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: 3,949 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? |
BeatNavy |
Jul 6 2019, 04:36 AM
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#2
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
Just to be clear, I believe there's only one setting (not adjustment) for TPS - it's either calibrated correctly or it is not. It is easiest to do it by removing it, but I have done it while still mounted on TB/plenum. I don't think that's your issue.
What curve are you using for the 1-2-3, and are you using advance or retard on the port? FWIW, once I installed the 1-2-3 I noticed that the idle speed was very sensitive to fuel mixture compared to the other dizzy that came with this engine (which was not correct, it turns out). With the 1-2-3 it does idle rock steady, but no matter what I do I really can't get idle below 1000 even with bypass screw all the way in. I try to run idle A/F around 13.5 to 14.5 to keep it steady around 1000. If I go richer than that I get idle closer to 1100/1200, IIRC. Much leaner and it will start to hunt. I also chased vacuum leaks for a long time, to the point of swapping out plenums and trying to spray carb cleaner everywhere, but I never found anything. I can't recall, is this stock 2.0 or 2056? If stock, and the MPS holds a pretty steady vacuum and is correct for your ECU, then that shouldn't be the issue. |
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