In the course of a week my car went from running great to running really crappy. I checked the timing and to my suprise it was retarded like 20 degrees at idle (distributor was down tight and did not move) So I set the timing back to stock specs. The car ran great for a week again and yesterday same thing. Car began to run really crappy and timing is way off, what gives. I'm thinking about taking the chip out and putting the stock one back in and look for trouble codes, any thoughts (aftermarket chip advances timing to 12 degrees)? Thanks

 

What condition is the knock sensor in? If it's failing (detecting knock that really isn't occuring) it will do its job, which is to retard timing in conjuntion with the rest of the ESC system.

If it were an actual component of the engine, such as the distributor gear, camshaft gear, or the timing setup, the timing retard would be almost instantanous from a start up.

 

I have to say that more than likely the distributor is bad. The piece under the rotor that spins to send the signal to the module will come loose and may shift its position. It will not spin freely.

Take the distributor out and remove the rotor until you get to the little metal thingy(looks like a star if I remember), it will prolly be corroded or rusty. Grab ahold of it and try to turn the distributor gear. It will probably move and you will know you need a distributor.

I know this because my dad's 1990 454SS Truck had the same problem and that is what we found. His truck only had 20k miles on it at the time. It did exactly as you described, the timing was off -10 degrees, we set it and by the end of the week it was off again and running like crap. Lucky for him I had an 89 305 tpi engine lying around and the distributor is the same part number.

Good luck.

 

are you using the correct proceedure when checking it?

 

Thanks for the replies, you were right fastz28, I checked that star piece under the rotor, tapped it with a screwdriver and it spun. I cleaned it up and epoxy'd it for a temporary fix, but it looks like a new distibutor will be in order. Laters

 

nice find.

 

I've never seen it personally, but another member reported the same thing a few weeks back.

 

Ok- i have got my engine in and all the tpi stuff hooked up,
itsa 358ci sb with vortec heads, 9.75:1 compression ratio, forged flat top pistons, forged rods, balacned rotating assembly, high flow baseplate& runners, Ported & polished plenum, stock TP 24# LT1 injectors. Shortty hedders 1 3/4 primarys 2.5" collectors.

ok- I have not had my Eprom reprogramed yet, so i was wondering if that might be ther problem right off the bat, but here is what happens.

The engine has to crank and crank and crank, probably added up to 3 mins of cranking. ( not strait cranking of course but about 7second intervals) and rotating the distributor

The timing changes from start to start.

Finally she will start up but run like crap and then when it warms up it will idle on its own but at about 1300 rpm's and surge to 1500 rpms. Then it will settle down and idle at about 750 but then she will surge and die again.
Whats wrong there?

Also- My fan only turns on when engine starts, and shuts off when the engine dies, Isnt it supposed to turn on when it reaches a certain temperature, and the computer shut it off at a certain temperature? It would turn on around 180 or 185 before..

Thanks for all your help!!

Please move this post to the proper board if this is not it.
Thanks.

Should i look for the same?