Hello to all!

[Migo54]

I was given a 1996 Firebird as a graduation gift to have a way to continue school independently. Through research about the car, I found out that the car comes equipped with the y87 package.The fuel economy alright as I make a 25 mile trip to campus, and I'd like to keep it that way. However, it is lower than the advertised 30 MPG; anybody got a solution for that? (I typically get about 24 MPG) Anyway, the car is in pretty good shape aside from a repainted right quarter due to a person running right into it, lack of maintenance from previous owner, overheating problem in traffic (only one fan turns on at 235°), a strange but bad shake over 70 MPH, and a super droopy headliner on my head when I drive it. Any changes would be black ZR1 wheels 17x9 all the way around, shorty headers, a slightly larger cam (perhaps a GT1) and a tune with a 1997 PCM. Honestly the car is fun to drive around, and (more relevantly) interested more things to fixing stuff here. Glad to meet you all.

[LETZRIDE]

Nice bird- it looks in pretty good shape.

Where abouts are you from? I have a fan sitting in my garage, but it wouldn’t be worth it to really ship it. Rockauto our site sponsor usually has replacement parts pretty cheap and you get an extra 5% discount through the forum code here: https://www.camarov6.com/forum/class...bruary-21-2019

What maintenance have you done to the car since getting it? You mentioned the previous owner didn’t maintain it all that well- you may be able to get a few mpg back with a good tune up.

Is it auto or 5 speed? And, what are your driving habits like?

[Migo54]

Nice bird- it looks in pretty good shape.

Where abouts are you from? I have a fan sitting in my garage, but it wouldn’t be worth it to really ship it. Rockauto our site sponsor usually has replacement parts pretty cheap and you get an extra 5% discount through the forum code here: https://www.camarov6.com/forum/class...bruary-21-2019

What maintenance have you done to the car since getting it? You mentioned the previous owner didn’t maintain it all that well- you may be able to get a few mpg back with a good tune up.

Is it auto or 5 speed? And, what are your driving habits like?

I'm in El Paso, TX so I deal with the heat in the summer, which is where i realized that the car wasn't being cooled off enough. As far as I know, the problem with the fans lies in the PCM, with the car throwing the P1651 code permanently. I ran power to both fans, and they work fine, they spin up freely.

Since getting the car in the summer, I've changed the oil, coolant, plugs (seriously a PITA isn't it?), Down stream O2 sensor, wheel balancing, and air filter. I also replaced the TPS to fix a very high idle in the cold weather and the next things on my list are diff oil, ATF change and the transmission filter.

Driving Habits are conservative in my opinion,I accelerate so that the engine won't exceed 2300 RPM(mind you, it is automatic) and I maintain 65 on the freeways. The only situation where I do get on it is when i'm entering the freeways via short on-ramps or on steep uphills. Focusing on absolute fuel savings may only yield 25 MPG, but I feel like a grandma doing so.

How would I go about tuning the car up further?

[Rebel550]

Welcome to the site.
You may also want to consider the sending unit that turns on the fan. It has a resistive(ohms) value that may be out of its correct range to turn the fan on sooner. I've tested sending units in a pot of boiling water to see when it makes up as the temp rises, then makes up the circut to turn on your fan. Sending units are finicky once they lose their ability to heat up and make a complete circut. They have a funny piece of copper the flexes when warming up and and touches a contact.

[LETZRIDE]

I'm in El Paso, TX so I deal with the heat in the summer, which is where i realized that the car wasn't being cooled off enough. As far as I know, the problem with the fans lies in the PCM, with the car throwing the P1651 code permanently. I ran power to both fans, and they work fine, they spin up freely.

Since getting the car in the summer, I've changed the oil, coolant, plugs (seriously a PITA isn't it?), Down stream O2 sensor, wheel balancing, and air filter. I also replaced the TPS to fix a very high idle in the cold weather and the next things on my list are diff oil, ATF change and the transmission filter.

