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jberger
Samba Member
Joined: November 17, 2003
Posts: 2476
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 Posted: Wed May 17, 2006 10:15 am Post subject: 86 Syncro too rich for my blood |
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So just picked up an 86 syncro and it seems to have a couple related issues..
#1 starts fine, idles a little high until warm
#2 when warm runs really rough, cutting out and such and seems to be really rich, lots of soot at the pipe...
Any thoughts where to start? Has new fuel filter, cap, rotor, plugs. Are these rigs prone to fuel pressure, ECU or ignition problems that cause rich rough running? |
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sc-surfer
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Joined: May 16, 2005
Posts: 865
Location: Santa Cruz, CA
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Buckly
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Joined: September 14, 2004
Posts: 1030
Location: Spokane, WA
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| Posted: Wed May 17, 2006 11:56 am Post subject: |
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back probe it at the connetor and check the voltage. should average .450 volts or 450mv. I had a rich condition and it turned out to be the O2 circuit shielding grounding out the signal, making the ECU think things were running leaner then they should be and trying to richen things up. the best thing to do is check out the signal with a osilliscope. O2 sensors fail much less than most people think.
An O2 verys voltage from 0 to 1.0 volt(1000 millivolts). It shouldn't drop below .2 and go above .9, but it will if things aren't running right. the lower the voltage the leaner the air/fuel mixture and the higher the voltage the richer. 450mv is average. theres a little more to it, but this is the basics.
the two white wires are the heater circuit and the black wire is the signal. check the black wire for proper signal to the ecu.
The ecu dosen't take the o2 into account until the engine reaches operating temp.
_________________
Cool runnins,
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Bucky |
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syncromat
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Joined: February 13, 2006
Posts: 84
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| Posted: Wed May 17, 2006 3:24 pm Post subject: Re: 86 Syncro too rich for my blood |
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| jberger wrote: |
So just picked up an 86 syncro and it seems to have a couple related issues..
#1 starts fine, idles a little high until warm
#2 when warm runs really rough, cutting out and such and seems to be really rich, lots of soot at the pipe |
My 87 syncro was exactly the same . It averaged about 16mpg.
Make sure the O2 sensor is working then run your engine to operating temp .
Disconnect the cable to the O2 sensor (there should be a connector)and attach a meter to the O2 and the ground to ground.
With the engine hot and running at idle check the voltage . It should read about .5 volt . If you have a 2/3 cable to the O2 then make sure you do not use the either of the 2 heater cables .
If the voltage is incorrect it will mean getting into the AFM.
Another check is to either buy a gas analyzer or get a mechanic to do it .
After I did all this I was up to about 18mpg.
I decided to pull the air filter body and intake tube , fit a
new filter and believe it or not the syncro is at 23.5 around town and 25 on long trips. |
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jberger
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Joined: November 17, 2003
Posts: 2476
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| Posted: Thu May 18, 2006 9:46 am Post subject: |
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| Tested the O2 sensor last night and found 1.5-2.0v at the connector and .7-.9v at the sensor, think I'll re-new it. |
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syncromat
Samba Member
Joined: February 13, 2006
Posts: 84
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| Posted: Fri May 19, 2006 8:53 am Post subject: |
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| jberger wrote: |
| Tested the O2 sensor last night and found 1.5-2.0v at the connector and .7-.9v at the sensor, think I'll re-new it. |
probably don have to replace sensor as this is reading the oxygen level in the exhaust system .
make sure the meter is attached to the sensor cable coming from the O2 sensor .
to get that .7 -.9 down to .5 v you have to tweak the AFM.
On the AFM at about 11 oclock is a hole which could be plugged or it could be open .
below the plug in the hole is an adjuster screw , but you have to remove that plug .bentley covers its removal .
screw the adjuster home fully counting how many 1/2 turns it takes to seat fully in .remember that number .
do not force it .
set up the meter and get the engine hot and at idle check the reading .
back off the adjuster 2 turns and recheck the reading .either screw it in or out until that reading is at .5v. it can rise to .6 or drop to .4 , thats ok .
next job is to adjust the slow running screw on the throttle body to get to 850-900rpm.
keep adjusting both of these until you are at 850rpm and .5v on the meter .
the next job is to the check your exhaust gases and if you have done the above properly it should be spot on . |
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jberger
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Joined: November 17, 2003
Posts: 2476
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| Posted: Fri May 19, 2006 2:32 pm Post subject: |
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| syncromat wrote: |
| jberger wrote: |
| Tested the O2 sensor last night and found 1.5-2.0v at the connector and .7-.9v at the sensor, think I'll re-new it. |
probably don have to replace sensor as this is reading the oxygen level in the exhaust system .
make sure the meter is attached to the sensor cable coming from the O2 sensor .
to get that .7 -.9 down to .5 v you have to tweak the AFM.
On the AFM at about 11 oclock is a hole which could be plugged or it could be open .
below the plug in the hole is an adjuster screw , but you have to remove that plug .bentley covers its removal .
screw the adjuster home fully counting how many 1/2 turns it takes to seat fully in .remember that number .
do not force it .
set up the meter and get the engine hot and at idle check the reading .
back off the adjuster 2 turns and recheck the reading .either screw it in or out until that reading is at .5v. it can rise to .6 or drop to .4 , thats ok .
next job is to adjust the slow running screw on the throttle body to get to 850-900rpm.
keep adjusting both of these until you are at 850rpm and .5v on the meter .
the next job is to the check your exhaust gases and if you have done the above properly it should be spot on . |
Ok, but what causes the rich running to begin with? All things being stock condition, something has to be out of spec to cause this... |
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syncromat
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Joined: February 13, 2006
Posts: 84
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| Posted: Wed May 24, 2006 12:43 pm Post subject: Re: 86 Syncro too rich for my blood |
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| jberger wrote: |
| So just picked up an 86 syncro |
would suggest this is where your problems start .
the car is nearly 20 ears old and things do wear and get out of adjustment and PO's are notorious for not knowing what they are doing . |
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jberger
Samba Member
Joined: November 17, 2003
Posts: 2476
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| Posted: Wed May 24, 2006 1:04 pm Post subject: Re: 86 Syncro too rich for my blood |
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| syncromat wrote: |
| jberger wrote: |
| So just picked up an 86 syncro |
would suggest this is where your problems start .
the car is nearly 20 ears old and things do wear and get out of adjustment and PO's are notorious for not knowing what they are doing . |
There was a cause, the o2 was faulty, the butterfly valve was sticking, throttle switch out of adjustment and dirty grounds. Purrs like a kitten now. AFM's should not fall out of spec, the trac can get wear marks (which cause dead spots) over time but this takes a LONG time, my 79 and this 86 both look new under the cover... |
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