24 lbs injectors are too lean.
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
24 lbs injectors are too lean.
A while back I had a thread on my newly built 383 stroker. Well, the initial start up was yesturday and it sounded great but it ran a little radical. A couple minutes later the hooker headers started to turn bright orange and the car was shut off at that time. My mechanic said he was going to go over everything to include vacuum, timing and fuel pressure for the greater part of today but he feels it will come down to bigger fuel injectors. With this engine I intially bumped up to 24 lbs on the build and I am wondering where I should go next. He feels I will need to go to 30 lbs. If anyone needs my specs. I will gladly email them to you. Also, once I do choice a injector size should I wait until later to have my chip burned? This is in a 1990 auto Corvette. Any advice will be appreciated! Thanks!!! 
Pro
Joined: Jul 2001
Posts: 557
Likes: 0
From: Taxahoma
Re: 24 lbs injectors are too lean. (vettefast)
Not sure what kinda of power your making or what type injector you have. If it's a ford injector it's acutally bigger than 24 either way there's no way anything is going to be correct without a chip change. I'm not going to get into the argument on how far one should push injectors but 24# injectors can make alot of HP if everything else is correct. I assume your over 400HP and playing with fuel pressure just ain't gonna cut it, it's chip time. My initial guess is your fine with injector size but i'm missing alot of info and it is a guess.
Ski or Cork should chime in on this, they've pushed injectors further than anyone here i'd guess.
[Modified by Black87c4, 8:30 AM 7/1/2004]
Ski or Cork should chime in on this, they've pushed injectors further than anyone here i'd guess.
[Modified by Black87c4, 8:30 AM 7/1/2004]
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
Re: 24 lbs injectors are too lean. (Black87c4)
Not sure what kinda of power your making or what type injector you have. If it's a ford injector it's acutally bigger than 24
Racer
Joined: Jun 2004
Posts: 391
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From: Lisle IL
CI 6-7-8-9-10 Veteran
Re: 24 lbs injectors are too lean. (vettefast)
What is you timing set at? I had the same problem with my headers. To fix it we played with the timing and it went away. I have it set at 6 degrees now. And yes I do have a 383 with 30lbs injectors.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: 24 lbs injectors are too lean. (bradvette)
It would be the injectors if you were running the engine well beyond 1/2 throttle. If you were doing that on a fresh engine,... that is wacked to begin with.
If the headers were glowing with part throttle or idle, the inj size is not your problem. What is your base timing? What vacuum do you have at idle?
I'd strongly suggest the inj size is not your problem.
If the headers were glowing with part throttle or idle, the inj size is not your problem. What is your base timing? What vacuum do you have at idle?
I'd strongly suggest the inj size is not your problem.
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Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: 24 lbs injectors are too lean. (vettefast)
Ask your mechanic to put a scanner on it to find out what the ECM is doing:
-is it going closed loop
-what are the BLM & Integrator values
-what is injector pulse width
The ECM may be able to compensate for a lean condition if he bumps fuel pressure, at leasst at idle.
-is it going closed loop
-what are the BLM & Integrator values
-what is injector pulse width
The ECM may be able to compensate for a lean condition if he bumps fuel pressure, at leasst at idle.
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
Re: 24 lbs injectors are too lean. (Blown383C4)
What is you timing set at?
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
Re: 24 lbs injectors are too lean. (bradvette)
is your chip re-calibrated in any fashion for your current buildup? i suspect it wasn't.
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
Re: 24 lbs injectors are too lean. (ZylaRace)
It would be the injectors if you were running the engine well beyond 1/2 throttle.
[Modified by vettefast, 11:40 AM 7/1/2004]
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
Re: 24 lbs injectors are too lean. (65Z01)
Ask your mechanic to put a scanner on it to find out what the ECM is doing:
-is it going closed loop
-what are the BLM & Integrator values
-what is injector pulse width
The ECM may be able to compensate for a lean condition if he bumps fuel pressure, at leasst at idle.
