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Ian89C4
Joined: 01 Apr 2011 Posts: 561 Location: North Carolina
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Posted: Sun Jun 02, 2013 5:25 am Post subject: hot running issues |
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I have the racer out at the track right now and I am running into the same issues that I had a few weeks ago. The issue is that when the engine starts getting hot, it seems like the engine is not getting enough fuel. This only happens at around 5k rpms with the throttle pedal planted. There is that little coughing sound from the engine like it has hit rev limiter but is having its fuel cut. For my second session today I richened up the fuel air mix as what I found when I pulled the spark plugs was that they were very badly heat glazed. She was running like a champ for a good while during the second session, but then we started having the issues again.
As I was having these issues last time at the track, here is what I did since then to try and remedy the problem:
Fuel pump is now on a switch
New Icu
What I think it could be:
Fuel pump not maintaining pressure under full acceleration
Heat soak so bad into the injector lines that not enough fuel can get to the chambers under full acceleration.
I want to try and run the four sessions tomorrow, but if I can't figure this out I may pa k up and head home, no use killing the car.
Thanks,
Ian _________________ Ian Edgerly
North Carolina
Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala") |
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Grenadiers
Joined: 20 Feb 2007 Posts: 3222 Location: Nelson, WI & Prescott, AZ
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Posted: Sun Jun 02, 2013 6:01 am Post subject: |
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Running a CIS test in those conditions would be tough. Losing fuel pressure can be attributed to most anything from the back to the front. Might want to consider an AEM/LC-1 wideband setup to keep track on the track. For the front end, might want to check fuel pressure on the CIS. Looking for stuck/worn FPR: weak spring, bad O-rings. Try adding shims to the FPR if you can't test the CIS at high rpm under load. Not sure how the WUR at that speed/rpm is affected. _________________ '83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke |
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Ian89C4
Joined: 01 Apr 2011 Posts: 561 Location: North Carolina
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Posted: Sun Jun 02, 2013 6:51 am Post subject: |
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Grenadiers I appreciate the fast response.
When you are talking the fpr you are talking the fuel pressure relief valve right? I didn't know that it would affect fuel pressure at high rpms under load. I have no way of replicating track conditions, so I will just try it. I think I will try the wide band as well and replace the fuel pump. Time to look for the next track event. I am going to do one more run in the morning and see if a hunch of mine is correct.
Cheers,
Ian _________________ Ian Edgerly
North Carolina
Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala") |
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Grenadiers
Joined: 20 Feb 2007 Posts: 3222 Location: Nelson, WI & Prescott, AZ
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Posted: Sun Jun 02, 2013 7:24 am Post subject: |
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Hey Ian, I have no clue where it's at, at high rpms. It works the same way as the oil pump valve, so, springs are involved, and in this case too, O-rings. It's an easy thing to check without spending much money. There are algorithmic geniuses on the board that do not throw crap on the wall to see what sticks. I'm not one of them! They'll chime in soon enough though. But, if you're at the track, and have a small, er, very small, washer, try it. _________________ '83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke |
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Fifty50Plus
Joined: 28 Feb 2008 Posts: 1354 Location: Washington DC area
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Posted: Sun Jun 02, 2013 10:11 am Post subject: |
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Ian,
On the left side of the fuel distributor as you are facing it, there is a 14 mm bolt. It is below the individual injector lines just below the line that goes to the frequency valve (electric relay on rear of fuel distributor). If you take off the 14 mm bolt, it's only about 1/2 inch long and seats a spring and plunger in the body of the distributor.
Place another copper washer (for a total of two) on the 14 mm bolt and screw it back in to seal up again.
This will richen up your mixture.
This assumes that you've already richened the mixture as much as possible with the 3 mm allen adjustment on the top of the flapper place.
If neither of these work and it still sounds like it's lean (can't pull revs and sounds like an electrical issue) then you have a fuel delivery problem (either bad pump, clogged screen in tank or clogged fuel filter).
HTH
Chuck _________________ 1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car |
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Ian89C4
Joined: 01 Apr 2011 Posts: 561 Location: North Carolina
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Posted: Sun Jun 02, 2013 12:01 pm Post subject: |
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Thanks guys!! I will dig into that stuff when I get home. I don't have the proper receptacles for catching fuel here with me at the track, nor do I want the little spring in the fuel pressure relief valve to go shooting across the paddock.
