hotrod85z

iTrader: (1)

the computer and chips are stock, the car has excellent power, but It idles as smooth as the stock 305 I pulled out!! other than a cycling up and down every few minutes, could it be a vacuum problem? I cant find any leaks,but at the intake manifold, I'm only getting 10-12 PSI of vacuum!! WTF, the timing is set at 8* adv, any less and it hesitates! I am currently looking into getting into chip burning,but I still think this car should run better than this!!!
, If you gas on it from a dead stop, and let off it will die! when you power brake it, and let off, it idles WAY down, then back up,

I have already tried readjusting the IAC, and the TPS, the car has a Brand new Bosch MAF sensor, and NO SES codes, any help would be greatly appreciated, thanx!!

3.492rs

u need computer tuning for that cam. 224*/236* dut @ .050
way to much for the stock chip

hotrod85z

iTrader: (1)

DO YOU THINK THAT IS WHY IT IS TRYING TO IDLE SMOOTH? BECAUSE i AM USING A FACTORY CHIP? i WENT WITH THE 85 VETTE CHIP B/C IT WAS INTENDED FOR A 350 tpi INSTEAD OF A 305, DONT GET ME WRONG,THE CAR RUNS LIKE A RAPED APE, BUT WITH THAT KINDA DURATION, IT SHOULD HAVE A LITLE MORE SOUND,THAN JUST SOUNDING LIKE IT HAS A MISS, AS SOON AS i PUT THE NEW MOTOR IN, THE maf WENT OUT, so i GOT A BOSCH REMMANED, iVE GOT A G2 INSTALL PLANNED FOR MY ecM ALONG WITH A BURN 1 PROM BURNER, i FIGURE, i SHOULD BE ABLE TO WORK SOME BUGS OUT, i WAS TOLD WITH THE G2 UNIT, I WOULD BE ABLE TO TAKE ADVANTAGE OF THE FLASH CHIPS OVER THE 2732 CHIP'S OLDER DINOSAUR TECHNOLOGY! i HAVE HEARD OTHER GUYS RUNNING THIS CAM IN THEIR TPI ON HERE, AND THEIRS SOUNDS PRETTY LOPEY,BUT MINE SOUNDS STOCK OTHER THAN THE CONSTANT UP AND DOWN CYCLING!!! damnit! IS THERE ANY WAY TO UP THE FUEL REGULATOR PSI, OR ADJUST THE IAC OR TPS TO HELP IT ANY FOR NOW?

irocdaddy

No quick fix for your problem bro-

I have the ZZ4 and it idles very much like stock. I have 1 5'8 headers and a slp catback and dual catco converters. Once you put yor foot into it though it sounds beefy. your idle issue lies in the chip, way too much cam for the stock 350 chip, but my ZZ4 will run pretty good off the stocker chip, no funny business like you are experiencing other than the occasional cycling of the idle.

Street Lethal

iTrader: (16)

Sounds very much like a vacuum leak, and I honestly doubt it's you're chip. We were able to run a more radical cam than you're ZZ4, using MAF, and the stock L98 chip (no surging whatsoever)...

Between the MAF telling the ECM how much air it thinks entered the engine, and the O2 sensor telling the ECM how much actually did (with the vacuum leak caught in the middle), pretty much points to the reason as to why she's surging.

If you already set the IAC, TPS, timing and have proper fuel pressure (while throwing no codes), it's more than likely a pesky vacuum leak.

3.492rs

he's not using the zz4 cam look at his sig. it will run with that cam but very poorly

hotrod85z

iTrader: (1)

it is a zz4 camshaft, I had adgersmith mic the cam, it is the exact gm grind,but he said the duration is slightly larger, and BTW, tha lift is with 1.52 rockers

gmgod

224/236 is more than slightly larger than 208/221.

Rob Wade

You can't mic a cam for duration anyhow!

hotrod85z

iTrader: (1)

thanx fella, I've get the top end aprt doing some head work, I'll check out all of the vacuum lines and replace what I find cracked/leaking, G2 installed and the Burn1 is on its way, thanx alot for your help!!!

Rob Wade

The amount of duration in that cam will defenately give you an idle that the stock prom isn't capable of working with. Do you know what the centerline of that cam is? TPI set-ups don't like low centerlines at all. Not unless you have the capability to burn your own proms. But even at that 114-115 centerlines are best suited to the long runner lengths of a TPI intake.

D's89IROCZ

I wondered when somewas was gongi to say that . I have the setup bellow in my sig . With the stock 305 APYS file ....it idled fine . Now I am running a APYP bin and the thing surges at idle and stalls some time .....but has great throttle response etc. WIth the 3.73 gears outback and a 5 speed ..... it breaks loose from 2500 in second when I tramp on it ( brand new Kuhmo Ecsta 712's) Once I get the idle figured out , it'll be all good . great little cam for TPI I think ....glad I picked it

Rob Wade

What do you think a ZZ4 will produce hp and torque wise using a TPI (TPIS base/Edelbrock runners/modded plenum/stock throttle body) set-up. I would think a small loss of HP but some torque gains. Any thoughts? Will a stock prom run it?

Street Lethal

iTrader: (16)

In my opinion, yes, the stock L98 PROM would run it... once you upped the fuel pressure, that is. Of course, it won't be near it's full pontential, but it will run it though.

hotrod85z

iTrader: (1)

i believe the centerline is 112.5 the damn thing runs great once you get a little throttle to it, I have power braked it and got the car up to 90 MPH and let off the brake and it still spins until you let off of it, really impressive for a stock engine ,balanced, with a better cam!

3.492rs

do u know how much to up the fuel pressure? i have the zz4 cam also

Street Lethal

iTrader: (16)

It honestly varies. You don't want to raise fuel pressure too much though, you're best bet would be to listen to how the engine idles with the new cam... and if she surges, slightly raise fuel pressure until you hear it smooth out.

But again though, to maximize it's performance with the added lift and duration, burning a new chip is mandatory....

3.492rs

thx