About a week and a half ago i was heading to work. I put the hammer down to pass a few cars. I was in 3rd gear at about 5k rpm when it cut the throttle and went into restricted performance mode.

So I limped to my exit. By the time I got off my exit, it was no longer in restricted performance mode and seemed to be running fine. I babied it to work and all seemed well.

Now there are no issues at all unless i wind it out at full throttle. Then it feels like the throttle is held back and doesn't pull nearly like before. It is also accompanied by what sounds like valve clatter like it has bad gas. Again, this only happens at full throttle at above ~3250 rpm. No issues whatsoever at low throttle revving it out even to redline.

I checked with my OBII scanner and there are no codes at all. If i hold it in second gear and wind it out with easy throttle there are no problems. It seems to only have problems when it's at full throttle.

This past weekend I replaced all the spark plugs because it was on my to-do list since I'm about to hit 75k miles and i figured it wouldn't hurt. I also replaced 4 coils packs that had not failed yet. So, all coil packs have been replaced. I also have NOT reset the ecu.
I plan to run the car with my OBDII tool/software attached to catch some stats.

Has anyone seen a similar issue or have any ideas I can try?

 

i disconnected the battery for a little bit to reset the ecu. took it for a spin and it's still is running bad at 3/4 to full throttle a little after 3k rpm. Only code after this was P1111.

This really reminds me of my old ford contour when the linkage that controls the secondary intake runners broke and were stuck closed. bottom end was great but top end was bad. If i manually set the secondaries open, bottom end was bad but top end was good. the resolution was to buy a new linkage for the secondary intake runner.

Heavy throttle anywhere below about 3250 rpm is great- fulls fine and revs perfect. But after that it feels like it's being held back and in 3rd gear is accompanied by some "clatter". Trying not to do it much to prevent damage

does the str have secondary intake runners that open after 3k rpm?

 

No secondary runners, but you may have a vaccume leak or one or both cats failed. The ECU will throw her into Restricted Performance, not allowing the engine to run over 3000 RPM as a means to not cause catastrophic damage. Check the air filter box for proper placement/sealing along with the hose running from air intake tube to drivers side cam cover, as well as the air intake tube to airbox and intake plenum. Check EGR to see if the EGR tube running from EGR to passenger side exhaust manifold is not leaking/rotted out. Clean or replace ($100) MAF sensor. Check to see if the cats are rattling. If your so inclined, I'd replace the cats with hi-flow versions, as these waken up this beast. What does the p1111 code mean? A smoke test can reveal a bunch as it had mine.

 

I wonder if a fuel problem could cause it. (I suspect so.)

That would include an inability to pump it, or a blocked filter but also a problem with delivery of enough peak current to the coils & injectors, so don't overlook the chance it could be an old battery that finally struggles.

Be sure to get and read the codes PDF especially the first 10 or so pages as they explain things like P1111.

You may not get codes - e.g. if the PCM can't home in on what to blame. It may still try to prevent damage.

I'd love to be able to home in on the clatter but I've right now no idea what it would be. Not having heard it or where it comes from I just have no idea.

As you have an OBD tool, I'd look closely at fuel trims. At idle, at 2500 in P, then when driving (record them or have a passenger do it). Don't rely on being able to read OBD values when the PCM's saving the car - they may or may not be readable (won't hurt to try).

 

I am having the same issues checking with factory diag. tool and A.L. what this car is doing is exactly as you are describing digging into data with a lab scope the ECM is turning off the duty cycle to both rear modules at the same time

 

Mixing these 2 in 1 thread is going to be really confusing. Please would a mod split the last one off?

Failing that I suggest you start a new thread unless the OP posts the same fuel trims etc.

 

A bit of a long shot but the STR has a unique fuel system and is different from all other S Types. It uses both pumps to feed the engine and above 3000 rpm both are kicked in full blast. It sounds to me like you are running out of fuel.

I hate to say it because the STR fuel pumps are so damn expensive!! About $900-$1100 each.

I am not sure how to test this because you must be under full throttle which means things are happening pretty quick!! Fuel pressure also seems way too high?

If you have 42.5 psi at idle the STR boost is limited to around 11-12 psi. So you really should not see fuel pressure above 42.5 + Boost pressure. Say around 55 psi max. Any chance you have a kinked or restricted fuel line?? Any idea when the filter was last changed??
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thanks everyone for the help!

code p1111 is standard - "If DTC P1111 is flagged after DTCs have been cleared, all engine management OBD diagnostic monitor drive cycles HAVE BEEN COMPLETED."

i replaced the fuel filter about 15k miles ago. She is due for an oil change so i plan to change the fuel filter as well to rule that out.

When i changed the plugs, i checked all intake hoses, and cleaned the MAF sensor.

The battery is an interesting point. Apparently they can cause so major issues in these cars. My battery isn't quite as strong as it once was. I may pursue that one

Once i get a chace, i plan to capture some data using my obdII software and laptop. Hopefully something interesting will pop up

 

I had the same issue on an STR and it ended up being a bad throttle body. Quite scary when it goes into limp mode if you are on the freeway.

 

here are a few graph- didn't have much time but wanted to get something quick

2500rpm is interesting between bank1 and bank2

 

With fuel trim so large at idle on both banks and much less at 2500 it looks like you have an air leak.

On an STR it's usually the air box, filter, or tubing from there towards the engine.

 

hmmmm, i'll have to take another look at the intake- good catch

what do you think about the large discrepancy between bank1 and bank2 on the 2500rpm SS?

 

See what it's like when (if) you find a leak?

 

I'll pop the stock intake tube back on and inspect the filter box tonight. Will report back tomorrow

 

this looks and sounds exactly like the issue i'm having. video in post #16 is exactly what i'm hearing. now i may have a good excuse to go ahead with replacing the cats and mufflers

 

And what did bfsgross suggest as to the cause and advize....? Fix the vaccume leak and "Mod that bitch out!".

 

hahaha i know buddy!

the answer was in the very first sentence of your post. I owe you all a case or 3 of beer.

but i still need to get the cat's cat fixed

everybody been ordering the magnaflow cats from summit?

 

Exactly...pop on and watch out!

 

CATS fault is suspension

 

"cats" (lower case letters) for catalytic converters