Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
Another "HOT START" problem

Ok I know this has been discussed before but I can't seem to solve this problem.
Starts and runs great cold. If I stop and start it right away warm no problem, but let it sit for 20 min. and I have to crank and crank to fire it up and then runs great.
Warm system pressure is bleeding down to fast. I have replaced the fuel accumulator twice, coil,cold start valve, WUR, front fuel pump check valve. Injectors were cleaned and tested which Chris at Turbo Kraft assures me are not the problem and also thinks not a fuel head issue as it runs so great when it runs.
I'm missing something here. Any idea's?
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-29-2010, 05:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
As an update I have make no further changes other then putting some miles on it and it seems a little better on the hot starting. Not perfect but better.......something cleaning itself out maybe?
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-30-2010, 02:53 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
mark houghton's Avatar
 
Join Date: Jul 2008
Location: Central Washington State
Posts: 3,777
New plugs...just to rule them out anyway? Check your ignition timing lately? Could be your CDI is starting to fail, getting heat soaked when sitting hot. Just some thoughts, no concrete answer yet.

Mine starts up in the first 1/2 second of cranking when hot.
__________________
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.

Last edited by mark houghton; 05-30-2010 at 04:09 PM..
Old 05-30-2010, 04:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
New plugs, cap, rotor, wires, fuel filter. Timing is checked.
Runs great just won't start quick when hot.
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-30-2010, 04:14 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
mark houghton's Avatar
 
Join Date: Jul 2008
Location: Central Washington State
Posts: 3,777
OK, so you've spent a zillion bucks replacing everything you can touch. Are you running with the stock CDI, or perhaps MSD or Permatune aftermarket setups? There isn't much left to look at other than maybe a weak spark when she's hot. Not much help....sorry. Sit tight, others will surely respond.
__________________
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 05-30-2010, 04:53 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
Stock CDI Mark. Ruled that out based on how well it runs hot when it runs but maybe I'm looking at it wrong. I should spend more time with my test gages but man these things are not easy to work on.
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-30-2010, 05:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
mark houghton's Avatar
 
Join Date: Jul 2008
Location: Central Washington State
Posts: 3,777
Quote:
Originally Posted by Hirevtuner View Post
Stock CDI Mark. Ruled that out based on how well it runs hot when it runs but maybe I'm looking at it wrong. I should spend more time with my test gages but man these things are not easy to work on.
Things gain temperature for a few minutes after engine shutdown, with no air circulating to cool stuff off. Residudual heat just bakes the engine even when she's "cooling down". I'm still thinking you've got a $hit spark when hot, but I'm just theorizing at this point. Know anybody with a CDI you can borrow, to rule it out?
__________________
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 05-30-2010, 05:29 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Tinkering Pays!!
 
mooney265's Avatar
 
Join Date: Sep 2008
Location: New Orleans
Posts: 1,365
Garage
I would try to enrichen your idle mixture and/or possibly lower your cold CP. I had a similar problem, then did just that [for another reason] and accidently fixed the problem... Turns out, it was starving for fuel on warm re-starts...

Just a thought...
__________________
LIVN80S - - Red '79 Porsche 930 Steel Slant Nose Conversion [in 1987] w. 46k miles 3.3L; 964 Cams; K27HF @ 1.0 BAR, with Garrettson Intercooler; Rarly Zork; CIS Flowtech Fuel Head & BL-WUR.
Old 05-30-2010, 05:29 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
full quack's Avatar
 
Join Date: Apr 2007
Location: Seattle-ish
Posts: 1,170
Send a message via Yahoo to full quack
Ok, I'll chime in and say, just because your injectors were cleaned does not mean that one is still not leaking down when shut off hot. I chased that gremlin for 2 years, I too did everything you have done.
Then out of pure frustration, I finally pulled the injectors AGAIN and had them checked and cleaned AGAIN. Finally now the car starts any time , anywhere, any temperature, any time sitting. Less than 2 revolutions and she fires right up.
My car did that very exact thing from the first day I bought it. I changed the check valves, the pumps, full tune up, full wires, BRL adj. warmup regulator, 2 new coils, new distributor wire, plugged this hose-plugged that hose, adjusted this-adjusted that, blah blah, blah.
Try the injectors again my friend.
Mark
Old 05-30-2010, 09:49 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered Driver
 
