This started Saturday night out of no where.

Pretty much My car will only rev to 4.5-5k RPM and then it will act like it's tearing itself apart. Shaking,popping,burbling type sounds and twitchy increase and decrease in rpm.

If driving the car I cannot go into booost at all. Not even 1psi. The car will start to buck and I will instantly let off to hoepfuly not hurt the engine. It usually farts a pop(possible flame ball) once I let off.

I had this problem happen a couple months ago. It was completely random. I found out how to fix it back them. I woudl turn the car off. Then restart it. The car woudl rev and boost fine.

Now the car is stuck like this every time I start and drive.

I have a S4 TII engine with S4 electronics and a Rtek 1.5.
Cleaned injectors w/ less than a 1 1/2 years of use.Primaries are high impedance and secondaries are low impedance(with resistor box).

Has any one had similar problems?

I'm trying to figure out if this is timing/ignition related or if it's EFI/injector related.

Now I did look at my AFR gauge and the bars are a couple notches richer than normal so maybe an injector is sticking?

The idle is as good as I could get it. Huge TPS loping and it runs around 1500-200 rpm idling.

I'm just guessing at everything.
Boost sensor faulting maybe?
Bad wire on secondary injectors?
etc.??

 

Oh yeah. The car drives perfectly fine under vacuum up to 4.5-5k rpm.

I drove to work at 80mph with out problem as long as I didn't have to accel too quickly to go into boost.

 

I pulled the manifold to look around. Wiggled a few wires and replugged the injectors in.
Didn't do anything although I didn't do any real change.

I'm really thinking the ECU is throwing some funky codes.
The injectors have about 1 1/2 years use on them after being cleaned and tested. I doubt their the problem. I know my fuel pump is fine because I get a constant pressure and the FPR is fine(aeromotive 1000).

I think the ECU is sending funky injector signals since this problem occurs only during boost,4.5k rpm or pretty much when secondaries start to really pump.

Ewspecially since this exact thing happened a few months ago and then disappeared out of no where and it's ran fine since then until this weekend.

I think I'm going to read the FSM on getting signals from a S4 and then I'll try and pull them.

 

does the car have a catalytic converter on it?

 

Cat, ECU.

 

No cat's or emissions on it.

I'm going to check ecu codes tomorrow. Just looking for the write up on it now.

 

Has your wastegate arm come loose? Can you slowly accelerate past that 'wall'?

 

Just remembered I had a 2 led ECU tester.

I just put it in and it held the LED for est 3 seconds for intial start up and then went blank. So.......... No ecu codes It's not going to be that easy.

I'll test voltage/resistance on the boost sensor tomorrow

After that I'm thinking of just swapping in some cleaned and tested 460cc inecjtors I have in the secondary slots to see if it really is the injectors

 

Let me get this right...

You're running a stock ECU with an Aeromotive A1000?!??!?


-Ted

 

It's just a FPR. It's a mechanical piece just like the stock unit. The ECU has no control over the FPR other than that stupid little hotstart solenoid.
I just have an adjustable FPR with 1:1 pressure increase now. I've been running this for 6 months daily driven.

 

I'm going to screw with my spark plugs and TPS tonight.

Maybe replace the plugs and try and test the coils.

Maybe unplug the TPS and see if it eliminates any problems. If not then readjust the TPS to the correct setting(currently set a bit higher to rid the loping idle)

 

Update.

Here is EXACTLY what I did.

Took off TMIC and put on my JHome Depot piping for better running access to the UIM.

I then disconnected the TPS completely and drove 3 miles to get a voltage tester.
The car ran fine! No rev limit or boost problems
I then connected the TPS again(engine off) and then adjusted the voltage to 1.025(a bit correction for wire resistance).

The cars running pretty good for now. I do get a bit of low end WOT hesitation but it clears right up and I boost up to 9 psi fine.
I am losing some top end boost but it's probably a different problem.

 

Fuel pressure at idle?
Fuel pressure at "0" manifold?
Fuel pressure at boost?


-Ted

 

I can't remember exactly so I might have this backwards.
40psi at stanbdard atmosphere
45psi under vac/idle
and it should 1:1 under boost but I don't have the gauge on an extention to stick out my hood while boosting.


