Head Scratcher...Only 2 Injectors Firing, 74 2.0 (D-Jet) |
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Head Scratcher...Only 2 Injectors Firing, 74 2.0 (D-Jet) |
BMartin914 |
Apr 12 2007, 07:29 PM
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#1
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||| Group: Members Posts: 1,408 Joined: 30-May 04 From: Oregon Member No.: 2,128 Region Association: Pacific Northwest |
I have a 74 2.0 w/ d-jet that is only firing 2 of the 4 injectors.
I have already: -swapped connectors on each side, problem moves with connectors -swapped trigger points, problem remains unchanged -checked continuity throughout system (injectors, trigger points, etc.) -case ground terminals brand new, female ground connectors have been cleaned Any suggestions (ideas) as to what may be causing this condition? I feel like I have been through most if not all of the appropriate troubleshooting procedures and still can't seem to put my finger on the problem. I have got to be missing something small... |
911quest |
Apr 12 2007, 07:38 PM
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#2
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Member Group: Members Posts: 277 Joined: 26-March 06 From: Louisville Ky Member No.: 5,773 Region Association: South East States |
On the two that are inop. have you checked for voltage check it across the connector and each wire seperatly
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r_towle |
Apr 12 2007, 07:45 PM
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#3
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Custom Member Group: Members Posts: 24,591 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
suspect the wiring harness, then the relay board, then the computer.
For the wiring harness, put a flashlight bulb on the connector (rig it up) turn car on, move throttle body...see if you can get it to light up. Check the lightbulb on the known good ones. If it lights, its an ignition problem. If not, you may have a broken wire or two inside the 35 year old harness, it happens. Rich |
john rogers |
Apr 12 2007, 08:26 PM
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#4
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Senior Member Group: Members Posts: 1,525 Joined: 4-March 03 From: Chula Vista CA Member No.: 391 |
Injector point, replace them with new only.
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swl |
Apr 12 2007, 09:59 PM
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#5
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
I agree with John. Trigger points are about the only thing I can think of that would effect 2 injectors - which 2 are not working?
You can check the trigger points and harness by pulling the connector off the ecu and using an ohm meter across 12 - 21 and 21 - 22. Spin the distributor and you should see the points opening and closing. If that proves good try pins 3,4,5 and 6 to ground. These are the runs to the 4 injectors. Should be be low resistance (coil of the injector - I measured about 3 ohms) |
Dave_Darling |
Apr 12 2007, 10:23 PM
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#6
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914 Idiot Group: Members Posts: 14,991 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
As the others have asked: Which two injectors?
The trigger points pair them up diagonally. I think the grounds are paired left and right. How are those grounds, anyway? --DD |
boxstr |
Apr 12 2007, 10:26 PM
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#7
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MEMBER:PACIFIC NORTHWEST REGION Group: Members Posts: 7,522 Joined: 25-December 02 From: OREGON Member No.: 12 Region Association: Pacific Northwest |
Does'nt that year have the injector ballast resistors? If yes, check the wires to the resistors, could be broken.
CCLIN914NATION |
JeffBowlsby |
Apr 12 2007, 10:26 PM
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#8
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914 Wiring Harnesses Group: Members Posts: 8,533 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None |
Which two injectors...its important
If cyl 1-2 or 3-4 are not working then it may be grounds, injector pairs on each side of the engine share a common ground in the harness If cyl 1-4, or 2-3 (diagonal cylinders) are out, then its trigger points because those are the two injector groups they control. I suppose it could also be an ECU problem, but those seldom fail. Bad injector coils...maybe? Injectors simply plugged and need cleaning? A kink in the fuel line serving one set of injectors? |
BMartin914 |
Apr 12 2007, 11:02 PM
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#9
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||| Group: Members Posts: 1,408 Joined: 30-May 04 From: Oregon Member No.: 2,128 Region Association: Pacific Northwest |
Injectors are diagonally-opposed. Either 1 and 4 or 2 and 3 depending on which direction the connector on the trigger points is facing (21,12,22 or 22,12,21).
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TROJANMAN |
Apr 12 2007, 11:05 PM
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#10
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Looks nice in pictures......... Group: Members Posts: 5,271 Joined: 5-March 04 From: Colorado Member No.: 1,753 Region Association: None |
ben,
didn't you have similar problems a year ago? |
BMartin914 |
Apr 13 2007, 08:15 AM
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#11
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||| Group: Members Posts: 1,408 Joined: 30-May 04 From: Oregon Member No.: 2,128 Region Association: Pacific Northwest |
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jasons |
Apr 13 2007, 08:32 AM
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#12
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Jackstand Extraordinaire Group: Members Posts: 2,002 Joined: 19-August 04 From: Scottsdale, AZ Member No.: 2,573 Region Association: None |
If its the diagonal pairs, its got to be your trigger points. The contacts may look good, but the little dudes that ride on the dizzy shaft wear out. When they wear out, the contacts don't open and close.
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TROJANMAN |
Apr 13 2007, 09:29 AM
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#13
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Looks nice in pictures......... Group: Members Posts: 5,271 Joined: 5-March 04 From: Colorado Member No.: 1,753 Region Association: None |
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BMartin914 |
Apr 13 2007, 01:47 PM
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#14
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||| Group: Members Posts: 1,408 Joined: 30-May 04 From: Oregon Member No.: 2,128 Region Association: Pacific Northwest |
He's helping too. I will look forward to seeing you then. |
pbanders |
Apr 13 2007, 01:56 PM
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#15
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Senior Member Group: Members Posts: 939 Joined: 11-June 03 From: Phoenix, AZ Member No.: 805 |
If you've swapped in known good trigger points, and checked the injectors and harness by measuring the resistance to ground of each injector at the ECU plug, then your ECU is bad. There are two output driver circuits in the ECU that each drive two injectors, most likely, one of yours is dead, probably one or both of the two Ge power transistors is out.
Oh, just thought of one more possibility - check you trigger contact point circuit at the ECU plug. You might have a wiring fault to the TC's. |
swl |
Apr 13 2007, 09:32 PM
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#16
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Senior Member Group: Members Posts: 1,409 Joined: 7-August 05 From: Kingston,On,Canada Member No.: 4,550 Region Association: Canada |
Either 1 and 4 or 2 and 3 depending on which direction the connector on the trigger points is facing (21,12,22 or 22,12,21). My bet is now squarely on the trigger points themselves. One side is not closing. The ECU is getting the signal for one pair when it is connected one way down 12. When he flips it around the other way it is getting the signal down 22. That pretty much confirms the harness and the ECU. |
BMartin914 |
Apr 13 2007, 10:34 PM
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#17
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||| Group: Members Posts: 1,408 Joined: 30-May 04 From: Oregon Member No.: 2,128 Region Association: Pacific Northwest |
The trigger points, injectors and ecu are all fine. I had to remind myself to spin the dizzy and operate the throttle at the same time. Obviously in a stationary position the system is only operating 2 injectors at a time.
The car still has a poor running condition that I *believe* to be a faulty MSD 6AL. For some reason it is causing the car to run like crap (will not idle and misses like crazy). Eliminate it and the car runs fine. (IMG:style_emoticons/default/huh.gif) Thanks for all of the input guys. |
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