c4vette383

Hey there started my build on my 87 c4 stick. The engine needed more power so i have decided to upgrade to a 383 stroker. From what my buddy has told me i am going to have to get a new computer so that when i take it on a dyno i am able to tune everything properly and to hopefully achieve 500 hp from this. I am asking anyone if they know where i could buy an ecm so i can make this all happen thanks in advance!!

aklim

I think your buddy is wrong. You take the car to the dyno facility and probably on a flatbed. You do NOT need a new ECM. You do not even need the old EPROM. They will take it out and UV light erase it and reprogram it.

BlowerWorks

AKLIM is sooooo right ! New ECM - you must be CRAZY ! Your ECM can do real time tuning for couple of hundred bucks and your ECM is sooooooo powerful !!!

See Moates.net for the Ostrich and TunerPro.com for the free software !!!! You should spend some learning time !!!!!!! lol greg

RME1993

Hey Aklim,


Question for you. I recently rebuilt my C4 Corvette. New heads, new cam, new injectors and a smog delete. Do I need to change my ECM and if so do you have any recommendations on ECM's and places that i can take it to have it installed.


Thanks in advanced,

aklim

No you don't need to change the ECM. What you need to do is change the programming. You should call Dynojet since they supply quite a few dyno machines and you can call them and ask if they work on whatever it is you have. Don't know if it is L98 or LT1 or location. Someone might know a place near you.

rssshen vette

I got a 383 and kept the factory ECM. I'm in the process of tuning my 85 that had the factory ECM 1226870. I swapped it out with a ECM from an 87 Vette (1227165). The ECM's from 86 and later are better equipped for tuning than the 85 ECM. I purchased an Autoprom (APU1) from Moates.net, and downloaded Tunerpro RT. Now I'm able to see live data, data log, make changes to my tune in real time, and I don't have to burn a chip. It's been a bit of a learning curve as I am new to tuning, but I'm making good progress. I've asked different dyno shops in my area about tuning my car and no one will tune it. No one will touch an OBD1 car unless it's been upgraded to Holley, FAST, Mega Squirt, FITech, Accell DFI or OBD2. Up grading to an after market would cost at least $2k. If it's not a self learning system then you would still have to pay for tuning. In my case i spent $60.00 for the an 87 Vette ECM, $330.00 for the APU1, and $230.00 for a AEM wideband gauge. Learning to tune my car and having it run better than a mail order tune is Priceless!

RME1993

vader86

Early C4s have a chip that sits in the ECM. The dash does not need to come out to remove the ECM. You just remove the hush panel, two 10mm bolts, and gently pull the ECM down. Remove the chip and note how it goes in and out so you don't put it back in backwards and fry the whole thing.

Chip tuners only need that chip to reprogram it with the new timing and fuel settings. Later cars have PCM with flash memory that is reflashed for tuning.

85 is a bit different in that its an older ECM and a little more limited in its computational ablities, so many folks with 85s invest in the software and stuff to do it themselves, or give that stuff to your regular tuner and they should be able to do it. Others just swap to the later ECM. You will need to do that or find a local speed shop that does dyno tuning with a WB O2. Mine cost about $500 on both the 86 and 88.

aklim

No, it is more like north of $500. You will be booking the dyno for 3 or 4 hours including strap down time, etc, etc.

I don't think so. See THIS link.

Edit. If you can, as Vader suggests, change the ECM without too much issue, I'd do that

blackozvet

there are other options too,
https://www.dynamicefi.com/

RME1993

Vader,

Take a look at this and tell me what you think. I'm now considering the route of just swaping the chip and calling it a day.

https://l.facebook.com/l.php?u=https...A4mP1fbBM5Whsi

vader86

If you have an 86-89 ECM and need a new chip because the old one is too brittle or won't take the new tune into memory, then i'd buy that chip.

Otherwise I do not see any good service that he's doing you, once you get into changing the engine around, simply going off a list of mods doesn't get the job done unless youre an experienced tuner who has done something very similar before for many clients, like Ed Wright @ Fastchip or the PCMforless tuners. I would not trust ebay tuners to get the tune right.

Even with the mail order tune, I would be in discussion with the tuner about taking my datalogs and tweaking his tune to get it perfect.

aklim

I don't trust any of the "guess a tune" guys. Either they datalog and make adjustments, for real or I bring it there. Many "custom tunes" depend on your butt dyno to make adjustments, if they do any.

