Power cold No power when warm
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Junior User
Joined: Mar 2003
Posts: 85
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From: Lake Stevens, WA
Power cold No power when warm
I have a 1990 Bronco XLT W/5.0 302 engine. Low mileage. When the engine is cold It has all kinds of get up and go but when it gets up to running temp it is like I am dragging something behind it.. It also runs high RPMs when First started cold for a few seonds like normal then when it drops down it dies. then I restart it does it 2 to 3 times unless i press the gas a couple of times. When it is warm and I start it it rpms run between 800 and 1300 a couple of times before it steadys out.
Any help would be greatly appeciated Thanks
Any help would be greatly appeciated Thanks
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Power cold No power when warm
Pull the codes and test the indicated systems according to the instructions in the Haynes manual, using a multimeter.
Junior User
Joined: May 2003
Posts: 56
Likes: 2
From: Katy, TX
Power cold No power when warm
See my post "Poor Acceleration and Backfiring Solved". I have a 90 Bronco XLT also. My symptoms were very similar to yours. Timing had to be reduced from 10 BTDC spec to about 6-8 BTDC to cure acceleration and improved starting. Basically, it drives like a new engine.
There are other things besides timing that might cause your symptoms. Once the engine shifts to closed loop engine control, a bad sensor (there are lots of them) could be causing the system to operate incorrectly. However, the EECIV should trip a code on a sensor that is out of limits.
good luck
There are other things besides timing that might cause your symptoms. Once the engine shifts to closed loop engine control, a bad sensor (there are lots of them) could be causing the system to operate incorrectly. However, the EECIV should trip a code on a sensor that is out of limits.
good luck
Junior User
Joined: May 2003
Posts: 56
Likes: 2
From: Katy, TX
Power cold No power when warm
I checked the timing chain for looseness, and it met the spec in my Haynes, no more than 5 degrees before the distributor rotor begins to move when reversing the motor rotation.
How would an engine run if timing has jumper a link or someone set the timing chain off by one link?
It's puzzling why retarding the timing cured my problems. I'm guessing perhaps a non-standard camshaft, timing mark error (I'm assuming the end of the fixed marker is the reference point for the moving timing position on the harmonic balancer), or the harmonic balancer is installed incorrectly (impossible I think). I don't know history of vehicle at all. Son and wife purchased against my recommendation.
The engine had a tendency to overheat before timing was retarded, and would become impossible to start until allowed to cool. These symptoms are consistent w/ timing too advanced, but timing setting was spot on 10 BTDC.
Since it's running OK, I'm not inclined to start tearing into the engine just to satisfy my curiosity.
If I have to replace the water pump, I may dig into the timing chain, otherwise it'll have to wait.
Regards
How would an engine run if timing has jumper a link or someone set the timing chain off by one link?
It's puzzling why retarding the timing cured my problems. I'm guessing perhaps a non-standard camshaft, timing mark error (I'm assuming the end of the fixed marker is the reference point for the moving timing position on the harmonic balancer), or the harmonic balancer is installed incorrectly (impossible I think). I don't know history of vehicle at all. Son and wife purchased against my recommendation.
The engine had a tendency to overheat before timing was retarded, and would become impossible to start until allowed to cool. These symptoms are consistent w/ timing too advanced, but timing setting was spot on 10 BTDC.
Since it's running OK, I'm not inclined to start tearing into the engine just to satisfy my curiosity.
If I have to replace the water pump, I may dig into the timing chain, otherwise it'll have to wait.
Regards
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Junior User
Joined: Mar 2003
Posts: 85
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From: Lake Stevens, WA
Power cold No power when warm
Thanks Texas Bronco for the Info. I will get that codes pulled agian to see if anything comes up this time. The Engine is on a Rebuild so it is very possible that the timing is off a little. I have not notice any Backfires but it is starting to hesitate a little before it goes. I put new plugs wires all that stuff in to it a couple of weeks ago and nothing changed. Thanks again for the info everyone.
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