Parts Catalog Accessories Catalog Tech Info Tech Forums
 
  Search our site:    
 Cart  | Project List | Order Status | Help    
  We salute a legendary member of the community.
Thank you for selflessly sharing your wisdom with us...
Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > Porsche 924/944/968 Technical Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
Hard cold start

Being a newbie, I've been taking a crash course on all things 944. Here's my problem: My 1984 is very difficult to start when sitting overnight. Once warmed up, she starts and runs fine. The following items have been performed:

1. Fuel pressure checked. 40psi once engine turns over,
2. Fuel check valve tested fine,
3. DME/fuel pump relay was replaced,
4. DME temp sensor was replaced,
5. Aux air regulator replaced,
6. All vacuum lines checked,

What's interesting is that when its hot outside, she usually starts fine however; the colder the ambient temperature, the more difficult the start. The engine will spin, catch, then die. Sometimes it takes me 5 or more minutes for the car to actually fire up and when she does, she sputters for a few seconds then settles in the correct idle speed. I've researched the forums and (I think) tried everything but obviously, there is a gremlin somewhere lurking about. I appreciate any help and thanks!
Old 08-18-2012, 06:47 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #1 (permalink)
yarfk
 
kfray's Avatar
 
Join Date: Dec 2009
Location: Binghamton New York
Posts: 355
Garage
I would run these fuel pressure test.
http://www.clarks-garage.com/pdf-manual/fuel-01.pdf
__________________
------Keith------kfray------yarfk-------
87 944 NA stock 116k
06 Honda Ridgeline 83k
10 Vibe 2.4 AWD (Wife's)
Retired My week consist of Saturdays and Sundays
Old 08-18-2012, 07:54 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #2 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
Thanks.
I'll try your recommendation.
Old 08-18-2012, 12:17 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #3 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
I've been away for a few days but tested fuel pressure at the specified intervals today; everything checks out. However, the car still refuses to start... Help.
Old 08-26-2012, 05:56 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #4 (permalink)
Toofah King Bad
 
Rasta Monsta's Avatar
 
Join Date: Oct 2006
Location: International Conference of Sports Car Clubs
Posts: 3,161
Garage
Check wiring to speed/ref sensors.
__________________
» 1980 931 - Got boost? ♦ 1987 924S - Pro44 ♦ 1987 924S - Junkyard score «

"DETERMINATION. Sometimes cars test us to make sure we're worthy. Fix it." - alfadoc
Old 08-26-2012, 06:45 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #5 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
Thanks!
It's ironic that you'be mentioned that because that's what I checked this evening.
The wires appear to be fine but the sensor tips did have a fair amount of debris on them upon removal/inspection. Here's the funny part; I dropped one of the sensor bolts by accident and ended up having to jack the front end to chase the bolt. It fell into the clutch bell housing and was fairly easy to grab from under the car. What's interesting is while I was down there, I snooped around a bit and found the vacuum line, running to the aux air regulator, was entirely severed as well as extremely brittle at the "Y". I'm planning on fixing it tomorrow and cross my fingers. As previously mentioned, I have to try to start the car after it's been sitting overnight so I'm being cautiously optimistic that the leaking vacuum line is the culprit. I'll post my findings after repairing this issue. Thanks again!
Old 08-28-2012, 08:00 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #6 (permalink)
Worst Mechanic You Know
 
Gawernator's Avatar
 
Join Date: Apr 2012
Location: East Bay Area, California
Posts: 5,093
Garage
Coincidental, not ironic! Hope you fix the issue. Vacuum line would make some sense.
Old 08-28-2012, 08:16 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #7 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
I guess both terms could be used...
Well, I replaced the vacuum hose and its still happening so the list of potential culprits is getting smaller. I need to research how to test the fuel injectors for proper operation. Is there a ohms test?
Old 08-29-2012, 03:12 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #8 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
An update: I tested the resistance value on the fuel injectors; all tested exactly 2.4 ohms. I then checked all cable connections once again and this is where I found something interesting. The bracket securing both reference sensor cable connectors appeared in good shape, however; the bottem connectors (male and female) were not totally mated together. I verified that they snapped together and were secured tightly on the bracket and the car started on the first try! I will attempt to start her up in the morning as the colder air usually will cause starting issues. Will continue to report my findings...
Old 08-30-2012, 08:46 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #9 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
Well, I work up early this morning and...
she refused to start so I'm at square one again. I think I may need some professional help (mostly the car but maybe me too). Any other ideas?
Old 08-31-2012, 06:49 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #10 (permalink)
Registered User
 
Join Date: May 2010
Location: Erie, PA
Posts: 237
Fuel injection temp sender? As I understand it, it acts like a choke during cold starts.
__________________
86NA944
Old 08-31-2012, 07:54 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #11 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
Thanks.
I've already replaced the tenp sensor.
Old 09-01-2012, 05:14 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #12 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
I meant temp sensor...
Old 09-02-2012, 12:29 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #13 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
So this morning, same thing... This time, I injected some starter fluid just before the intake manifold, tightened everything up and she started right away! My question is: is my MAF out of adjustment or is something worse going on? Once she starts, the car runs great. Thanks for any input!
Old 09-03-2012, 02:25 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #14 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
Oops again...
I meant Air Flow Meter; I'm still in the process of learning this car.
Old 09-03-2012, 02:44 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Aug 2012
Posts: 14
replaced the air flow meter they let go all the time .
Old 09-13-2012, 05:59 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #16 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
I'm going to replace the fuel check valve tomorrow. It appears that I'm losing fuel pressure when resting for a few hours. The AFM was replaced by the PO so I want to examine the lower cost items before this. Thanks!
__________________
1984 944 NA, constant tinkering
Old 09-13-2012, 07:56 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #17 (permalink)
Patrick
 
pfarah's Avatar
 
Join Date: May 2012
Location: Plymouth MA
Posts: 719
Garage
Well I've replaced the fuel check valve and still no dice...
I also tested the fuel regulator for vacuum leaks; I applied about 15psi of vacuum with no drop (@3-4 min). I believe my next option will be to remove the fuel rail and thoroughly clean all components. I've noticed a very small stain around injector #1's base so seal replacement is in order. I don't think that would prevent a cold start but it's on my list.
Any other suggestions? Thanks!
__________________
1984 944 NA, constant tinkering
Old 09-15-2012, 07:12 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #18 (permalink)
Registered User
 
Join Date: Nov 2004
Location: Alberta, Canada
Posts: 2,615
Maybe one or more of your injectors is not closing properly. If this happens the fuel pressure drops overnight as the injector(s) leak. It's amazing what a good cleaning will do for the injectors. For you Yanks, Witchhunter is the place to send them. Or just get a new set.
__________________
'84 944 - new-to-me DD!
'83 944 - looks like ass, runs like horse - in primer.
'82 931 - roadster project - forever incomplete.
'80 924 - spouse's yellowjacket.
Some wrecks and a 924 racer.
Old 09-15-2012, 08:34 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #19 (permalink)
Worst Mechanic You Know
 
Gawernator's Avatar
 
Join Date: Apr 2012
Location: East Bay Area, California
Posts: 5,093
Garage
I'd rebuild... OEM injectors are pricey
Old 09-15-2012, 08:51 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #20 (permalink)
Old 09-15-2012, 08:51 AM
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 11:30 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.