Power Hesitation at 5k rpm with stock twins
 

Hey so my turbos work pretty well but most of the time just before passing through 5000 rpm the car bucks because there's a loss and sudden regaining of power, I'm thinking this is either the Charge Control Valve or an inadequate grounding issue. Anybody have experience with this happening? Thanks

setup:
stock series 6 twins
stock rebuild
power fc
twin power
550/1300
v-mount
dp, mp, cb
pullies

Wow. Your car is running again? Congrats.

What is your boost pattern like?

Haha yeah it's been awhile, I hadn't started it for two years, I changed the battery and it cranked right up in less than a second I was impressed! And I decided to hold off on my single turbo motor, just want to drive it to sevenstock and do some trackdays on the twins :)

I'll have to pay closer attention but I think the pattern is correct, just a bit inconsistent because I have a midpipe and stock wastegate. So 12-10-12.

Ok I did some more testing today, boost pattern seems to be 11-6-13. I assume this is due to the creep as my boost control is set to 12. And that's from my Defi gauge which always seems to read I think a psi higher than the boost controller even though theyre teed on the same nipple. And importantly this hesitation I have seems to occur about 4800-5200 rpm, after the transition, not every time and it's like the car looses power for a second then instantly regains it. I know that my compression is a bit low and I may have a stuck side seal and my primary turbo leaks oil and they both seem tired but this seems like it might be electrical possibly due to the insufficient stock grounding? My battery is relocated to the bin and attached directly to the starter to power the engine harness and grounded below the bin. I will try putting another ground on the ecu.

i had same problem it was solenoid valve...

try this - if you have boost controler take it out (unhook the vacumm lines and hook them up to stock locations)

on the wastgate you will have two vacumm lines - take off the one thats on the right side of the wastgate.... and cap the wastgate niple - ( cut the vacum line and put a bolt in it will work )

you car should only boost 8 psi at wastgate and you car wont be bucking anymore or creep

and after this test...if you dont have anymore off thos problems ...just chang your solenoids

Ok, so which solenoid did it end up being for you? Thanks

for me it was the one - labeled in diagram with [ I ]

http://www.fd3s.net/turbosystem.jpg

but it might be more then one

did you do the test

I experienced a problem like this once, and it turned out that the fuel map was really rich after the transition resulting in a similar symptom; as if it were laying down momentarily. Took out fuel there and it was fine.

Note that Solenoid "I" is the waste-gate control.

Hm I don't think it would be that solenoid since I have a boost controller with it's own.

Did some more testing today, it appears as though right at the transition the boost doesn't ramp up smoothly but rather slams on real quick, may be due to the midpipe with unported wastegate? I will do some poking around, want to check the charge control valve, charge relief and associated systems.

yea check everthing....as i sayed it could be more then one thing

i had full 3" exhaust no cat

i also had boost controler that was making my boost patern bad and creep

your boost pattern is really bad

i just needed the car to drive
so i did what i told you....it shouldnt take you more then 5 min to do... take it for a drive reprt back

i drove it like that for about a year as i just whent singl turbo after that and took all that stuff out

it will stay flat at 8psi insted of 11-6-13 turbos will still work sequentially

How is your boost controller hooked up? Is it controlling both precontrol and wastegate? Or do you have the factory precontrol

It controls both.

I experienced a similar problem when I still had the twins. In my case, the issue was a leaking fuel injector. This is an issue that just started happening for you, I take it? By saying that it happens between 4800 and 5200, and is intermittent, suggests either an injector or the leading coil. The reason I say that is because either one of these issues will cause intermittent problems, as I have had both happen to me more than once. ;)

That being said, I vote for either a leaky fuel injector (or injectors), or a failing leading coil. Also, verify that the harness running to your coils is good. :icon_tup: Mine was shot, and was in need of being replaced. FWIW, I was running the HKS Twin Power as well when I had this problem...

Sorry for the Thread jack OP.
 

