rx7speed811

WARNING: THIS IS A LONG POST, please read it only if you have time and think you would like to help me out. i hope not to sound like an *** in saying this, but i dont want you to waste the precious and sparse bandwidth here if you are looking for something optimistic about our cars' reliability. thanks. i just wanted to be as descriptive as i could be. i just want to fix my car for the last time. here goes...

for a while now, i have had a pretty new engine (~12000 miles) and good used replacement turbos with new seals and gaskets, but i was still being plagued with boost and idle problems, so i decided to take everything control-related apart and fix them.

just for the record, i have full exhaust (turbo-back), intake, and power fc. i never really got any good consistant boost though.

i had very low (~2-3psi boost) most of the time, with a very occasional good ~13psi run through a single gear (until i let my foot off the gas), but with lots of spikes to ~15psi. i only got this good boost once in a long while though. my idle was bouncing around from ~600rpm-~1500rpm rythmically every second or two--very rough and uncomfortable, and very embarassing at stoplights and parking lots...

i finally got my car back together after over a month (all of my time outside of college, work, girlfriend) of changing old brittle hoses to silicone vacuum hoses, replacing physically broken solenoids, replacing a leaky pulsation dampner, removing airpump, replacing rubber injector seals, spark plugs, plug wires, salvaging two broken oil lines, replacing a pinholed coolant line, replacing overtorqued bolts (my fault) and some more dumb ****...

i was so happy to start it up last night, everything seemed so great. i was boosting a solid .9 bar (~13psi) almost all the way through to redline, idle was relatively smooth compared with before, car was less stinky (but still very very stinky--no cats). i drove it a lot last night, and quite a bit more today after work, i wanted to come on here and write about how great it felt after fixing all the boost problems, i really did. i thought i was TROUBLE FREE...

boy, was i wrong! the problems started to slowly creep back up on me tonight on the way home.

the boost is still pretty good when it comes on, but it spontaneously decides when it doesnt want to work for me. when it does come on, which is most of the time, it feels very strong, but is preceded by a loud surging type sound (a WHOOOOOO sound, kind of) at around 3200rpm, and is usually at almost, but not completely, full wide open throttle. kind of like i have to lift my foot off the pedal just a little bit before it will make the noise and boost. i didnt have to do this last night and this morning when things were good, i would just floor it and it boosted hard.

but sometimes tonight, it wouldnt boost anywhere past .2 bar (~3 psi, very very sad) all the way throught the power band until i let off the gas and start the revving again, then it would boost fine. when the boost is in this gimp mode, the surging WHooo noise comes at the same time as my blow-off valve. this is how the turbos were performing most of the time before i did the hose job. i think it feels something like what a naturally aspirated fd would feel like.

after driving a while more i noticed that the idle started to drop lower and get a bit rougher. i didnt think about it much at first because i thought it was because i removed the airpump, or maybe it was the power fc getting used to the new boost it was feeling, or something i didnt have to worry about. but the idle kept getting rougher and rougher at every light, and it became more and more reminiscent of how it was before i "fixed" it. by the time i got home, it was bouncing up and down just like before. i was so pissed...

i opened the hood, and nothing seemed out of place. i shined the work light around some, and didnt see any loose hoses or anything different than when i finished it last night. i am almost positive that none of the new vacuum hoses popped off because i zip-tied all of those bad boys on pretty tight.

i already checked the pcv, idle dashpot, map sensor, and most obvious problems for the rough idle already.

the only thing i did notice was that there was a lot of oil sprayed around the area where the spark plugs and oil filler neck is. i traced the source of the leak before, while i had everything apart, to the exact area of the knock sensor thats tapped into the block about an inch above the front trailing plug, but everyone said that couldnt be leaking oil because it isnt connected to the lubrication system. so i left it to fix next time, thinking it might have just been because i overfilled the oil recently, and it was just venting out somewhere. could a faulty knock sensor or something in that area be causing these problems?

CLIFF NOTES: i thought i had everything fixed last night, but the same problems i had before (erratic low boost, rough jumpy idle) came back on me tonight, almost like i didnt even fix anything.

im thinking, it has to be something small and easy to fix. i already changed to a new engine, good turbos, good hoses, etc, so all the big things are covered, i hope. it has to be just a faulty sensor or something somewhere. i need someone here to point me in the right direction!

PLEASE HELP ME OUT GUYS!!! i know somebody here knows enough about this complicated car that you can help me solve my problem, and give me the power and reliability i worked so hard on the dumb car this whole last month for. i will be ever appreciative, thank you so much for your help. i am desperate!

come on people, PLEASE SAVE MY CAR (and my empty pockets) FROM THE SHOP!!!

