1989 Pontiac Firebird Formula 350

TheRookie · Post by **TheRookie** » Sun Dec 30, 2007 9:55 am

I won't recap most of the thread that preceeds the purchase of this car. If you'd like to see the first set of pics or read the thread, here you go:

http://www.tiresmoke.org/phpBB/viewtopi ... 7&start=45

Basically, this use to be wxo's car, then his neighbor's kid had it for a while. It's been sitting and finally needed a new home. I'm the lucky guy. The funds should be in NC about the time the wxo gets back from a trip and some parts arrive. Next steps are a new battery, drivers door handle, and some hood struts and taking care of the rich condition at idle (old gas?). We'll take it slow and steady until she's roadworthy and some paperwork and plates has been shuffled back and forth.

So I probably spent about 3 hours yesterday on the thirdgen.org site learning and planning a bit. From a mods perspective, the exhaust will probably be the first thing. The popular choice are some hooker headers that have a real nice y pipe included. Some get it ceramic coated. Cat-back is just personal preference on sound and materials. There's lots to choose from.

Any chance wxo that you know what the rear-end gear is on that? Seems a lot of them came with a 2.77 and 3.42 or 3.77 would be a good choice. I'm also going to look around about some nice seat covers or good used seats. BP thinks we should be able to repaint that area of the hatch without having to worry about it being perfect since it's small and not next to original paint.

Well, all of that is just a bunch of speculation. Getting her up and running and here is what counts.

wxo · Post by **wxo** » Thu Jan 03, 2008 6:42 pm

The hood lift supports and driver's door handle arrived today. Not too exciting, but will be real convenient when working on the car. It was a real pain going around to the passenger side to open the driver's door every time I forgot and closed it.
I have confirmed from two sources, but not visually, that this car does not have a cold start injector. Apparently the ECM enriches the mixure by pulsing the injectors longer. So the plan now is to fix the exhaust leak and perform all the tests to check out the injection system. If that checks out OK, I need to get a fuel pressure gauge and verify that the injectors will hold pressure. If not, then I'll probably have to pull the runners and plenum and do something with the injectors. New ones, maybe? Have the old ones cleaned (again)? They were sent out and cleaned some time in the past. I don't remember the mileage.
Another option is to try to clean them by running injection cleaner through the gas tank. Anyone know if a very high concentration of injection cleaner will hurt anything? I'm thinking of adding a bottle to very little gas in the tank and running it for a while. Any thoughts?
In the mean time I have a lot of honey do's to take care of. I better get to 'em.

TheRookie · Post by **TheRookie** » Fri Jan 04, 2008 9:05 am

Well, Lucas states that exceeding the recommended dosage for their stuff isn't harmful. That stuff did great on the Lincoln Town Car.

http://www.lucasoil.com/products/displa ... 2&loc=show

I got the quart bottle so I could do multiple tanks of heavy doses. I was getting about 26 MPG on the freeway with that Lincoln.

I plan on having this car for a while, so I'd rather go with new and/or upgrades on the exhaust and injectors if they really need replaced.

wxo · Post by **wxo** » Fri Jan 04, 2008 9:50 am

I'm thinking about trying the heavy dose of injector cleaner to avoid ripping apart the intake runners, etc. If it doesn't work and I get to the point of removing the injectors, I think it best to replace them all. Then you have removed questionable injectors as a source of problems when you get around to some serious tuning later.
On the other hand, I'm concerned with running the engine for any period of time in this overly rich condition. It could mess up the cats and O2 sensors.
As far as the exhaust goes, there is a leak at a connection point between the cats and cat-back system. I've had problems with it before and I intend only to mess with enough to stop the noise and possible effect the leak may have on the ECM. You can deal with the permanent upgrades later. In addition, the heat shield is rattling and driving me crazy so while I'm in the area, I'll try to fix that.
Again, don't expect too much too soon. I'll get to it as time permits, but I will get it done.

TheRookie · Post by **TheRookie** » Fri Jan 04, 2008 12:32 pm

I'm on your timeline, not mine

Just letting you know from a strategy perspective on upgrades/replacement. Much appreciated and not expected anything more than what it takes to make it roadworthy and so you could work on it and be sane.

MostMint · Post by **MostMint** » Fri Jan 04, 2008 12:32 pm

If the ECM thinks the engine it cold, it could dump gas in like you describe. I speculate that an engine temp sensor has failed or is disconnected. That sure would be easier and cheaper than replacing injectors.

