Matthew91-Z28

Hey...need a little clarification. I fully understand why I need to change to a 350 chip when I swap out the 305 ci for the 350.

BUT, I don't understand why fastchips.com say that I can't just buy a new chip for a 350. They say I need to get my 4-letter prom code so they can custom burn a chip for me.

When I swap out the engines, I plan on using the stock 350 injectors (22#, right?), 350 manifold, etc. Even if I use all the parts needed for for the 350 engine, are there subtle differences in other areas of my car's performance that would require a custom chip instead of just using a chip for a stock 350??


Thanks,
Matt

StealthElephant

i could be wrong, but each individual chip needs to be burned to work with your unique 4 number PROM code, it's not that the "settings" on the chip are custom, but that number unique to your computer is....i could be wrong...just a shot in the dark since no one else replied.

DJP87Z28

If you return to the Fastchip web site, look for a chip for 1988 350
TPI engine and not the custom one where youi fill out info form. They cost $150 for a stage 2 chip. Thats the one I am using on my 350.

Guest

Whats been done to the engine?

I'd say go to the dealer and order one for your car, with a 350 instead of 305.

tregnab

I swapped my 305 for a 350 and finished it last month. I did not change anything except the injectors, and I'm running 21 lb/hr units now. The car runs excellent, I've had absolutely no problems. I also replaced a few of the sensors, just so I'd have new units I could trust.

My 350 came from an '88 IROC AT, and was put into a '91 Z28 (originally 305) T-5. The only thing different on the two blocks was the starter. I used the '91 smaller-style starter.

Matthew91-Z28

Sorry its taken me a while to get back to this post. LOng week. No nothing has really been done to the engine in now (the 305) nor do I plan on doing anything extravagant with the 350. Besides maybe a high flow intake manifold, its gonna be stock.

Yeah...what exactly does that 4 letter prom code signify?

Well I called fastchip wanting to order that 350 chip for the tpi ($150). They asked me what my prom code was. I told them it was actually for a swap (305 to 350). I was told that it would be a custom chip and that I needed that 4-ltr code on my 305 chip to do the new one.

I never bothered to asked if it was going to actually cost me what a custom chip would ($350). I think he may have been using the term 'custom' loosely.

I'll have to call again today and find out for sure.


I'd read previous posts on people who did the engine swap but didn't change chips. Some say it did not matter. Others say it does make a difference.

DJP87Z28

I think there is some confusion with what you are trying to order.
Just ask Fastchip for their Chip for a 1988 350 TPI engine that costs $150 and that should be it. Unless they change the process
and now require the ECM code. Really no problem, its on the ECM under the dash on the Passenger side.

Matthew91-Z28

Actually, thats exactly what I said to them when I called. I never even mentioned I had a 305 until he asked for my prom code. Thats when I thought it may be important to let him know that I was swapping. Thats when he told me that was going to be a custom chip and that I needed to get that prom code.


Itsa realyl no big deal to read my prom code. I just don't want to be charged $350 for a "custom chip" for a stock 305 swapped for a stock 350.

freestylzz

Hi. I have the same issue to deal with. Last month I dropped a complete 350 TPI from a '91 GTA into my 5 speed '87 Iroc-Z in replace of the 305 TPI in it. I am running the 350 with the 305 Hypertech chip and computer that was in the '87. The car starts up fine, but idles high and doesn't drop down. It does drive good and it definitely has alot of lower end torque than the 305. The 350 pulls like a SOB up to about 5000 rpm when I notice it seems to "run out of breath". I'm not sure whether this is a problem with the computer or that I might need a higher flow fuel pump ( have stock). The 350 has the original injectors, Edelbrock Hi-flow intake, Edelbrock Performer Aluminum heads, Fuel pressure regulator, 1.6 roller rockers, MSD 6A, pully's, MAC headers with a 3 inch straight pipe to a 2 chamber Flowmaster, and a cam ( not sure as I didn't build it). I've been told I should program the chip for my combination......the 305 computer won't cut it. Hmmmmmmmm?

RB83L69

This motor has TPI on it, correct?

That's about right then. As long as that's on top of it, it doesn't really matter too much what else you have, that's your brick wall.

A TPI motor should be carefully optimized for maximum torque at about 3600 RPM, since that's what the intake system wants to do. Try to do something else, like put too much cam in it or things like that, you'll be fighting something you can't change (the acoustic tuning of the runner length), and the car will slow down. The same acoustic effect (pressure wave) that produces the famous TPI torque peak at 3600 RPM also starts to reduce volumetric efficiency and therefore torque starting at 4500 RPM or so, regardless of motor displacement. That's in addition to the flow limitation of the small-diameter runners with a 180° bend in them.

