I am trying to find some guidance on a multitude of issues im having with my 92 Firebird. I am having some timing issues and nobody i take it to can seem to figure out what is wrong.
My first issue starts after i do my inital timing. i disconnect the computer lead to the distributer like the book says and set the initial timing to 10 deg. the car will purr like a kitten. i then plug the lead back in and it wil continue to run great as long as i dont turn the car off. When i go to restart the car it runs like comlpete crap if it starts at all. if it does start and i can get the hood up before it dies, i unplug the ECM lead and the car smooths right out and runs great other than using a lot of fuel.
Now i have tried replacing the ECM itself a number of times, making sure its a 7730 from a similar year and engine car, and i have also tried about 7 different MEMCAL/PROM chip sets to no avail. i replaced the computer again this week with one from a 92 Camaro with the same engine and tranny, and the car wouldnt even start. i checked the codes and it popped a 46 which is the VATS but i still had starter power injecter pulse, though the pulse was extreamly weak. i tried swapping the MEMCAL/PROM from a different ECM into the new one and it fired right up.
I have been chasing this problem for two years now and i am at my witts end here. i really need some help and guidance please.

 

When the est is plugged back in does the timing go retarted ?

 

Only after i have shut the car off and then try to restart it.

 

If the timing is going retarted 2 things that will cause this false knock or the distributor pickup coil wires are reversed. With a scanner or tunerpro you can see the knock counts and timing based off static reference.

 

Would a basic OBD 1 scanner be able to tell me this? The last time i tried one it was giving me an unable to communicate with vehicle error. I havent tried one since.

 

Please don't be offended .I don't know what procedure you use but this is mine.Whether this makes any difference I don't know.
Disconnect the EST wire, start car, adjust timing, shut off car , reconnect EST wire.
https://www.thirdgen.org/settingtiming

 

None taken, i actually havent tried it that way. I will try it as soon as i get home from work and see what happens. I have always disconected the EST, started the car, set the timing, plugged the est back in and then shut the car down. Thank you Ron U.S.M.C.
I will post how it goes after i try it.

 

I redid the timing the way you sugested Ron and it is running a lot better, in a sense. It no longer take a quarter tank of gas to go 16 miles like before. lol It does however run really rough when i first start it, but after i give it a little time it smooths out. It also will pop and stutter and miss when i put my foot into it while driving. I'm thinking I might need to pull the distributer and clean it up, it was looking a little rough around the Magnetic Pickup when i had it out and was rebuilding the engine. got to love the corrosive nature of the Pacific North West.
I think i am slowly getting the bugs worked out of this car. My next issue is the Speedometer. It will only register up to about 13 mph and even that is very slow. i have replaced the VSS and tested it with a drill. But it still wont work right. All the rest of my gages work fine so i know it isnt the fuse. I've read multiple post but nothing even close to this isssue, they were all about completly non functioning speedometers. any ideas?

 

Sorry but I just happened to drop in on this thread, but isn't the speedo on our 3.1's driven electrically by the distributor? Could it just be the distributor as a whole (pickup coil, ICM etc) that's failing causing your related problems?

Speed.

 

The vss sends a magnetic pulse signal to the 1227730 ecm . The ecm has a vss buffer internally to send a optical signal to the speedometer and cruise control.

 

Ah, and to a complete newbie tekee like me I'll take it my suggestion was wrong?

Speed.

 

The speedometer has nothing to do with the distributor to function.

 

Exactly Tuned. I knew it went through the ECM, and im sure my speedo problem is somewhere between the ecm and speedo itself. Ive replaved the vss and it did nothing along with multiple ecm's. The speedo isnt completely dead, it will register up to about 13 mph. So im not sure exactly where the issue is. Im going to pull the dash apart this weekend and see what i can find, if anything.
As for the distributor, i just pulled it and cleaned it all up. The rust was bad inside and i found the ciol point in the cap was stuck fully compressed and not making good contact with the rotor so i replaced the cap and rotor. I also found the prongs on the ignition module were rusted too so i cleaned them all up and put it back together. I also found the magnetic pickup rotor was making contact with a couple of the solid points so i adjusted that too. Just gave the car a quick test run and its running much better. It still sputters some, but nothing like it was doing before. Im thinking new plugs and wires should help there. Just have to wait till payday for them.

 

The easiest way is to see what the ecm is seeing bye using a scanner or tuner pro.
If the input is good the most common problem is the speedometer it self but check the IIRC brown wire that feeds the speedometer for a solid connection.

 

I will check the connection this weekend when I pull the dash apart. I would like to check and see things with a scanner or Tuner Pro but i dont have one or know anyont that does. Im sure it is something brtween the ECM and speedometer since the issue hasnt changed after 4 or 5 ECM changes. I am pretty decent at the mechanical side of things with cars but not so good when it comes to the electronics side of thing. Guess thats why im a Metalsmith and not an Electrition. Thanks again Tuned, i am forever greatfull for the help.

 

Pin B11 of your ecm a brown wire is the speedometer signal to the gauge.
https://www.thirdgen.org/forums/inte...eeds-help.html

 

Thanks again. I have that written down so I wont forget it. I will start by checking the resistance of the wire between the ECM and speedometer to see if there is a break in it or a possable short. If it checkes good then it im guessing the Speedometer itself is bad. I'll know more this weekend. Thanks and i'll update here with my findings.