problems holding freeway speeds

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Feb 7, 2007 | 06:08 PM

hans99

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Joined: Feb 2004

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From: N.E. Ohio

problems holding freeway speeds

I have a 90 bronco with the aod and a 302, 3.55 gears and 31" tires. The engine has been just been tuned up. While on the freeway it wont hold speed, I can be going 65 and it seems to slowly drop speed I have to kick it down a gear and speed back up and the same thing happens again. I am at a loss on this one, I have two ideas but I am not sure where I should start looking. Do I focus on the trans. or do I go more to the engine??

Any help would be a huge help.

Feb 7, 2007 | 06:52 PM

8996EBBroncos

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From: Eastern, NC

I had the same problem. I advanced my timing a little and that did the trick. It might help you, but obviously you may have other issues.

Feb 7, 2007 | 07:40 PM

b4hntn

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From: Longview, TX

If you have a lot of miles on the timing chain, say 150,000+, then the cam may be late which causes the valves to be late. The pistons and spark may have come and gone before the fuel mixture gets there. If the shop set the timing per specs and the timing chain is worn you may try drive timing until you get a little knock then backing off just a little until there is no knock. Also, how about the fuel filter, and did he install copper plugs which seems to be the favorite?

Feb 8, 2007 | 09:39 AM

scurbiedog

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From: B.F.E.

Is it a standard? My 82 did the exact same thing and it was the clutch.

Feb 8, 2007 | 03:06 PM

hans99

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From: N.E. Ohio

When I tuned it up I installed autolite 25 plugs gapped to factory specs. a new cap and rotor plug wires and pcv valve and the fuel filter. I did not adjust the timing, I dont have a timing light, my next step is to advance the timing a bit and see if that helps. What I was wondering if the trans could be slipping or if it might be a sign or my torque converter going bad, I have heard that the aod converters had a history of slipping on the lock up portion

Feb 9, 2007 | 10:36 AM

Kemicalburns

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Joined: Jul 2002

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From: Bend,OR

service the tranny an see if that helps. install an aftermarket cooler and remote filter, get a timing light and bump the timing to 12*btdc with spout connector removed.

Feb 9, 2007 | 02:40 PM

hans99

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Joined: Feb 2004

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From: N.E. Ohio

Here is the latest I have checked the timing (with the spout connector removed)and it is dead on 12* btdc. The timing mark dosent move around too much this leads me to believe that the timing chain and gears are in good shape. The trans fluid is full and looks to be decent, no burnt smell. Thanks to all the have commented the help has been great.
I guess that I will have to dig deeper to find the problem I will keep you updated