Driving Habits are conservative in my opinion,I accelerate so that the engine won't exceed 2300 RPM(mind you, it is automatic) and I maintain 65 on the freeways. The only situation where I do get on it is when i'm entering the freeways via short on-ramps or on steep uphills. Focusing on absolute fuel savings may only yield 25 MPG, but I feel like a grandma doing so.

How would I go about tuning the car up further?

How did you determine it was PCM related? Other than running power directly to both fans to verify the fans were good - did you test the relays / fuses? They have been known to go bad and I would suspect a relay or short in the wiring far before the PCM - the PCM doesn't typically go bad in these cars.

As far as a tune up goes - do the air filter as well. I would also suggest sea foaming the car to clean the TB and intake out. You can even dive into cleaning out the IAC as that can contribute to your idle issues. You can also take this one with a grain of salt as I am an Amsoil dealer - however, I ran a bottle of this before an oil change in my beater neon I had for about 2 years that ran like total crap because it was neglected (but I bought it for $350 when I blew my 3.8L motor and it could get me around). Amsoil Oil Engine Flush - My neon ran noticeably better afterwards - it was still a piece of crap though lol. But it actually gave me enough power to chirp the tires where as before I couldn't accelerate faster than a bus. I plan on running it in my 2008 Colorado this summer as well as I don't think the previous owner had the best of maintenance on mine and I'd like to get about 25mpg on my truck (about 21-22 now). I am not saying it works for every vehicle or to expect magic especially if a vehicle was well maintained- but I personally noticed a difference on my neglected neon.

Also - why did you only replace the downstream o2 sensor? Was it lazy or were you getting a code? Typically it is recommended you do all O2's at the same time.

And yes - the spark plugs were a pain - but with headers and my back passenger side engine bracket removed I could do them in about 45 minutes with a beer!

[Rebel550]

Yeah Amsoil works and the synthetic oil smoothed out the idle on my 06' Mustang GT

[Migo54]

Alright, the both of you gave good leads to further the investigation on the fan problem, so thanks for that. Though would the sending unit be the one for the coolant temperature?

The o2 sensor was replaced because of a code that I was getting with my scanner, and to see if fuel economy could potentially go up, though I guess I should finish replacing them like you suggested. Getting to the fuel economy, would resetting the PCM's learned fuel maps and what not allow the car to tune itself internally?

As for the PCM diagnosis, the scanner would throw a code that says something about a controlled relay, however, the car's relays and fuses seem to be fine. The code I mentioned earlier is the one that pertains to the fan issue, though I probably just read the info wrong and blamed the PCM. I remember seeing a relay outside of the fuse box that was wired up with the circuit always turning on a fan indefinitely until the car was shut off, though I disconnected the ground from that relay because the car isn't supposed to have the fan constantly running.

[Rebel550]

Alright, the both of you gave good leads to further the investigation on the fan problem, so thanks for that. Though would the sending unit be the one for the coolant temperature?

The o2 sensor was replaced because of a code that I was getting with my scanner, and to see if fuel economy could potentially go up, though I guess I should finish replacing them like you suggested. Getting to the fuel economy, would resetting the PCM's learned fuel maps and what not allow the car to tune itself internally?

As for the PCM diagnosis, the scanner would throw a code that says something about a controlled relay, however, the car's relays and fuses seem to be fine. The code I mentioned earlier is the one that pertains to the fan issue, though I probably just read the info wrong and blamed the PCM. I remember seeing a relay outside of the fuse box that was wired up with the circuit always turning on a fan indefinitely until the car was shut off, though I disconnected the ground from that relay because the car isn't supposed to have the fan constantly running.

The sending unit that installs on the radiator is what makes the fan work...that is if the fan is ok which it sounds like the fan is good because it eventually turns on.
Those codes that come up from what I have learned dictate so many faults that lets say after 50 faults the check engine light will come on. Also the sensor may not have enough current running through the circut and fail to work, I have a Snap-on scanner that shows not only what sensor it is but the actual current flow through each particular sensor it reads. It can pin-point codes and make the problem an easy fix.
I forgot to mention that you have a nice Firebird there...that's next on my bucket list.
(I'm not a know-it-all but I install,service and repair elevators and I have a couple of solid state electronics degrees,(37 years out in the field and I'm happy to help trouble shoot issues with anyone.)