There may be more than one sensor, one for the ECM and one for the gauge, so make sure you get the right one.

There have to be some other f-body owners that have had this issue. Anyone check any message boards/search the internet?

wxo · Post by **wxo** » Fri Jan 04, 2008 2:33 pm

Thanks for the reminder, Andy. I had thought of that earlier and then it slipped my mind. I'll be sure to check that and all the easy stuff before moving on to the complicated stuff. I have already visually checked one of the temp sensors and it seems to be connected. I don't know, yet, if it's working. I'll do a resistance check on it as the engine runs.
I have the correct shop manual for this car. It will help a lot in diagnosing this problem.

MostMint · Post by **MostMint** » Fri Jan 04, 2008 4:21 pm

OK this is really dumb, but is the air intake passage clean? Rodents tend to live in those places on a car that has been sitting.

wxo · Post by **wxo** » Fri Jan 04, 2008 4:36 pm

Already checked that and it's clean. Since we talked last I found the coolant temp sensor for the ECM. It's connected. I still need to test it.

TheRookie · Post by **TheRookie** » Fri Jan 04, 2008 9:22 pm

Ok, here's what a read of the forums state for possibilies outside of a leaking injector, which seems to be most common.

1) General tune-up items (plugs, wires) - popular choice as starting point
2) Along the line of MostMint, the coolant temp sensor (code 15) - try pulling it
3) Blocked exhaust/intake (as already mentioned) or IAT sensor
4) Fuel pressure regulator
5) IAC valve
6) O2 sensor
7) EGR valve

Cleaning of throttle body
9) MAF sensor

#1 seems like something to be done anyway. These are in order of most recommended. #4 may be interesting as it only happens at idle. Are those the stock injectors or perhaps they were upsized too much?

wxo · Post by **wxo** » Fri Jan 04, 2008 9:58 pm

The problem would appear to be idle related, but probably is occurring throughout the rev range. When the throttle is opened, the extra gas is being used and it only seems to go away. The other piece of info that you don't know is that the problem, according to the previous owner, came on by itself during the time in storage. The injectors are stock. They have been professionally cleaned once in the past when I owned the car.

wxo · Post by **wxo** » Sat Jan 05, 2008 4:35 pm

I just finished checking out the coolant temp sensor (for the ECM) and it appears to be working correctly. The resistance gets lower as the temperature rises and it is in the range of values specified in the book. Also the new hood support struts are installed and the driver's door panel is off and I'm getting ready to install the new outside handle. The passenger side handle is probably going bad, too, but it is not used as much as the driver's door so it's not as much of a pain in the butt. I have to leave something for Rookie to work on.

TheRookie · Post by **TheRookie** » Sat Jan 05, 2008 6:23 pm

At breakfast, BP was all in favor of a full tank of fresh gas, some heavy injector cleaner, and a few miles. If you think the injectors are shot, I located a rebuilt set w/ warranty for only $125.

Basement Paul · Post by **Basement Paul** » Sun Jan 06, 2008 10:27 am

I'm not sure how much of the old fuel is in it, but if you haven't already, at least try topping the tank off with fresh gas to mix in with the old. And like was said already, put in a double dose of injector cleaner. I like the Chevron w/ Techron (whatever Techron is), and Matt likes the Lucas stuff. A bottle of dry gas couldn't hurt either.

My '87 Trans Am used to need a dose of injector cleaner about every 5000 miles or so, and it was noticed most at idle and just off idle. The rest of the RPM range would be fine.

-BP

wxo · Post by **wxo** » Sun Jan 06, 2008 4:48 pm

Two problems getting fuel in her. No license plates and insurance plus I'm concerned about messing up the cats and O2 sensors by running it too much with all that blubbering going on and black smoke coming out the back. The gas gauge is close to empty and I already have a container of Techtron in it.
To be honest, based on experience, I have never seen spoiled gas cause symptoms like this. I'm convinced it's too much gas getting in to the motor. In fact I can see where the gas gauge has moved toward empty just with the minimum running in the garage. It's so bad that it burns my eyes if I stay near in there too long. I may get a 2.5 gal can of premium filled and dump it in, but I'm not for going down to the gas station yet.
The previous owner now has Rookie's check and I'm waiting to get the notarized title so that I can ship it North.