A 350 and a 305 have diffferent fuel and timing requirements in terms of duty cycle and advance at any given RPM. They fill their cylinders differently when fed by the same induction system. That's why the chip needs to be different.

Jade Grey

iTrader: (1)

Matt,
I'm going to repeat what madmax said. If you are staying nearly stock, I don't see why you can't use a stock 350 chip. The different four letter codes also signified different car options such as AT/MT, rear gear ratio, tire diameter, etc.

Below is search results for the correct prom for a SD 350 TPI from AC/D's site. There's only one available for 5.7L but a few different variations for the 5.0L. I only included the relevant listing.


The price for the cal-pak via
GMPartsDirect.com is $45.45.

Unless I'm missing something, all you need to do is change to this cal-pak in your '730 computer. This should be the easy part of your swap.

Matthew91-Z28

right on Jade....thanks for providing your search info. I am trying to find out what the 4-letter prom would be for a 91 350 with AT and 2.73 rear. That listing you posted, interestingly, seems like its showing 3 prom codes all under the same invoice number. Maybe they ask when you order it.


Let me clarify one thing: does 'cal-pak' = chip?

Jade Grey

iTrader: (1)

The cal-pak would be the whole "blue" box housing. I believe that the ESC chip and limp-home chip are also contained therein. I think that ordering a stock chip by itself is impossible. That is, the part number listed is for the entire cal-pak. To be sure PM one of the TGO veterans like Traxion, Vader, madmax, etc.

Matthew91-Z28

GM PART # 16151348
CATEGORY: Emission Control System Hardware
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $90.91
OUR PRICE: $45.45
DESCRIPTION: EPROM ELECTRONIC CONTROL MODULE (ECM)
This is the right part number if your ECM has 4307ANJF, 4312ANJ, 1350AUJP.


When searching for ECM @ scoggin-dicky, all the invoice #'s start w/ 12xxxxxx.

I understand that the word '350 chip' may be layman's terms. What is the actual GM terminology for this piece? Is it the ECM or eprom or what?

Jade Grey

iTrader: (1)

If it starts with a 12xxxxx, as in 1227165, the '86-'90 MAF computer, or 1227730, the '90-'92 SD computer, then you are looking at the entire ECM not the cal-paks.

Below is a quote from Traxion's Prom Intro article. He uses the term Memcal instead of cal-pak.

As a side note i didn't know you could search for GM part numbers directly from the SDPC site. The 16151348 memcal is priced at about $60 from SDPC. That's cheaper than Van DeVere Olds and comparable to gmpartsdirect after shipping.

GM's technical term is somewhere along the lines of calibration eprom. If searching SDPC try using just eprom as the search word or try the part number directly.

The four letters on the prom signify revisions to the code. the last version released by GM when the SD 350 TPI's were being produced was the AUJP. If you have the means to burn a chip, you could download a .bin image from Mike Davis' site and possibly use it to replace your stock 305 chip. Just giving you another option if case you thinking of trying DIY prom work.

Matthew91-Z28

I'd love to do some DIY prom burning. And since this swap won't really happen probably until December, I may just go ahead and buy the parts to do it myself just to make everything is properly tuned.

But, at least now after your clarification, if I don't do my own burning I can get what I need for $45-$60.

Thanks for the link to Mike Davis' site. Pretty informative and the bin library has an a^^load of files.

novakm

I just put TPI into my '71 chevelle. Engine is nowhere near what a stock L98 is, but here the chipfor L98, from www.GMpartsdirect.com
Category: Emission Control System Hardware
Part Number 16151348
Description: EPROM ELECTRONIC CONTROL MODULE (ECM)
Min.Qty: 1
Unit Price: $45.45
Quantity: 1
Ext.Price: $45.45
Core Charge: $0.00


==================================================================

SUB TOTAL: $45.45
SHIPPING: $9.09
TAX: $0.00
TOTAL WITH TAXES: $54.54

Started and ran just fine with no tuning. Not "high performance" fine, but "good daily driver" fine, (after I disabled VATS, EGR, and canister purge). I am tuning now. Need lots more timing, because my compression is much lower. 5d advance woke it right up. Can't wait to see how good it gets with more work. It's already way more fun than it was with the 4barrel Edelbrock.


My guess if your engine is close to the L98 specs from '91, it will just pop right in and work reasonably well.

I also bought the pocket programmer and Craig Moate's adapter and chips, so I can tune it myself.