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bobhill8 Samba Member
Joined: June 09, 2017 Posts: 734 Location: MA
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Posted: Wed Mar 17, 2021 8:04 pm Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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what is the harm if i run the engine without the O2 sensor connected? i do not have to pass emissions as this is registered as an antique. i'd rather have a working emissions system, but... i'd also like to go camping with my son. |
It's time to have some fun. The mania is too deep right now. _________________ 1986 Westy
1971 Squareback |
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Wed Mar 17, 2021 8:16 pm Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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bobhill8 wrote: |
"what is the harm if i run the engine without the O2 sensor connected? i do not have to pass emissions as this is registered as an antique. i'd rather have a working emissions system, but... i'd also like to go camping with my son."
It's time to have some fun. The mania is too deep right now. |
i had forgot to connect the AFM back in, so while it may idle great, it stalls out off idle. with the AFM connected it performs poorly and gets terrible gas mileage. i'd rather take the time in Smarch so come May it's adventure time with the engine woes behind me. _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
BiWerks Design, LLC |
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4715 Location: Bemidji, MN
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Posted: Wed Mar 17, 2021 8:34 pm Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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ok. your timing is good, that's good. new injectors, that's good. you're not confusing terms and your engine runs better with the AFM disconnected (i thought maybe you meant O2 disconnected)
now, with the engine runnining and the AFM cover off and plugged in, manually push the AFM vane forward and back. is there a sweet spot where it runs better? if you have to push against the spring tension to make it better, loosen the tension. visa versa. i did days of tuning on my spring tension to find the sweet spot to eliminate a bog on acceleration and not trash gas mileage. i used the mixture screw to get as close to 0.5v O2 sensor voltage at idle with the O2 sensor disconnected. i probably err'd on the high voltage side and let the ECU trim it back.
simple compression numbers should tell you whether you should've taken the other heads off. i'm thinking they're ok, we still might have a tuning issue here.
you gotta KNOW the injectors mist evenly, look at the spray patterns, don't assume. your ignition system is in top order, i've had wire sets fail in a couple years. your ignition coil tower and distributor cap is CLEAN, remove the black RF shield if present to inspect for cleanliness.
and for all the frustration, a 3 wire Bosch O2 sensor is $58. they have a replacement interval of 60k miles on this generation. i consider it a tune-up item.
anyway. you're a sharp guy. you'll get this. _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32432 Location: Reading Pennsylvania
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djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32432 Location: Reading Pennsylvania
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4715 Location: Bemidji, MN
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Posted: Thu Mar 18, 2021 6:34 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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that's a generic product with an "application" for Vanagons along with a thousand other cars. clever bit of marketing. it is strictly to get the CEL light to turn off. quoting from the website:
"No, oxygen sensor simulators are solely designed to treat oxygen sensor related codes. They are not intended to diagnose or control your engine management..."
stay away from this!! _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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4Gears4Tires Samba Member
Joined: October 08, 2018 Posts: 2982 Location: MD
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Posted: Thu Mar 18, 2021 6:50 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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djkeev wrote: |
Using voltage feed back from the O2 sensor is genius !
Your idea? |
That's how all cars are tuned. Usually the voltage is converted to AFR when displayed so it's easier to understand though.
A narrow band O2 sensor reads either plus or minus, as Dan said. But if you install a wideband you can get a spectrum of voltages to convert to AFRs. Usually 10-22 AFRs, which makes tuning a lot easier. _________________ '87 Syncro
Ferric Oxyhydroxide Superleggera Edition |
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djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32432 Location: Reading Pennsylvania
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4Gears4Tires Samba Member
Joined: October 08, 2018 Posts: 2982 Location: MD
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Posted: Thu Mar 18, 2021 6:58 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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I have had a few headaches with the Innovate LC series (you also need to buy the gauge separately), the AEM UEGO has given me much easier performance.
https://www.aemelectronics.com/products/wideband-u...-afr-gauge
https://www.innovatemotorsports.com/products/lc2.php
The hardest part would be welding another bung onto the exhaust for UEGO. But, the LC-1 has a nice option that it allows you to split the signal and output both a wideband and a narrowband. So it could install directly into a Vanagon, output the narrowband into digifant and the wideband can go to the gauge. _________________ '87 Syncro
Ferric Oxyhydroxide Superleggera Edition |
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Thu Mar 18, 2021 7:15 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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here's the recap.
i bought a tin top with compression gases that were displacing coolant. i decided to rebuild the engine instead of just doing the head reseal routine.
once that engine was apart, it was apparent that it was worn out - the cam was toast, the jugs not great.
Dave had an engine he gave me. i tore it apart. the cam, lifters, crank, pistons and jugs were used with the case from the tin top. the jugs were honed at a machine shop and the pistons inspected.
i bought used AMC heads. i bought a GW exhaust. i bought a new 3 wire Bosch O2 sensor.
the engine had a misfire at idle after the rebuild.
over time the misfire progressed into more concerning running issues. the vast majority of these were resolved as i chased down leaks - the brake booster, the intake manifold boots, an injector seal. the backfiring and running issues all went away except for the random misfire at idle. it then started to get worse the more i drove it. it has about 2500 miles on it.
when i bought the Westy, the engine was running but had leaking head seals, very bad leaking. the engine ran and the Westy drove, it just was a coolant leaking disaster. it idled smoothly no misfires.
i pulled the engine from the tin top and put it in the Westy, the problems followed to the Westy. i swapped ecu, afm, coil, icv, iscm... no changes.
all FI sensors are within spec. all voltages are within spec.
the running issues have worsened over time. the last outing in the Westy it got 12MPG down from the 18 MPG i would get and there was a noticeable decrease in power... hills it climbed with aplomb were now walls to struggle up.
