Car loses ET (alot) after a few rounds?
#1654861
08/04/14 10:00 AM
08/04/14 10:00 AM
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Joined: Feb 2003
Posts: 2,563 S.E. Michigan
cl440
OP
master
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OP
master
Joined: Feb 2003
Posts: 2,563
S.E. Michigan
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We are struggling to figure this out. We have had this issue since the start of the season. Car runs great first few rounds. Saturday for example the car went 9.190 - 9.197 - 9.200 - 9.197 then started falling off 9.215 - 9.230 - 9.263 Sunday the car went 9.158 - 9.158 - 9.203 - 9.277 DA was pretty stable between runs only changing a few hundred all day and this is a methanol setup so it should not affect it this much. On the majority of the passes the car just stops pulling, I can feel it lay over and struggle to get to its 6800 shift point. Fuel pressure is a steady 7.5# so fuel delivery to the carb does not seem to be an issue. Float levels are 50% into the glass front and back. We have checked valve lash and its perfect compared to where we set it a couple months ago. We replaced plugs, wires, checked and cleaned cap and rotor, installed new pick up in distributor, tested MSD and coil with MSD tester. Timing is locked out at 35* Installed new intake gaskets also. Pump is Magnafuel 500. Front mount fuel cell and all lines, fittings etc. are new at the beginning of the season (-10 from cell to pump and pump to regulator, (2) -8 from regulator to carb). We are going to try a different carb this week as one of the big changes this season was adding the Alky SV1 from prosystems. Not sure why the carb would be the issue since it runs great the first few passes but we have got to try something. We also disassembled the carb and cleaned it thoroughly just in case there was something floating around in there blocking a passage? Trans shifts good and the car still 60's great it is generally at the top of second and in third when It lays down. Anyone have any clues as to what might be happening?
Last edited by cl440; 08/04/14 10:02 AM.
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Re: Car loses ET (alot) after a few rounds?
[Re: mafo]
#1654866
08/04/14 10:32 AM
08/04/14 10:32 AM
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Joined: Feb 2003
Posts: 2,563 S.E. Michigan
cl440
OP
master
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OP
master
Joined: Feb 2003
Posts: 2,563
S.E. Michigan
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Quote:
Could be converter slipping when oil temperature goes up
Not feeling any over rev condition. This is a loss of power condition where it simply struggles to pull
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Re: Car loses ET (alot) after a few rounds?
[Re: cl440]
#1654867
08/04/14 10:37 AM
08/04/14 10:37 AM
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Joined: Nov 2009
Posts: 3,410 Belpre,Ohio
CHAPPER
master
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master
Joined: Nov 2009
Posts: 3,410
Belpre,Ohio
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Are you running an alternator or charging the battery between rounds? Is battery in good condition? May be that the voltage is getting a bit low and the ignition is laying down on you..
If you like drag racing, support your local track.
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Re: Car loses ET (alot) after a few rounds?
[Re: cl440]
#1654869
08/04/14 10:55 AM
08/04/14 10:55 AM
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Joined: Nov 2004
Posts: 3,544 Syracuse,NY
CompWedgeEngines
master
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master
Joined: Nov 2004
Posts: 3,544
Syracuse,NY
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Voltage to the fuel pump stable? at speed?
Are you monitoring tranny temps?
I know it SEEMS like fuel, but from what you are posting, not sure.
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Re: Car loses ET (alot) after a few rounds?
[Re: CompWedgeEngines]
#1654870
08/04/14 11:01 AM
08/04/14 11:01 AM
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Joined: Feb 2003
Posts: 2,563 S.E. Michigan
cl440
OP
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OP
master
Joined: Feb 2003
Posts: 2,563
S.E. Michigan
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Its been a head scratcher for sure. We do not have a trans temp gauge but the fluid color and smell are like we poured it from the bottle. We do not lose fuel pressure when it happens. We do run a GM one wire alt. (80 amp) and 2 batteries. I charge after every couple rounds just to make sure.
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Re: Car loses ET (alot) after a few rounds?
