Hey guys. I just bought my first third-gen a few weeks ago, and immediately looked for a forum community to get involved with and found you! I've been spending my nights scrolling through the forums learning about these cars, and its been a lot of fun. I didn't anticipate having to post my own question so soon, but sadly, I'm having to do that. Here's the story.

I bought the car two weeks ago in FL. All original, 1992 firebird with the 5.0 TBI. Immaculate inside and out; garage kept by the one and only owner. 42000 original miles.

When I bought it, I test drove it twice, got the carfax, had a mechanic check it out for good measure and was told to buy it. I paid for it, but a tank of premium in it, changed the fluids, and set the trip odometer. Everything was going great... for the first 86 miles.

At 86 miles, the trip ODO stopped working. I noticed it was just stuck. Everything else worked fine, but the ODO and trip ODO were both stuck. I also noticed the fuel gauge never came off of full. I drove it about an hour home that night and decided to deal with it later.

The next day, I got up, and drove errands / around town for about 4 hours. It stalled once, then I noticed the ODO started counting mileage, but in the wrong increments. The "tenth" digit was reading as full miles. (got on the freeway between mile markers to figure this out). So, when it read 2.1 miles, it meant 21 miles. When it read 3.0, it meant 30 miles. ...Very bizarre... It runs fine for a couple hours.

Then, at about 4 in the afternoon, sitting at a stoplight, it stalled out of nowhere. I fired it back up, it ran for 5 or six blocks, then did it again. then it got harder to start... and started to stall at every light as I looked for an appropriate place to pull off the road. Then it wouldn't start at all. I ended up towing it to my mechanic. I jumped online and pulled as much info as I could.

I called him, told him to replicate it and said I thought it was:
1. IAC valve or motor
2. MAP sensor
3. Fuel Pump / Filter
4. EGR or EVAP system
5. Fuel Cap
6. Rotor
7. ECM
8. Vacuum Lines

Anyway, he ends up keeping it 5 days, runs it everyday, takes it to lunch, idles it for 4 hours, tells the secretary to take it to lunch, drives up and down the highway, and never gets the thing to even hiccup. After 5 days, he hands it back to me cause he can't figure it out. No codes, all the sensors read good, vacuum lines are good, fuel pressure good, no codes, and fuel gauge starts working. So, he gives it back to me.

As I'm driving home, the ODO starts working as normal again.

I'm absolutely confounded. I have no idea what to think... What do you guys think it could possibly be? ECM? More than one problem?

 

HMmm , From your description , I wonder if your possibly having wiring harness issues ? ..... Specifically , a connector with corroded pins or maybe a wiring harness slowly cooking on a manifold like mine was ? I had all kinds of weird electrical malfunctions that came and went that turned out to be the wiring harness being fried by an exhaust manifold (I'll try to post a pic) ... The problems were intermittent just like you describe , and all went away with the repaired/repositioned harness ...

Course , could be a number of other things as well , but Wiring would be my #1 suspect here .

PS , was the Speedo reading right while the odometer was flaking out ? Cause if so , since they both run from the same little circuit board , maybe that's a side or secondary problem not involved with the bad running ?

 

Can you pull trouble codes from it? Do a search here for 'paper clip' for details.

As far as the odometer goes, I can't see how that would cause the engine to quit. However, it might mean your car actually has 420,000 'original miles'

 

Thats a scary thought. I wouldn't believe 42000, but just from the condition of the car, I think its probably less than 80000. Anyway, The SES light came on when the car stalled, but I had my mechanic lug his old OBD1 scanner out and there were no codes stored in the system. When I first purchased the car, there was one code in there that he scanned, so I know the thing works...

 

Mike

May have two issues, the way you describe your drive, it sound like you may have a fuel issue. Try getting some "water remover" for the gas tank, Like "Heet" and run for a few miles. Then change your fuel filter. If the vehicles set a long time without a full tank of gas, the tank can rust real bad. I've had them so bad that the filter would need to be changed once a week for about 5 or 6 filters.

On the speedo, pull the gauges out and see if the printed circuit has connection issues. If everything looks good, still clean the connections and add an extra ground to the system.

See if your tech will let you drive the car with his scan tool hooked up. Be sure to cover it up or remove it when your not in the car. I have 2 new scan tools and 2 old ones at my shop, he may have an old one setting around for you to rent for a week or so. If you have never used one, have him show you how to get it to your car. Then make a work sheet. write down all the names on the scan tool face. Leave lots of room to write, and start doing data logging. When it goofs up something will change. post it here or show your mechanic. You'll start seeing the normal data over and over. then when something is wrong you maybe able to spot it. The newer scan tool can also do a snap shot. Like 15 frames before the event and 15 frames after the event, and can be triggered to record by hitting a button when you feel it.

Have fun, get a pair of walking shoes or phone a friend when it breaks down!!

Dave

 

I would have taken that car back and rammed it in his yapper... Can't stand people who sell crap. Wish you luck brother.

 

Thanks for the tips. I like the idea of running some heet through. I ran it all weekend and havnt had a problem with stalling, but now the odometer and trip odometer are completely stopped.

That's terrible that you had that much rust. I'll recheck the fuel filter and run the heet through and five an update. Anyone ever run bg44 in their tank? Some guys swear by it.

In terms of the odometer, I'll have to pull the cluster out and check. My mechanic said te odometer cable runs to the ECM and then te ECM runs the odometer and speedometer on separate circuits. Is that true?

@danceswithdeath: yeah, totally right. I did it wrong though and purchased in in a private sale from the owner of the lot. In hindsight, I guess I see why he did it that way...

 

Well guys, wanted to give you an update. I tried to drive to Texas from Florida, and 200 miles in, the car died on me. Needless to say, I finally got the car here and started working on it trying to resolve the issue.

Interesting finds. I took the air cleaner off today, and low and behold, I found out the coil was completely unbolted from the block and just dangling by the cable that runs to the distributor. What a surprise! I don't know what kind of nutcase last worked on the car, but he completely forgot to bolt down the coil.



Then, I did a fuel filter replacement. This was probably the most interesting thing I found. It looked like pure mud and silt in coming out of the filter. Literally, take a look at the pictures.

 

drop the tank and clean it out really good, making sure to blow the lines out relly good.. also pull the injectors out and clean them up with some carb cleaner..
the speedo/odometer is a separate issue but not something that shouldn't be expected on a 20 year old car.