Slow acceleration, high fuel consumption after spark plug change

Question

I have a 2000 Ford Ranger 4.0 L V6 4x4 model. I recently was having some problems with the truck idling too low when cold and I decided to change the spark plugs. I put in 4 out of the 6 new plugs and things seemed to work fine.

Unfortunately, during the change, I accidentally broke a little vacuum hose that goes to a small black globe towards the front. From what I have heard, this hose just controls things like the vents and such. I put some hose tape on it and drove it to work, planning on getting a replacement that day, and I barely made it there - after 10 minutes there was almost no acceleration, I had to pull over, wait 15-20 minutes, then go. The gas consumption was insane, like 5 miles per gallon.

Immediately after work I replaced the little hose, and now the stop-and-start stuff is gone but the acceleration and fuel consumption are still terrible. I'm going to try and get the code read at AutoZone today, but I don't see a check engine light on so I'm not optimistic it'll tell me what's wrong. Is there something I can do to fix this?

Unfortunately I changed two things - broke the tube and changed the plugs, so I don't know which one exactly caused the problem. From how sluggish it is it feels like maybe a few cylinders aren't firing (I've checked all the plugs, pulled them out and put them back in, tightened them, etc), but I imagine it could also be some problem with a bad fuel mixture. What could cause this? What is my next step?

Thanks.

Update: Forgot to put some pictures in here. This is the hose that broke, with the place of the break indicated:

And here's a picture of where it attaches to this little vacuum globe thing:

Update 2 Since I don't know what caused this I haven't accepted an answer, but for future sufferers I'm going to detail the further symptoms and will update when I find an answer. One problem was that the plugs that Amazon recommended were very much the wrong plugs. I should have been using AGSF-22PP from Motorcraft or equivalent, I was using NGK TR6 - same size and heat rating, but way different gapping, it's a copper plug not a platinum, etc.

I've been trying to triage this so I pulled codes and found 2 cylinders not firing, plus a third spark plug I saw a hairline crack in, so I replaced only those 3 cylinders, plus all the spark plug wires (one of the wires was rusted and useless when I examined them, so I got a new kit). That didn't fix it, but I took apart the throttle body and the MAF - everything looked fine there, but when I put it back together, the truck ran very well for about a week or so. Yesterday I started losing power at the high end, so it seems like whatever the problem is it's coming back. I cleaned the throttle body and MAF again but this did not help the situation.

Answer 1

Reset the ECU. It has learned to work in the conditions of a vacuum leak(busted vacuum line). From experience in working on my family's 01 v6 explorer sport, 91 bronco, and 2001 f150, the vacuum system is all one connected system. So, a broken vacu line can cause an overall vacuum issue. I don't know like with my jeep there is an ECU purge procedure,but generally disconnecting the negative terminal on the battery overnight or at least for a few hours will do the trick to purge the adaptive memory. Jeeps do a 50-warm up cycle learning period, don't know on fords. So, if it fixes your issue, give it a week or so before judging whether your issues are totally resolved or not. If it comes back again, replace all your plugs and wires. Newer fords seem very sensitive to vacuum leaks as my dad's v6 explorer sport was getting less than 10mpg and had poor acceleration as well until I reconnected the hose for the heater core coolant valve which was dry and popping off the fitting.

Answer 2

Have no idea about this particular globe thing... does not look like PCV of any kind... but I'm not sure.

I'd start by double checking the spark plug gaps. Maybe it's so off you are just not burning the fuel. how is the smoke coming out the exhaust?

Then check how much oil is in that hose when you changed. Also, use a flashlight and check the combustion chamber when you take the sparks out. Maybe that hose kept the oil out of the combustion chamber by some pressure change? maybe you combustion chamber is full of oil?

Again, have no idea about that car :) just things I would try if it were me without a manual.

Answer 3

Make sure you gapped your plugs and they are proper heat range

Answer 4

Old thread I see but even so, It sounds like you lost vacuum to your fuel pressure regulator. Remember, the fuel pressure regulator reduces pressure to the injectors, and its lack of operation for whatever reason, turns plugs black, causes poor fuel economy, low rough idle, black puffs of smoke, - rich condition. It is a difficult fault to recognize.