Sidestick

iTrader: (1)

I think you may be having problems with your charge control valve or it's solenoid valve. The ccv is located on top of the y-pipe just forward of the turbo outlet. It has a little rod coming out of it that is out when the engine is off. Check that the rod is 'sucked' into the actuator when the engine is started.

As for your idle, there could be a myriad of things to cause a rough idle, I don't know where to suggest to start. I once had my idle suddenly start bouncing around on me till the engine shut off. My quick fix, though I'm not too sure it was the right thing to do, was to just shift the TPS slightly till the idle smoothed.

P'cola FD

Try resetting your ecu. That might be a start to see if it is learniong the behavior. If you don't have a shop manual go to fd3s.net and download section F. Check the readings on ALL of your sensors. Your idle might be caused by a bad clutch switch(stoplight switch), or any number of other things. THe boost could be your charge relief, so "T" into the line going to the actuator to see what it's getting and when it's getting it.If you have a PFC then it is easy as pire to check your sensors. So check all of them and get back to us.

rx7speed811

yeah, i already checked the tps too, voltage was fine. i am pretty sure the clutch switch is fine, i can see the status of all the sensors/switches on the pfc commander. i already reset the ecu twice too. i dunno what to do???

i will check the the ccv later, thanks for the pointers.

hey, p'colafd, did u ever figure out what was wrong with ur car? i know u can relate man.

rx7speed811

i think i might have found something, but im not sure...

what is the sensor in the power fc commander sensor display that is abbreviated "PAC"? when my idle goes up and down, that sensor light blinks on and off intermittently.

rx7speed811

help! what is PAC on the pfc commander display?

P'cola FD

It's the Port air control. Mine is doing this too along with the APR the air pump relay. I don't know if it's abnormal though.

rx7speed811

OH ****!!! i think i might have something!!!!!!!!!
while the idle jumps up and down, the pac and apr sensor lights flicker intermittently with every pulse...

I JUST REMOVED MY AIR PUMP, and the wiring harness is just hanging there, not connected to anything. could that be the cause of all this ****?????? what should i check/do to correct this???

PLEASE HELP ME OUT HERE GUYS, I AM VERY ANXIOUS TO GET MY CAR RUNNING WELL FOR ONCE!

rx7speed811

anyone? please? anything!
ill lick your toes! and i think p'cola fd will send you $100 too!

folicor

OK, slap me from bringing this thread from the dead. But I'm currently having the same exact problem as rx7speed811 posted in the first post. I've searched and searched, and couldn't seem to find a thread that came close to my problem but this description hit the nail on the head. From the boosting, to not boosting, and even the wierd noise when the BOV should be sounding.

rx7speed811

damn, i guess somebody here definitely does not need lessons on how to use the search function i just got your PM, and i am afraid i have bad news for you mr. folicor.

i am assuming you have already changed all of your vacuum hoses and electronically checked all your control solenoids for proper functionality, as well as vacuum/pressure testing your pressure and vacuum chambers (the little black plastic air tanks that are routed in your turbo control system) as well as all the lines and connectors that lead to them. id recommend doing all of the above first before reading the following...

the problem you are having is most likely due to a faulty turbo control actuator (or the solenoid that controls it, or the vacuum hoses that connect to it, or the wiring to the solenoid that controls that, etc...), or a boost leak due to a crack around the flapper, which is what my problem was. it is not a cheap or easy fix, and you are probably best off buying a whole "new" used set of turbos, which i did (or you can use this as an excuse to get rid of the twins and go single, forget about all those vacuum hoses and boost problems forever. say hello to trouble getting smogged though. its a lose lose situation).

id recommend going the single route. even though it may seem like it makes more economic sense in the short run to go with another set of used twins for $400, it really doesnt. even then, you have a lot of headaches in store for yourself in the form of more boost problems and vacuum line issues in the future, and you will still be just behind the single turbo guys at the track or on the dyno. you will end up having big turbo envy and spending countless hours tracking down boost issues. at least thats how my experience went (hindsight is 20/20), your mileage may vary.

good luck anyway, and i hope you find your boost gremlin. feel free to get back to me if you have any more questions.

folicor

Well, I have checked all the solenoids and they seem to work properly. I haven't yet vac/pressure tested the vac and pressure chambers. I guess I'll start with that. Everything I have read, is leading me to believe it is the TCA. I just don't see how sometimes it would boost to a full 10 psi, and sometimes not if there was a leak. Also, now to add to the mess, I was hoping somehow when I installed my profec B it might solve the problem (yeah, that was hopes and dreams) Now, even with the boost controller off (the wastegate should limit the boost to the stock 10 psi) I would sometimes boost to 15 psi (not spike, it would hold 15 psi, then fuel cut would kick in and it would drop to about 13-13.5psi) I am already on the verge of sayin F it and go single turbo........Thanks for the reply, I'll let ya know how it works out when I get around to it.