95craz28

If i'm in the wrong spot then please redirect me as i'm new here and not all that bright. Alright, down to business. I have a 95 z28 that i have converted to a 383 stroker lt1, with (deep breath) all forged scat crank, 5.75" rods, 2 valve relief sl pistons, clevite bearings, trickflow cam 530/530 113 lsa (should have gone bigger), 185 cc trickflow 21° heads, ported intake, 58 mm throttle bbk tb, 44 lb injectors, 255 lph fuel pump, holley adjustable fuel regulator, bahnhoff stage 3 clutch, blah, blah, blah. I ordered a new tune from pcmforless. Problem i am having is that the car turns over but won't catch and fire. When I put in the old tune it will run but not idle. I need a little help!!! Car sounds amazing when it runs though.

Injuneer

If it starts with 44 #/Hr injectors on the "old tune" and the old tune was for significantly smaller injectors, may be a problem with low fuel pressure. What is the set pressure for the adjustable fuel pressure regulator? Have you checked the fuel pressure.

Cam specs appear to be incomplete. Appears tha 530/530 may in fact be 0.530"/0.530" lift. What is the duration at 0.050"?

Have you scanned it for codes?

95craz28

fuel pressure regulator is set to 43.5 psi and with the new tune no codes are shown. I tried putting the stock injectors back in but got the same results.

95craz28

at .50 it is 108/118 lift

Injuneer

I don't think so. You need the duration of the intake and exhaust in degrees, when the lift is at 0.050". Typical values for an LT1 performance cam are in the range of 220-240 degrees, with the exhaust duration typically 6 - 12-degrees longer than the intake duration. My cam, for example, is 230 I/242 E at 0.050", and gross lift is 0.590" I / 0.590" E with a 114* LSA. That is a complete cam spec.

Possibly you meant 208 I/218 E, which would be a small cam for a stock engine, let alone a 383. Stock 95 LT1 is 202 I/207 E.

Injuneer

Appears you have this Trick Flow cam:

95craz28

Yes, that is the one. Thanks for the lesson.

Injuneer

After the rebuild, did it ever run correctly? Or has this problem existed since you first started up the 383?

That heads/cam kit is rated by Trick Flow at 430HP. They recommend 30 #/HR injectors, and that is consistent with my normal guideline, which is to multiply flywheel HP x 0.07 to get the minimum injector size (430 x 0.07 = 30.1 #/HR). The 44's would appear to be a bit of overkill, but if the PCM is tuned correctly for them, there is no downside.

What brand injectors do you have, and are they high impedance (12 - 15 ohms)? Was pcmforless provided with accurate info?

95craz28

Im running accell 44# 12 ohm impedence. I gave them the correct info. Just to be totally clear i am not saying it is the tune, nor blaming them. this began after the rebuild/instalation this past mon. i plan on double checking the fuel pressure regulator today or tommorrow. The Pcm comp. has asked me to mail it back and they will send a different pcm (same tune) to me, very fair IMO.

Injuneer

And I wasn't suggesting there was anything wrong with the tune... just making sure they had the correct info.

95craz28

didnt think you were. I didnt want to come off as blaming someone for something that is more than likely something I overlooked ie too big of fuel injectors. I wont be able to recheck the fuel pressure until tommorrow, is there anything else I should look into? Im almost positive im flooding it out.

Skedaddle

What happens if you put your stock injectors and previous tune back in?

The Accel injectors had a bad rap many years ago.. not sure if they have improved.

As long as the tune and the injectors match, going "too big" should not be a problem.