Below is a pick of the plugs...they have been getting better all day but still show high speed glazing
Here is a sideways of my fuel pump...I don't think it is supposed to be doing that....leaking that is....
But....she is looking good today
And she is getting worked even with the problems...about 2 seconds off of the average SCCA ITB pace...not bad for not being able to put my foot half way down in 3rd on the second lap of each session...
_________________ Ian Edgerly
North Carolina
Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala") |
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morghen
Joined: 21 Jan 2005 Posts: 8879 Location: Romania
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Posted: Sun Jun 02, 2013 5:51 pm Post subject: |
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tighten and check for leaks or replace that pump ASAP...dont be on fire _________________ https://www.the924.com |
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Ian89C4
Joined: 01 Apr 2011 Posts: 561 Location: North Carolina
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Posted: Sun Jun 02, 2013 8:10 pm Post subject: |
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Morgan, I would have to agree with you there. After thinking it over, decided its not worth it to chance it today, so I think I'll pack it up and reattack at a later date. Oh...there were also fuel stains under the fuel pump this morning.....taking it to the house.
Thank you guys for all of the assists.
Hope to see you next week chuck
Disappointed but thank full for the service of the board,
Ian _________________ Ian Edgerly
North Carolina
Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala") |
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Ian89C4
Joined: 01 Apr 2011 Posts: 561 Location: North Carolina
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Posted: Mon Jun 03, 2013 11:58 am Post subject: |
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Well....got the car unloaded today and went in for some lunch...went back into the garage to start unloading the truck but walked into a wall of fuel smell. I started sniffing around the car and opened the hood...looked around and saw that my FPV was leaking like a sieve. There was fuel everywhere. I ended up pulling the entire air plenum fuel dizzy assembly as the seal underneath them was completely soaked with fuel...probably a very good thing I did not run the car today.
Now to the point....
Below is a pic of the FPV from my off the car (left hand side) and the one from the spare dizzy that I have (right side). I was missing both of the small shims and the washer...could this possibly be the source of the problems I was having?? I guess I can't see something so small having such a huge affect...well, plus the fuel pump.
seal looks good.
now to the fuel pump. _________________ Ian Edgerly
North Carolina
Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala") |
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Fifty50Plus
Joined: 28 Feb 2008 Posts: 1354 Location: Washington DC area
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Posted: Tue Jun 04, 2013 12:11 am Post subject: |
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Ian,
The two little shims behind the spare spring would cause the car to run very very lean. Don't put them on the car. The larger washer is for sealing and preventing fuel leaks (as you found out).
If you put two large washers on. you will reduce the pressure on the spring and richen the mixture.
Regards,
Chuck _________________ 1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Tue Jun 04, 2013 1:20 am Post subject: |
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Time to buy a CIS tester. . .don't toy with your race motor. Check system pressure and pump volume per FSM. _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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Fifty50Plus
Joined: 28 Feb 2008 Posts: 1354 Location: Washington DC area
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Posted: Tue Jun 04, 2013 2:59 am Post subject: |
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^+1
But when you start diddling with enrichment, you also need a wideband O2 sensor and data acquisition to know where you stand under WOT running conditions. CIS tester just tells you component health and status at idle (which is good to know as a starting point).
Inovate sells a nice wideband O2 sensor and gauge for about $200 and another $100 for a recording device.
Chuck _________________ 1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Tue Jun 04, 2013 4:27 am Post subject: |
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I can get you the AEM setup for similar pricing... _________________ erstwhile owner of just about every 924 variant ever made |
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924RACR
Joined: 29 Jul 2001 Posts: 8803 Location: Royal Oak, MI, USA
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Posted: Tue Jun 04, 2013 11:29 pm Post subject: |
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Yeah, I chose to go with the AEM after reviews of both by my coworkers. It's actually in the DSR, not the 924...
Worked great, plug'n'play and drops right into my DL1 logger (as with most DAQ systems). _________________ Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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Ian89C4
Joined: 01 Apr 2011 Posts: 561 Location: North Carolina
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Posted: Wed Jun 05, 2013 11:22 am Post subject: |
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Thanks guys!
So....the shims put more pressure on the spring which does not allow the piston to move back thus not allowing more fuel to enter?
I did not put two washers on, I will have to get another one.
Dan - PM Sent _________________ Ian Edgerly
North Carolina
Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala") |
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