2002 V8 - thumping/hesitation problem

[jia]

I'm experiencing a hard "thumping"/hesitation when under hard (full throttle)and moderate acceleration. The problem is most noticeable when
the acceleration is from a stop or a slow speed. The feeling is like the transmission is slipping or the engine is missing - I don't think the cause of the problem is either one of those - that's just what it feels like. I've been to two different Ford dealerships (both easily experienced my problem) - one wanted to replace the transaxle; the other gave me some story about it being the locking hubs and it was normal for the 2002 V8 and it's 4X system. Since the vehicle is under still under warranty I'll get it resolved one way or the other but I was just wondering if anyone else with a 2002 V8 is experiencing this problem or anyone else has any experience with this particular problem or advice.
Thanks - jia

 

[Robert]

Well it's not your locking hubs since you don't have any. Your front wheels have a permanent connection to your front differential through your CV joints. There aren't any locking hubs involved. Maybe the dealer meant it was your Control Trac kicking in and out under hard acceleration? I doubt that is the case though since the Control Trac was revised to accomidate the 4.6L. I would hope Ford took into account the increased horsepower over the V6s. Does yours have Control Trac 4WD or AWD? It looks like yours has the Control Trac 4WD. If it does go to a straight road and put it in High. Take off briskly and see if the problem is still there. Don't make any turns on the pavement though when you are locked in High. If the problem is gone when you are in High then it is the Control Trac kickin in and out as it detects the rear wheels slipping. If the problem is still there then it is probably in the drivetrain.

 

[jia]

Robert,
Thanks for the reply. Yes, you are correct I have
a Control Trac vs. AWD. Believe it or not I've actually done what you suggested and did not experience the problem. So, I suspect the problem
is with the Control Trac system - at least I hope
it is. I can't imagine that Ford would engineer the V8/Control Trac to work that way. It
really has become a safety concern for me because I have no confidence in the vehicle that when I need rapid, smooth acceleration I will get it.
Thanks Again,
jia

 

[4.0SOHC]

I have an 02 with the V6. Control Trac. system. and it thumps alittle when I get on it, but mostly when I am turning or on a loose surface. Nothing bad. but I don't have a lose on power or anything, and the engine noise is the same as it normally.
I can't say that I am a big fan of the Control Trac. I wish it was 2wd until I wanted 4wd.

I say take it in.

 

[Robert]

I wonder what Ford has done to the Control Trac that makes people hate it so much since my '97 was built? Ford even dropped the Auto mode from the '01 Sports (maybe it was '02). I love the way mine works. I get no pulsing at all under hard acceleration regardless of surface. I have had my Control Trac disabled off and on for the last couple of months while I run some mileage comparisons. Just last week I was pulling out of my companies parking lot when there was a small amount of water running down the 12" wide gutter. I took off a little too quickly while my Control Trac was disabled and did a very squirly power slide. I had the same conditions yesterday except my Control Trac is re-enabled and it was just instant acceleration. It felt like the rear tires slipped for just an instant and then I felt the steering tighten up as the front tires started pulling. My Explorer stayed totally stable without any hint of pulsing or hesitation. I have also driven in up to 12" of snow while in Auto and was completely impressed with the way it handled it. I could tell the rear tires slipped a bit every time I took off but once it did it felt like I immediately switched it into 4WD and stayed completely stable. When I switched it to High the initial slipping went away but I felt the pull of the front tires a lot more once at speed. I don't chance the Auto mode in deep sand though. I switch it into High as soon as I get in the sand.

Ford did issue a Technical Service Bulletin back in '98 for the Control Trac engaging too easily. The fix required a software update to the general electronics module (GEM). Maybe Ford is due for one again?