1981 Vanagon backfire through intake

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sat Jul 02, 2016 5:10 am

Where does the coil ground to? On a vanagon the coil is mounted on the side of the engine compartment versus on the fan shroud on a baywindow. I can pull my coil out of the mount a without loosening anything. Could this contribute to my weak spark, and intake backfire? IE, bad ground?
Scottie

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asiab3
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Re: 1981 Vanagon backfire through intake

Post by asiab3 » Sat Jul 02, 2016 8:52 am

As per my local electrical guru, coils do not need to be grounded. I have held them in my hand while running.

I'm not convinced the "spark color" test has any merit. The color of what you see will be largely based on the atmospheric gases surrounding the jump. But the spark quality may be a sign, or it may not be.

I think your goal for today should be to get the spark "good and strong and at the exact right time" and then we can go from there.

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sat Jul 02, 2016 10:54 am

So, I looked at valves while my father was cranking. The rockers weren't moving. I preloaded all of them, 2 full turns past 0 lash. I'll have more to share in a couple hours.

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SlowLane
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Re: 1981 Vanagon backfire through intake

Post by SlowLane » Sat Jul 02, 2016 11:15 am

energyturtle wrote:So, I looked at valves while my father was cranking. The rockers weren't moving.
How is that even possible? Got good oil pressure? Changed oil and filter lately?
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sat Jul 02, 2016 12:09 pm

Yes, oil pressure is fine. I turned all lifters i'm 2 turns from 0 lash. It ran ok, still backfires. I then went to 0 lash, it won't start. Where my problem seems to lie is , not enough or to much preload. Where do I go from here? Can I go 3 turns past 0 lash? All lifters are in various states of pumped up, which means the preload would be different for each lifter. Adjusting them equally seems to result in some valves staying open causing the backfire phenomenon. Its about to drive me CRAZY. Colin, where you at?
Scottie

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asiab3
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Re: 1981 Vanagon backfire through intake

Post by asiab3 » Sat Jul 02, 2016 1:52 pm

Scottie,

You're on the right path! You can totally do this. Your visual of the rockers was a great step, and it gives us some decent clues. At this point, I would be counting turns from initial screw contact throughout the preload range until the plunger bottoms out. This will give you information on which lifters need more help pumping up. The oil light works in this van, RIGHT? And it has been behaving normal if you drag the engine down in 4th with the clutch and your foot firmly on the brake pedal?

I do hope that you do not have an oil system issue causing the lifters to bleed out permanently, though I do not exactly know if that is even possible.

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sat Jul 02, 2016 2:35 pm

Yeah. The vacuum pull on the booster is normal. The oil lights is functional and has never even flickered while running. I'm going to go back out and adjust valves AGAIN, and I will record the turns past intial contact and report back in a bit. Robbie, as always, thanks dude.
Scottie

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sat Jul 02, 2016 3:36 pm

Their all pumped up fairly well now. I readjusted them at the specified 11/2 turns past o lash. It started. I ran it for about 5 min. The backfiring was minimal. It started to smooth out, and I could get about 2K RPM at full throttle. I unplugged the temp sensor II, it did absolutely nothing , good or bad? I unplugged the CSV, did not change anything. I cleaned the fuel filter again, no change. The valves seem to be ok. Its almost as if it's starving for fuel? It will get a RPM surge, almost like a bucking symptom, then Peter out and fall flat. We're making progress. I don't really no where to go from here?
Scottie

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sat Jul 02, 2016 4:09 pm

I pulled the plugs. They are a carbon fouled, sooty mess. They were clean when I installed them right before this last attempt at startup. During 5 min of running like shit, it carbon fouled the plug to the point that it will not spark? There has to be a vacuum leak i'm not seeing. I'm going to remove every vacuum line, Tee, and everything else on the fuel injection system, with the exception of the plenum and intake runners. Robbie, sleuthing ain't easy. The struggle is real:)
Scottie

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asiab3
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Re: 1981 Vanagon backfire through intake

Post by asiab3 » Sat Jul 02, 2016 4:34 pm

Have you ran a fuel pressure test during the issues? (Use RandyInMaine's guide from on here!) Have you tested the TSII resistance to ground from the connector? Unplugging it with no change does very little when the engine is cold. When the engine is hot, it could cause a stall or stumble.

The CSV is out of play in eight seconds at freezing temperatures. It's out of play in one second or less after startup on a hot day cold start.

I have seen the intake runner hoses blown off in intake leaks. Check them visually! I have also seen the small fuel injector clamps damaged in strong intake backfires. Again, these were intake backfires due to an EXTREMELY incorrect valve adjustment. So your penance towards correct valve adjustments does not go unnoticed.

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sat Jul 02, 2016 5:02 pm

I disassembled the FI. The s-boot is cracked, the brake booster tee is split, the other thing that is not the thermo time switch (auxiliary air regulator) is cracked at the rubber connector to the s-boot. i've got pics I'll upload shortly. I had all of these taped off as best I could. The S-boot is a new finding. I can't tell if it's cracked all the way through or just highly stressed. Anyway, there is where I stand at the end of the day. I will go searching for vacuum tees and connectors tomorrow.
Scottie

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SlowLane
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Re: 1981 Vanagon backfire through intake

Post by SlowLane » Sat Jul 02, 2016 11:27 pm

asiab3 wrote: The CSV is out of play in eight seconds at freezing temperatures. It's out of play in one second or less after startup on a hot day cold start.
Minor correction here: the CSV is electrically out of play the instant you release the key while starting. In addition to the time and temperature constraints, it is only active while the starter is cranking.

However, if the CSV is leaky, then the presence or absence of an electrical signal to it is moot. It will be leaking as long as there is adequate fuel pressure. But since you aren't getting a black sooty idle exhaust, this would not seem to be your problem.

Mr. Turtle, I have noticed in all this that you are timing statically, which is fine, but do you know if your ignition advance is working correctly?

Don't forget, you can disconnect and block off all ancillary stuff (like AAR, brake booster, decel valve, EGR) hanging off the intake system in the search for vacuum leaks, because those bits aren't needed for normal operation. They only come into play under certain conditions. Same with the CSV, which can be bypassed with a length of FI-rated fuel hose if you suspect it of leaking.

Which reminds me, does your van have a working EGR valve? If not, is the EGR port properly blocked off? If so, are you sure that it is working and hasn't got a ruptured diaphragm?
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
- Terry Pratchett

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sun Jul 03, 2016 4:54 am

I did no know you can block of those things, its good to know. The EGR is long gone and blocked off properly. Just 3 weeks ago I tubed the engine, set dwell, etc. The vacuum advance was working properly at that time.
Scottie

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SlowLane
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Re: 1981 Vanagon backfire through intake

Post by SlowLane » Sun Jul 03, 2016 9:38 am

energyturtle wrote:I did no know you can block of those things, its good to know. The EGR is long gone and blocked off properly. Just 3 weeks ago I tubed the engine, set dwell, etc. The vacuum advance was working properly at that time.
Scottie
Block items off in an orderly fashion, simply as a troubleshooting aid, mind you, to pin down the source of the leaks.

Okay, vacuum advance works, how about the mechanical advance?
'81 Canadian Westfalia (2.0L, manual), now Californiated

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance."
- Terry Pratchett

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energyturtle
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Re: 1981 Vanagon backfire through intake

Post by energyturtle » Sun Jul 03, 2016 11:46 am

Yes mechanical advance works as well. I have changed my distributor out with 2 known to be good ones. The results were the same.

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