this is what made me think there was an issue with the heads, specifically a leaking exhaust valve.
i will perform a compression test. i opted for a leak down test since i was looking for leaks.
i will say after the heads were replaced, the idle with the AFM and O2 disconnected is much smoother than it ever was. there is a random miss present. with the AFM connected it is a gurgling backfiring beast. _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
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AceTaylor Samba Member
Joined: July 15, 2009 Posts: 137 Location: PERKASIE, PA
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Posted: Thu Mar 18, 2021 9:16 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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Seems like you checked all the boxes except camshaft timing. Is it possible that when it went back together the camshaft is off a tooth? Just throwing it out there. |
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Thu Mar 18, 2021 9:47 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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AceTaylor wrote: |
Seems like you checked all the boxes except camshaft timing. Is it possible that when it went back together the camshaft is off a tooth? Just throwing it out there. |
cam is correct, i have a photo of it somewhere... when it was first run after rebuild it only had a random miss. it started to run rough and those problems were unmetered air related. the idling improved as i addressed each of the issues. now has returned to that rough idling with the AFM connected. _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
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djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32432 Location: Reading Pennsylvania
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Thu Mar 18, 2021 10:18 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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djkeev wrote: |
Cam lobe go?
Dave |
it idles well with the AFM disconnected - just has a random miss. connect the AFM and it instantly starts gurgling, missing, and backfiring. _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Thu Mar 18, 2021 2:28 pm Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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and the compression numbers are...
***drumroll***
#1 - 133
#2 - 135
#3 - 133
#4 - 135
as Dave said, "nothing wrong there."
now for glamour shots of the plugs!
cylinder #1 - um, a touch wet?
cylinder #2 - powdery carbon
cylinder #3 - they all looked like this when i put them in
cylinder #4 - powdery carbon _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4715 Location: Bemidji, MN
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Posted: Thu Mar 18, 2021 3:04 pm Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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okay... some guesses. yes, #1 is drenched and either isn't firing well or there's something nasty with the injector.
#2 are way too rich, which if #1 isn't firing makes sense because the O2 sensor is sensing extra oxygen from cyl #1. also supported by your low O2 volts unplugged.
#3, while the nicest burn, SHOULD be over rich so i'm guessing a clogged injector that with the extra dwell time the ECU is turning on the injectors, this inadvertently compensates for the clogging.
all this is guessing. were this van mine i'd immediately pull the injector pairs and look at the spray. next, i'd replace the O2 sensor if it hasn't been done in 60K miles. lastly, i'd strongly consider new plug wires, i know you said they're 'pretty new'. i'd also measure the AFM spring tension to make sure it is somewhere around 110 grams on lifting off of rest position. i think you said you had a new Temp II sensor, if not, change that out too for $15. _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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DanHoug Samba Member
Joined: December 05, 2016 Posts: 4715 Location: Bemidji, MN
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Posted: Thu Mar 18, 2021 3:26 pm Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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one more thing..... i'd put a NEW set of plugs in ASAP. it sounds like you put used plugs in. don't worry about getting NGK BP6ETs for this, just buy some new Champion or whatever swill from the nearest FLAPS to test with. you've very likely got firing issues going on.
actually, what i'd REALLY do is put this on the SUN Ignition Scope i restored but that'd be cheating. _________________ -dan
60% of what you find on the internet is wrong, including this post.
'87 Westy & '89 Westy both 2.1 4spd
Past projects can be found at--
www.thefixitworkshop.com |
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dabaron Samba Member
Joined: June 21, 2018 Posts: 2558 Location: Philly, mang
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Posted: Thu Mar 18, 2021 3:49 pm Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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i bought the plugs, wires, temp2, and a new coil in Jan 2020 hoping they would resolve the issues. these are not resolved. i pulled the plugs and they are all firing. i threw in four new Bosch no change.
only thing left is injectors. i'll swap those out tomorrow, i'm tired of getting rained on. _________________ 1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
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djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32432 Location: Reading Pennsylvania
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Posted: Fri Mar 19, 2021 4:05 am Post subject: Re: The mania deepens: 1991 Full Westy rescue |
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So, the Vanagon ECU has a map built in to run without feedback from an O2 sensor.
Can we assume it has a "limp mode" programmed in to run without the AFM plugged in?
I remember when Judo Jeff picked up his current Van from my house. I had done some pretrip work, mainly fixing a huge fuel leak above the starter.
I failed to plug in the AFM and he took off!
He called, it ran, but not well.
Upon inspection he found the AFM plug hanging there.
Plugged it in and off he went!
Anyway, if there is a limp mode programmed into the ECU and the engine runs much better with the AFM unplugged, does that not scream bad or misadjusted AFM?
Maybe a cracked wire in the harness?
With no AFM there is no air temperature feedback or throttle position feed back. Except for the throttle position switch which only comes into play at idle or full throttle.
At idle, the TPS is telling the ECU to activate the Idle Control System.
Is there an interaction between the AFM and the Idle Control? Good or Bad?
Thus Unplugging the AFM cancels this interaction resulting in a smoother running engine?
At idle, except for the Air Temp feedback, the AFM is essentially "off duty"?
The Idle Control System is now in charge...... Yes?
If so, what is that interaction and how do you find it?
If you unplug the AFM and jump terminals 1 & 4 on the AFM to the proper locations on the plug....... what happens?
You would be putting the air temp back online without involving the air door circuit.
Dave _________________ Stop Dead Photo Links how to post photos
Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
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djkeev Samba Moderator
Joined: September 30, 2007 Posts: 32432 Location: Reading Pennsylvania
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