Warm start issue, stage 1 cams - Forums at Modded Mustangs
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post #1 of 12 Old August 25th, 2015, 11:48 AM Thread Starter
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Warm start issue, stage 1 cams

A few weeks ago I installed cms stage 1 cams and since then the car will have some issues on warm start ups. It will start but when it does it idles very low and either catches itself after a few seconds or dies. This does not happen every time and the more time the car sits the less frequent this happens. It does not have any issues with cold starts.

I have a base tune from tricktuners but this problem started with the stock tune. I know its a fuel issue, but can anyone point me in the right direction? I don't know a whole lot about the fuel system, but I will do my research to troubleshoot any suggestions. Thanks in advance.
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post #2 of 12 Old August 25th, 2015, 12:36 PM
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Your car may have larger injectors installed. If it does then you might ask Joe to increase the Crank Fuel duty cycle and lower the injector crank pulse width.

This will usually help with hot start issues with larger injectors.

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post #3 of 12 Old August 25th, 2015, 12:48 PM Thread Starter
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I have the stock pink top, 21 lb injectors.
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post #4 of 12 Old August 25th, 2015, 01:07 PM
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Quote:
Originally Posted by Crimson View Post
I have the stock pink top, 21 lb injectors.
I must have misunderstood, I thought you were saying you weren't sure what kind of fuel system you had.

In any case you still may try those fixes I listed above, if anything it should still help at least.

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post #5 of 12 Old August 25th, 2015, 01:18 PM Thread Starter
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Originally Posted by Sc9tt View Post
I must have misunderstood, I thought you were saying you weren't sure what kind of fuel system you had.

In any case you still may try those fixes I listed above, if anything it should still help at least.
Gotcha, I know the fuel system is stock, I'm just not familar with every part within the system that could be the culprit.
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post #6 of 12 Old August 25th, 2015, 06:28 PM
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I have the same exact cams and had the same problem, I went all over the place. I smoked my vacuum system to check for air leaks and pressure tested my fuel system too and it all checked out good.

It ended up being the tune wasnt adjusted right. I took it to my tuner and he changed the tune a little and now it runs fine, i would get ahold of your tuner again and explain and he should be able to adjust it.

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post #7 of 12 Old August 25th, 2015, 08:39 PM
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I had the same issue. Told joe and he fine tuned it at the end. I also replaced my IAC for a third time and between joe and that the issues is all but gone. Just let him know what is going on so he can fix it.

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post #8 of 12 Old August 25th, 2015, 08:51 PM Thread Starter
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Alright thanks guys. I'll let him know. Still on the base tune trying to work out another issue.
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post #9 of 12 Old August 26th, 2015, 02:41 AM
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Its a tune issue... you need too add a good amount of timing to ease starting of cammed stock compression cars. I typically will add 5-10 degrees below 700 RPM and I target 800-900RPM idle. This really helps with stalling issues and also helps starting. One of the tricks of the trade dealing with cars that die returning to idle coming to a stop is to add spark BELOW where the target idle speed is... so say we target 800RPM idle.. Then at 750RPM I will add 5 degrees and at 500RPM I will add 10-15 degrees. So when the idle does drop suddenly its not all up to the IAC to add air and catch the falling RPMS before it dies. When spark rolls in the engine will automatically get more efficient, fire harder and idle higher then when the RPMS go back up the timing comes back out and the IAC takes over... sort beautiful 50 yard pass where the running back is running like hell and the ball magically lands right in his hands and score a touchdown.... something like that haha.
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post #10 of 12 Old August 26th, 2015, 07:22 AM Thread Starter
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Thanks for the explanation Nitmare.... That makes a lot of sense
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post #11 of 12 Old August 26th, 2015, 08:12 AM
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Quote:
Originally Posted by Nitmare67 View Post
Its a tune issue... you need too add a good amount of timing to ease starting of cammed stock compression cars. I typically will add 5-10 degrees below 700 RPM and I target 800-900RPM idle. This really helps with stalling issues and also helps starting. One of the tricks of the trade dealing with cars that die returning to idle coming to a stop is to add spark BELOW where the target idle speed is... so say we target 800RPM idle.. Then at 750RPM I will add 5 degrees and at 500RPM I will add 10-15 degrees. So when the idle does drop suddenly its not all up to the IAC to add air and catch the falling RPMS before it dies. When spark rolls in the engine will automatically get more efficient, fire harder and idle higher then when the RPMS go back up the timing comes back out and the IAC takes over... sort beautiful 50 yard pass where the running back is running like hell and the ball magically lands right in his hands and score a touchdown.... something like that haha.
Thank you Nitemare. I've been plagued with this since I added my cams years ago. No tuner I ever spoke to could help me out. I'll be giving this a shot as soon as the car is together again.


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post #12 of 12 Old August 26th, 2015, 12:17 PM
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Nitemare, I like that tip you suggested of bumping the advance up under your targeted idle speed.

On my auto car with a 3400 stall converter its fine when shifting into drive at idle but when its just a little under full operating temperature sometimes when you shift into reverse the engine bogs and stalls.

Apparently something about the locking TC clutch setup on the aftermarket converters puts more drag on reverse shifts when they are still a little cold, I'm going to try your advance trick and see if that fixes it.

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