D jetronic problems |
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D jetronic problems |
Edchina |
Mar 25 2013, 01:30 PM
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#1
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Newbie Group: Members Posts: 17 Joined: 18-March 13 From: Bremen/New Orleans Member No.: 15,665 Region Association: None |
Hi,
I have been troubleshooting the D jetronic on my 914-4 1975, 2 liter engine. Bought a fine car, but the previous owners messed the D jetronic system up. Vacuum hoses were missing, throttle switch was new but not adjusted, fuel lines clogged up and temperature sensors not connected. Here is what I have done so far: -Overhauled fuel tank. -Installed new fuel pump and filter. -Checked fuel pressure at the regulator (2 bar) -Changed all vacuum hoses (no leaks) -Adjusted valves -Checked trigger contacts (looked like new) -Checked dwell angle (46 deg.) and breaker points -Adjusted timing -Adjusted throttle switch -Compression test showed 121 Psi on all cylinders -Installed new pressure sensor after the old one failed during vacuum test (membrane cracked) -checked electric system with Bosch tester -checked electric system manually Problem: Engine is running rich and the idle is high (around 1200 RPM). By installing a vacuum gage between pressure Manifold and pressure sensor the vacuum changes (-0.65 ~ -0.5 Bar) rather than being constant. Adjusting the bypass screw at the trottle does not change the idle much. The CO value is around 4% and does not change much when adjusting the potentiometer at the control unit. My question is what is causing the vacuum to rise and fall causing the RPM's to increase and decrease by 400 RPM. Thanks |
76-914 |
Mar 25 2013, 02:47 PM
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#2
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Repeat Offender & Resident Subaru Antagonist Group: Members Posts: 13,647 Joined: 23-January 09 From: Temecula, CA Member No.: 9,964 Region Association: Southern California |
What Curt said (IMG:style_emoticons/default/agree.gif) Also, you bought a new MAP or used MAP sensor? If used or rebuilt check it out. Do you know about this site....... http://members.rennlist.com/pbanders/ One other thing......Didn't see a condenser on your list. That's not the problem, though. Two of the most overlooked vac leaks I see are the AAR and Decel valve. Did you change the rubber hoses on intake runners and the injector seals. Be sure the injectors are seated by hand before tightening that 10mm nut down. Just because that gasket is new doesn't mean it sealed. Hang in there, you'll find it. Lean conditions are quite often the result of a vacuum leak.
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