Cold Start Stutter

A

arcadewilco

New member
My truck is stuttering when starting up especially at cold start. It will die on cold start then eventually fire up. Once its fired up it runs perfectly. Idles perfectly and drives just fine.

Could it be a fuel injector issue? Should I put in new ones. I had them cleaned about 6 months ago. I'm not getting any codes from the computer.

Thanks
 
S

Static

Member
Re: Cold Start Stutter

Next cold start I would try this. Key on, let the fuel pump prime, Key off. Do this twice and then try to start and see if it starts better.
 
A

arcadewilco

New member
Re: Cold Start Stutter

Static said:
Next cold start I would try this. Key on, let the fuel pump prime, Key off. Do this twice and then try to start and see if it starts better.
Click to expand...

I tried that today actually and it still stuttered. It hasn't been turning off the last few days on first try so that's good at least but it's still shaky. Checked the fuel pressure and its at 40.

This did start happening after I installed the larger throttle body from RPM. Not sure if its related though. My IAC counts are at 47 and I can't get them any lower to the recommend Turbo Tweak settings of 25-35.
 
Don W.

Don W.

Stab it and steer it
Re: Cold Start Stutter

arcadewilco said:
I tried that today actually and it still stuttered. It hasn't been turning off the last few days on first try so that's good at least but it's still shaky. Checked the fuel pressure and its at 40.

This did start happening after I installed the larger throttle body from RPM. Not sure if its related though. My IAC counts are at 47 and I can't get them any lower to the recommend Turbo Tweak settings of 25-35.
Click to expand...

Hate to ask this but lowering the IAC count requires -opening- the throttle butterflies. Are you going the correct direction?

And if I understand, once it actually fires it immediately runs fine? Just for S&G next cold start, before you crank, hold the pedal to the floor. This puts the ECM in flood mode and doesn't fire the injs. See if it starts that way. Unlikely but worth a try. You'll know right away.

Once it does start what's your WB show? Also what are the Xcnts.

Have someone watch and see if it's making black smoke when you attempt to start.

What's you plug gap?
 
A

arcadewilco

New member
Re: Cold Start Stutter

Don W. said:
Hate to ask this but lowering the IAC count requires -opening- the throttle butterflies. Are you going the correct direction?

And if I understand, once it actually fires it immediately runs fine? Just for S&G next cold start, before you crank, hold the pedal to the floor. This puts the ECM in flood mode and doesn't fire the injs. See if it starts that way. Unlikely but worth a try. You'll know right away.

Once it does start what's your WB show? Also what are the Xcnts.

Have someone watch and see if it's making black smoke when you attempt to start.

What's you plug gap?
Click to expand...

If I turn right on the throttle screw the idle gets higher and my IAC count climbs. So I turn the screw all the way left and it has no pressure on the throttle body. It idles fine there at 800 RPM and IAC is stuck between 42-47.

I recorded a start just now and there is black smoke coming out as its attempting to start.

WB is that the AFR Tgt? If so, that reads at 14.7

Xcnts reads at 128.

I'm told the shop to gap the spark plugs at .030.
 
Don W.

Don W.

Stab it and steer it
Re: Cold Start Stutter

arcadewilco said:
If I turn right on the throttle screw the idle gets higher and my IAC count climbs. So I turn the screw all the way left and it has no pressure on the throttle body. It idles fine there at 800 RPM and IAC is stuck between 42-47.

I recorded a start just now and there is black smoke coming out as its attempting to start.

WB is that the AFR Tgt? If so, that reads at 14.7

Xcnts reads at 128.

I'm told the shop to gap the spark plugs at .030.
Click to expand...

Idle screw sounds backwards. As you close the throttle the IAC has to open to compensate so you would open the throttle using the idle screw to lower the IAC. IOW thy work opposite each other. Check that the butterflies are, in fact, closing all the way. Idle speed is a bit high. SB 500-650 IMHO I find it helpful after I adjust idle to bump the throttle and let it return to idle and see if the IAC returns to where I set it or close.

Black smoke = rich. Try a cold start with the throttle held wide open like I mentioned.

The wide band I'm referring to is the actual gauge reading, if you have one.

.030 is fine for this.

HTH
 
D

Damian

Member
Re: Cold Start Stutter

Why would anyone "reset the IAC"?? I've never once reset it and I've had my battery disconnected several times. I always just let the engine idle for a bit and the ECU figures it out itself.
 
A

arcadewilco

New member
Re: Cold Start Stutter

Thanks. By the way the truck is for sale on EBay it's #225. Trying to fix this start stutter for the buyer but I'm going to just be asking $15k as is. It's a nice truck with only 35k miles. Tuned up and refreshed based on Sportmachine and this forum's guidance.
 
D

Davemc1963

93 Ty Owner
Re: Cold Start Stutter

Damian said:
Why would anyone "reset the IAC"?? I've never once reset it and I've had my battery disconnected several times. I always just let the engine idle for a bit and the ECU figures it out itself.
Click to expand...

May be you've never fitted a new IAC valve.
Not knowing the full history of the OP's truck, it seemed reasonable to rule it out. I've fitted a couple in the past and have always had to do this.
When you fit a new IAC (not that the OP has, but could have) the pintle should be retracted or in a retracted state to avoid damaging it when screwing it into the TB.
If the IAC isn't reset, it usually causes a high idle speed, because the ecu dosen't know its new or current position. 'Resetting it' closes it and then when the engine is started, it allows the ecu to establish a 'correct' idle speed.
If you know this fine, some may not, just trying to help out with limited knowledge of the truck in question.
 
A

arcadewilco

New member
Re: Cold Start Stutter

Tried to reset the IAC this morning but no change in IAC counts or idle (still at 800RPM). I did run datamaster and I noticed that the EGR Act is between 70-97. The EGR Tgt is at 4.3. On previous run without the stutter these values were at 0.0 So I'm thinking I have a bad EGR? Again its only on starting the car that it stumbles but then once it finds idle its smooth. Running the truck is real smooth as well with no hesitation.
 
You must log in or register to reply here.
Top