selonoid valve I am using isn't connected to any power source, is there a plug or something I should connect it to? I was looking in the factory service manual and it was talking about testing the valve by connecting 12vs to it. If I need a power source where is it and what does it look like? Thanks

RylAssassin

wow theres more talk of nipples in here than in a strip club.
I have a simple solution, get rid of the s4 turbo with the horrible twin scroll system (its a severe piece of ****) go stand alone and throw (or burn) your entire vacuum spider/nest away.
Ive have an s4 TII also with the same problem and ive eliminated as much vacuum crap as i can and seeled every possible gasket and still have that anoying 1500 rpm pulsing. They only thing i can conclude at this point is that the ECU is causing this due to the heavy modifications i have made and from what it sounds like you have too.

EDIT
oh as far as that boost problem your having, how is your wastegate? That sounds like a wastegate problem from what your describing

eriksseven

iTrader: (6)

Hey, you should really just tap your twin-scroll vac. line into the same vac. source as your BOV, pressure-sensor etc. Just the 'main' nipple on the pass. side of the UIM. If your twin-scroll isn't hooked up, you WILL get turbo-lag until around 4k RPM's with the stock turbo. If you have ANY question about this, or you're not quite sure what/where I'm talking about just ask. Hooking up your twin-scroll properly is key in fast (s4) boost response.

Also, about your LACK of power... Well, the fact that it comes on right when your 2ndary fuel-injectors start spraying is *probably* not a coincidence. Perhaps they just dump ruthless amounts of fuel? Not sure if this could be an ECU issue, (or just dirty injectors?)

Regardless, someone else had a good point about the jacked up WG. If you're WG is somehow disconnected, or there's a break in the line somewhere, your OVERALL boost response will be very slow, laggy, weak and 'peaky'. It'll hit it's max boost for a moment before bleeding off badly. At least this is my personal experience with a disconnected WG attempting to run 12psi on a small stock/hybrid.

Also, about the 1500 RPM pulsing... Everyone of my FC's; s4 N/A, s4 TII, s5 N/A have had it, which is---->

danec020

Thanks for the input guys.
RylAssassin: The rats nest has been removed already, as for the heavy moding... This car is my 10th AE that I am trying to keep mostly stock. Hopefully will have another 7 shortly for a money pit. The wastegate is fine, I just rebuilt the turbo, but I checked my TID and noticed the split that was made to fit the turbo has cracked further down and am thinking this might be the boost problem.

eriksseven: I know what vacuum source your talking about. Is there a limit to how many things you should Tee off of one source? Does it mess with the registering of the vacuum? As for the 1500rpm pulsing I am thinking the same thing, my friends does it too. Atleast its at 1500rpms and not idle .

Thanks again guys, I will let you know if the new home depot TID i made fixes it.
Dane Caro