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Author
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Topic: 5.0 slow to come up to idle speed when started
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steeters
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Member # 14324
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posted
 
 
I searched around, but I am just not sure I'm using the right descriptive terms to find the answer. So here goes:
Started my bone stock '94 Cobra with no problems, drove it about 1/4 mile and shut it off.
Waited for about 5 minutes, started the car again and here's the issue: It cranks just fine, but the car was really slow to get to its normal idle speed. It doesn't seem like a battery or starter...but more like a fuel/spark issue.
Getting it to idle speed wasn't "crisp" or quick. Very sluggish to fire up.
No drivability issues to report.
I recently changed the fuel filter (stock)...BUT, before I changed the fuel filter I released the fuel pressure at the schrader valve. I expected fuel to blast out for a second or two, but there was hardly a dribble of fuel. I don't recall how long the car sat between starts (I don't know how long this car would hold fuel pressure between starts).
Could these two things be related? Fuel pump, fuel pressure problem?
It seems to drive fine otherwise.
Suggestions?
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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Martinna
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Member # 12493
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posted
The fuel pump is primed when the ignition key goes in the on position. This pressurizes the fuel rails for startup. Is the problem your car cranks for a long time before starting or the RPMs take a long time to come down to 700 after starting?
Posts: 1093 | From: City | Registered: Oct 2012
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steeters
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Member # 14324
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posted
it cranked for the normal amount of time (maybe 1-2 seconds) before it started. The starter seems to be operating normally (I'm going by ear)
But it was like it was running at 200 RPM (two hundred RPM, not a typo) for two seconds before it slowly got up to a normal RPM idle speed (probably took 1-2 seconds to get up to normal idle speed).
I hope that helps.
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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NEIGHT
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Member # 8741
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Did you have this issue before you changed the fuel filter?
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-Savage Habits-
1992 Summer Edition
1986 Hatch- catfish killer
1964 Impala hard top
Posts: 18548 | From: EA$T $IDE REDWOOD CITY | Registered: Nov 2008
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steeters
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Member # 14324
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posted
quote:
Originally posted by NEIGHT:
Did you have this issue before you changed the fuel filter?
A: No I did not have this situation before the filter change.
I also just went out to confirm that the filter had the arrow pointing toward the driver's side of the car, and it is in there correctly.
However, this was the first time I recall where I only drove for 2 minutes and shut it off, and tried to start it 5 minutes later.
Never had this "slow" start condition before under any other circumstance...but usually I would have longer periods of time before shut off/restart.
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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NEIGHT
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Member # 8741
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posted
quote:
Originally posted by steeters:
quote:
Originally posted by NEIGHT:
Did you have this issue before you changed the fuel filter?
A: No I did not have this situation before the filter change.
I also just went out to confirm that the filter had the arrow pointing toward the driver's side of the car, and it is in there correctly.
However, this was the first time I recall where I only drove for 2 minutes and shut it off, and tried to start it 5 minutes later.
Never had this "slow" start condition before under any other circumstance...but usually I would have longer periods of time before shut off/restart.
Maybe you still have air in your fuel system. ![[Confused]](confused.gif) Only thing I can think of if it ran fine before the filter change and you have it installed right.
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-Savage Habits-
1992 Summer Edition
1986 Hatch- catfish killer
1964 Impala hard top
Posts: 18548 | From: EA$T $IDE REDWOOD CITY | Registered: Nov 2008
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Martinna
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Member # 12493
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Do you have a stock MAF and injectors?
Posts: 1093 | From: City | Registered: Oct 2012
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steeters
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Member # 14324
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posted
quote:
Originally posted by Martinna:
Do you have a stock MAF and injectors?
Yes, it is all stock.
I should add that this hasn't been a problem every time I start the car...it is limited to when I shut it off, and then restarted within a few minutes.
