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Explorer 'bogging Down' Help !!

turnbulltj

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Year, Model & Trim Level
1997 XLT
Please help, can't rev above 3000rpm.

:uk:
Good afternoon Guys. I am new to this forum, but have found some of the readups extremely helpful. I have an 97 4.0 V6 Explorer, which suddenly about 2 weeks ago went from running superb to seriously bogging down and losing power. It runs but will tick over very lumpy and will not rev out over about 3000rpm when stationary. On travel it will increase speed gradually, but will lose power if I floor it. I have read the forum and done the following on the advice of others, but still to no avail.

Changed the MAF Air Sensor
Changed complete exhaust system including Cats.
Changed Oxygen Sensors (Lambda) in exhaust.
Changed Air Filter
Changed Spark Plugs (One of which was serioulsy cracked)

I have also read about resetting the engine whenever you have had a tinker, but do not know how to do this???
The engine also now seems to go from ticking over nice to running as though it has lost a cylinder. In general it has gone from a nice smooth V6 to a gutless problem. I would be most grateful of any help or advice. As you can see I am going through the relatively cheap processes of elimination and am just hoping that it is not something like a timing chain slippage. My gut feel having had a tinker is that it is something small and insignificant, albeit a bugger to diagnose. Please help, all suggestions gratefully received and definitely tried, I just want to get mt beast back on the road. Being a predominantly USA vehicle we have very few experts over here that we can turn to for advice on these monsters. Thanks again. Will keep you posted guys ;)
Trevor
 


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Bwana Bob

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92 XLT
Bogging

I just went through a similar problem.

Could be bad petrol, but I suggest that it is a fuel starvation problem. Check the fuel pressure at the test port on the fuel rail. It should be about 35 psi and rise to about 40 psi under acceleration.

Also, replace the fuel filter. A clogged filter will cause the truck to bog down even under gentle acceleration, even though fuel pressure reads normal at idle. (When I replaced my fuel filter, last weekend, there was an instant improvement, though she is still recovering).

Bob
 




Bwana Bob

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92 XLT
I forgot to mention:

The fuel filter requires a special fuel line disconnect tool. It is the same type of snap-together fitting that is used on the air conditioner plumbing. I believe that the 1/2 inch size is correct. Do not attempt to disconnect the fuel lines without this tool.

Bob
 




BrooklynBay

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Welcome to this forum! Did you do a compression test? You mentioned that one plug was broken. Do you have a smell of the engine being flooded? You could have a bad engine coolant temperature sensor. Check the timing with a timing light. The camshaft or crankshaft position sensors could be out of alignment.
 




rmcknight

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2004 4.6 SOHC v8 Explorer
Right on the money Aerostar man! You need to know if its running rich / lean first!.
As you have just done the plugs, you must ensure you put the leads on right as its easy to confuse 2 of them as it goes 123 465 or something special like that!
If you haven’t replaced the leads you should to those next as they should have been replaced with the plugs anyway. + you should put double platinum's in.
Next you might have a vacuum leak into the TB (after the MAF) or right into the upper intake manifold (this is a very common issue) + a nice little job to fix.
If you do fix that & you have the SOHC - you should also do the front cam tensioner at the same time for about $30.00 (if that hasn’t already been done). the 1997 + 1998 year 4.0s are poorly designed to say the least, possibly deliberately designed to cost you money even!
 




T

ThePhoenix

I forgot to mention:

The fuel filter requires a special fuel line disconnect tool. It is the same type of snap-together fitting that is used on the air conditioner plumbing. I believe that the 1/2 inch size is correct. Do not attempt to disconnect the fuel lines without this tool.

Bob

and its not easy to get off...
 




sahtt57

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Houston, tx
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04 XLT
Based on what you've said, a broken/misaligned timing chain is not likely but possible [same with cam sensors]. I'd start with a compression test, specificially on the cylinder with the broken spark plug. After that, I'd make sure each cylinder is actually firing both on idle and under load [say 3k rpms]. If the rev's will go above 3k, it's not the MAF. Then I'd go back to making sure the timing is all correct.

At that point, move on the the fuel system if you are getting adaquate spark. You can start by testing the ohm's of the injectors resistance, then the fuel pump. My bet is you'll have some progress by then. Look here for checking the fuel system ford explorer fuel problem Also, none of the above should cost you anything besides an ohmeter if you don't have one and some free time. Good luck.
 








mecp_316

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City, State
wichita ks
Year, Model & Trim Level
95 xplorer xlt 4.0 v6
hey curious i have a 95 xlt 4.0L it sputters when started as well sometimes dies an you have to give it couple hrs an fires up fine it throws a check engine light ocassional but not storing any codes took it to 2 shops they used different scanners as well they just say waiting for codes... so dont know where to look at i checkd the idle air valve the resistence reads fine ??
thanx!!
 




chuckar

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1994 XLT
Did the fuel filter solve the problem?

I just went through a similar problem.

Could be bad petrol, but I suggest that it is a fuel starvation problem. Check the fuel pressure at the test port on the fuel rail. It should be about 35 psi and rise to about 40 psi under acceleration.

Also, replace the fuel filter. A clogged filter will cause the truck to bog down even under gentle acceleration, even though fuel pressure reads normal at idle. (When I replaced my fuel filter, last weekend, there was an instant improvement, though she is still recovering).

Bob

Hi B Bob,
Did the fuel filter solve the problem, or did you end up having to replace the fuel pump?

Chuckar
 




turnbulltj

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1997 XLT
Ended up being the inevitable timing. Recon engine with new timing gear and a £1000 quid later and everything is just fine again . Still worth it though.
 




Cobraguy

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DAMN! I was betting on the fuel filter!
 




BrooklynBay

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