RME1993

Alright,

I just need to do some more research. There are other members on different threads that suggest leaving the 85 ECM alone because it can be adjusted. Many other's are suggesting swapping to the 86-89 ECM so I can install pre-programmed Chip's such as the one in the link I posted. As of right now I'm essentially running performance heads with an aftermarket/medium camshaft, Smog Delete and new injectors with my Cold Start (9th Injector) removed as well. My car runs and performs good under load. However, upon start up it takes longer than I'd like to turn over and when i'm idling, the RPM's skip around a little, Plus I dislike the factory settings for when my fan turns on. I'm trying to turn the fan on around 180F. That being said the car needs a tune and I'm trying to figure out the best way to keep the cost down and tune my car myself. As of right now I've managed to build this C4 myself without taking it into a shop.

Thanks,

vader86

If you want it all done at home, get the required software to do it yourself, and buy a WB02 sensor for tuning and tune with that. You won't get all the WOT runs done without a dynojet but you can get all the partial throttle and idle right, those take the most time anyway.

aklim

That is incredible if he could do it without the car and be as good as a dyno tune with adjustments for off WOT running. Pretty much "guess a tune". You want to do all the work and hobble it with a SWAG tune, sure. I would not if it were my car.

ctmccloskey

It is always nice to be able to tell right away whether or not the new part helps make power or is costing you power. I have been tinkering for many years and one of the best investments I had made was buying a "GTECH Pro". This little baby attaches to your windshield and has the ability to show you right away whether the part really made any difference. I bought mine 15-20 years ago and it does not have some of the newer features like the Road-Racing unit comes with.

You simply set up the device and then hit the gas and go for it, you can do 0-60 or anyway you want to test your car. I preferred to check my horsepower doing 0-60's but there are several ways to test your car. It will show you the quarter miles times and so much more. The best part is that you can set it up, make the changes and then test it right away. No waiting for Dyno Rooms and all their related expenses.

If you are worried about accuracy read about these things on their own web site: https://www.gtechpro.com/

There have been naysayers who can't trust this little box, there is a video on the web showing a car being tested both ways, Dyno and GTECH and the results were very close. This gadget is way more accurate than your average "Butt Dyno" It is not cheap but then how much for 6 hours of Dyno room and setup time. I suspect this gadget could save the average upgrader some serious money and cost less than a couple hours at the Dyno facility.

There are more ways to calculate your horsepower but none so easy like the GTECH makes it. My GTECH actually has shift lights and tells you when to shift when it detects that you are at or near the peak of power making in that particular gear. It is a very handy tool in the hands of someone modifying cars and wanting to know "How Much did it help?" or how much did I gain/Lose making those changes.

The only catch is you need to know how much your car weighs and it has to be accurate. I took my Corvettes to the landfill where they have a very accurate scale and gave me the correct weights for free. If the weight is not accurate then the results will suffer as well. I weighed my cars with no cargo but the driver and a full tank of gasoline. When you are done testing you can see an accurate Horsepower and torque curve that you just made.

I wish you all a Very Merry Christmas and a New Year full of awesome Corvette experiences!

aklim

Butt dyno is worthless so most anything will be better than that.

Sure but what are you doing for 6 hours in a Dyno room? Having lunch? Most of the people I talk to think it will take 3 hours to get a few WOT runs in and spend time on the low to midrange.

It won't tune the thing for you so you are comparing apples to oranges. If you are talking "dyno days", a run can be had for pretty cheap to see what power you have. If you are doing serious mods that will show some serious gain, I would say the "dyno days" or the device will be great.

Socalsalas

I was wondering if you could PM me to tell me more about your smog delete? My state does not require emission testing and I want to free up the restriction that recirculating the exhaust creates

aklim

I would leave the EGR on if you can. Otherwise you have to find someone who will reprogram your chip to remove the Code 32 which will come up when you remove the EGR. The Air Injection Reaction stuff, aka AIR (not to be confused with air) system is easily removed. Take the valve going the 4 pipes that feed each pipe in the exhaust manifold out and cap it with a pipe cap. The system can be removed and the wires to the diverter valve insulated.