D_jet trouble shooting question - car is home, journey continues, June, update- no more problem-- the fix was simple.... |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
D_jet trouble shooting question - car is home, journey continues, June, update- no more problem-- the fix was simple.... |
DRPHIL914 |
Dec 15 2014, 12:39 PM
Post
#1
|
Dr. Phil Group: Members Posts: 5,767 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
OK. car has been in shop for the past week, and today Bob spent several hours on it but what he found was when the MPS is disconnected from the vac hose it will idle and run, but when it gets connected it goes immediately lean and dies, and will not run with that hose on there- the MPS holds Vac no loss of pressure, but that doesnt mean that its not bad.
1- i thought that if an MPS went bad it defaulted rich? but when this is getting vac it goes lean right away and dies. but it will run and idle with out the vac , the AF meter then shows 9.8-10.2 or so which is of course rich but not flooding out. so the question is why is it going lean when hooked up? when this issue started about 2 weeks ago, it had been running just fine and all of a sudden it quit running. 2. could there be another issue we dont see that would be making it way to lean other than the MPS? might need to test another MPS, my 2nd one i just bought from someone here and it has never been opened but will not hold vac (slowly looses vac pressure) so it probably need to be opened and re-sealed. not a good candidate to trouble shoot with. ------ FYI- 1975 d-jet 2.0. newer wiring harness , CHT is newish(replaced 2 months before this issue started and was running perfect at that time) |
DRPHIL914 |
Dec 17 2014, 01:00 PM
Post
#2
|
Dr. Phil Group: Members Posts: 5,767 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
D-Jet Trouble Shooting On the MPS check the ohms between: Terminal 7 & 15 = 90 ohms Termianl 8 & 10 = 350 ohms Check each terminal to the MPS case for ground short. Get the car home. you can do all the testing with an ohm meter, well most of it. Rich i went over and tested the MPS at lunch time- holds vac, and T7-15 was 92ohms, and T 8-10 was 340. (IMG:style_emoticons/default/confused24.gif) so that means its good, right? i also have 2 other s and one does not hold vac perfectly but the values were the same on it, 92 and 335. i think from here i can still test a known working MPS but i need to go thru the harness like Rich suggested since it seems like it may be something else making it super lean and taking the hose off the mps makes it default rich so it will run -? i kind of suspect either the new CHT went bad or that circuit did, either way this is what thact could cause. hm.... |
SLITS |
Dec 17 2014, 02:19 PM
Post
#3
|
"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
i went over and tested the MPS at lunch time- holds vac, and T7-15 was 92ohms, and T 8-10 was 340. (IMG:style_emoticons/default/confused24.gif) so that means its good, right? The only thing you didn't state was whether you tested each of the terminals to the MPS case (short to ground). The ohms are in specification so the coils inside are good. |
DRPHIL914 |
Dec 17 2014, 02:22 PM
Post
#4
|
Dr. Phil Group: Members Posts: 5,767 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
i went over and tested the MPS at lunch time- holds vac, and T7-15 was 92ohms, and T 8-10 was 340. (IMG:style_emoticons/default/confused24.gif) so that means its good, right? The only thing you didn't state was whether you tested each of the terminals to the MPS case (short to ground). The ohms are in specification so the coils inside are good. i did but did not know what i should be reading on this. i tested all 4 and the meter stayed at 1, ( sorry for my ignorance, i forget which is good - but it showed 1) |
Lo-Fi Version | Time is now: 23rd May 2024 - 09:30 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |