Hi all
Can anyone help Over the last couple of weeks my STR has lost power Started as more noticable top end but gradully more general lack of "go"! especially over 4K rpm
No error codes Runs sweet with no misfire etc No odd mechanical noise. Only thing is that there appears to noise from the crank vent thing ( left side as you look from the front) which stops for a second if you press the top. Supercharger spins OK and no evidence of the belt slipping
Got so bad today wont make 120mph ( sorry officer) 0-60 seems about 9 seconds. Seems as if I have lost all boost

Any suggestions most welcome

 

How many miles on car? If you could measure the boost while driving this would help determine if that's the problem. Have not heard this complaint before??
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60K No seem pretty unusual Fuel pressure has been suggested! Ill change the filter Check vacumn hoses etc and see if that helps

 

Check coolent level and temperature, and thermostat. Who knows if there is a air gap in coolent lines and/or thermostat is stuck open spiking engine and supercharger temps too high causing knock then timing retard.

 

Check your air filter. I noticed over the last year the throttle response on my STR was getting poorer and poorer. After scratching my head I pulled the K&N filter and cleaned out the air box and inlet which wasn't all that dirty just a little dusty, left the air cleaner out and went for a drive and put some stick to the old girl and jaysus what a difference.

Got back and took some compressed air to the filter which also wasn't all that dirty and damned if that filter must have clocked up with the cleaner/oil treatments the K&N air filter requires at the same intervals as a paper replacement. With the filter back in almost as responsive as with no filter. I will be going back to paper filters next week.

The K&N air filter appears to be a "one step forward two steps back" failure...

 

Thanks I will try along with checking coolant for airlocks etc Filter has only done approx 3K miles but looks filthy and also changed the thermostat recently Performance has most certainly got worse since that so worth checking things out Thank for the suggestions

 

I will definatly check this out as the stat was faulty ( cold weather going into restricted performance syndrome) and changed a week or so back Performance definatly worse since then

 

Latest update Tried today with the airfilter out Immediatly started to run unevenly and poor pickup under acceleration Got to 51/2K rpm and there was and felt as if the rev limiter was hit. Put the air filter back in and all the stumbles went Has anyone else had this? Seems odd that removing the filter would have such a dramatic instant effect.

 

...mine didn't do that when I removed the air filter. Check and clean your MAF sensor. If memory serves me I used a spray brake cleaner on my Land Rover MAF sensor a couple of years ago. Shake off the excess, let it air dry and don't touch the filaments. Make sure spray brake cleaner is the right thing to use.

My memory is not what it used to be at 62yrs of age, notwithstanding all the copious quantities of mind altering substances ingested, smoked and otherwise administered purely for health reasons of course. I'm reasonably sure I never ingested spray brake cleaner but not entirely certain. Hence, check my advice as it's worth exactly what ya paid for it...

 

Hate to be captain obvious here but has the temperture gotten a lot hotter in your area over the last few weeks? Just a thought...

 

Only for a couple of days and even then the performance loss is exessive

 

Some ideas:
clean the MAF, preferably using MAF cleaner (LOL)

disconnect the MAF (car will substitute values but not run as it should)

use an OBD tool to read lots of sensors (IAT & ECT plus MAF & TPS, at least) looking for any oddity

take to a dealer and see what they can diagnose (lots more things they can read that you can't easily with an ordinary OBD tool)

 

Thanks
I have fitted a new MAF only a week or so ago so dont think its that. Had another look today and the throttle body was filthy inside with a black sticky gum
Cleaned as best as poss in situ as not much time and performance is improved Still not great but alot better Wondering if a really dirty throttle body is my problem!!

 

hmm, well, it could be except you need an explanation as to where the filth came from! The air filter is there to stop such stuff.

Careful about cleaning the TB. Don't use anything that may affect its coating.

Thing is, you could clean and swap a lot of good parts since you have no readings to guide you. That's what diagnostic tools can help avoid.

 

SORTED!!!! It was the cats!! No rattles or usual broken cat stuff but after cleaning and checking everything else 'as one last shot I have had the cats replaced with high flow option (Jaguar only have RHS available in the UK!) Performance better than ever (indicated 160 on the way home tonight)
I can sleep again at last and think about a TS conversion :-)

 

Hooray!!

Er... 160? Even km/h that's too many

 

Yep Indicated 160mph Limited to 155 I know but hit its limiter at a big 160

 

160 Km/h is only 100mph My Daewoo Musso will do that

 

Er..... we don't use km/h over here!!!

And the speed limit is 70mph on our fastest roads.

 

I know I am over here too