Recently got the car back from the tuner and noticed a knocking at idle I never heard before. They say the engine is in good shape and just replaced the eManage Ultimate with UTEC and bigger injectors and shop says its making more power then before and running alot better all around. I filled up with 93 octane from a different gas station and it was still there. Its very slight and can only hear it inside the car with eveything silent. Once off idle you can't hear it anymore [whistle takes over] and it seems fine at highway cruise. No unusual A/F or idle problem. But if the shop says the engine is in good shape and is strong what else can it be?

ProCharger
UTEC
720cc inj
return fuel syst

 

Can you explain the knocking a little more? How loud and how frequent is it? And, is it loud enough to tell where it's coming from in the engine bay?

 

Does it sound like it is coming from the top or the bottom of the motor?? Could be a cylinder head issue or a rod bearing issue.

 

might be injector noise.Those 720cc's are loud.

 

yea was just gonna say, injectors maybe. good call MRC.

would you strictly define the sound as a knocking, or could it be a ticking?

does it sound like its coming from the top of the engine or the bottom?

 

Simple check, does it make it with the clutch pedal in as well? My latest install has the throw out bearing being very noisy until I push the pedal in.

 

He has 5AT. Im thinking injectors too.

 

yah.. 720ccs are huge for the numbers you might be running which i am going to guess 370whp +-20whp

 

720cc on a PROCHARGER!! WAAAAAY to big, I would have a nice set of 550cc's max.The problem you could have with larger injectors like those is at idle and part throttle they can dump a ton of gas in the cylinders and the gas does whats called "washing the walls" where it actually washes off the live lubricating oil that keeps you engine fit..Defineitely down size those bad boys.

 

yes and sell them to me

 

Well originally I had 380cc, those got maxed out so I went with 440. I had the tranny biult and a few other things done and this latest tune in about 50* weather they said the 440's were maxxed out and decided to go with 750's [sorry for the typo, not 720!]. It does idle alittle rich at times, upper 12s to low 13s and usually corrects its self in a few seconds. I watched them tune the car and saw the injector duty cycle in the 90's with the 440cc.

As for the knocking, I can only really hear it at idle with the A/C off and everything quiet. You cannot hear it in the engine bay - mainly because of the ProCharger being so noisy. Making the best guess I can I say its comming from the top. As far as I can tell it "goes away" just off idle - but again, things get noisy at that point and the noise might just speed up with engine speed until its disquised with everything else. Car seems to run fine and idle fine.

We have run into a slight problem of hitting a rev limiter while under heavy throttle usually no matter what gear it will happen around 5,000RPM. Hoping its just fould plugs [they are nearly a year old and been through aloooot of tunes]. Were gonna switch those out tomorrow and hoping its just a misfire the UTEC pics up and trys to protect the engine or something.

 

I will buy your injectors if you decide to sell.

 

+1 hehehehe and if u think 720 cc's r loud lol come and listen to my 1000 cc's
relax man its ur injectors.

 

If you have a UTEC this sounds as if it is the overboost fuel cut(which is unlikely on a SC) or the UTEC detecting knock and retarding the timing.Have your tuner look at it ASAP.

 

look into your UTEC knock parameters. If it is set to pull alot of timing degrees when it detects knock, it will seem like a rev limiter. the car will immediately fall on its face. I don't remember, but isn't the UTEC default setting something 10* it will pull if you surpass your knock threshhold?

 

back offf lol
i called dibs on them first hehe

 

Wow, I'm running 650cc injectors on a fully built 500hp car without maxing them out......

When I had that Procharger those 380cc PE injectors were more then enough.

Do you have a return line installed? What kind of fuel pressure are you running? Stock pump or have you upgraded?

 

When I had that Procharger those 380cc PE injectors were more then enough.
...Yeah I know. Weird, huh? They were enough for the 1st 3 months, then 3 months after that 440 wasnt enough... 750 should do... 3 months later. Lol.

Do you have a return line installed?
...SGP Racing return fuel system is all.

What kind of fuel pressure are you running?
...NO idea. I have the gauge... it just isn't working at the moment

Stock pump or have you upgraded?
...Still using the Walbro 255 you sent me.

 

sounds like the shop you use isnt up to par . The 440's should have been plenty , and if they were maxing out . It was more than likely that the fuel preasure was very low . The shop is either milking you or dont know what they are doing . Find another shop....IMPO

 

Interesting, I would check your fuel pressure ASAP. A drop in fuel pressure will max your injectors out quickly. In fact, your fuel pressure is very important number to know, as you should always keep your fuel pressure at the same pressure that the car was tuned at.

I had a Mallory regulator and it tended to drift a bit, so I always had to keep an eye on it.