Those who have had cold start issues, list your fix.

[5spd GT]

I know many 5.0L's, like my own, have a cold start issue.

What I mean by this, is upon first start-up, the engine will not want to idle and die very shortly after turning it on. It can often take a few starts (with no extra gas), or rev it up a little for about 10 seconds or so.

What I want to know is, how did you guys fix your cold start problem permanetly

I have cleaned out my IAC valve and it works for a while, but it will often start-up again within several weeks.

It is the stock IAC. Is their any other issues that could cause this, that you guys found out

 

[302RollinHard]

I found that setting my base idle to 850-900 helped cold starting issues. that way your IAC doesn't have to work so hard or be very exacting to smooth the idle. This especially halps those with a fairly agressive camshaft profile.

 

[Grn92LX]

+30% in the cold compensation menu in my PMS. Perfection Its a cold start lean issue.

 

[ninety15.0]

I disagree grn92LX...i do not think its a lean issue. In fact i think its the opposite...its a rich problem.

The issue at hand here is a problem of injector size and MAF calibration. The computer uses a start up table that controls fuel delivery for the first XX seconds after start up. This table has time or ECT on one axis and subracted fuel ratio points on the other. Subracting AFR points (ie 14.67 -3.0 = 11.67) really richens the mixture on start up. The start up table is quite rich even with the stock injectors and MAF and when you combine larger injectors and a "calibrated" MAF you can see start up air fuel ratios into the single digits. The colder the temperature, the more fuel is needed to get the car to initially turn over.

Without a tune of some kind, there is no way to alleviate the cold start issue. With the tweecer, i set all values in that table to 0 and i can now start the car on a freezing cold morning without touching the pedal and it will slowly settle into low idle. Adjusting fuel pressure may help a little bit...but you run the risk of not having enough fuel pressure when you need/want it. A tune is you best bet.

 

[Grn92LX]

Its a cold start lean problem, as stated. Lots of guys have this problem with larger than stock injectors and 'matched' mass air meters. Its lean on cold starts which is why it shuts off on the first few attempts, not getting enough gas With tuning devices it takes a minute to fix, w/o one its something you'll usually have to live with OR maybe try and get the eec to learn it correctly. Try disconnecting the battery for a while to erase the KAM and restart and hope for the best. You ca try adding fuel pressure as a temp fix but that may hurt you everywhere else.

I see cold start a/f in the mid-high teens, then it settles down to 14-15. I can only imagine what his and others with this problem are like.

I too can start my car in the coldest of winter and the hottest of summer with out doing a thing but turning the key

 

[5spd GT]

I had this problem before big injectors and the maf.

I also know that from the factory, these cars did not have this issue. So I can presume that it is sensor or IAC related

My car runs rich at idle.

Disconnecting the battery doesn't help.

This is not a big issue, because I usually do not 'idle' my car anyways, I start it up and go.

My car drives better after it warms up, and just after start-up and until the car warms up to operating temperature, the car is very jumpy with a little depression of the gas. I have read that the idle surging (so-to-say) is also due to a rich condition.

Keep ideas coming, for those that fixed the problem

 

[ninety15.0]

It depends on the symptoms. Its not a cut and dry lean problem like you seem to think grn92lx! If you are getting a quick fire then die, you may be right with the lean condition. But if you are getting a very rough surging idle when cold, which is what many people have problems with. Your problem, 5speed, is most likely a rich condition...AS STATED. This is not a blanket statement as there are way to many variables in these cal's MAFs. You need to find someway of assessing which condition you are experiencing and make the proper adjustments.

You added fuel to your tune...i had to take a lot out and so have many others. seems to me if i had to take a lot of fuel out that i surely didnt have a lean condition. yikes

 

[5spd GT]

Yeah, the mustang game is so full of variables in every aspect

Thanks for the response...

 

[Grn92LX]

His problem is a cold start lean problem. He said it dies right after trying to start it. Its lean and needs fuel. I didn't say everyones issue is the same as his, but HIS issue IS a cold start lean issue. Since he said disconencting the battery doesnt help, he basically has to either live with it or tune it. Try turning up the regulator a bit as a temp fix and see if it helps.

It sounds like you had a cold start surging issue so obviously removing fuel would take care of it. He has the opposite. Super easy fix if you have the tools to do so.

