bad computer?
 

for the past two weeks the iroc has been running like crap, some days it ran fine and others it felt like i was running on 2 cylindars, it was throwing a code for the maf sensor, but i replaced that with a friends and it still ran like *&$# it will start up fine, but when i give it gas it will just fall on its face...now its running like crap all the time, i barely made it home today. I was told it could be a bad computer... anyways we put a computer from a 89 350tpi car but it wouldn't crank over, do i need an 88 350tpi computer or are they interchangeable?

anyone have some advice

Start by checking the basics, fuel pressure, spark, compression etc.

did u disconnect the battery when u replaced the MAF? If you don't the computer will see a new sensor as as invalid part because it stores its serial number....but once you disconnect the battery it loses all serial numbers and relearns them on first start. another thing to consider is relays. there are the 3 on the firewall but there is also one on some cars on the passenger side of the radiator. i would also check the condition of the MAF harness as I have had one burn up on me before

Have you tried looking at the reading from the o2 sensor? Sometimes a bad o2 can do that.

yes i disconnected the battery, i havent run an 02 since last year and it always ran fine, but maybe that could be it, checking the relays now..ill be back

Open loop tune?

- Justin

Why don't you run an oxygen sensor?

put headers in and there was only a bung welded on the outside as a fake 02 bung

My $0.02 from playing with factory EFI in the past: Get it back together correctly. It makes everything work better and makes troubleshooting easier. Go get an O2 bung welded in and put an O2 back in the car. If you don't know how enlist a professional. You'll be miles ahead of the game. And in the long run it is cheaper than replacing parts via guess work. Been there, done that, have the receipts to remind me never again.

another question... do the maf and fans run into the same relay on the pass side fender over the battery, or does that maf go to the relay on the DS firewall?

they will not share a relay if that is the question.

Check the autozone site, they have wiring diagrams and component locators for a lot of cars.

alright, i was just wondering cause my fans went bad with this whole deal too, but they seem to be working now ive only heated it up a few times though

Without an O2 I would assume you are in LHM = pull timing, dump fuel, turn on fans. Could yo have killed the fans or relays with them running all the time?

Do you can access to a scanner? Can you monitor what the ECM is getting for data?

i dont have access to a scanner, im gonna replace the relays today just so they are new

you can jump the last 2 terminals to the left on the top row to pull codes via the "SES light flash" method. as far as the relays on the firewall they can be in any various order depending on wheather or not they have been changed. one is "MAF Power Relay" one is for "MAF Burn Off relay" and one is "Fuel Pump Relay". now there can also be a 2nd MAF relay not listed on autozones site but is listed in ALLDATA as there on some and not others. this relay is located on the passenger side of the radiator kinda of under and in front of the air intake if your intake goes to the passenger side. if your intake doesn't you should be able to spot it. now the relay is the same size as the ones on the DS firewall so it should be able to find it easily if you have it. there should also be another small relay down there. NOW THIS IS IMPORTANT!!! contrary to what advaced and autozone will tell you the MAF relays are NOT the same as the fuel pump relay. they may look the same but they aren't. rockauto.com carries all 3 relays (or at least they did when i had a third gen) make sure you get the proper relay and the resistances are different and its a really easy way to burn up a harness. if you have any other questions on this PM me...I have a lot of experience when it comes to tracking down MAF codes in a third gen

How many $10 relays are you going to buy before you start testing things?

yes i have been doing the ses blinking method, and it is telling me it is the MAF sensor "33", so i swapped the MAF with a friends (working MAF) and got a new relay, no i guess im waiting until i can find the right computer to test, meanwhile i got an o2 sensor and will either drill out the bung or have a shop do it

An '89 computer will not work unless you swap your '88 chip into it - the '89 Camaro had VATS and the ECM will be looking for a key with a chip in it to start.

+1....swapping the chip is easy

alright and how would i go about swaping the chip

You have to remove the two screws on the back side of the ECM, pop off the plate, then open the clips on either side of the chip. Use a tweezer or very small screwdriver and GENTLY pry the chip out - you don't want to bend the pins. It's not too bad at all.

so if i swap the chip the computer can be from a different year third gen or does it have to be engine type specific?

the "prom", "chip", or "memcal" whatever you want to call it is engine specific

i believe the ecm swap compatibility is 85 alone(due to maf and maf burnoff relay), 86-88(maf), 89(due to VATS and MAF), and 90-92(Speed density) edit: 85-86 may be the same, i forget)
and then youd have a prom for 305 or 350.

TBI in the later years has a different ecm as well(lo3 motor), same with the CCquardajets (lg4, l69)

and the v6 also have their own depending on 2.8 or 3.1

doesnt apply in your case, but a side note... 90-92 speed density TPI cars use the came ecm as the 90-92 3.1 V6 cars.. just a different PROM(chip)

The '86-'89 MAF TPI cars all use the ECM ending with a 165 - doesn't matter if it was a 305 or 350, as long as it was TPI. If I remember right, the VATS stuff is only in the program on the chip, so as long as you swap the chip from your car (350, auto) you can use any other '165 ECM.