150k miles on her. No engine light. When giving 2/3 or more throttle, the van has spurts of hesitation that seem to only occur in the low to mid rpm range. It is somewhat subtle (no real jostling or bucking) but it is more noticeable when going uphill. Happens most but not every time. Otherwise the van starts, idles and cruises great. Already replaced fuel pump, fuel filter, air filter, spark plugs and wires, changed trans fluid and engine oil, new egr valve, new battery. Just ran a bottle of techron too. Dont really want to keep throwing money at it but should I change coil packs next?

 

Which E Series?
You can have a couple dozen of DTCs without triggering a CEL.
When you say hesitation the engine ever stalled or not and were you able to restart it right up, a bad MAF is highly a possible cause, never underestimate the importance of "air" related.
You said "low to mid rpm range", how can you tell? You have a tachometer? At what mph and rpm?

 

It is an E150 Conversion. I hooked up a code reader and there were no pending or current codes. Engine has never stalled and never refused to start. I can tell that it more mid range rpm by the sound of the engine (no tach) and it feels smooth at higher rpm. Its like a second of hesitation followed by maybe a few split second blips then it will accelerate as normal. It will happen at any speed as long as you are really getting on the throttle.

 

Can you do this,,,,,,,,

Remove air cleaner assy and look at the throttle blades. If they are black and full of carbon, there is a proper way to get rid of some of that carbon.
It can and DOES affect your air intake and a careful cleaning of the blades and throttle body can make a world of difference.
There are some sprays available and without forcing anything,gently clean some of it off.
Let us know how you make out with this, thanks.

 

Pinpoint test index page shown above, Pinpoint-Test-All.pdf attached below.
When you say hesitation, it's usually air related so I randomly picked out just pinpoint DC and HU, easier to go over than the huge pdf.
Among air, fuel and ignition, air has the highest possibility on hesitation, if you can obtain the LTFT value that can narrow things down.

Just run a bottle of techron is useless, you need to deep clean it for the first time, then you run techron every 2 fillups. To deep clean you use Berryman 2611. Then you can run Berryman 2616 and use Berryman 0116 just like Techron. You are highly urged to run 2611 first, whether or not you have very high LTFT, a sign of vacuum leak.

 

I cleaned the maf sensor and intake temp sensor, and replaced both ignition coils and symptoms are still the same. I unplugged the MAF sensor and when starting it acts like it will die for a second and then it idles fine. When I give it any throttle whatsoever or even if I just put it in drive, the engine will immediately stall out. I replaced spark plugs and wires with NGK brand a few years ago. I was reading these engines prefer motorcraft so I will change them again.

 

Just out of curiosity, when was the fuel filter last replaced ?

 

I changed both the fuel filter (motorcraft) and pump (felphi) less than a month ago. Going to pop off the doghouse and take a look at all vacuum lines, egr, evap purge, dpfe, and throttle body.

 

To anyone reading this in the future, check your plug wires and spark plugs. The boots of the aftermarket wires had dielectric grease pre applied and it made a barrier on one of the spark plugs causing it to arc. Replaced all plugs and wires with genuine motorcraft and she runs great now.

 

The purpose of the dielectric grease is to prevent moisture from getting between the metal terminal at the end of the wire and the top of the spark plug. What is usually the cause for a poor connection there is ,, the person installing the boot did not push the wire terminal all the way down on to the spark plug..
If you don't feel the click of the terminal going on to the spark plug, IT IS NOT ALL THE WAY ON !