After driving to work today I've found that the problem isn't completely gone.
It still stumbles a bit around 3500 rpm but clears up and boosts fine. UNLESS I am in 4th/5th gear. Then anythign over 5psi will cause the car to buck and shake like it's about to throw a seal.


I'm getting really pissed off at stock ECU's and 16 year old engine harnesses.
I want to try and get this fixed for now but I think I have to save up for a Haltech.

 

Yeah, it sounds like you got that backwards.
And if those numbers are accurate, you're running about 5psi too much pressure.
That's enough to cause rich hesitations like you described.
If possible, pull the spark plugs and check their condition?


-Ted

 

I'm going to pull the plugs tonight and check them. They have ummmmm I think 5k on them.

Lately I have found that the problem has just diminished but not disappeared.

The car will boost but if I try and reach more than 3psi of boost under the secondary injector swithc it will buck and jerk. I then let off and do 1psi up to 3.5-4k and then I can hit 7 or so psi fine usually.

I also noticed that the turbo will spool really quick sometimes during those situations which leads me to believe I am still running pig rich. Although the car doesn't feel as fast as it use to at those psi levels. So I think somehting is still making the car run super rich so the HP went down.

This is my DD so pulling injectors and sending them out to be cleaned really sucks. Especially when they only have 1 year of use on them. ALthough I do have some cleaned 460cc inecjtors I could use as temp's and be careful on.

 

Here ya go ReTed

They look prett damn clean compared to my older plugs(usually crudded up w/ black deposit on leading and tan on trailing)

This is the front trailing then leading(left to right).


The rear look very similar although with a bit more tan to them.

 

Okay, we can eliminate one thing off the list then.
The spark plugs show that the engine is burning correctly and not rich.


-Ted

 

Yeah. I replaced them last night anyway.

I'm clueless as to why it's doing this. I think I might pull the TPS and do a quick highway drive to see if it remedies the problem.

If it does then it has to be the engine harness since I've already replaced the TPS 2 months ago. Now I did test the resistance and I always get a break/infinite at the 3k ohm range. Although I think my multimeter is just getting old and is the cause since it did the exact thing on both TPS's.

 

I was having this problem for awhile, picked out the codes and it was pulling an 08 and 18 (s5) which was AFM limp mode and TPS narrow range at WOT. Replacing the TPS resolved the issue.

I had the same exact symptoms, break up at 5krpm popping, sooting up the rear bumper. It just wasn't burning fuel properly above 5krpm.

 

I'll get my NA AFM back from my friend and test with that to eliminate that out of the problems.

I just checked Autometer's site on my AFR guage.
According to the readings my O2 sensor is reading in the .850-.950 volt range under WOT and those conditions where it stutters.

Before it would hang right around .750-.800 volts.

 

Well I unplugged the TPS and the car didn't want to even leave the driveway. It bogged and almost died.

It's also changed the characteristic of the problem. On regular streets it will hesitate and buck under 3+psi and doesn't want to go over 5k rpm.
On the highway it boosted fine up to 9psi in thr rpm range of 3-5k no problem.

So I'm going to just start replacing everything.

1st. My injectors. I'll get 2 550's and swap the secondaries. If it doesn't work then I'll switch placement to primaries.
2nd. Boost sensor
3rd. Engine harness
4th ECU
5th Going Haltech.

 

Well, Maybe the car heard me.

It's driving fine right now. Although it is still rich.
It hesitates at the injector switch but doesn't buck or rev limit at all.

Man I hate these problems. It's gotta be electrical.

I did noitce that the car won't hold high boost though. 1-3rd gear will hit 9psi quick and then drop right down to 6psi. So I'm guessing the excess gas is causing a loss of boost and power(feels sluggish).

Now I gotta find a way to gfet the ******* thing back to normal AFR's

 

Hrm, Sounds like it's wiring to/from the TPS. IE: un plug it, bogs, plug it back in again, appears to work fine. I'm actually having another problem (after replacing my TPS where if i cruise with my foot just barely on the gas (<10% throttle) it will start to buck and it gives that 'throttle on/off' feeling. But it's hard to make it happen. I plan on going through and making sure all of my throttle linkages, and tps sensors are moving cleanly through out the full range.