So I've sort of inherited my dad's E420 (188k and counting) since he now drives a company car (Ford 500 with 80k and a slipping transmission ).

I've been in love with the thing ever since he got it when I was 11. It's the only car in my family that I truly enjoy every day (we have GMC pickup trucks, BMWs, and VWs). There have been absolutely no problems with the thing other than the lifter tick.

Anyway, I've been having a problem with it for some time now. There is a ton of hesitation between about 1300 and 2000rpm that is very noticeable at low speeds. It is so bad I could be flooring it and it just bogs up to about 2.5k and then like a light switch takes off. And during that time I'll start to even experience engine braking if I am going downhill or it upshifts into this rpm zone. It is especially bad with the AC on.

I haven't REALLY been under the hood in a few months, so I can't remember exactly what it was, but I remember some vacuum hose (it was very long, I think went from somewhere near the manifold to the back of the engine, then down. Heck it was probably the crankcase vent hose) was completely torn up. There may have been more hoses like that. Also, the car has never thrown a CEL.

Other than that, maintenance is all up to date. I don't think it is the MAF because the engine accelerates normally up to redline. The only issue is in that 1300-2000 area. I guess the fuel line, filter, and pump can be ruled out too?

My guess is an intake vacuum leak or the fuel pressure regulator (or whatever regulates fuel pressure in this engine). But I'm not sure. If I were on a motorcycle and experienced this (which I have), it would be a miserably rich mixture in that range. That's what it feels like. Definitely not something an intake leak would cause.

Any advice? I'm stumped.

Thanks for any and all responses.

 

hose.

Fix the oil feed tubes.
Both problems fixed.

 

I replaced the hoses and it is still having problems. Any other advice???

I don't think it's the MAF because it runs fine all the way up to redline with no hesitation or cut-off...

 

Oxygen sensors.... did they cause that on mine at 140k and the CEL had not come on. If never replaced, they could easilty cause that. You can buy any 4-wire bosch sensor and cut/splice the wires to reuse the connector (do a search). I would also replace the MAF. If you do it yourself, you are looking at about $400 for all. Ebay is a good place to look.

 

Thanks for your reply. I will have to check with my father (who just gave me the car), as I remember him and his mechanic unsuccessfully trying to fix this problem by switching out O2 sensors. I'll have to ask him.


When a MAF sensor starts to go, doesn't it reveal itself by hesitation and cutoff near the redline? As I understand it, when the platinum wire gets coated with gunk, it underestimates the amount of airflow and doesn't tell the ECU to supply enough of fuel.

I am going to try to clean the MAF before I replace it. What product should I use to do this?

Now, if I end up having to replace it, which "brands" am I safe with purchasing (I'm thinking ebay)? Not looking to dump too much into this car, so if I can safe money on a MAF, that would be great.

Thanks again.