[Re: CompWedgeEngines]
#1654871
08/04/14 11:05 AM
08/04/14 11:05 AM
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Joined: Jan 2003
Posts: 11,721 Portage,michigan
B3422W5
I Live Here
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I Live Here
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Posts: 11,721
Portage,michigan
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Did you guys ever actually swap out the 6al box? Remember, like we were talking, that tester is only looking at THAT moment in time your testing... And that most likely isn't a moment in time the box may be producing a fault. From troubleshooting computer systems earlier in my life for 15 years, I found setting up conditions to force something to fail can be tough. I would definately swap it out, think you said you had a spare?
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, 10.40 @127 1/4 1.41 best 60 foot 6.60 at 103.90 1/8
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Re: Car loses ET (alot) after a few rounds?
[Re: cl440]
#1654873
08/04/14 11:23 AM
08/04/14 11:23 AM
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Joined: Nov 2009
Posts: 3,410 Belpre,Ohio
CHAPPER
master
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master
Joined: Nov 2009
Posts: 3,410
Belpre,Ohio
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Probably should check valve spring pressure. Problem doesn't sound like the usual signs of weakness, but a check couldn't hurt.
If you like drag racing, support your local track.
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Re: Car loses ET (alot) after a few rounds?
[Re: CHAPPER]
#1654874
08/04/14 04:50 PM
08/04/14 04:50 PM
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Joined: Jan 2003
Posts: 276 Mid west
Gearhead383
enthusiast
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enthusiast
Joined: Jan 2003
Posts: 276
Mid west
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Hmmmm.... track conditions going away?? Might try short shifting; say 6500-6600 RPM. Are the fuel bowls running out? Do you have the spacers to increase the fuel bowl capacity? Just throwing out some food for thought.
Last edited by Gearhead383; 08/04/14 04:54 PM.
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Re: Car loses ET (alot) after a few rounds?
[Re: Gearhead383]
#1654876
08/04/14 04:59 PM
08/04/14 04:59 PM
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Joined: Feb 2003
Posts: 2,563 S.E. Michigan
cl440
OP
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OP
master
Joined: Feb 2003
Posts: 2,563
S.E. Michigan
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Quote:
Hmmmm.... track conditions going away?? Might try short shifting; say 6500-6600 RPM. Are the fuel bowls running out? Do you have the spacers to increase the fuel bowl capacity? Just throwing out some food for thought.
-Track was good and the 60's were 1.27 and 1.28 all weekend
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Re: Car loses ET (alot) after a few rounds?
[Re: Gearhead383]
#1654878
08/04/14 05:02 PM
08/04/14 05:02 PM
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Joined: Feb 2003
Posts: 2,563 S.E. Michigan
cl440
OP
master
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OP
master
Joined: Feb 2003
Posts: 2,563
S.E. Michigan
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Quote:
How do the 1/8 mile times compare?
Don't have the slips in front of me but when it started going away it was all after the 60'.
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Re: Car loses ET (alot) after a few rounds?
[Re: cl440]
#1654879
08/04/14 05:12 PM
08/04/14 05:12 PM
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Joined: Jan 2003
Posts: 276 Mid west
Gearhead383
enthusiast
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enthusiast
Joined: Jan 2003
Posts: 276
Mid west
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Quote:
Quote:
How do the 1/8 mile times compare?
Don't have the slips in front of me but when it started going away it was all after the 60'.
As long as your confident the track was not going away, then all indicators seem to point towards a converter. I had a buddy who would change converters as soon as hit 60' started moving around. As soon as he replaced it, he back to winning again. Good luck
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Re: Car loses ET (alot) after a few rounds?
[Re: Gearhead383]
#1654880
08/04/14 05:17 PM
08/04/14 05:17 PM
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Joined: Jan 2003
Posts: 19,376 Las Vegas
Al_Alguire
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I Live Here
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Las Vegas
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Take a close look at your incrementals. They should tell you where you are loosing ET. Back track from there, in otherwords confirm where it is loosing the ET.
You say it feels like it will not pull up top but do the incremental times show that? Or is the problem form the get go. If it is that you are loosing ET the entire track I would be looking close at the converter or trans itself. Maybe pump pressure is being affected as the trans heats up? Know where it is loosing the ET will help diagnose where the issue is. Takes a BIG problem to loose that much ET on the top end of the track. I suspect it will be found elsewhere.
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