The combination is A 350 ZZ4 short block. AFR/Tpis cylinder heads 53CC chamber. Compression is10:8:1
running a Comp Cam Xtreme energy276. 224and 230 on exhaust @50. Lift is around 550" with my 1:6 rockers. I have a Holley Stealth Ram with a 52 mm TB. ADS 350 street Injectors running 49psi. Timing is set at 10 degrees base. Car barely idles and runs very rich. Throws a code 34. Everything like vacuum leaks and all the other possible problems have been checked. Is my problem something with a computer chip or the mass air. Code 34= low air flow indicated from Mass air sensor.

 

I would install a after market computer from F.A.S.T. There computers plug directly into the stock harness and is tunable by either a hand held, or a lap top. second replace the stock mass air with a unit from a later camaro like an LT1 car. all you will have to do is addapt a later plug into your harness to go with the sensor. when you get the car tuned out I think you will be verry happy with it.

James @ F-Rated Performance

 

I like your suggestions. But I just ordered the granatelli adjustable mass air sensor, the company says this will address my drivability concerns. Don't know if it will work? But I sure know it's got to be a better piece than the stock Bosch tpi unit. As far as the FAST management system. How much does it cost? And do you really think that this is my only option as far as optimum tuning. Thanks for the reply.

 

Is 49psi with no vacuum? Too much pressure at idle, and or low vacuum will cause injectors to run rich at idle.

Did you set the minimum air and idle?

Do you also have the ADS Peformance chip?

Are the new injectors larger than stock? If yes, and no Performance chip, then did you update (reprogram) the ECM with the new injector size?

Set the base timing at 6° get it running right then you can bump it up where it gets happy.
Keep use posted, we'd like to the solutions to problems like this.

 

Unless i"m mistaken the the fast computer is about 6-700 and no its not the only way to go. But it is the best way to go incase you deside to change your setup later on. Yes the G Motorsports mass air unit will more than likely fix the problem you have right now but it won"t alow you to tune the ignition curve, injector timing, fuel curve, and cooling fan on/off, and weather conditions among other peramiters that will alow you to get the apsolute most from your combination. I would still get the mass air unit so you can at least drive the car. As for the timing I would run about 15 base, thats what I have my car set at and I have about 11.5 to 1 comp and 45-49 Psi. with no vacume is about the norm, with the vacume connected the pressure will be about 30 give or take at idle. with iron Vortec heads just run good fuel (93) and the car should be happy.

James @ F-Rated Performance

 

The problem is likely the chip programming - it's not compatible with the cam. I have a similar setup (cam and compression wise), and mine ran pig rich at first. The lower vacuum is causing the computer to add fuel. I'm running SD, so I can't help you with the MAF, but I would strongly suggest getting the car scanned / data logged - so you can see what's going on.

If you are not computer challenged, you can burn your own chip for the car. Check out thirdgen.org and moates.net for more information and the needed tools. I'm learning on my Z, and the improvements are noticeable.

 

Thanks. As far as fuel pressure goes I'm a little confused. The Holley stealthram fuel pressure regulator does not have a vacuum port on it like the factory setup. Ihave it set up at 49 psi. at idle is that too much? If I understand it correctly you are running 30 psi?

 

whats the car idleing at now?

sounds like it needs some computer tuning to me

OR

CARB IT

keep us posted man

 

I had a customer with this same problem with a 400 in an IROC once (when I worked at Jegs). After some digging, it appeared to be that the TPS voltage was set too high (.67 is the max) and it thought the throttle was open and it was not seeing the extra volume of expected air through the mass air meter. I won't say that is the problem or the only problem in your case, but I'd start there.

 

Thanks for all the feedback. But no I definately do not want to carb it. EFI in my opinion is the only way to go. Once it's tuned correctly there's no comparison as far as seat in your pants power compared to a dinosaur carburetor. Has any one used the granatelli adjustable mass air flow sensor in any of there buildups? If so tell me about it.

 

The vacuum port is where the adjustment screw is....so when you're done adjusting pressure put the vacuum line back over the screw.

 

Wow that is one awesome Iroc Mr. Georgia. Just curious why you went with the holley 950 ECU. Coudnt you have got a custom chip to run the factory computer. My setup is almost identical to yours as far as the motor buildup. I can't wait for my chip to be burned by TPIS they are expensive but those guys seem very knowledgeable. They also said 30 LB. injectors would be overkill, why do you want to use them? Right now I just took the car out on its first run, my god the stock chip in this thing makes it run terrible. It feels so slow and pigish. I hope the chip wakes this expensive buildup run like it should!

 

Well, I was gonna go with the DIY prom burning route but after looking at the C950 and comparing the price and ease of tuning I decided against prom burning. Another thing was time...prom burning requires some in depth reading and understanding to make it work right and just didn't have time for that...plus I'm not exactly a computer savvy person. With my job requiring me to work odd hours, and going on the road for weeks at a time I'd rather not screw around with chips trying to get my car to run. Don't get me wrong though, I'm not ******* out prom burning....it's just not for me at this time. I will venture into it though at a later date when it's more convenient.

As someone mentioned above, check out thirdgen.org prom burning. Personally I would not pay for a "custom" chip, especially a TPIS chip. Do a search there and you will see why. For what they charge you for a chip you can buy your own equpiment and do it yourself, if you're willing to learn.

About the 30lb injectors...a datalog of one of my dragstrip passes showed my injector duty cycle hitting above 90% with 24lb inj's in the higher rpm ranges. A lot of it is because of the fairly large cam I have...remember you need to give the motor what it wants, not what you think it needs! This is why it's so important to either learn to burn chips/tune your ecm or find someone local to you that knows how....unless you send a chip burner a datalog of what your engine is doing, they'll never know that kind of info over the phone and they're just guessing on what they think you need.

Good luck with it!

 

Just wondering. I did order the custom prom burning from TPIS. But aside from that. Is that little chip that important. I built this motor with all the top shelf parts. I can't begin to tell you how upset I am with it's performance. I thought the ADS chip would have been adequate. Has anyone run into this situation,is it all the chip? Please give me some peace of mind! It feels like the car is a 305 out of a NYC taxi!!

 

How do you figure? Mine has the vacuum port. You know tha thing you adjust for fuel pressure, that ist he port.