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> Fuching DJet issues, Running out of things to try
rjames
post Jun 12 2019, 12:19 AM
Post #1


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From: Shoreline, WA
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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?
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Posts in this topic
rjames   Fuching DJet issues   Jun 12 2019, 12:19 AM
GregAmy   Just a note on "known good MPS"...I was ...   Jun 12 2019, 05:23 AM
BeatNavy   Based on hunting idle it sounds like you're ru...   Jun 12 2019, 06:00 AM
rjames   Based on hunting idle it sounds like you're r...   Jun 12 2019, 11:13 AM
BeatNavy   What is the T1/ambient air sensor located? It...   Jun 12 2019, 02:33 PM
Bleyseng   I can loan RichD my wideband to check the AFR on y...   Jun 12 2019, 07:53 AM
rjames   I just installed a wideband sensor on my car but h...   Jun 12 2019, 11:04 AM
IronHillRestorations   Trigger points   Jun 12 2019, 05:18 PM
914_teener   Post a pic of your engine compartment. Are you ru...   Jun 12 2019, 06:12 PM
rjames   I'm using the decal valve. 75 2.0 with smog r...   Jun 12 2019, 06:19 PM
BeatNavy   If you disconnect the T1 sensor I just want to see...   Jun 12 2019, 06:45 PM
rjames   If you disconnect the T1 sensor I just want to se...   Jun 12 2019, 08:34 PM
JeffBowlsby   Its frequently the case when the MPS is going bad....   Jun 12 2019, 11:08 PM
rjames   Its frequently the case when the MPS is going bad...   Jun 13 2019, 12:08 AM
sixnotfour   food for thought http://www.914world.com/bbs2/inde...   Jun 13 2019, 01:07 AM
rjames   food for thought http://www.914world.com/bbs2/ind...   Jun 13 2019, 08:58 AM
rjames   Ok, more testing = more results. Distributor cani...   Jun 13 2019, 01:47 PM
BeatNavy   Good news is it sounds like you confirmed the cond...   Jun 13 2019, 02:03 PM
jagalyn   Found this series of D-Jet Articles online. https...   Jun 15 2019, 12:29 PM
saigon71   You are running lean at idle. Try truning the ECU...   Jun 16 2019, 06:12 AM
ChrisFoley   my 914 idle hunts the least with mixture knob ...   Jun 16 2019, 07:28 AM
JeffBowlsby   A lean condition may also be corrected by increasi...   Jun 16 2019, 07:58 AM
rjames   The idle hunt isn’t a slight hunt. It’s from 1...   Jun 16 2019, 01:44 PM
rjames   Okay, problem remains after replacing the fuel fil...   Jun 20 2019, 08:34 PM
JeffBowlsby   No effect during adjusting the air screw points to...   Jun 20 2019, 09:16 PM
rjames   No effect during adjusting the air screw points t...   Jun 20 2019, 10:45 PM
JeffBowlsby   If the air screw is fully closed, the engine shoul...   Jun 20 2019, 11:15 PM
rjames   If the air screw is fully closed, the engine shou...   Jun 20 2019, 11:31 PM
jcd914   If the air screw is fully closed, the engine sho...   Jun 21 2019, 12:40 AM
Spoke   Why do the rpms drop so much when hooking up the ...   Jun 21 2019, 06:05 AM
BeatNavy   I think you may also want to verify your vacuum li...   Jun 21 2019, 05:28 AM
rjames   AAR is good. Eschewing vacuum leaks for a second...   Jun 21 2019, 03:55 PM
914sgofast2   Sounds like the source of your vacuum leak is the ...   Jun 21 2019, 07:42 PM
rjames   Playing with it again, now it only idles high whe...   Jun 21 2019, 09:34 PM
914sgofast2   In my experience a vacuum leak causes the idle to ...   Jun 22 2019, 10:46 AM
Rand   I'd say not dizzy. The thing about the dizzy ...   Jun 22 2019, 01:05 PM
rjames   I'd say not dizzy. The thing about the dizzy...   Jun 22 2019, 05:09 PM
rjames   Any chance this is a compression issue?   Jun 22 2019, 09:59 PM
Rand   Any chance this is a compression issue? It ran f...   Jun 23 2019, 01:17 AM
rjames   Updates and new info: Installed new coil and 123 ...   Jul 5 2019, 07:21 PM
BeatNavy   Just to be clear, I believe there's only one s...   Jul 6 2019, 04:36 AM
rjames   Stock 2.0 liter with correct/matching FI parts. MP...   Jul 6 2019, 08:59 AM
914_teener   Stock 2.0 liter with correct/matching FI parts. M...   Jul 15 2019, 10:06 AM
rjames   Stock 2.0 liter with correct/matching FI parts. ...   Jul 17 2019, 12:27 AM
rjames   Beyond frustrated now. Started again from the beg...   Jul 14 2019, 07:42 PM


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