Thanks SERBRX7! It works for me, But i only get 5psi of boost :( , my car has been bucking like a bronco lately from 3k rpm and above randomly. Although, i still have the bucking problem, driveability has increased! :icon_tup:

So from the diagram, you're saying take off the green hose from the wastegate and cap the other side??

replace wastegate it should be 8psi

whats the condition of your turbo how much miles on it

just take the green hose from the right side of the wastgate and cap that wastgate niple...

the one on the left stays conected....:icon_tup:

What are you a/f ratios doing? Rich spot in the map maybe?

Yeah but then what about the hose itself? Plug that as well?

Also what would be the result If the wastegate nipple was left uncapped? Could that cause overboost?

Yeah but then what about the hose itself? Plug that as well?

there is no need for that as the selenoid wont be controling the wastgate anymore

just use tight silicon line with bolt and ziptie


Also what would be the result If the wastegate nipple was left uncapped? Could that cause overboost?

yea...wastgate would not open as it need to build presure to open

wastgate control solenoid raises boost by relieving air pressure from wastgate.. so by caping that niple you will only make the boost at your wastgat spring presure

if you still have problems after this i would change out all the solenoids as you are all ready in there...i think you can get them for a good price from one of the vendors

(E) (F) (H) (I) (J) http://www.fd3s.net/turbosystem.jpg

also if you are on the stock ecu and you did bunch of upgrades

that might be throwing off your ECU and causing this problem

most times this happens right at turbo transition

car bucks and then burst of power

going to PFC ecu and a tune would be one way around it... but that would be a project...

so chang out solenoids and return your car to stock as much as posible


------------------------------------------------


if you are on PFC check you tune
1300cc injectors are known to go bad

Well... I bought a JDM Series 7 motor, so i assume its low mileage. I'll report back, if i solve this issue. By the way, I did a auto to manual swap retaining my auto harness and ecu, Hold light is flashing and i have 2 Engine codes which are, AWS & Purge solenoid. I have a notorious bucking problem, saving up to get a PFC.

Yeah recently i had been experiencing overboost. At first i thought it was ignition breakup because i would get flat spots at around 5k.

Then i started to look at my boost gauge and noticed it was going way past 10psi.

I decided to look into the turbo area for unhooked/missing vacuum lines and saw the wastegate nipple was left free.

Maybe the cap was broken off and i didnt know about it. Im non seq but i never had this problem in the past.

Im on the stock ecu with the stock cat so i was wondering why im overboosting like this.

Anyway i capped that nipple and im gonna go for a drive today to see if that helped.

Thanks for the advice man.

i think you were hitting fuel cut from over boosting

try to take some pic of your setup

ok....i think your vacuum line burst or poped off just conect it back up from that wastgate niple to solenoid [ I ] as shown in the diagram...http://www.fd3s.net/turbosystem.jpg
as your solenoid is probably ok

yep!!! That certainly was the problem. A missing cap from the wastegate nipple. Now I get a rock solid 7-8psi.

But now my car feels slow LOL.

If I wanna get a boost controller again, would I leave that wg nipple capped?

I'm gonna get a simple bc this time. Grimspeed sells a simple Manual one for 80 bucks.

Thanks again for the advice man. :)

http://turboxs.com/shop_prod.php?what_category=1

Bleed type boost controller

you can hook it up at the niple you caped off and let it just bleed of some air pressure from wastgate to increase boost


you should get PFC as you got way to much mods for stock ECU

you also need fuel system upgrade

modifay you 850cc secondary injectors to 1300cc
or
modifay you primary rail to fit 850cc injectors

also supra fuel pump and HKS twin power

also make shour you have proper non seqential conversion

and then you will be able to increase boost



if you keep on driving you car as it is now you are just asking for truble
anything pass 10 psi is to much on stock ecu

my recommendation - if you drive it stay out of boost, dont race it

I have a supra TT pump already.

I basically have all the bolt ons minus midpipe and PFC. I still have the stock cat.

So you're saying if i get another boost controller again, install it in-line with the nipple i capped off?

