Hesitation when first driving car between 1500 and 2000 rpms.

[alcgraham]

I have a 2004 expy with 250,000 miles on it. Last week it started hesitating when accelerating then stopped then a few days ago it started idling really hard and was also hesitating but would stop after driving for awhile. We put some fuel injector cleaner in it but and then decided we should replace the fuel filter as it has never been done. We did that two days ago. The hard idle is gone but it does still hesitate a bit when first driving it between 1500 and 2000 rpms. I have purchased some fuel system cleaner to try as it seems fine beyond that. Any other suggestions?

 

[whtbronco]

Sounds to me like it's either misfiring, has low fuel pressure or maybe still has dirty injectors. A scanner will show if it's misfiring. A fuel pressure test kit will show you what the fuel pressure is. Fuel pressure should be 55psi.

I'm also wondering since the fuel filter had never been replaced, maybe it needs new spark plugs, a new air filter, cleaning the intake and checking for any vacuum leaks.

 

[alcgraham]

Thanks for the ideas. My husband changed the spark plugs 50,000 miles ago as well as the air filter. I am thinking the injectors may be still clogged too as we had to keep adding gas as we were traveling so the bottle of cleaner got diluted.

 

[whtbronco]

I use Motorcraft SP-479 plugs in mine and they are pretty much worn out at 50-60k miles. If the air filter hasn't been replaced in 50k miles it's due, I replace mine annually and sometimes twice a year if it's been in dusty environments. I also clean the MAF sensor annually when I change the air filter since it's located in the air filter housing. CRC makes a MAF sensor cleaner that works very well.

My experience has been that only 2 fuel system cleaners work, Amsoil PI and Chevron Techron Complete Fuel System. You should be able to find the Chevron one locally so something to consider. I use 2 bottles of Amsoil PI in a single tank once a year and run that tank down low, at least below 1/4. I'm sure there are other products that work and some I have never tried, I typically find something I like and stick with it though.

 

[Hamfisted]

Yeah, like bronco said, check the fuel rail pressure. If it's the original fuel pump it's probably getting tired.


2004 Expedition Fuel Pumps at Rock Auto




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[alcgraham]

We just replaced the fuel pump a few days ago. I am planning to run some Royal Purple MaxClean fuel system cleaner through it with the next fill up

 

[Hamfisted]

We just replaced the fuel pump a few days ago. I am planning to run some Royal Purple MaxClean fuel system cleaner through it with the next fill up

Oh ok. I didn't see that in your post. Do you have a scanner that will read live data ? What are your long and short term fuel trims ? Combined they should be less than 10% on each bank.






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[alcgraham]

I don't have a scanner.

 

[whtbronco]

The fuel system cleaner is a good idea along with considering the maintenance items I mentioned. As Hamfisted noted, I suspect you're gonna need some data to figure out the issue and a scanner is pretty much the only way to get it.

FORScan.org offers a scanner program that will provide lots of data and runs on a Windows laptop or a cell phone. Either will need an ODBII adapter, there's a few options on the FORScan Products page. A good scanner is an invaluable resource.

 

[alcgraham]

Thanks for the tips. I really appreciate it!! We are going to start with the cleaner then go from there. I will check out the scanners as well.