Bog/hesitation on hard acceleration

[RichardH]

Howdy:

I have a '01 4.6 2wd with about 186k miles. Everything is running well except for this stumble/hesitation on hard acceleration. If I accelerate 'normally' no problem. Only apparently on WOT it hesitates hard then it goes. I have no check engine light on. Although recently I have replaced the PCV valve and the hose, air filter. No other under-the hood maintenace.

I did have the CEL for the leaking PCV hose, but again after replacing the hose and valve then clearing the code no CEL.

Any assistance will be appreciated.

Cheers,
Rich

 

[AbbadonTD]

Check your Throttle cable to see its tight. It could be that and it takes about 5 seconds to check. Pop your hood and see if the cable has any give. Your "stumble" may just be the moment longer it takes for your throttle to open when you push down.

 

[Bedrck47]

Have you ever cleaned the exhaust ports thru the throttle body??

 

[RichardH]

Thanks for both recommendations. I will look at both and let you know. It feels like it is starting to accelerate then bogs, then takes off. It almost seems like a fuel delivery issue but then as I mentioned no check engine light is on so all parameters are within normal range according to the trucks brain. I'm interested to get to the bottom of it.

 

[Bedrck47]

There is a good video on youtube about cleaning the exhaust ports in the throttle body The 4.6 engine is well known for those to clog up.

 

[docraymund]

Check fuel pressure and repkace fuel filter. Also clean the MAF sensor.

 

[RichardH]

OK, so many hours at work kept me from checking into these until yesterday. Plently of time now since I was just laid off, lol. I have a backup 2nd job I was already in the midst of.

Anyhow, I will look at some of these over the next few days and see what's up. i want to do the fuel filter, clean MAF sensor.

 

[Bedrck47]

Make sure you use the correct cleaner on the MAF sensor

 

[RichardH]

Still chasing the bog down...

But I replaced the PCV hose after seeing the p0171 p0174 code. I started with just the valve replacement, no go. Then ordered a new hose, didn't realize it came with a new valve also. So here is a pic of the hose that caused the codes above. This part of the hose that's cracked is where it connects in the rear (near the firewall). Took like two minutes to snake through and hook up.

Chasing down little gremlins one at a time!

 

[Bedrck47]

http://www.expeditionforum.com/191356-post1.html

 

[RichardH]

Well took too long but cleaned the downstream port of the throttle body (actually both ends). Wish I took a before picture, but here are after pics of it.

 

[RichardH]

I might have found the solution after many months.

I decided to do a little refresh so changed the plugs and all coils. I had three coils go out in the last year which I believe can be caused by excessive gap. Also did a MAF cleaning. Holy gap batman!

I think the culprit on the hesitation was plugs. Here is a sample of one.

 

[docraymund]

Glad you solved the problem! Good job!

 

[Geofisherman]

I might have found the solution after many months.

I decided to do a little refresh so changed the plugs and all coils. I had three coils go out in the last year which I believe can be caused by excessive gap. Also did a MAF cleaning. Holy gap batman!

I think the culprit on the hesitation was plugs. Here is a sample of one.View attachment 22790

 

[Geofisherman]

I had the same issue coils are a common issue and some good spark plugs look like the original ones...

 

[RichardH]

I had the same issue coils are a common issue and some good spark plugs look like the original ones...

Holy cow. You think these plugs are from 2001?? They were never changed??

I should follow my uncle's advise and change ALL fluids and plugs/coils, filters when buying a used car. I need to do the differential fluid after cruising through Hurricane Harvey flood waters a few months ago. I understand there is a breather line on the diff that can let water in and cause problems.

 

[Haggred]

I'm having the same problem with my 03 expo 5.4 I replaced the maf sensor, didn't help. I guess i will try fuel filter. Bogs every time I'm starting off going somewhere.

 

[RichardH]

I'm having the same problem with my 03 expo 5.4 I replaced the maf sensor, didn't help. I guess i will try fuel filter. Bogs every time I'm starting off going somewhere.

I think the plugs did it for me. Maybe do a plug swap. I actually forgot to change the fuel filter.

 

[Haggred]

Plugs are good changed recently

 

[1955moose]

A bog on hesitation usually indicates a lean fuel condition. Make sure you have no exaust or intake leaks. Have your fuel pressure tested, make sure air intake clamps are tight. Also run a simple codes test. Spark plugs could be adding to your problem, but usually cause missing under a load, like climbing a grade. Plugs are a very tough job on these vehicles. I'd probably save that one if your other tests pass.

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