I recently put a 350 TPI into my 305 TPI Iroc and I want to purchase another chip. which chip do you guys suggest. I had one of the ADS ones for my 305 but I sold it. do you suggest a Jet Chip, Hypertech or ADS???????

1986 350 TPI auto with 2500 stall and 391 gears and tonnes of mods.

edit. BTW, pictures not relating technical assistance to the thread at hand are not appropriate.

 

None of the above. Learn to burn your own, or be content to play with your fuel pressure and initial timing. I guarantee you could go faster w/ a day of TnT at the track then by buying an off teh shelf chip.

 

Since the ECM is the same for '85-'89 5.0&5.7L F & Y bodies, get a used chip for a 5.7L engine on e-bay, don't toss $$ at a chip for a lightly modified MAF engine.

Just do the air flow mods and use an AFPR to tune fuel flow and a a fan sw to take care of cooling mods. You can offset the TPS (to about 0.65Vdc at base idle position) to advance the spark curve a little.

 

You can't run a MAF 350 chip in a 305. The injector constant is higher (22 vs 19) so you'd run way lean as your ecm would *think* it had bigger injectors.

 

Ed's right if you are running the original 19# injectors. MAF doesn't know (nor care) about the actual displacement of your engine (that's because the MAF does that by measuring airflow). The only thing you need to be concerned with is ensuring the eprom has the proper injector size. 305s used 19# and 350s used 22#.

In fact, as Ed alluded, it shouldn't even be called a "305 vs 350" eprom for MAF cars. It should be "19# vs 22#" eprom for MAF cars. Also, auto vs manual...there is a diference in the controlling of the IAC.

 

I have swapped a 350 into my IROC and I now have 24lb/hr injectors - can I switch to the 350 chip?

 

Nope, you will run too rich or have to seriously reduce fuel pressure (which probably won't be sufficient nor is the proper thing to do). And if those are SVO injectors, they are rated 24# at 38 psi, not 42 psi like GM injectors.

Sorry, but you need a new prom for the larger injectors if you don't want to be running rich all the time.

 

are fastchips any good?

 

I was going to get a chip from fastchips but was persuaded to write my own. So in the next couple of months I start on the learning curve of PROM burning. Should be fun

Rob

 

Since I am running a 24lb injector wouldn't it make sense to run the 350 chip unitl I learn to burn my own? Won't the 305 chip think that I'm still running 19lb injectors and try to compensate for the extra cubes?? If I had the 350 chip then it would assume that I'm using 22lb injectors and my resulting fuel mixture won't be as rich as the 305 chip, right?

 

"Learn to Burn" baby!

JD

 

That doesn't help right now as I am a "burn idiot". I do have an '89 350 chip that I was going to put in but I won't if it isn't going to help at all.

Glen?? Help!!

 

You'd definitely be better off starting with a 350 MAF chip since thats what you have now. But instead of spending a dime on any PROM, just buy the stuff to burn your own, a bare bones set-up w/ burner, chips and free editor would be 160-170. You can get the bin you need online. Then you simply change one number (the injector constant) plug it in and run it. It's that easy. And you'll be *JUST* as close as any 'fastchip' that you order from someone who hasn't seen your car. If your car is fairly stock you might not even want to change anything else. A lot of guy's swear by he ARAP bin in MAF cars, it's a factory prototype GM chip they put in magazine cars for better numbers. Want an idea of how good it is, just do a search on ARAP on the PROM board.

You can find all the info you need to further understand what i just said over on the DIY PROM board, and in TRAXION'sintro to prom burning tech article. But yes it really is that easy. And yes it really does cost less than anybody's chip.

 

Wellll poop! Now I gotta go learn something new . . .

 

Yup. For SVO 24# Injectors you generally need to set the Injector Constant from 25-26.5# depending on your fuel pressure that you are running.

The Pocket Programmer costs $149.00. For a Bin Editor you can buy TunerCat for $80 total, or use the "freebie" WinBin. To start, I'd use WinBin, but do look at TunerCat.

For a Scan Tool, look at Craig Moate's Software (it's free) and run off a Laptop.

The total cost is about the same for a "basic" custom eprom for the change to the injector constant. Then you can modify to your heart's content. The change to the Injector Constant is a "simple" change and when you do it, you'll ask yourself "and they wanted $150-200 for a custom eprom just to change the injector constant"?

Then you can do some REAL tuning.

 

If you edit a bin and burn your own chip, is it still possible to use a regular Scantool? Anyone?

 

Yup, thats another advantage. A scan tool works perfectly because that code is stock. Aftermarket PROMs sometimes dont work w/ scantools because they whack the code either on purpose or by accident.

 

...But now I run much faster without it. I just added timing and fuel psi and im in the $$$

 

For most it works fine, that's how we tell if the changes we made are working right.