Ljet

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Amskeptic
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Re: Ljet

Post by Amskeptic » Mon May 15, 2017 7:42 pm

Latest post of the previous page:

dingo wrote:
Mon May 15, 2017 6:25 pm
Yeah thanks will do. I did do that, but at this point...a re-do is all i got

I did notice that with harness plug removed pin10 get 12v with IGn ON...and Pin4 only get 4,5,6V as i crank....perhaps this is not enough
(i forget what site i got this testing protocol from..i just scribbled down 'pin 4 voltage while cranking')


I just got a fuel-injected bus going after two years of every possible question and test, ohms, voltage, and fuel supply, regarding the fuel injection system. I did a lousy job of explaining my hunches, but we had two weird moments.

1) a test lamp showed voltage persisting at the series resistors even after the ignition was shut off until an eventual click from the double relay shut things down. I think it was a blown diode in the double relay.

2) Even though the injector plugs showed twelve volts at both sides, we concluded that the plugs had to be in the circuit with the solenoid coils accounted for for the ECU to give us proof of grounding. I forced the ECU to prove the grounds by having the injectors pulled, plugged in, charged with full fuel pressure, and I manually opened the breaker points with a screwdriver to watch the injectors actually spray at every other point opening. Thankfully the fuel was stale, so no explosions.

His bus drove well enough and started readily by the time I left. You should note that the basics were critical:
a) fresh battery charge and fresh gas
b) clean and gap the points and make sure the plugs are dry and clean and gapped
c) call out that Itinerant guy when he is in your neck of the woods, we're batting a thousand.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 204,875 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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dingo
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Re: Ljet

Post by dingo » Tue May 16, 2017 10:57 am

Ok it seems like it should be easy to test an ecu on the bench.
I can simulate the input trigger with a spare coil, dizz and spark plug..and watch the output pins for grounding action. Question is, at what pin does the ECU get its running power to run the circuitry ? Any ideas welcome...
Most of the pins are associated with auxiliary gadgetry...so it must be fairly simple to set up a test rack to make sure its doing its switching function.
Thx
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by sgkent » Tue May 16, 2017 12:06 pm

depending on the year the schematic with pins is about page 40

https://www.thesamba.com/vw/archives/ma ... Manual.pdf
Thank You -

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Machine Work/Shop Recommendations: http://kentcomputer.com/77VW/machinework.pdf

Pointers on rebuilding an engine: http://kentcomputer.com/77VW/rebuilding_a_vw_engine.pdf

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Re: Ljet

Post by dingo » Tue May 16, 2017 4:46 pm

Thanks.

Per AFC manual...get Pressure Up, Ign Off, Remove harness, jumper Ground (16,17) to Ign pins 14,15,32,33
Then turn Ign ON. I did this and injectors spray nicely into their collector cups. So that part of system works fine
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Amskeptic
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Re: Ljet

Post by Amskeptic » Tue May 16, 2017 9:19 pm

dingo wrote:
Tue May 16, 2017 10:57 am
Question is, at what pin does the ECU get its running power to run the circuitry ?
#10, straight from the double relay.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 204,875 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: Ljet

Post by dingo » Thu May 18, 2017 10:34 am

Every Ohms measuremen checks out fine within spec. The system is intact and no shorts. Volts measurements check out too, with the exception of Pin4, which does no live up to the 'Min 9.5V while cranking'. Pin 4 seems dedicated toTTS and CSV, so im not sure if this is perinent.
This leads back to my initial issue with the starter. Replaced bushing, starter and cables...things got better but not great.
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by dingo » Thu May 18, 2017 5:08 pm

ok finally got a flicker at the injector......
voltage at batt 12.5v...with IGN ON, voltage at Igniion lead is 12.15 v.....when connected to coil+ drops to 10.75v, tho i do hear he relay click

so volt drop at ign sw ? or bad relay contacts ?
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by dingo » Fri May 19, 2017 2:07 pm

... jumped Batt+ directly to coil+..and took the following readings.
IGN ON
Batt 12.39 v pin 10 12.33
88b 12.33, 88a 12.33v

Ign ON, AFM flap open (fuel pump running)
86b 12.17v
pin 20 12.18

Ign ON, starter engaged
86 9.5 v
pin #4 9.5 V
(for both of these, dips down to 8.5 v as starter runs)

* prior to addressing he f.i. , i had replaced the starter with a 'reman' and replaced the starter bushing...altho engine turned by hand freely..the starter always seemed sluggish..or intermittantly sluggish
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by dingo » Fri May 19, 2017 5:35 pm

Volt drop tests :
using remote pushbutton starter, from B+ terminal to starter+ bolt, it drops .4 - .5v
from B- terminal to starter case, it drops .12 V
so internal or mechanical resistance to account for the 3v drop during cranking ?

