Van bucks over 3000 rpm....especially when climbing

[shorepig]

I changed my fuel filter, and did the Bentley test procedure for the coil. The first test was ok but test two failed. I'll install a new coil tomorrow and report back.
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85 Westy
92 Mitsubishi Mighty Max 4x4 V6
74 Honda CB500T cafe racer
2013 ktm 690r
Sector nine pintail

[consvws]

We just had an issue with an air-cooled vanagon where it would run & drive fine until 4000 rpm's then it would sputter out and shake the engine all over. Every now and then you could very slowly ease past 4k rpm's if you were very careful. We replaced the fuel pump & filter (because they were not BOSCH parts), but it did the same thing. It turned out to be the fuel pressure regulator that solved the problem.

[insyncro]

A Vanagon Rescue Squad call sent a 90 Vanagon back home with issues at 2500rpms......a new air filter fixed it.

[shorepig]

Ok. The coil was actually fine. The o2 sensor failed testing. Now I can't get it unscrewed! I've also sealed the BIG hole in the exhaust. I put a 2' extension on my wrench and also soaked it with wd40 but it won't budge. I don't have a torch. Any other ideas to get this old o2 out?

Btw, I was mistaken about the speedo jumping around when the problem occurs. It was the tach that was all over the place.
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85 Westy
92 Mitsubishi Mighty Max 4x4 V6
74 Honda CB500T cafe racer
2013 ktm 690r
Sector nine pintail

[j_dirge]

[Randy in Maine]

Soak that bad boy with PB Blaster or Kroil. Might take a couple of days of soaking, but it should come out with the correct O2 socket.

It would be nice to know what kind of voltage you are seeing from the alternator when it wimps out. That is the only connection I can make between the jumping tach and the loss of power.

[insyncro]

[insyncro]

Have a Buddy or local Pro with an oxy/acetylene setup heat it cherry....it will turn right out.

[NC Dude]

toss PB blaster right around the thread area and hit it a few times gently with the side of your wrench. Apply another coat of PB and go open and toss back a beer. Should come right out by the time you've killed the brew

[shorepig]

Thanks for the help guys.

I finally extracted the damn o2 Sensor. It's unbelievable how tough they are to get out of there. I have a feeling that the combination of the LARGE hole in the exhaust by the header was the biggest problem. It was big enough to stick my pinky into !!!

So now the van is purring like a quiet little kitten. Hopwfully I've solved the problem, but then again, you know how these intermittent problems can be.....

I still don't understand why the tach would jump from 0-3000 pretty much instantly when the problem was occurring? If I was cruising at 80 km/h when it happened there is no way the rpms could do that. So how do you explain this? I'm still thinking the evil is lurking...somewhere in the electrical system

And by the way, the van is an automatic if that makes a difference.
_________________
85 Westy
92 Mitsubishi Mighty Max 4x4 V6
74 Honda CB500T cafe racer
2013 ktm 690r
Sector nine pintail

[pmcgrath]

I've got the exact same problem, and it's an 85 Westy automatic too!

The intermittent nature of the problem makes you think you have fixed it and then it happens again 1 month later. In my case, there have been 3 episodes of sputtering loss of power with tach jumping down to zero each time, like someone has unplugged the power cord to your lawnmower and instantly plugged it back in. These tach jumps with sudden engine power loss occur 2 to 5 seconds apart randomly until ypu pullover and turn the engine off for an hour. Or in the case yesterday, Westy had a tach jumping episode as I limped into my campground and it was still having the problem as soon as I left the curb the next morning after shut off all night.

I'm going to test the ignition switch. Please let me know when and if you solve the mystery, so I can fix this problem too. I'll let you know if I learn anything new as well.

Happy hunting,
Patrick