After reading about every post I could find, I'm leaning towards my car having a bad ECM and was hoping to get others input.

1987 Firebird 305 TPI Automatic

Here is a list of all the items I have changed or fixed so far.
Fuel Pump
Fuel Pressure Regulator
Accell Fuel Injectors
IAC
TPS
Coil
Ignition Module
Plugs Wires
EPROM Chip to eliminate 9th injector
Temp sensor in intake
Temp sensor in head

I have also replaced several plugs and connectors as the wiring was pretty bad (See pics)

The engine light does come on after several minutes something about the TPS (don't remember the code off the top of my head)

I have the same issue as a lot of TPI owners the car will not start cold. It will act like it wants to start but never fires up. You can crank it for 5 minutes before the thing will fire up, then it runs pretty rough for a minute or so. If i hit it with starting fluid it will fire right up.
As soon as the engine fires, both cooling fans run wide open. Have replaced both fan relays.
So after all this I have decided that possibly the ECM was bad. I pulled the ECM back out to get a number off of it and realized it was a RE MANUFACTURED ECM from Mexico. Also didn't realize it has a Hyperchip in it.

If anyone could help shed some light, I would greatly appreciate it. Also if anyone has an ECM they would like to sell please let me know. THANKS

 

First, it will be important to get the actual numbered error code which is being generated. We would only be guessing without that bit of information.

Second, it would be best to install a stock MEMCAL in place of the Hypertech, regardless of whether the ECM is replaced or not.

 

And the Dark side cometh out of the works

How ya been?

 

Check your CRANK fuse is good. ( this fuse will only send power to the cold start injector and switch when the key is turned to START. )

Get a helper: disconnect distributor. Have helper crack engine while you probe PURPLE wire on cold start injector and cold start switch. Should carry power when key is turned to START. This diagram is from an 85 - but your car should be similar.



** Be sure to closely inspect the plugs and terminals on the cold start injector and the cold start switch. I've had a couple cars with corrosion on the terminals that didn't allow voltage thru the purple wire to reach the switch.......

You'll also have to get the ECM code and chase that issue down till resolved. There's is obviously something the ECM doesn't like to see and that could be effecting your cold start problems.

 

Thanks for the help.
I got another throttle body and swapped it out, now the service engine light is no longer coming on but it still will not crank when cold.

John in RI i did check the crank fuse it is good. I checked all the fuses just to make sure.
As far as the 9th injector goes, does the re-flashed eprom that I purchased from TPI Parts not eliminate the 9th injector?
It is supposed to have an 88 flash on it, if I remember correctly.

Thanks

 

I don't have any info on that,... I do know that the 88 was still a cold start set-up & when there's a problem starting a cold 85-88 TPI the first things to check are ALWAYS those cold start items !

 

Seems in a lot of these threads, the basics get skipped.

You have thrown a lot of parts at it, do you know what you IAC is setting at (Steps)? How about your base timing? What voltage is your TPS reporting at the TB and at the ECM? Fuel Pressure KOEO and during cranking?

It sounds more like a fueling issue to me since it will fire up on starter fluid. I would check fuel pressure first before replacing any more parts. The other issue you have now is "NEW" doesn't mean "GOOD", unfortunately.

Also agree with going to stock chips and knowing what the actual Error Code is.

 

The piggyback adapter chip would have 89 programming

 

The car is at my Dads at the moment, will get over there this weekend to do more checking.
I did check the TPS voltage last time I was there its set to 0.56 and that did away with the service engine light.
I checked the fuel pressure after I put an new pump in and when I turn the key on it pumps to about 45psi, will check again what the psi is when cranking.
I have never checked the timing, but will next time I am there.
I do not have a stock chip, unfortunately, but will see if I can locate one online.
Thanks for the help.

 

If you need a stock memcal I have one send me a pm.
i don’t think it’s needed unless your having a code 41 or 51.

https://www.ebay.com/itm/87-Camaro-F...wAAOSwVH9b63RA

 

With all this virus stuff going around I haven't been over to my parents to mess with this car. My Mom is 75 not taking any chances. I'm not 100% its not a fuel issue either. The car was completely stock and original when I purchased it. It would not crank, I assumed possibly injectors were the problem. Bought a new set of Accell but it did not make a difference.

The fuel pump was bad it would not hold pressure. As soon as the relay on the firewall kicked off the pressure would drop to 0. When I pulled the tank Im not joking when I say there was a bucket full of dirt in the bottom of the tank. Not sure how that happens?? So i replaced the tank, pump, sending unit, fuel filter, and pressure regulator. When I turn the key on the it pumps up to 45psi, and when the pump kicks off it holds at 40psi.

I'm wondering how much of that dirt got sucked into the new injectors and possibly ruined them??
But that still does not explain why the fans both turn on wide open as soon as the engine starts?? I've soldered in new pic tails and replaced the relays so still scratching my head wondering if it is not a bad ECM??

