Ok. So I bought the car recently...kid says it had 20k on new motor...which I found out was untrue. regardless so the car will start and idle fine...driving whilst granny shifting. Fine as well. NOW the problem. Anytime I give ANY kind of heavy acceleration or even more than %50 throttle it will rocket up to exactly 4000rpm...then sputter real bad not going pass that point then the moment i release the throttle it backfires. it does it every gear. Now here's what ive changed. and some probable points to be known. I HAVE changed the plugs, fuel pressure regulator, battery and alternator. no sort of check engine light has come on. Also I'm not positive but i have 2 possibilities. Either the fact that both cats are hollowed out (no back pressure) or its a fuel problem. I dont think it could be ignition (coil packs, wires) but I could be easily wrong. ANY input, thoughts, or suggestions on my case are greatly appreciated. My rush is reason being I want the car to run well before winter so I can proceed with the body work and other fun customizations I'm going to do on the car. Rotary motors I am not familiar with though.

 

Does it do this when car is cold?
just thinking it might be your omp. Sometimes the check engine light wont come on when your car goes into limp mode...

 

too be quite honest...i believe the car runs normal when its cold....oh and i forgot to mention that this problem happens id gues 80% of the time more than normal lately....but sometimes it runs fine...VERY SLOPPY in combustion and accel and what not...but doesnt die at the 4G mark

 

if the cats are gone then your 5th and 6th ports are not opening. either you need to wire them open, install a main cat to get the backpressure back or install an electronic switching device like Kevin Landers has up on his website.

 

I do agree about what karak said about the aux ports, but that isn't what is causing your problem. It is most likey something causing to the secondaries not to come on.
One likely possiblity is that you have bad grounds. Search for "3800 rpm hesitation".

 

so all this disappointment of getting laughed at bc my friend's stupid subaru beat me is because of my back pressure....soo easy fix would be just getting new cats put on and solving the back pressure?

 

well if you have no cats i don't see how the ports can be opening, my car had the same issue when the ports were sticking, it would hit a wall at 4k and creep up to about 4500 but barely go any further. it could be an injection issue but if there is no back pressure then that is the most likely cause.

 

"i do agree about what karak said about the aux ports, but that isn't what is causing your problem. It is almost likey something causing to the secondaries not coming on.
One likely possiblity is that you have bad grounds. Search for "3800 rpm hesitation"."

someone had mentioned something about the 3800 mark...and grounds..so should i spend my time and check all grounds?...if so how many are there. or even a place to start looking?

 

see that was my first thought was a fuel issue...hence the pressure regulator....also the injectors seem to be working properly...as well as i ran Lucas cleaner thru with 93 octane thinking that should clean out a system that has been sitting for almost a year previous to me buying the car

 

Really? I ran mine with no tube whatsoever running to the actuators and it ran fine, just with less top end power.
Also, its not technically a fuel issue, but a problem with the control of the secondary injectors. They come on at 3800 rpm, so once you hit that speed if the secondaries dont come one you suddenly have half the fuel you need and hits a wall. Most of the time its just a quick stutter or hesitation, but sometimes it can just hit a wall. There are other causes besides bad grounds but I can't think of them off the top of my head.

 

well the simple way to find out is to just take some wire or zip ties and wire open the ports and take it for a drive and see if it helped, if it didn't then the injectors/grounds would be the next place to start.

 

wait...does someone have a pic of what the actuators look like...bc there are 2 devices on my motor that someone noticed were shaking at idle.. because they looked "loose"

 

2 canisters right above the exhaust manifold, sitting at 45* angles sort of facing each other.

 

like i said...the car sometimes will break that 4-4.5 barrier...so its possible that they sometimes open?

 

well, if the port actuators are loose on an S4(86-88) engine then they likely are not opening at all since the air ports to the canisters are part of how the canisters mount to the engine, if they are loose then the passage is incomplete and that air to open them is lost.

 

alright well it looks like i got a few things to check out tomorow after work.... on the day every other place is closed haha

 

gah!

i forgot tomorrow was labor day... too bad i'll be working hah!

 

Try removing the actuators and zip tying the aux ports open like karak said and see if you still have the problem. That way we can at least isolate the problem and go from there. Anyway, its late here and I gotta get to bed. I'll catch up with this tomorrow.

 

im going to try opening the actuators but im not REALLY sure how.....umm also i just called the guy i bought it from and he said i have an S5 motor...not sure if it changes any...but i figured i want the most accurate facts to solve the problem.

 

Yeah, that does change things, actually. On the s5 motors the aux ports are opened with air from the airpump, not exhaust pressure. So as long as your air pump is still there, then the aux ports are probably working. You can get a long tube and connect it to the actuator and blow into it to see if they are stuck or not.

 

I think the problem is Fuel related. Forget the Actuators. That wont cause the car to not rev. I think its the injector clips or injectors themselves. Easy to check

Pull the UIM off, check the injector wires. Get/borrow/buy a 'NOID light' used for checkign injector pulses. remove all 4 clips. Get someone to crank the car. The blinking ones are the primarys (u have to attach the noid to the clips). These are conected to the 'primary' injectors. Inspect the wires. If they are frayed or damaged, you should replace them. U can go to autozone and get injector cips for your car. They will have to be soldered onto the existing harness. (cut the old ones off one at a time as to not mix thme up). Any time you buy a new FI car you should inspect the injector clips etc. I would also take the secondaries and get them cleaned. U can send to to RC engineering or find a diesel/truck shop in your area they probably offer testing/cleaning service.

Best of luck

 

you don't need to pull anything off to check the secondary injectors.. if there was a primary injector issue the car would run like pure *** at idle and have a serious lack of power.

 

OK well my post was basically for him to check all the injectors, but on a s5 I guess your right . For a S4 Turbo (which I have first hand knowledge of) you do. Sorry if I posted misinformation, however, I stand by my analysis (His problem is fuel or electrically related, not 'Aux ports not opening).

 

I definately agree that it is related to the secondaries not working properly. I was just posting about the aux ports cause they are easy to check and it will help eliminate talking about them so we can concentrate on the injectors.
It seems to me that one of the secondary injectors is majorly clogged, making the engine effectivly run on one rotor above 3800. Since the history of the engine is in question, it would be a good idea to get the injectors proffesionally cleaned anyway. www.cruzinperformance.com does it for 12 per injector plus shipping, which ends up coming out to about 60 total. That includes new gromets, pintle caps, etc. It is well worth it.

 

how much did you pay for that?? its nice.