I'm having trouble getting some help with chip burning and I lack the $$ to buy the equipment for 1 burn. I have a 350 with 305 components including the chip and injectors. I would like to get the 350 chip but I hear my car may run or idle funny.

Can I buy an AFPR and pump up the pressure to get it to work better or am I up a creek w/o a paddle?

Basically I want the cheapest easiest way w/o spending $200+ on injectors or $200+ on burning equipment.

Thanks!

I've programmed a 350 to run on 19# injectors with about 4 PSI extra pressure. It does O.K. until the RPMs start getting to around 5,800, then it starts to lose power. My assumption is that the TPI is about done at that point anyway, so it's getting by just fine. It can be done.

Vader,

Out of curiosity, what are the BLM values?

howabout the otherway around, 24lb injectors on a 305 with lt1 cam and tpi?

I would saw at WOT, you should be running very rich.
At cruising around conditions, the BLMs should bottom out or nearly bottom out,,, that means that the computer is taking alot of fuel away.

But what about with no changes to the chip, just as if I swapped in 19lb injectors?

If you don't change it in the chip, it the computer doesn't know how long to leave the injectors open, no matter how much pressure you put behind a 19# injector, it will not be enough. If you make too much pressure behind the injector, you take a chance on it, the fuel regulator, or the fuel pump failing or wear out quickly until fault in one or all.

If you change it in the chip, you are only changing one constant. The injector size constant will be around 22 stock, and you need to change it to 19. While this won't be the best, it will take care of the engine until higher rpms, then it will be too lean they will be to small that they will be static and fail. If the engine is totally stock, the 19# injectors will be enough until near redline.

Best options is to get 22# or 24# injectors.

It's pretty tough to find a good reading within 12 seconds...

Actually, I found through some trials that with a 355 TPI, the best overall was a constant of around 18.6 to compensate for pump gas ethanol, for best starting, and best open loop.

Ideally, larger injectors would be the proper method.

Vader, are you trying to tell us you run the 1/4 mile in 12 seconds?????

Actually, at WOT the BLM value is set to 128, in other words, the part throotle driving fuel correction (BLM value) does not effect the WOT fueling.

12 second car,,, hahahaha.

OK, I'm calling you out. Where can we meet in Summer 2006?
I'm located near Monroe, Mi.

Actually (again), I'm just funning with you. But it would be fun to meet up with you and others some day.

Franken T/A:

If you have a stock 350 chip in the computer and a 350 engine, but install 19#/hr injectors,,, the ECM is programmed for 22#/hr injectors, 350 cubes, and 43.5 psi fuel pressure,,, that is what the fueling equation is based on.

So,,, the 19#/hr injectors will not be able to supply the amount of fuel that is needed on the initial PWs (pulse width) that the ECM equates (at part throotle and idle). So, the engine will initially run lean,,, the O2 sensor will pick this up and tell the ECM to add more fuel by increasing the BLM up from 128. I think the max allowed BLM value is 158, so if you hit that value the ECM should put out an error code for you.

At WOT there is no fuel correction, so you should be running major lean, and either be saved by knock retard retarding the timing or blowing the engine up due to detonation.

But what if he had an AFPR? Would he be ok?

If the AFPR was set to get the fuel pressure up to 58psi, then the 19s would be flowing almost 22#/hr. The ECM should be happy with that, to the best of my knowledge.

How dangerous is 58psi? Isn't stock like 43psi? But Vader you only bumped up the fuel pressure 4psi over stock, so around 47-48psi, and it runs fine?

I've had 19lb injectors with my 350 w/ 305 heads (but with the 305 chip tune) for over a year now and according to the dyno shop owner the a/f ratio is near perfect. So the 350 memcal will make it run lean?

First, that '57 isn't my car. It was just a TPI/tuning/wiring project.

Second, yes, with a 4 PSIG increase over stock (running at 48 pounds with no vacuum), an adjusted injector constant, a little creative MAF table tuning, a little better timing table, and a few other tweaks, it runs surprisingly well for what it is. It pulls to 5,800 RPM and shifts at 6,200. That's not quite right for a TPI, especially a MAF TPI, but it does it anyway. I guess nobody told it that it shouldn't do that.

Finally, who said anything about ¼ mile?

Yes, there should be another Midwest Meeting when the weather improves. It's been a few years for me. But that's a different topic for a different board.

Back to the original question - If it's ONLY the injector constant you want changed (or since you have an SD car, you could use your original chip and just increase the cylinder displacement size in the chip to let it know it's now a 350) - find someone with the equipment that lives near you and get them to change it for you.

Most guys who have the equipment will be happy to make a simple change like an injector size or cylinder size. If you lived near me, I'd tell you to drive over one weekend and bring a half-sack of beer. Though I could do the change before I even finished the first beer, I'd baffle you with BS by showing you all the other things you could change in the eprom so I could drink the other five.

I'm sure that would be one fine, spot-on, precise calibration by the time that fourth or fifth pull tab was released...

Vader, I would make the change FIRST and THEN I would do the "show" (while the beer lasted). I learnt a LONG TIME ago to be careful with beer and computers. The last time I got really drunk when working on the computer was when I was filing my taxes a number of year ago and ended up with an audit.