-is it going closed loop
-what are the BLM & Integrator values
-what is injector pulse width
The ECM may be able to compensate for a lean condition if he bumps fuel pressure, at leasst at idle.
Safety Car
Joined: Apr 1999
Posts: 4,623
Likes: 2
From: Ohio
Re: 24 lbs injectors are too lean. (vettefast)
BTDT, got the blown motor to prove it...your distributor is not installed correctly. It's got to be off a couple of teeth and it's causing an extremely lean condition. Sounds like your using the same carbureted engine builder I did...
Get the distributor installed correctly first, the set your timing at 6*. You MUST get a prom tuned for YOUR motor, or you will screw it up. IMO, your car will run fine with the 24's, to a point. If you plan on running a road course for instance, where your right foot will be flat on the floor down a long straightaway lap after lap, I think your 24# injectors will get tired of running maxed out and will prematurely die. Most of the road race engine builders I have since run into, run a 28-30# injector on a stroker motor. Having said that however, I do not think that is your problem just yet.
Get the distributor installed correctly first, the set your timing at 6*. You MUST get a prom tuned for YOUR motor, or you will screw it up. IMO, your car will run fine with the 24's, to a point. If you plan on running a road course for instance, where your right foot will be flat on the floor down a long straightaway lap after lap, I think your 24# injectors will get tired of running maxed out and will prematurely die. Most of the road race engine builders I have since run into, run a 28-30# injector on a stroker motor. Having said that however, I do not think that is your problem just yet.
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
Re: 24 lbs injectors are too lean. (h rocks)
Sounds like your using the same carbureted engine builder I did...
Well, I thing the shop found the problem. They said that the Accel Street ram intake is taking in air at the base which is causing a lean fuel problem. He will need to take it apart and refit it. Hopefully this will solve my problem. I think in the mean while I will be looking for a company to burn my chip.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: 24 lbs injectors are too lean. (vettefast)
Glad they found it.
This is a MAF setup, right? You should be able to run on the stock PROM. i.e. This should not ruin/break anything. No glowing pipes or anything. Course, to get it all optomized, you want to burn a new PROM.
This is a MAF setup, right? You should be able to run on the stock PROM. i.e. This should not ruin/break anything. No glowing pipes or anything. Course, to get it all optomized, you want to burn a new PROM.
Thread Starter
Drifting
Joined: Sep 2003
Posts: 1,652
Likes: 2
From: 1990 383 Stroker Baltimore Maryland
Re: 24 lbs injectors are too lean. (ZylaRace)
Thanks ZylaRace
It is a 1990. I would like to run on the stock chip because what I really like to do is find a company that can burn me a chip while on the dyno. I have heard this is the best way to burn a chip correctly.
[Modified by vettefast, 2:46 PM 7/1/2004]
It is a 1990. I would like to run on the stock chip because what I really like to do is find a company that can burn me a chip while on the dyno. I have heard this is the best way to burn a chip correctly.
[Modified by vettefast, 2:46 PM 7/1/2004]
Melting Slicks
Joined: Jun 2002
Posts: 2,152
Likes: 243
From: Northern VA
Re: 24 lbs injectors are too lean. (vettefast)
Tony's Corvette in Gaithersburg has just installed a superflo dyno with equipment to burn chips. I am not sure if they have it up and running yet but they have been doing about 4 months testing on it to make sure everything is right. You should give them a call. This way they can burn the chip on the dyno.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: 24 lbs injectors are too lean. (jerkyboy)
MAP,... all bets are off. I'm not sure how close the stock cal is for bigger cubes. Maybe one of the other 383 MAP guy's can chime in.
MAP means that a certain vacuum at a certain RPM is drawing X amount of air in. i.e. Cal applies to that # of cubes at that Vol Eff.
MAF is sooo much easier.
MAP means that a certain vacuum at a certain RPM is drawing X amount of air in. i.e. Cal applies to that # of cubes at that Vol Eff.
MAF is sooo much easier.