The Coil+ wire loses all .5v at the ignition switch. With ign ON, incoming is 12.5 and ougoing is 12.1 at the switch. When wire Connected to coil+, it reads 10.75 V..and that returns to 12.0 when green dizz wire is pulled. Is this normal behavior ?
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by dingo » Sat May 20, 2017 3:26 pm

Coil + reads 12.10 with points open and 10.75 with points closed.
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by Amskeptic » Sat May 20, 2017 6:40 pm

dingo wrote:
Sat May 20, 2017 3:26 pm
Coil + reads 12.10 with points open and 10.75 with points closed.
Do you think the starter is pulling the system voltage down too far?
Colin
BobD - 1978 Bus . . . . . . . . . . .110,334 miles
Chloe - 1970 bus . . . . . . . . . . . 204,875 miles
Naranja - 1977 Westfalia . . . . 72,350 miles,
Pluck - 1973 Squareback . . . . . 55,478 miles

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Re: Ljet

Post by sgkent » Sun May 21, 2017 9:08 am

The normal procedure would be to measure voltage between battery POSTS with the starter off then cranking. If it still drops to 9.5 v have the battery checked. If is holds at 12V +/- then move to the battery TERMINALS and test again. Then between vehicle ground and 12V + POST. You will isolate the place the voltage is being lost. Once you do you can actually measure across where you are losing it and see it fall. For example, if you thing it is the ignition switch that is costing you coil voltage, measure the voltage across the ignition switch on and off. If the switch is at fault you will see the voltage drop across it. If a battery cable is bad for example, you will see the voltage drop across the ends of the cable. If the drop is say between the battery post and terminal you will see the voltage drop between those two points. Loss at any connector should be almost zero which would mean the meter sees no voltage. If it reads voltage between two points, that is the loss.
Thank You -

Merlin The Wrench

Machine Work/Shop Recommendations: http://kentcomputer.com/77VW/machinework.pdf

Pointers on rebuilding an engine: http://kentcomputer.com/77VW/rebuilding_a_vw_engine.pdf

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Re: Ljet

Post by dingo » Mon May 22, 2017 4:02 pm

Volt drop from B+ to strater is rediced to acceptable 0.2 V

Batt : 12.45 v (drops to 10.2 during cranking)
Coil + 12.15
Pin 10 12.42 v (drops to 10.1 v while cranking)
All injectors get 12.42 on pos terminal
Pin 4, during cranking is a steady 9.25...which is below the spec 9.5...tho this pin feeds hermotime switch and cold start injector..so im not sure how or why that would affect injector grounding.

Starter spins freel;y now, but now i get NO flickering at injectors..i.e. No grounding
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by sgkent » Mon May 22, 2017 8:12 pm

If you are between battery posts and not the clamp on terminals, and the voltage drops to 10.45 volts you need to check the battery. If it is 3 1/2 to 4/1 2 years old or older it Is probably worn out, sulfated or both.

Try turning the engine by hand a little. If it turns freely I would suspect a dead or discharged battery. If the engine is harder than normal to turn then it could pull the battery down but I would suspect a bad or discharged battery first.
Thank You -

Merlin The Wrench

Machine Work/Shop Recommendations: http://kentcomputer.com/77VW/machinework.pdf

Pointers on rebuilding an engine: http://kentcomputer.com/77VW/rebuilding_a_vw_engine.pdf

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dingo
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Re: Ljet

Post by dingo » Tue May 23, 2017 7:31 pm

Engine turns freely by hand. The batery is 'new'...some generic brand..i might have been on the shelf for years. , but it went from store to Bus. When cranlking, the volt drop is initially to 9v as the starter pauses, then as it gets momentum, the volts are steady at 10.2 or so

with charger plugged in and on 'engine start' mode,(about 13v or s) i get the flickering at the injector plug
I guess this Batt is Krap
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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Re: Ljet

Post by dingo » Wed May 24, 2017 10:18 am

As explained to me, this seems to be the case of a cell dropping out under load. It makes sense as each cell carries 2.1V and that is exactly what iam losing duri ng cranking
'71 Kombi, 1600 dp

';78 Tranzporter 2L

" Fill what's empty, empty what's full, and scratch where it itches."

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