Anyone know why my computer is advancing my timing to 16 degrees btdc at idle? And will it hurt my newly rebuilt motor to drive it like that. Its not pinging and it runs real strong. Could it be because i put in a bigger cam? The label under the hood says its suposed to be at 6 degrees btdc at idle. Any suggestions will help a lot.

Was the EST circuit unplugged when you checked?

Yea it was unpluged and i set it at 6 degrees btdc. thats what the label under the hood calls for. When I pluged it back in and cleared the code the est advances it to 16 degrees. Is that normal. Sounds a bit high but i dont know about these computer controlled cars. Also how does the computer control the idle? does it use the timing curve to maintain the idle cuz it is idling at around 1100 rpms. I know the throttle position sensor has somthing to do with it but it seems like the idle goes up and down with the timing.

Depending on what type of cam you put in, the computer could be advancing, thinking the car needs it to keep running. Idle is controlled by the IAC. With the idle at 1100, sounds like you may have a vacuum leak somewhere.

Well it sounds likes everything is just fine man. idk wut kind of cam your running to be able determine wut idle it desires but from the rest of the specs, you got it dead on!!

Sorry if I'm beating a dead horse, but with the EST disconnected you set it at 6* correct and then connected the EST and now you checked with the EST connected and it's 16*?

That's normal. I rememeber checking my timing awhile back and I was like WTF??!! when i saw that amount of timing advance, then I forgot the EST was Connected. So I disconnected it and voila, 8* where I set it.

Again, it's normal, or both our cars are freaks and run perfectly fine with that much advance on pump gas.

Thanks alot for the info guys. This helps alot cuz now I know im in the right neighborhood for my timing. This car runs crazy fast and I havnt realy got on it yet. Still have to put a few more miles on it til its broken in. I have a t-5 tranny and took out the 305 and put in a 350 from a 91 t\a. The cam I put in is 459 lift 210 duration @ .050 and 112 lobe seperation. I keep getting two codes popping up they are 34 and 42. 34 is for the mass air flow sensor and 42 in for the est. I think its cuz of the motor swap. Im taking it to a computor shop to have the chip programed for the 350. Its running realy rich cuz I used the 22lb injectors and the computer thinks it still has the 19lb injectors from the 305. It might be even faster when its done. Ill post again and let you know what happens.

Do you have the 305 prom in the comp? You might try swapping it to a 350 prom, may like the injectors and cam better, unless you are having it tuned right away.

Well I went to the computer shop and they said that they cant reprogram my computer cuz it is a read only eprom. I have to buy a custom chip. My problem now is that i am using the knock sensor for the 350 and my computer is getting different volt readings from it. After driving for awhile the est shuts down and my timing goes back to base timing and dosnt advance. It backfires and runs bad. Im going to try using the knock sensor from the 305 that went with my computer. Im hoping it will read correct volts and work the way its supposed to. it always throws codes 34 and 42 then shuts down the est. Im now thinking its cuz of the different knock sensor. This is bumming me out cuz when it is running right its awsome. On top of everything im moving back east to Pa. and Im afraid its gonna kill my new motor driving it back there if the timing is bad. Supposed to be leaving Wed. morning the 28th. Im putting the 305 knock sensor in in the morning. Ill post again and see what happens. Looking for any suggestions at this point.

Yea the knock sensor have a different part number. That might be the cause. If you are looking for a chip, this looks like a pretty damn good deal to me right here and is for your exact vehicle.

http://www.thirdgen.org/techboard/mi...chip-87-a.html (FS: ADS Superchip for '87, 5.7 TPI)

Ok, I went to get a smog check and found out that the car was not running rich like I thought. It was running super lean. The smog tech said that I must have masive vacume leaks. He was right. I found leaks from some hoses and intake manifold. Fixed them and code 34 does not come up anymore for the mass airflow. Now the only code comming up is 42 for the est. Book says to replace the ignition module and so im going to the parts store to get a new one.

Make sure you check all the connections in your distributor. BTW, did you reset the codes and get them to come back after you set the timing? 42 may be in there from when you set the timing. I would do this first and see how it goes.