 Fuel injector voltage, Correct reading? |
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| timofly |
 Dec 5 2016, 03:31 PM
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#1
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Member  Group: Members Posts: 164 Joined: 21-February 09 From: VA Member No.: 10,082 Region Association: MidAtlantic Region  |
My 2.0 with stock fuel injection has a consistent missing at idle and all engine speeds. At idle, disconnecting the wire to the #1 fuel injector makes no difference, but disconnecting any other injector wire makes problem much worse and eventually stalls the engine.
The voltage reading from the #1 injector input plug varies from .19 to .28 volts at idle. That doesn't seem like much, but what should it be? (I didn't test another cylinder because I ran out of time to fool with it today.) Plugs are new and valves have been adjusted. Seems pretty clear that the problem is at #1 cylinder. |
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| TheCabinetmaker |
Dec 5 2016, 04:45 PM
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#2
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Just check the voltage on the others and compare.
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| timothy_nd28 |
Dec 5 2016, 07:29 PM
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#3
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Advanced Member Group: Members Posts: 2,299 Joined: 25-September 07 From: IN Member No.: 8,154 Region Association: Upper MidWest 
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You will need a oscilloscope if you want to measure voltage while the injector is firing.
If it was me, I would replace the injector connector. They sell them with 8-10" of wire. |
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| reharvey |
Dec 5 2016, 07:56 PM
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#4
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Senior Member Group: Members Posts: 573 Joined: 16-July 08 From: N. E. Ohio Member No.: 9,308 Region Association: North East States |
The injectors operate at 3volts. Got that info from a Bosch D-jet manual. Ray
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| timofly |
Dec 5 2016, 08:33 PM
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#5
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Member Group: Members Posts: 164 Joined: 21-February 09 From: VA Member No.: 10,082 Region Association: MidAtlantic Region |
QUOTE(reharvey @ Dec 5 2016, 08:56 PM)  The injectors operate at 3volts. Got that info from a Bosch D-jet manual. Ray OK thanks. I missed that. |
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| walterolin |
Dec 5 2016, 08:47 PM
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#6
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Senior Member Group: Members Posts: 685 Joined: 30-November 11 From: Louisville, Ky Member No.: 13,838 Region Association: South East States |
The signal is a pulse, nd28 is likely correct - you will need an O-scope.
Swap the injectors, might be a stuck injector. If that doesn't work, swap the 1 and 3 connectors and see if 1 fires. If it does, it's the signal on 1. I suspect spark. |
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| Spoke |
Dec 5 2016, 09:01 PM
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#7
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Jerry Group: Members Posts: 6,976 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None
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You can use a voltmeter if you integrate the pulse width over the period from one pulse to another. If you assume the pulse width is 1/10th of the period, then the average dc voltage measured would be 1/10th of the pulse voltage or .28x10=2.8v.
Best to check the other injector voltages. You could Swap injectors and see if the failure follows the injector or is the connector. |
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| timofly |
Dec 8 2016, 08:16 PM
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#8
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Member Group: Members Posts: 164 Joined: 21-February 09 From: VA Member No.: 10,082 Region Association: MidAtlantic Region |
QUOTE(Spoke @ Dec 5 2016, 10:01 PM) You can use a voltmeter if you integrate the pulse width over the period from one pulse to another. If you assume the pulse width is 1/10th of the period, then the average dc voltage measured would be 1/10th of the pulse voltage or .28x10=2.8v. Best to check the other injector voltages. You could Swap injectors and see if the failure follows the injector or is the connector. The failure follows the injector. Looking for replacement but local guy says $310 for one. I have four old ones that have been in a bag since I hauled the car out of a junkyard in 2006. I've tried two so far, and it's definitely better but still not right. |
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| Frankvw |
Dec 9 2016, 02:54 AM
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#9
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working on my first 914 ! Group: Members Posts: 651 Joined: 13-April 16 From: Holland, the Netherlands Member No.: 19,896 Region Association: Europe |
Hi Timofly, you guys have Mr.Injector (*) in USA, I read good stories about them, only 17,50 dollars per injector...I wish we had that service/price over here.... just drop all 4 there plus 2 from your spare ones to have good spares as well.
(*)Of course there are many similair services/companies, but I just picked one that I see sometimes mentioned on forums. |
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| timofly |
Dec 9 2016, 10:38 AM
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#10
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Member Group: Members Posts: 164 Joined: 21-February 09 From: VA Member No.: 10,082 Region Association: MidAtlantic Region |
QUOTE(Frankvw @ Dec 9 2016, 03:54 AM) Hi Timofly, you guys have Mr.Injector (*) in USA, I read good stories about them, only 17,50 dollars per injector...I wish we had that service/price over here.... just drop all 4 there plus 2 from your spare ones to have good spares as well. (*)Of course there are many similair services/companies, but I just picked one that I see sometimes mentioned on forums. Frank, thanks. I have already sent them a note. Good tip though. |
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