 

[5spd GT]

I have a cold start surging issue, or atleast that is how I describe it. I can let it 'idle' in gear while coasting and it will be 'kicky', and if I get on the gas a little bit during tip-in, it will kick as well. It is not smooth.

It seems I have both scenarios

Could it be a bad IAC? Because when I clean it up real good, it starts up and idles just fine. No messing with injectors or maf at all. But a few/several weeks later, it starts doing it again.

 

[ninety15.0]

Are you pulling oil into the intake? How is the IAC getting dirty so quickly. I just had mine off the car while doing an EGR delete and took it all apart and it was impressively clean. The last time i cleaned it was over two years ago?!?!

 

[5spd GT]

Yeah, oil gets into the intake thru the pcv valve. My oil fill tube line is not connected to the throttle body area, so it is not coming from there.

Well the IAC doesn't 'look dirty', but when I clean it, it will temporarily fix the issue and it will idle higher. But a few weeks later, it starts to fade pretty quickly.

I am not stressed about this issue, but just curious what other people did to fix their issues. I am trying to avoid using a 'tune' to fix it, because factory 5.0L's did it just fine.

The 4.6L (newer cars) swap out injectors and maf's and they don't typically have the issue. Most get tunes anyways, but not all of them.

Thanks for the help ninety!

 

[backfocus]

Not any help David, but just want to reiterate , as you knew, your not the only one.

I had the same thing going on with my car before I pulled the motor. I had lived with it for 2 years, although I don't drive it that much. But yeah, on cold start up it would die. Start it back up and give it gas it would run, but not smooth until it warmed up. I went through the check list many times and cleaned IAC and it seemed to go away for a bit then would come back. I even bought a new IAC and the same thing.

I agree it is probably tuning from an initial lean start up condition. But under normal idle my car ran rich also.

Hopefully once the motor is back in with new everything and I get it tuned, the former problem will not reappear.

So until then subscribing...

 

[jrichker]

See "Help me create the Surging Idle Checklist" at http://forums.stangnet.com/showthread.php?t=698148
for help with your idle problems. The first two posts contain all the updates to the fixes. I continue to update it as more people post fixes or ask questions.

See item #1 on the checklist.

 

[Daggar]

I'm having a similar issue. It's one that I did not have last year while it was cold. I'm hopeful that it's only a temperature sensor (AIT or coolant) that's causing the problem.

What's worse is that I sent my custom chip back to the tuner recently for another issue and he added a little fuel at startup to correct the problem. So far, that's had no effect.

It would be easier for me to diagnose if my AFR meter came up faster. I'll be messing with that in the near future so that I can get the meter up, warmed up, and running, ready to read before I start the car. Then I'll know for certain whether the problem in my instance, is too much or not enough, fuel.

 

[5spd GT]

Thanks Mike, I feel better now So where did you get the engine done at? Was it Kuntz? I can't recall I know mine had the problem before and after the rebuild...

Thanks Jrichker, I'll check those out with a volt-meter sometime, hopefully soon.

Daggar - If you find something out, let us know, that could be pretty helpful.

 

[mbsprinks281]

Engine coolant temp sensor..............

 

[backfocus]

Thanks Mike, I feel better now So where did you get the engine done at? Was it Kuntz? I can't recall I know mine had the problem before and after the rebuild...

Hopefully I won't have the cold start issue anymore as I am getting all new Throttle body, Mass Air, and probably replacing most of the sensors as well. Then once I get it back together I am going the Memphis to have it tuned. Rebel Rebuilders machined my motor, which took forever, but it is done, I just need to pick it up and I am assembling it myself. I really wanted a 331, but choose to save my money and put it elsewhere, like a turbo or SC. Rick was very helpfull with questions about my old high-port heads and I am getting a custom cam as you suggested.

As for the cold start problem, I went through that list like 10 times. It is a great list, but didn't fix this problem in the end. The only thing I could find, as you stated was cleaning the IAC helped briefly. All voltages and vacuum readings where good, along with the fuel. I even replaced the IAC, TPS and EGR just for piece of mind, no difference. I wish I had a tweezer to look at things at startup.

 

[5spd GT]

I wish I had a tweezer to look at things at startup.

Me too

Good Luck with the build Mike, and let me/us know how it goes