(Unrelated but I had a different car years ago and I backed it out of the garage to wash it. So it only ran for 1 minute. I started it again after I was done washing it 10 minutes later and it acted the same way, like it was flooded. It had the same slow sluggish idle for 30 seconds and then cleared up. Maybe this is just a fuel injection thing that occasionally creeps up?)
I'm not losing sleep over it, but if this indicates a problem that I can correct before I get a no-start problem, I'd like to stay ahead of it.
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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Martinna
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Member # 12493
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posted
Don't worry if the computer has no stored error codes and you can't repeat the phenomena.
Posts: 1093 | From: City | Registered: Oct 2012
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steeters
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Member # 14324
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posted
I "think" I have an update to the issue of the slow starting issue. I appreciate everyone's input
After a short drive yesterday it was slow to start. No click click click, but very slow cranking. It did start, and ran fine.
What I notice when this happens is that when I normally start the car it jumps to about 1200 rpms, and then settles down to idle speed.
With the intermittent condition I described, it struggles up to idle rpm speed and stays there. It never revs past idle speed before dropping down to idle rpm.
This morning I tested the battery (battery is new). It was 12.2V. When I started the car, it started fine (it was cold, and with no accessories running).
Once it warmed up a bit I put the electrical system under load and it was at 14.7V. I drove it around for 5mins with no problems.
I shut it off, and tested the battery 12.84V.
30 minutes later it was at 12.59V
60 minutes later it was at 12.51V
I understand that it will trickle down from 12.84V a little, but because it kept draining past 12.6V I was surprised.
Soooo...I'm starting to think the battery is fine, the alternator is fine, and I'm suffering from a parasitic battery drain. A condition that becomes obvious after a short drive.
I found a link on how to test parasitic losses, but if anyone has a suggestion on where to start on a '94 Cobra I would be interested.
(backstory...I bought this SN95 from the original owner who said he drove it infrequently and the battery would die...so he installed a cut off switch at the battery cable to fix this. I wonder if this was unknowingly his fix for the parasitic loss)
Thanks,
Steve
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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Martinna
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Member # 12493
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I don't think battery drain is your problem. Do you have an amp meter? Not hard to measure parasitic drain with one. Has an aftermarket electronics like an ignition box, stereo or amplifier been installed?
Posts: 1093 | From: City | Registered: Oct 2012
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steeters
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Member # 14324
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posted
Aftermarket head unit to replace the factory one (which I was told failed). Nothing fancy and appears to be cleanly installed.
It has the MACH sound system.
I'll check for the parasitic draw tomorrow.
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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4IDFOX
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Member # 9921
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Might want to check your egr. It could be sticking when warm.
Might check injectors. Could be leaking. Does your oil smell of fuel ?
Posts: 375 | From: Redding CA | Registered: Apr 2010
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steeters
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Member # 14324
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posted
quote:
Originally posted by 4IDFOX:
Might want to check your egr. It could be sticking when warm.
Might check injectors. Could be leaking. Does your oil smell of fuel ?
Worth a shot...I'll investigate in the morning and update. Thanks,
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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i
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Member # 12534
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Looks like you don’t drive the car often.
Start your car 3 times a week so it won’t drain the battery.
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86 Caged Coupe 5.0
91 Salvaged Coupe
Posts: 1901 | From: Sacramento | Registered: Nov 2012
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steeters
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Member # 14324
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posted
quote:
Originally posted by i:
Looks like you don’t drive the car often.
Start your car 3 times a week so it won’t drain the battery.
True, it doesn't get driven daily.
What's odd is that in the garage, after sitting for several days, it will start up with no problem.
But if I drive it 2 miles, park it, and try to start it again I have gotten this intermittent sluggish start condition.
The two might be related, but I'm thinking there is something else contributing.
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Steve
Posts: 33 | From: Sacramento | Registered: Mar 2016
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Martinna
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Member # 12493
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posted
Long tubes can heat a starter so it doesn't start until it has cooled down.
Posts: 1093 | From: City | Registered: Oct 2012
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