After breaking a piston on my new 383, I installed a set of 84 lb/hr Delphi injectors in my '95 LT1 with LJ's Accelleronics Impedence Converter.

With an 86 lb/hr injector constant, the Lterms are 126 - 131. The car idles and drives fine, and the A/F ratio at WOT looks good.

However, when cranking the car (cold or hot), it doesn't start very well. If you hold the throttle open, though, it starts up fine.

I have set the injector offsets to zero at 8 - 10 volts to lean it on start up, which has helped. However, it still doesn't start quickly.

I've seen in the tuned port and '93 LT1's a table for Crank Fuel Addition. However, that table isn't in TunerCAT. I think that leaning this table would make my car start right.

Does anyone know how to access that table?

Any other suggestions?

Thanks,
Mike

 

In LT1 editor there is a volumetric efficiency table for 0 - 340 rpm, that would be the cranking rpm. Some people running the large fuel injectors have reported better hot starting when you multiply that table by 60 - 80%, thus leaning out the crank air fuel ratio. If Tuner cat has an equivalent table you might explore that.

Cold start ... I have the same problem with my SVO 42# injectors.

Just a shot in the dark

LWM

 

TunerCAT apparently doesn't have that table. The lowest the VE table goes is 400 rpm.

That's strange about your SVO 42's. I just took out a set that started fine in all conditions.

Mike

 

<<However, when cranking the car (cold or hot), it doesn't start very well. If you hold the throttle open, though, it starts up fine.>>

I have this same exact problems sometimes with my 50# injectors. If you hold down the throttle as you said it seems to work fine too and idles without any syptoms. And mine only does it when the car has been sitting for a day or two and its cold out. My injectors were flow tested and I never had this problem before in the warm weather.

Mabee more folks can chime in and let us know if they found a different solution.

PS, my fuel pressure is fine when starting and the car does not throw any SES codes nor does it idle funkie at all.

Thx,
Claude

 

what hes saying here sounds very similar to what was told to me by a friend who was having a similar problem with large injectors...

 

So you have no cold start tables? It sounds like your defiantly lean on the cold start so I can see why when you hold the throttle to the floor it would start.

 

I don't think he's running lean on the cold start, sounds like the opposite. FWIW, my 40# injectors do the exact same thing. It usually takes me about 10-15 seconds of cranking to get the car to fire, and you can smell the fuel when it finally does. I discussed the problem with a friend of mine who does alot of supercharged Mustangs, and he says the problem is common on 302s with large injectors. If LT1 edit allows you to access the cold start tables, I might have to look into that.

 

Hi,

On my car running the Seimens 72#/hr injectors, my car fires up right away, literally turn key and boom to start.

It starts so much easier now after I redid the battery cables and grounding to the chasis from the battery and the motor and added in the LT4 starter that is properly shimmed. This eliminated the tick-tick-tick probelm. At the same time, while we were tuning the car, LJ had set my injector offsets to 0.33 msec from 12.4 to 16.4 volts.

In the PCM, my VE table and IAC is basically stock.

good luck