Meaning run a vacuum line from the nipple, to one end of the boost controller, then what about the other end? Where does that line go to now?

Bleed type boost controller

that would be it, there is no need to connect the other side

you would screw it in all the way to make that 7-8 psi and to increase the boost you would let it bleed some air pressure out

the other side you could just run to air intake or just open -- do not cap it

Cause ultimately i wanted this boost controller.

http://www.grimmspeed.com/catalog/pr...roducts_id=165

Simple, small and only thing i need. Which is why im selling my dual stage unit, cause there will be no high boost for me since everything is stock.

If i get that grimmspeed bc, i can just hook up one line to the wastegate nipple and leave the other end open you're saying??

Thanks again for all the help man. I appreciate it.

i never used that boost controller....but it should work

i like TurboXS its the same price and race proven
==========================================

If i get that grimmspeed bc, i can just hook up one line to the wastegate nipple and leave the other end open you're saying??

yes...you would hook it up to that nipple you just caped....this way it works just like the stock solenoid...

you can also set it up traditional way

keep that nipple on the right caped

and install the boost controller between the nipple on the left and the turbo



let me know how things work out or if you need more help

Yeah my old boost controller wasnt hooked up to that wastegate nipple. I actually didnt know you could hook it up there as well.

But i want to sell my current boost controller before i get another one. I guess for now im stuck with 7psi.

My car is really dog slow now lol. Took forever to get to 100mph today. lol

Pm'ed you serb ;)

Check your spark plugs

So I tested pretty much everything, all the solenoids seem fine, I forgot that the end of the nipple broke awhile ago on my turbo control vacuum solenoid output but it still tested fine. Check valves, viton lines, hard lines and vac/pres tanks were fine (but I didn't have time to test them for extremely long). Charge relief was fine. Turbo control actuator seemed to take a lot of pumps to pump up on both sides (pres and vac) but once there it held fine (I think this is due to it having so much volume).

And one thing the smaller diaphragm on the charge control valve (constant pressure from primary turbo) was not holding pressure but it wasn't dropping too slowly so maybe with constant supply from the primary it would be ok but this could be enough of a problem to cause my issue??<<<<<

I also need to get under the car and watch the turbo control work etc. but I get the feeling it's ok.

I did the simplified sequential and removed my emissions (along with a/c and p/s!) and now the primary doesn't boost until very high rpm DOH! It sounds like I have a boost leak though so I will just get back in there and seal all my block offs etc. better.

Looped line steering is maybe a bit tougher than I had hoped at slower speeds (doesn't help my wrist is injured working) and I need more time to evaluate road feel but so far I like it (especially the big hole in the side of my engine bay, that is great!!!)

Well rather than figure out the sequential issue I created, I decided to go non-sequential. The car only goes on track now so it was logical for my simplification. That fixed the boost but now I'm getting an extreme hesitation around 5k it's almost like a rev-limiter. I'm going to try some little things such as grounding the pfc and engine to battery but I really want to switch the plugs, the car sat for awhile and they are about due I think so maybe that's it.

Have you verified that your injectors are not sticking/leaking? What about your coils? Have you verified that they're working properly? And the harness going to your coils?

Is there any way to check the injectors without taking them off the car or shipping to rc engineering etc. to be checked? I had them cleaned maybe 25k mi ago so they seem less likely. I'm more worried about the coils and harness, the twinpower could have burned them out? These parts have 85k and the twinpower was put on about 25k ago as well. Is there a procedure for testing them in the FSM?

I've put some more thought into this issue lately and I'm wondering if it may have to do with the racelogic traction control. I changed the tire sizes without inputting the new diameters into the controller and maybe in every gear right around 5k rpm the wheels are spinning at the right rpm to make it think they're slipping? Anyway I just need to drive the car and test it, do some logging. I never take it out anymore except for the track. I had thought it was related to my boost issue at 5k rpm but that may have just been with the solenoids and actuators. Will post up once it's solved and tested on track.