 

Most people have problems with their fans not working. I jumped the inside of the main relay wire harness with a paper clip for the main fan so its always on while the key is on. Then cut and grounded the signal wire to the aux. relay (tan wire), spliced in a switch for the secondary fan. Its all good except when I forget to make sure the fan is off before I start the car. Both fans run off 20 amps but spikes briefly to 40 amps when the aux. fan kicks on. This 40 amps plus the starter kicking blows the fan fuse like everytime.

 

I ordered an ECM from Hawks supposed to be here this week. Im keeping my fingers crossed that is the problem. Thanks for the fan tip, if this doesnt work will have to do something different.
Thanks

 

Finally got the new ECM in the car. It cranks for about 5 seconds then fires right up. Both fans still come on as soon as the motor cranks, still not sure why, but at least it runs. I'm just happy it starts and runs now can live with the fans being on all the time, at least they are working. I've changed all the relays and soldered in new pigtails for all the fans, anyone have anymore ideas? Thanks for the help.

 

Check the ground wires that come from the fan relay. When I bought my car it was the same way, both fans came on with key on. I traced my wires and found the green/black (IIRC) wire cut and grounded directly to the chassis.

 

Funny that I also solved my cold start problem with a new ECM after doing everything else just the same as you... See my thread... Feels good!

The "low temp" fan is not controlled by the ECM but a temp switch on the head...I agree it sounds like a wiring issue... Maybe someone grounded the circuit...

 

Im not to great with checking wiring, so just wondering when you say grounded, is that something I can check with my volt meter to make sure I have the correct voltage to the temp sensor in the head??

Thanks for the info.

 

I read your post a while back and that is what got me to thinking that it could be the ECM. The guy I got the car from put a re manufactured ECM from Auto Zone so I didn't think that was the issue. After reading all the posts in these forums that I could find I started leaning that way.

I ran into the guy I bought the car from the other day and he told me that this car was a stereo demo car back in the day, had a huge system in it, and won a bunch of sound awards and it took him forever to get all that stereo wiring out of the car. That might explain a lot now that I know that.

I didn't know the low temp fan was not controlled by the ECM. I did replace the temp sensor in the head, but we know that is not a guarantee. Im not to good with checking wiring, so just wondering when you say grounded, should I take my volt meter and make sure I am getting the correct voltage to the temp sensor in the head??
Thanks for the help

 

The low temp fan is a grounding switch. When the sensor gets to it's setpoint, the switch grounds to the head closing the circuit, and the fan starts.

I test mine by disconnecting the wire from the sensor, and ground it against the body... If the fan still runs with the wire disconnected, it's getting power from somewhere else.

It's not really a temp sensor, it's a temp switch...it's such a pain to get to... Under the exhaust manifold on the passenger side on my car....and removing it always dumps coolant in my face....such fun.

 

My car has one in the drivers side head, and one in the passenger side head. The one on the passenger side has a connector that looks like the ones you would find on a knock sensor. I'm assuming that is the one your referring to??

Thanks

 

Yep...that sounds like the one.... Not positive but the drivers driv one may be for the temp gauge.

 

Finally got a chance to look at that switch. I disconnected the wire and grounded it to the frame, with the motor not running, The fans did not run, but I could hear the relay switching on an off. I started the car with the wire connected and disconnected and both fans still start as soon as the motor starts

 

My fans only come on when the motor is running. I can turn the key on and they do not run. I disconnected the wire going to the switch in the right head and it has 11.75 volts with the key on. When I ground it to the frame I can hear the relay clicking. When I ground it to the frame and I can hear the relay clicking, should the fans not start running??
Here is the new switch and new pigtail that I soldered in.

 

Did some more research and wondering if it could possibly be the ac fan switch??

 

I put some liquid electrical tape on that bare spot in the orange wire. I backprobed the black/red wire which goes to the fans and connected it straight to the battery with the relay disconnected, should the fans not have come on??

 

ok played around again today. I have two relays for the fans, so I grounded the green/white wire on the one relay and the fans do not come on but the relay is clicking, also swapped it with another relay just to make sure. I grounded the green/white wire on the second fan relay and both fans come on. So i guess my question is should the fans be coming on when I ground both relays?? One worked and the other did not??

Also checked when I ground the green/white wires I get 12 volts out of the red/black wires on both relays. One relay is turning the fans on and the other is not. Wondering if I have a broken red/black wire after the relay but before the fans??? Thanks for the help

 

Sounds like someone cut the RED/BLACK wire ( power to fan ) from one of the relays and spliced it into the RED/BLACK wire from the other relay.

 

Man your good. I decided to pull all the fan wires up and strip away the plastic and guess what the wires were cut and spliced together to run off of one relay. Got the wires connected back together properly and now when I start the car the drivers fan comes on right away, but now the passenger fan is not running, so I guess I got one of the fans fixed.

Also now when I ground the wire going to the temp switch in the right side head now, the right fan comes on, which I believe is the way it should work correct??

 

Yes.

going from memory here: (The fan plugs *could* have been moved from side-to-side, so I'll call the fans primary and secondary rather then Left & Right)

The primary fan should get controlled by 1 relay; that relay should get activated by the ECM.
The secondary fan gets controlled by the second relay; that relay should get activated by the switch on the pass side head.


