Hi everyone,

New to LS1 FI-cool forum!

Running custom twin turbo system on C5. 67MM turbos. 42lb. injectors w/t Kenne Bell Boost a Pump. ZO6 MAF w/t IAC wired in. Tuned w/t LS1edit. Running 7lbs. of boost. TR6 spark plugs. Single intercooler.

Everything seems to be perfect until I reach about 430RWHP @ 4,500 the car loses about 30-40hp almost like its cutting out? Perfect driveability! After it drops power it will start to make power again? 11.5 AFR that does not change at all. 15 degrees of timing through out WOT. Fuel pressure 60lbs. thru-out power band. Could this be in the tune or computer somehow? I see some of the boosted kits coming w/t new valve springs? Can the stock valve springs not handle 7lbs of boost? If anybody wants to see my LS1edit file I will gladly email it for your review. Any help would be greatly appreciated…

Codes: P1133 manufacturing fuel and air metering, P102 MAF sensor low circuit frequency, P1153 manufacturing fuel and air metering, Disabled P1514 code and multiplied out calculated flow---Are these normal codes on a boosted C5-I tried swapping out MAF with another ZO6 with no change.

 

replace stock springs. I have had terrible luck with them

 

Yep...valve springs would be my first guess. We always replace them whenever we add a turbo kit to an otherwise stock LS1.

 

Yep, I agree...if the springs are stock from 1999, they are about due for a change anyway. This is common practice on the Buick GN/T's. You are also talking about ONLY 7lbs. of boost from TWIN 67mm turbo's...that's moving a BUNCH of air.

Rob - good to see you posting. I talked to your wife a few weeks ago about buying the Grandpa' Stage motor Buick...damn you! you sold it! hahahaa...now I gotta find something else.

 

First I would close the gap up on your plugs depending on what you have them at now, since that is the easiest thing to do and also a cause for missfire at higher boost levels. Next I would then think about the valves springs, but they won't be quite as easy to swap out.

Jose

 

Im running .35 gap on the plugs that I double checked.

Are the comp cams 918s the way the go with the valve springs? When you guys have seen them float would they start to make power after the power dropped off? Wheres the best place to get them? Thanks Matt

 

You shouldn't be throwing any codes to do with fueling or the MAF. Have you raised the maf fail frequency? The 918 are great springs and can be used in the stock seats. I've never seen a bad set of springs start to make power again after it dropes off so i'm thinking you have ather problems besides the springs.
Do you have a copy of the dyno graph you can post up? Last time i threw a p102 code it was caused by bad wiring, you might want to make sure all your maf connections are correct.

 

how long have you had the system and how long has the problem been occuring??? after those questions are answered what air filter are you running. I just had a problem with the same codes and I found out with a K&N filter that the oil somtimes mess' up the MAF. I just took the MAF off and GENTLY cleaned it with alcohol and then reset the computer and that solved my problem. hope it gets figured out and hope this helps
Wesley

 

I think CC918's are good to 6500 rpms or so. I assume you are shifting your turbo car below that though.

 

We ran the system originally with-out air filters on the dyno and it was cutting out on the dyno. I have been driving the car for about three weeks straight now with-out any problems until about 4,500 rpms. And also the codes...Thanks for the help...

 

check out the patriot dual springs that fit in the stock pocket. Seems like a spring or a spark issue (spark blowout at higher rpm) to me

 

What should the MAF fail frequency be set at? Could that set multiple MAF codes? Thanks

 

67mm turbos??
only 7lbs of boost?
you on stock engine?

oh and lets see some pics

 

I'm with Chris on the spark blow-out theory. Perhaps a stronger spark is needed. Is this anything like Noyzees issue...he would launch, fall on his face, then take off like mad...

 

I'd set the max frequency to at least 14,700hz. Yes that can cause multi. codes.

 

Do you have a boost referenced fuel reg?

 

Yes. I am using a Kenne Bell that increases voltage to FP based on amount of boost. Fuel pressure stays constant @ 60 through out power band.

 

So are you saying I could coil issuess? I am running brand new MSD wires w/t TR6s @.35...

 

I set the max freq @ 14,700hz. That took care of the PO102 code, but still setting P1133 & P1153 codes? Cutting out about the same? Thanks for the help...If you have any other suggestions w/t the tune I would appreciate any ideas..

 

Stock motor w/t 408 ready for when I get the issues straighted out or when I blow it up ! I plan on increasing the boost when I figure out this cutting out issue. We originally ran it on 110 on the dyno with every intention of turning it up!