Lack of power, Low compression....Cylinder Head replacement

[bosstyn]

Hey guys. os heres the deal. Out of the blue (more or less) my van started running like a three legged dog. Wouldn't go over 45 or so and feels like its fighting a 40 kt headwind.
To get it started i have to floor the gas to get it to catch and after that it smells like its running pretty rich. It runs rough really giving the engine a rocking and backfires on occasion. It was running like a top yesterday.
My friend (aircraft mechanic and all around handy guy) looked it over and heres what we found:

• Injectors seem to be spraying appropriately and in a good pattern.
  
• The O2 sensor was changed.
  
• All grounds that we can see appear to be in good working order.
  
• We cleaned the dist. rotor and contacts.
  
• All plug wires have good spark.
  
• No MAJOR exhaust leaks. Maybe a small one but it doesn't seem to be a huge issue.

As far as the AFM goes, we tested the Ohms on the current in place one and a spare i have. Both tested with pretty small ranges. At about 1/4 inch open it reads Over Limit.
We tested this in place on the running engine. Hand manipulation of the AFM with the throttle seems to make it run better, but its hard to match the two by hand. (the throttle deceleration switch checked out fine).
That being said, should i drop a small fortune on a new AFM?
Does anyone have some good insight as to the appropriate working ranges of a normal AFM?
Do these things just drop dead?
Any ideas as to what else might be the cause?

Thanks everyone!
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Donquita, 85 Westfalia GL

[crazyvwvanman]

Ohm readings are done with POWER OFF. If you want to take readings with the engine running you should measure voltage, not ohms.

Mark

[pomfritz]

Check out these guys

http://www.fuelinjectioncorp.com/

They can test it for you and rebuild it if needed.

I'll be sending mine in soon as I know it's got a few worn track areas. $200

I believe the ones GW sells are done by these guys.
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83.5 233K. GW 2.3, SS exhaust, My German Frau named her Stefi

[djkeev]

Before spending money on an AFM, pull the plugs, take a compression test.

Slip in new plugs if compression checks out, see if things are better.

If you live in the current wet zone....PNW, I'd for sure suspect wet wires or distributor cap.

Dave
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[Wildthings]

[Luckyphil]

Replace your temp2 sensor, its in the side of the thermostat housing.

[nacradriver]

[pushkick]

i have been having the same problem and i found a thread that talks about the altenator harness
http://www.thesamba.com/vw/forum/viewtopic.php?t=642882

my engine seems to run fine one day and low power the next day and rough idle and low gas mileage. some one needs to make a obII compliant ecu for this van. what ever happened to gowesty mass flow meter upgrade to replace the afm
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1990 vw automatic camper

[insyncro]

Get a DigiTool.

[Ahwahnee]

Also worthwhile to verify that the O2's center lead is not shorting to the grounded coax (probably a fat green wire). Several threads describing this, can be checked in a minute with your ohmmeter.

[bosstyn]

The Ohms were tested with the AFM out and off. The throttle deceleration switch was also tested when off.
As far as maybe bad gas, it sounds plausible. Ive just never experienced bad gas and I'm curious if it would make my van idle like crap and feel like it was driving through molasses. It will drive and get up to RPM but it never gets out of that lower end. Kind of like it never hits its power band.
We changed the plugs maybe thinking it fouled a plug and had a dead cylinder. No dice.
i can check the grounds again and more extensively. Could grounds really make that much of a stark one day to the other difference?
Ill change the plug wires and see if i can find a junkyard AFM to slide in there and see if theres any change.

Doe anyone knowhow the ohmmeter testing of the AFM should look? I know it needs to be steady and not erratic when testing Ohms, but it only goes about 1/4 of an inch before testing OL.

O2 sensor wire seems to be in god shape.
I did find a wire that goes from the ignition box to somewhere under the engine. (oil pressure sensor?) it melted at some point in its life and was zip-tied up. But grounding it out on metal while it was running didn't seem to make any difference.

So as it runs now, like i said, it feel like molasses. The throttle is a bit dogged when you operate it by hand. The engine seems to run fine at high RPM but its really lacking power. And it idles like crap most of the time. Rough enough to bounce that thing side to side enough that its clanging metal.

Any thoughts are appreciated.
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Donquita, 85 Westfalia GL

[Ahwahnee]

[Merian]

do the cheapest and easiest things 1st - T2 sensor repl. & drain all the gas out (yes, bad gas can cause those symptoms) - change filter too

you HAVE replaced your fuel lines and used the correct new hoses and clamps, right?

if not, then take you time and do it - repl. rubber brake hoses with new rubber & flush the system every 2 years also

send the injectors in for cleaning & they'll be back by the time you're done with the hoses

you can test or repl. the O2 sensor afterwards - they aren't all that spendy - don't try a hack splice, repl. the entire unit and coax

[syncrosimon]

Link


Making that video helped me understand how the AFM works. Hope it helps, as it's real easy to see if your AFM is running nice and smooth. The analogue meter really helps to see if you have a nice smooth output.

Simon
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1991 16" 2.1 DJ Syncro factory hightop ex Finnish Army Ambulance, now sold.
Thinking about Thing or 181 (182) ownership.

[Wildthings]

Maybe add some 90-99% isopropyl alcohol to your tank (either from a pharmacy or the red Iso-Heet from a FLAPS) and see what that does. If you have gasohol with a lot of water-alcohol mix hanging out near the bottom of the tank it will help to disperse the water throughout the fuel. If the seals in your fuel tank and/or expansion tanks are going bad water that gets thrown up onto the top of the tanks can get in and really mess up the way your engine runs.

[bosstyn]

fuel treated and subsequently drained. Re-filled with new gas. No dice.
AFM appears to be operating normally though not as smooth as the video.
Fuel pump is supplying pressure.
Got spark in all the cylinders. Plugs cleaned up and replaced.
Grounds checked.
O2 sensor replaced.

Motor still running rough, dogged and accelerates sluggishly. Like its not getting the right fuel mixture. (hence chasing the bad gas thing). floored its only getting up to 45 mph or so. Feels like its driving through molasses.
It was starting to run like crap, and the next day i was trying to accentuate exhaust leaks, plugged the exhaust with a rag and hand for a few seconds and it died. started running like hell after that. (did i blow something up with my exhaust plug move?).

Could the CAT be my culprit?
Maybe a bad AFM?
kinda running out of ideas.
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Donquita, 85 Westfalia GL

[syncrodoka]

Pull the cat and verify that the insides haven't shat out and is blocking the exhaust flow to the muffler.

[bosstyn]

Ill pull the CAT tomorrow.
Planning on replacing the temp II sensor, fuel pump (can't hurt to have an extra) and fuel filter in the morning.
Hopefully one of those sheds some light on it.
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Donquita, 85 Westfalia GL

[nacradriver]

[bosstyn]

The fuel pressure regulator is on my list.
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Donquita, 85 Westfalia GL