4.2 glowing manifolds(not cats)
12-04-2011, 04:04 PM
#1
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4.2 glowing manifolds(not cats)
1997 f150 4.2l (255ci) v6 5 speed 2wd 149xxx timing troubles
The truck slowly became worse over the course of about 300 miles it started with lack of performance in the low end and bad fuel consumption and continued to get worse now it barley idles and feels like it is towing a mountain. If you rev it up it takes along time but does pick up engine speed and runs much better in the high range. after a period of running for 10 or 15 min the exhaust manifolds glow red. The exhaust smells of unburned fuel.
what I have tried to do so far...
. checked for exhaust blockage and replaced cats no luck
. checked ERG with no luck
. played with REF and checked for vac leaks no luck
. checked o2 sensors and MAF replaced one of each no luck
. checked the cam position sensor no evidence of problems
I have had no luck with these steps. next i will try the timing chain/ gears but i don't know if that would make sense for the gradual onset of the symptoms. it also previously tripped engine lights for bad 02 sensor and accelerator position sensor.
The truck slowly became worse over the course of about 300 miles it started with lack of performance in the low end and bad fuel consumption and continued to get worse now it barley idles and feels like it is towing a mountain. If you rev it up it takes along time but does pick up engine speed and runs much better in the high range. after a period of running for 10 or 15 min the exhaust manifolds glow red. The exhaust smells of unburned fuel.
what I have tried to do so far...
. checked for exhaust blockage and replaced cats no luck
. checked ERG with no luck
. played with REF and checked for vac leaks no luck
. checked o2 sensors and MAF replaced one of each no luck
. checked the cam position sensor no evidence of problems
I have had no luck with these steps. next i will try the timing chain/ gears but i don't know if that would make sense for the gradual onset of the symptoms. it also previously tripped engine lights for bad 02 sensor and accelerator position sensor.
12-04-2011, 04:16 PM
#2
I Voted For Bill and Opus
Stop right now. take it to either your local Ford dealer , or a private tune shop with experience. You have a serous problem, If I had a guess I would look at a bad ECM. You can throw expensive parts at it and not fix what is wrong. let an experienced mechanic with the diagnostic equipment take a look at it. You will probably save money in the end. I have been working on my own vehicles for many decades and I recognize when it is time to take it in to somebody that has the equipment to handle a problem.
12-04-2011, 07:33 PM
#5
I Voted For Bill and Opus
If this was in the old days with a points and coil ignition this is a classic example of a set of points that do not open because of wear or have not been tighten down properly. This causes the spark to fire through an open exhaust valve causing super hot exhaust manifolds, and serious engine overheating or if you are lucky back firing through the intake manifold. and at worse blowing the carburetor off the engine. That last is easy to fix the former can cause serious engine damage.
