 Testing D-Jet FI, Got a few questions |
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| Spoke |
 Apr 6 2008, 11:25 PM
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#1
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Jerry  Group: Members Posts: 7,084 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None 
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I'm prepping a 1.8L engine for the red 914 to replace the leaky 1.7L with one cylinder low on compression that's in the car. The installed engine has dual IDF40 Webers on it now.
When the PO bought the car, it had FI and was not running or was not running good. He took it to a local 356 shop and they pulled the FI and put on a single Weber just to get the car running. When the 356 shop moved locations, I received a box full of FI stuff from the car. My goal is to test each component and get the FI running again. I've tested most of the components including the distributor contact points, temp senders, throttle switch, and MPS. For the MPS, I just tested for vacuum leakage. It was leaking pretty badly so I took it apart and sealed it. I'll test it when I test the FI brain. I got a few questions that I'll get to in a few posts. First question is will it damage injectors if they are operated w/o fuel pressure? I plan to run the brain with injectors dry. Here's all the stuff I received: Attached image(s) 
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| Spoke |
Apr 7 2008, 12:35 AM
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#2
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Jerry Group: Members Posts: 7,084 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None
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Below are some scope traces of distributor contacts (trace 1, top trace) and #1 injector voltage (trace 2, bottom trace). The top trace shows a period of 150ms. This equates to 1/0.150 x 2 x 60 = 800 RPM. Each trace is 5V/div vertical and 20ms/div horizontal.
For the following trace, the MPS has no vacuum and the CHT sender is open circuited. Note the very long injector pulses (trace 2). Question: Note the injector voltage (trace 2). The injector voltage spikes up to 12 volts then settles to about 5V. Is this normal? I would have expected the entire spike to be 12V. The injectors seem to be operating even with the low voltage.  Same speed, 800 RPM with the CHT sender connected and cold (3500 ohms; room temp). No vacuum on the MPS. Note the injector pulse is shorter.  Same speed, 800 RPM with the CHT sender connected and hot (1000 ohms). No vacuum on the MPS. Injector pulse even shorter. Warmed up engine condition.  Same speed, 800 RPM with CHT sender connected and hot, and MPS in vacuum. This is the normal warm engine idling condition with MPS in vacuum.  |
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Posts in this topic
Spoke Testing D-Jet FI Apr 6 2008, 11:25 PM
Spoke To test the brain, I made a temporary harness to g... Apr 6 2008, 11:39 PM Spoke Here's the brain with all its components conne... Apr 7 2008, 12:00 AM Spoke The drill+distributor worked well to show that the... Apr 7 2008, 12:19 AM swl wow - creative stuff! keep it coming.
:popc... Apr 7 2008, 06:27 AM root Spoke,
I haven't scoped the injector voltage ... Apr 7 2008, 07:38 AM Bleyseng looks like its working but I would junk the inject... Apr 7 2008, 09:23 AM freezing14 thats a really great set up you have there , but I... Apr 7 2008, 06:31 PM Spoke Root,
Thanks for the info and link. Excellent rea... Apr 8 2008, 03:21 PM Spoke Now to test the throttle contacts.
I did the open... Apr 8 2008, 03:27 PM Spoke Still checking decel operation. With throttle clos... Apr 8 2008, 03:32 PM Spoke OK, now I don't know how to interpret this. My... Apr 8 2008, 03:44 PM
r_towle two things.
Your TPS is out of adjustment, or its ... Apr 8 2008, 09:38 PM |
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