Fuching DJet issues *SOLVED*, Running out of things to try |
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Fuching DJet issues *SOLVED*, Running out of things to try |
rjames |
Jun 12 2019, 12:19 AM
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#1
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I'm made of metal Group: Members Posts: 3,910 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest |
Last summer all of a sudden my car wouldn’t stay running. If I could get it started the idle would hunt and the car would die unless I kept on the gas. Lack of power at times. All somewhat erratic.
Found that the MPS wouldn’t hold vacuum. Replaced the bad mps with a known good one. Car idles high when cold (higher than I think it should ~1600 rpm) so AAR is good, then when it warms up idle hunts from ~900rpm to the point where it almost dies unless I open the throttle body bleed screw quite a bit and turn the ECU knob just a few clicks away from full clockwise. So I did the following hoping to fix the issue: Replaced all vac hoses including intake runner to plenum hoses. New intakecrunner gaskets Verified plenum isn’t leaking New throttle body gasket Installed NOS throttle body Rebuilt the distributor New condenser Rebuilt injectors and flow tested New fuel lines Fuel pump is less than 2 years old Set timing and dwell with advance disconnected New CHT (resistance reads 1.7 w/engine off @70 degrees in the garage) Calibrated the TPS, even unplugged it to take it out of the equation, didn’t change anything. ECU matches the MPS (both correct part #s for a ‘75 2.0) Tried a known good ECU from a ‘74, no change. Feels like the MPS needs to be calibrated...but then again, these are all the same symptoms I had with the old bad mps. Replacement mps is from a Jeff B and was tested, but I haven’t retested it to see if it’s holding vacuum. (Don’t have the necessary tool, but maybe that’s the next step) Help! What am I missing? |
JeffBowlsby |
Jun 20 2019, 11:15 PM
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#2
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914 Wiring Harnesses Group: Members Posts: 8,470 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None |
If the air screw is fully closed, the engine should shut down because it would have no air for the combustion process. When air is still getting into the intake from somewhere, it keeps the engine running when the air bleed screw is closed. This is 'free air' or uncontrolled air - air that should not be getting into the intake. A vacuum leak.
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rjames |
Jun 20 2019, 11:31 PM
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#3
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I'm made of metal Group: Members Posts: 3,910 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest |
If the air screw is fully closed, the engine should shut down because it would have no air for the combustion process. When air is still getting into the intake from somewhere, it keeps the engine running when the air bleed screw is closed. This is 'free air' or uncontrolled air - air that should not be getting into the intake. A vacuum leak. Why do the rpms drop so much when hooking up the distributor? The RPMs don’t go above 1000 when the vac line is connected. |
Spoke |
Jun 21 2019, 06:05 AM
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#4
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Jerry Group: Members Posts: 6,972 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
Why do the rpms drop so much when hooking up the distributor? The RPMs don’t go above 1000 when the vac line is connected. So a question could be what is the vac line to the dizzy doing to the timing? It obviously changes the timing such that when the vac line is disconnected and plugged the idle stays at 1600RPM. When you plug the vac line and idle stays at 1600RPM, have you tried adjusting the timing to reduce the RPM? How did you verify there are no vac leaks? Did you spray carb cleaner on everything with the engine running or do the smoke test? Is the AAR closing when warm? |
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