car starts with 25 BTC timing, but not at 10 BTC timing

[psu1994]

I just picked up a 91 LX Conv 5.0L auto with 80K miles. The car was undriveable so I had it hauled here to my house.

The car definitely sounded like it was out of time when was running, with a miss here and there. Checked the wires, cap, firing order, all of that. Changed the tps and iac, then checked the timing and found out it was running at about 25 BTC. Turned it down to about 12, would barely idle, shut off, and wouldnt start back up.

Took off the Ignition module, had it tested at autozone, said it was bad, put a new one on, same problem. Tested for codes, everything passes.

As far as I know, the car is all original, and hasnt been apart. Dont see any vacuum leaks.

Anyone have any suggestions as to what the problem maybe? Maybe the pickup in the dist?

 

[stang22]

Were you doing all of this with the spout out? With the spout in, you should be between 25 and 30 on the balancer. Did you spin your balancer?

Tim

http://www.leemotorsports.com/stang22/timing2.htm

 

[HISSIN50]

Good questions Tim.

 

[psu1994]

No, I had the spout connector out.

As far as the balancer goes, it looks like a rubber bushing pushing out the back of it. It is possible to spin one, I thought they were keyed?

 

[stang22]

Is it the stock balancer?

Tim

 

[stang22]

Good questions Tim.

Thanks Coach!

Tim

 

[psu1994]

Yeah, its the stock balancer. Atleast it looks original. I went out and compared it to the one on my 87GT. I'm starting to wonder if its a wiring problem.

 

[HISSIN50]

If the elastomer in the balancer is coming out, the outer ring might have slipped, which means your timing marks are no longer accurate. The inner hub is keyed to the crank, but the outer ring is bonded to the inner ring via the elastomer.

Tim - I think not.

 

[stang22]

Tim - I think not.

Just teasin with ya JT, no sweat.

Tim

 

[HISSIN50]

Just teasin with ya JT, no sweat.

Tim

Yeah, my point was that you teach more people than I do.

 

[stang22]

You got me beat all the way around man. I am just learning from the pro's here.

Tim

 

[psu1994]

Thanks Tim, thats something I definitely never would have thought of !


Jerry

 

[oz]

How long has it been sitting? Could the gas be bad? More advance would help a bad gas situation I would think since the gas wouldn't light off as fast (need more time to burn)... just a thought. All the same, I would probably siphon the old gas out and put some fresh in if it's been sitting for more than a few months.

You can probably find TDC by taking the #1 plug out and feeling the piston come up to the top. I would CAREFULLY put the end of a hanger in there and let it rest against the piston and I slowly turned the balancer. You can get it close enough to TDC to know if the timing ring on the balancer has moved.

 

[psu1994]

Just for S and G's, I check the timing again with the spout connector in and the timing didnt move much, its about the same with or without the connector in. Car idles around 1500 rpm. Pulled a vacuum line off the t on the firewall, didnt make any difference in the idle.

Turned the dist in case the balancer spun, trying to smooth it out, wont idle any better.

I'm gonna pin out the TFI to the EEC tomorrow see what I come up with.

Are these BAP ssrs supposed to have a vacuum line? Mines got what looks like a white plastic cap on it.

 

[HISSIN50]

BAP sensor should not have a vac line.

Timing should jump pretty decent (I last did the SN's timing, and as soon as the SPOUT went back in, I gained over 10* base timing).

Good luck.