Helmsy's Avatar
 
Join Date: May 2008
Location: South Australia
Posts: 281
Garage
You said you have replaced the WUR. With a BL WUR? Have you got the gauges to check your fuel pressures?
__________________
Ben
'85 930 - Black on Black
'95 993 Turbo - Silver
Old 05-30-2010, 10:07 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
Join Date: Apr 2008
Posts: 138
same hotstart problem here. after hotstart the idle afrs are far too lean, around 17. cruising afrs are fine. coldstart idles are fine. does your car have an afr gauge installed? my speculation too is that after sitting and heatsoaking, the fuelpressure leaks away somewhere.
__________________
Joe
---------------------------
91 C2 Turbo, K27 7006, headers, Greddy EBC, 1bar
Old 05-30-2010, 11:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
Thanks for the input.
I show a drop in warm fuel pressure between the fuel head and WUR, in fact it will zero out in about 5 min after bringing it to full pressure.
I will try and get another set of injectors to try.
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-31-2010, 06:13 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered User
 
mark '87 930's Avatar
 
Join Date: Feb 2006
Location: Toronto, Ontario
Posts: 727
Garage
Replace your fuel accumulator. It's a crappy $250 part that offers no additional power or efficiency.. but the car will start right up after.
__________________
1987 930
1956 Chevy 3100
2009 Subaru Forester
2003 KX250 X2(I like my toys!!)
Old 05-31-2010, 07:02 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
Replaced it with a spare and then bought a new one but still no change.
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-31-2010, 07:21 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
mark '87 930's Avatar
 
Join Date: Feb 2006
Location: Toronto, Ontario
Posts: 727
Garage
check-valve at the front pump? (Not sure if your car has one).
__________________
1987 930
1956 Chevy 3100
2009 Subaru Forester
2003 KX250 X2(I like my toys!!)
Old 05-31-2010, 07:52 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
81 930 has a front fuel pump check valve and I replaced it.
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-31-2010, 08:16 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
mark '87 930's Avatar
 
Join Date: Feb 2006
Location: Toronto, Ontario
Posts: 727
Garage
i just noticed you wrote all that in your first post, sorry about that.

Once your pressure is at 0 (after 5 mins), have you tried turning the key to on and running your pumps? if so, what does your fuel pressure read then (without trying to start the car).

Have you check to see if you are getting spark after that time?
__________________
1987 930
1956 Chevy 3100
2009 Subaru Forester
2003 KX250 X2(I like my toys!!)
Old 05-31-2010, 08:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
After the next project
 
x98boardwell's Avatar
 
Join Date: Sep 2006
Location: Central Valley, CA
Posts: 1,522
Garage
Another idea

I had the same issue for a while. I replaced the fuel accumulator and it helped alomost everything. I realize you have replaced yours twice so that is probably fine.

My issue continued and I finally found out it was an air-leak. The motor heat soaked after driving and then the little air leak would turn into a large one. The AFR's would be very lean (very hard to start) and as soon as I was able to get some air in the system and it cooled everything down the leak tightened back up and went away, normally after cranking and holding the pedal down to keep it running.

Not a guarantee but worth a shot. You could use a spray bottle filled with very soapy water on the motor before you start after heat soak.. then look for bubbles. Make sure you have good light all over so the visibility is good. It could be around your inter-cooler area, turbo up pipe, by the throttle body or even the injector blocks (which I know are hard to see).

Let us know what happens. With everything that you have already done this is nothing. Best of luck,

Bryan
__________________
Previous cars:
2007 GT3, 2006 Cayenne TTS, 1991 928 S4, 1987 930, 1975 914 2.0, 1989 944 Turbo S, 1991 964 Targa, 1991 964 Convert, 2004 996TT Convertible, 550-6 Spyder with a 2.4 liter twin plug "S-spec'd motor"
Current cars: 2012 Cayenne TT, 1997 993TT, 1984 Jeep Grand Wagoneer, 94' 928 GTS, VW GTI
Old 05-31-2010, 11:19 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
Registered User
 
mark houghton's Avatar
 
Join Date: Jul 2008
Location: Central Washington State
Posts: 3,777
Quote:
Originally Posted by Hirevtuner View Post
Thanks for the input.
I show a drop in warm fuel pressure between the fuel head and WUR, in fact it will zero out in about 5 min after bringing it to full pressure.
I will try and get another set of injectors to try.
Are you saying that your system pressure (normally around 6.8 to 7.0 bar) is dropping to zero? That's like no bueno, amigo. Gummy fuel distributor, maybe. Have you taken out the pressure regulator from the fuel head and checked to see that it's not all gooed up?
__________________
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 05-31-2010, 01:56 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Registered User
 
Hirevtuner's Avatar
 
Join Date: Oct 2007
Location: Calgary
Posts: 364
Well maybe not zero. I removed the gauge at 1 bar but it did drop fast.
Do you think the fuel head would be the offender? It runs great once started.
__________________
1981 411 rwhp, Ruf intercooler, 964 cams, Turbo Kraft injector blocks, Extrude honed intake, 7006 Turbo, Tial wastegate, RarlyL8 exhaust, MSD6al
Old 05-31-2010, 03:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 05:49 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - 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.