[Migo54]

The sending unit that installs on the radiator is what makes the fan work...that is if the fan is ok which it sounds like the fan is good because it eventually turns on.
I forgot to mention that you have a nice Firebird there...thats next on my bucket list.

I'll take a look around and see what's what with the sending unit. Thanks for the info

[LETZRIDE]

The sending unit that installs on the radiator is what makes the fan work...that is if the fan is ok which it sounds like the fan is good because it eventually turns on.
Those codes that come up from what I have learned dictate so many faults that lets say after 50 faults the check engine light will come on. Also the sensor may not have enough current running through the circut and fail to work, I have a Snap-on scanner that shows not only what sensor it is but the actual current flow through each particular sensor it reads. It can pin-point codes and make the problem an easy fix.
I forgot to mention that you have a nice Firebird there...that's next on my bucket list.
(I'm not a know-it-all but I install,service and repair elevators and I have a couple of solid state electronics degrees,(37 years out in the field and I'm happy to help trouble shoot issues with anyone.)

I believe the 3.8 fans turn on an off as a result from the input of the ECT sensor located on the front of the lower intake manifold and the numbers it feeds the pcm. I don't remember any sending units being on / in the radiator on these cars.

Make sure that temp gauge is reading correctly.

Did you say the car is overheating any? I can't remember the stock temp the second fan is set at to turn on.

I remember seeing a relay outside of the fuse box that was wired up with the circuit always turning on a fan indefinitely until the car was shut off, though I disconnected the ground from that relay because the car isn't supposed to have the fan constantly running.

Can you explain this a little bit more? Or snap a photo? How long were the fans running after the car was shut off? There is a countdown timer that once the car hits a certain temperature the fans will run for a period of time after being shut off.

On first read it sounds to me like someone has jumped the relay to provide constant power to your fans at all times which is likely where your problem is. Reconnecting the wires back to factory and swapping out your relay will likely solve the issue if they were jumping constant power and bypassing the relay.

[FirebirdGT]

I believe the 3.8 fans turn on an off as a result from the input of the ECT sensor located on the front of the lower intake manifold and the numbers it feeds the pcm. I don't remember any sending units being on / in the radiator on these cars.

Yes - everything runs through the PCM.

There is a countdown timer that once the car hits a certain temperature the fans will run for a period of time after being shut off.

Not on a 96 PCM.

On first read it sounds to me like someone has jumped the relay to provide constant power to your fans at all times which is likely where your problem is. Reconnecting the wires back to factory and swapping out your relay will likely solve the issue if they were jumping constant power and bypassing the relay.

Sure sounds like someone hacked the fan controls.

[Migo54]

Both of you hit the nail on the head; there is a relay that was wired up and hidden between the air filter box and the fuse/ relay box in the engine bay. I wanted to follow the wiring to see how it was connected, though it was hidden into the wiring harness that happens to pass through there. There is a ground wire that completes the circuit to turn on a fan as soon as the ignition key is turned to the "on" position, and this fan wont turn off until the ignition is turned off itself.

For about half a semester of school, I disconnected that ground wire to experiment with the temperatures as I drive, and just by simply idling the car for too long I experience temperatures up to 235 degrees, where a fan would finally turn on and cool the car 10 degrees reliably. I avoid traffic on purpose and find other routes just to keep air flowing through the car.

Besides digging out the wiring and deleting codes what else can be done to help correct the problem?

[FirebirdGT]

https://www.yearone.com/Product/1982...93#prettyPhoto

[LETZRIDE]

The only way to get it to work like stock would be to trace the wires down to and reconnect things the way they are supposed to be connected. Take a picture of what you got there now and we'll see if it resembles anything currently on the market for adding a fan switch like Robert posted above.

[Migo54]

I'll post pictures of what is on the car soon, then.

As for the manual fan switch, pretty much any solution will work, no? I remember seeing a wiring diagram on shbox.com for manually operating fans. What do you guys make of that?