Rough start and rough idle.
#1
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Location: Tallahassee/West Palm Beach, Florida
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Rough start and rough idle.
Well I have a 95 Camaro Z28. Let me describe the problem I am having. Sometimes my car will struggle to start and sometimes won't start at all. However, usually if I try to start it and then come back later it will fire up. It also seems to struggle more after sitting over night or an extended time. Sounds like the engine might be getting flooded with gas when I am cranking it over and I have read that I should check my coolant temp sensor. My coolant dummy light is actually on, but there is plenty of coolant, and it has been that way for some time even when the car was running much better. Are these sensors connected?
Anyway, when I do get it started, it usually runs rough at idle with it surging a little. I can hear what sounds like a spark if I open the door and listen every once and awhile when the engine dips in rpm. It does, however seem to run pretty well at load, sometimes it seems like it is lacking power, but that could be my imagination. I decided I needed to change the plugs and wires anyway since it has been awhile and changed the 4 driver side, but didn't have the time to tackle the passenger side yet. Didn't seem to change anything.
The more I read though it sounds like it could be some other problems, such as a dirty IAC, MAF, intake leak, etc. I am gonna check those all out this weekend. Another thing I noticed is that I usually run my car with the cutout open, but decided to close it so the neighbors wouldn't flip out when I am taking 30 seconds to start my car at night and I don't know if it was just my imagination but it almost seemed like it ran better and started much easier after I closed the cut out. I left it closed and it seemed better for 3 days or so, but the problem is back now exactly as it was before. Well any help would be appreciated. Thanks.
Anyway, when I do get it started, it usually runs rough at idle with it surging a little. I can hear what sounds like a spark if I open the door and listen every once and awhile when the engine dips in rpm. It does, however seem to run pretty well at load, sometimes it seems like it is lacking power, but that could be my imagination. I decided I needed to change the plugs and wires anyway since it has been awhile and changed the 4 driver side, but didn't have the time to tackle the passenger side yet. Didn't seem to change anything.
The more I read though it sounds like it could be some other problems, such as a dirty IAC, MAF, intake leak, etc. I am gonna check those all out this weekend. Another thing I noticed is that I usually run my car with the cutout open, but decided to close it so the neighbors wouldn't flip out when I am taking 30 seconds to start my car at night and I don't know if it was just my imagination but it almost seemed like it ran better and started much easier after I closed the cut out. I left it closed and it seemed better for 3 days or so, but the problem is back now exactly as it was before. Well any help would be appreciated. Thanks.
#2
Re: Rough start and rough idle.
Check your fuel psi.
When was the last time you changed the fuel filter?
If it takes a while to start the fuel pump could be dying and the fuel psi will come up slowly.
When was the last time you changed the fuel filter?
If it takes a while to start the fuel pump could be dying and the fuel psi will come up slowly.
Last edited by Gripenfelter; 06-30-2006 at 02:02 PM.
#4
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Re: Rough start and rough idle.
Alright I will check those out. Since I have owned the car I have never checked the fuel filter. Not sure what the previous owner had done. As for teh O2 sensor I think that has gone bad on me before and I replaced it, but this feels like a different problem than that although it was awhile ago.
#5
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Re: Rough start and rough idle.
I was working on fixing a bunch of interior problems with my car this weekend and didn't get around to the engine which I should have concentrated on. Anyway, I was thinking about it and when at idle I can hear a random sparking sound like a wire is arching. It only does it at low rpm, when I would listen for it at around 1000 and up it wouldn't happen, but at low rpm it is loud enough to hear inside the car with the window down. Could this be a cause of my car struggling to start as well. Everytime I hear the spark the engine stumbles. Is this definitely a wire problem or could something else be causing the problem?
#7
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Re: Rough start and rough idle.
Waited until it was dark out and made sure to go in a dark area and fired up the car. Once the engine got warm the arching happened more frequently. It seems to be towards the front of the engine, but I can't tell exactly as I was only looking from the top. I will have to jack to the car up to get a better look I guess. The engine would stumble whenever the spark occurred, but does this explain why it would be so hard to start the car. Sometimes 15-20 seconds of cranking. Or is that a completely different problem?
#8
Re: Rough start and rough idle.
As suggested above, your hard starting may be fuel pump related. Hook up a fuel pressure gauge and see if the fuel rail holds pressure (around 36 psi) when the fuel pump primes (turn key to on, not start).
If you're seeing arcing near the top front, it's either your coil wire or the coil itself; this will cause your miss.
If you're seeing arcing near the top front, it's either your coil wire or the coil itself; this will cause your miss.
#9
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Re: Rough start and rough idle.
Originally Posted by OBE1 95Z28
As suggested above, your hard starting may be fuel pump related. Hook up a fuel pressure gauge and see if the fuel rail holds pressure (around 36 psi) when the fuel pump primes (turn key to on, not start).
If you're seeing arcing near the top front, it's either your coil wire or the coil itself; this will cause your miss.
If you're seeing arcing near the top front, it's either your coil wire or the coil itself; this will cause your miss.
Thanks for the reply. I will get a fuel pressure gauge tomorrow and check it out. If that is the problem am I looking at having to get a whole new fuel pump or could a new filter fix it? With the coil or coil wire should I just replace it or is there something else I should look for? Thanks.
#10
Re: Rough start and rough idle.
Shoebox has a great site that includes how to test your fuel pressure:
http://shbox.com/1/4th_gen_tech2.htm...essure_testing
As far as the arcing, you need to pinpoint the source of the arcing otherwise you're just going to spend a lot of money buying parts.
http://shbox.com/1/4th_gen_tech2.htm...essure_testing
As far as the arcing, you need to pinpoint the source of the arcing otherwise you're just going to spend a lot of money buying parts.
#11
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Re: Rough start and rough idle.
It was the coil wire. It was all corroded inside the boot and on the connection to the coil. Fixed both the hard start and the stumble at idle. Always nice when it is an easy fix. Thanks for all the help.
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