The fan that runs as soon as the motor is started is getting activated by something. Obviously the relay is there,... but something else is activating the relay; or power is getting 'jumped' to the fan directly. ( regardless of what happens at the relay ) Check the GREEN/WHITE wire on the primary relay for ground when the car is started and the fan kicks on....... if there's ground on that circuit when the car is cold, there might be a ground wire jumped/spliced to the GREEN/WHITE somewhere.

* the fact that the primary doesn't turn on when the key is in RUN,... but turns on when the key is in RUN and the engine is STARTED is significant. There are not many factory circuits I can think of 'quick'; that are only active when the engine is actually running. Most circuits are 'switched' by the key, so you'll have to find out what circuit is active only when the engine is actually running. If you unplug the primary fan relay and the fan doesn't turn on when the engine is running,... then 1 of the wires feeding that relay has been tampered with, the relay is faulty, or the ECM might be defective & always sending a ground signal to the relay.

 

After seeing what the rest of the fan wires looked like, I think your right I might need to go deeper into that wiring. I hope its not something with the ECM since i just replaced it LOL..

Thanks for all the help and info

 

Won't the ECM turn on one of the fans if a/c is requested? IS your a/c on at startup?

 

The belt was cut when I got the car so assuming the compressor is bad. If what I have read is correct, the left primary fan is controlled by the ECM, which comes on as soon as the motor cranks. The right fan, or secondary fan comes on when the AC is turned on or the motor gets hot enough to need the second fan and is controlled by the sensor in the right head. The right fan has not come back on yet because I cannnot turn the AC on and since the primary fan runs all the time the motor has not got hot enough. I can ground the wire to the relay and make the second fan come on now so it is working properly. Gonna trace the green/white wire back to the ECM and see if there are any breaks in the wire or its grounded somewhere.

 

Ok finally got back to messing with this wiring again. What I have found is that when the car is running, the primary fan relay the orange wire is hot, the tan/white wire is hot, the green/white wire has nothing, but the black/red wire is hot so the fan runs all the time. This confuses me because if the Green/White wire comes straight from the ECM and tells the fan to turn on, there is no voltage at the relay so why is the Black/Red wire HOT??


On the secondary fan relay the orange wire is hot, the tan/white wire is hot, the green/white wire is hot, but the black/red wire is not hot.
So looking at the picture above this is connector C101. I cant find in any wiring diagrams I cannot find what the black wire is slot D comes from? From the diagrams I can find it should be Green/White In and Green/White out. You can see it in the wiring diagram.

Thanks for the help it is greatly appreciated

 

Primary:
ORANGE is HOT AT ALL TIMES - even when there is no key in the ignition

TAN/WHITE should ONLY be hot when key is turned to RUN.

GREEN/WHITE on Primary Relay is GROUND from ECM. ECM should only apply GROUND on that circuit when the temp sensor tells it too. ECM temp sensor is mounted to the front of the TPI manifold. Ground at all times ( a problem ) = wiring, temp switch, or ECM problem.

If all other wiring is correct but there is voltage on BLACK/RED when there shouldn't be,... ( no ground on GREEN/WHITE for example ) the relay is suspect.

Secondary:
ORANGE is HOT AT ALL TIMES - even when there is no key in the ignition ** SAME EXACT CIRCUIT AS PRIMARY

TAN/WHITE should ONLY be hot when key is turned to RUN. ** SAME EXACT CIRCUIT AS PRIMARY

GREEN/WHITE wire is GROUND, from pass side head switch. should NOT be hot !!

C101 PIN "D" is shown on the diagram that you posted; Should be the circuit GREEN/WHITE for the secondary fan is on. The BLACK wire in that location ( ECM harness side of the plug ) could be a replacement wire from the previous owner or a color variation based on the year of the harness. ( I don't remember it ever being black ! ) That wire should be plugged into the temp switch on the pass side head; unplug the C101 connector then unplug the pass side head switch and test the wire ( OHM, voltage, ground, what-ever ) from switch to C101 PIN 'D' for continuity.

Should only get voltage from RELAY when ORANGE is HOT ( that's OK ) when TAN/WHITE is hot ( Key in RUN, that's OK ) and when GREEN/WHITE has ground. If those 3 circuits are OK ( proper ground on GREEN/WHITE ) and no voltage on BLACK/RED,.... Relay is suspect. * Also be sure to verify GROUND wire on secondary fan plug.

 

OK that makes sense then. I was looking for voltage on the Green/White wire and the ECM just uses ground so there would not be any voltage at all correct??
Since my Green/White wire is grounded all the time, guess I need to start there. I did put a new temp sensor in the intake but could possibly be bad. I also replaced the ECM and still have the exact same problem, so I think I will start with the temp sensor and the wiring to the ECM.

A while back I unplugged the wire from the temp switch on the passenger side head and grounded it out, and the secondary fan did turn on like it was supposed to, so that wiring should be good.

John thanks for all the help. Wiring is not my strong suite so would be lost without your help. Will let you know how it goes. Thanks again.

 

No problem,... & your welcome !