Engine only stutters at 7:00am

[Florida]

I leave for work at 7:00 am. I idle out of the drive way with no problems. As I push the pedal to accelerate onto the main road the engine slows, misses and stutters for about 5 seconds. After that it runs perfectly fine. This never happens at any other time, it only happens when I leave at 7 am. Any ideas? I have a 2002 chevy astro van


thanks for the help

 

[rbh]

Re: Engine only stutters at 7:00am

Maybe a indication of an issue with the high idle on start up to idle (electronic choke thingy)

 

[wifisher]

Re: Engine only stutters at 7:00am

Does it do the same thing EVERY morning? Is it parked outside and can get moisture on it? When you say accelerate onto the main road, how fast are you accelerating (half throttle?, more? less?), and at what speed does it happen? What is engine temp when it happens? If you step harder on the pedal, does it clear up or get worse? Have you ever changed the fuel filter?

 

[Florida]

Re: Engine only stutters at 7:00am

It does the same thing every morning and it is parked outside. I accelerate slowly to about 35 mph. I would say less than half throttle. The engine temperature is totally cold when I start it in the morning. If I further depress the pedal when the engine is stuttering it stutters more until something catches and then it starts roaring We have a lot of condensation here in Florida. Every morning water is dripping off the roof.
Thanks for the help

 

[Fireman431]

Re: Engine only stutters at 7:00am

The same thing happens in my truck. It is the Idle Control Circuit. Allow it to warm up a little more in the mornings (3-4 minutes). That stops my issue.

 

[wifisher]

Re: Engine only stutters at 7:00am

Have you ever let it sit until later in the morning before driving it? Does the problem go away? That would indicate a moisture problem. Another way to check moisture issues is to pop the hood, and start the motor. Take a garden hose and mist the entire engine compartment.

If the problem goes away when the car is left to sit until warmer weather, I would check the IAT sensor. (intake air temp) I don't think that the temp is a factor in florida, as it doesn't change much, but maybe.

Could be a MAP or TPS (manifold absolute pressure or throttle position sensor) but I would expect a code with either one bad. They may be reading, but not correctly. Scan tool and test drive is the only way to check these.

It is a hard problem to fix remotely. Without driving the car it is hard to feel what it is doing. A miss like that can be caused by a lot of different things, and without plugging in and driving it I am just guessing.

 

[paultjohnson]

Re: Engine only stutters at 7:00am

Leave at 8............

 

[MTboatguy]

Re: Engine only stutters at 7:00am

I don't think waiting an hour would help, but perhaps leaving at 6:48AM would work, !

LOL

 

[mommicked]

Re: Engine only stutters at 7:00am

I sometimes have the same problem getting out of bed too early in the morning

 

[puddle jumper]

Re: Engine only stutters at 7:00am

Just something to add. It may be an engine problem but the trans lock up in the torque converter may also be the problem. I have seen it before. Best way is to hook it up to a scanner and go for a ride with some one.

 

[Tim Frank]

Re: Engine only stutters at 7:00am

I leave for work at 7:00 am. I idle out of the drive way with no problems. As I push the pedal to accelerate onto the main road the engine slows, misses and stutters for about 5 seconds. After that it runs perfectly fine. This never happens at any other time, it only happens when I leave at 7 am. Any ideas? I have a 2002 chevy astro van


thanks for the help

The trouble with coming into a thread like this late is that all the better smart-a**ed answers are already gone....

On a serious note...leaving at a later time...if the vehicle has not been run at all....say 8:30...have you actually done that with no symptoms?

 

[Autotech]

Re: Engine only stutters at 7:00am

Is it 4.3? My first thought was fuel pressure seeps down over night. Which means fuel pump or fuel pressue regulator. That is if it has CSFI . Cycle the key switch 3 or 4 times before cranking the engine in the morning. Pump will run 3 seconds before turning off, each cycle: That will cause the pressure to build up before cranking. Needs to have 56-62lbs of fuel pressure. if you have a gauge check it. Other thought is a map sensor. Is the Check Engine Light On? If it is DTC will be set for MAP.
Hope this helps.

 

[j_martin]

Re: Engine only stutters at 7:00am

My bet is old spark plug wires and condensation. Those Astros are hard on wires.

 

[RogersJetboat454]

Re: Engine only stutters at 7:00am

My bet is old spark plug wires and condensation. Those Astros are hard on wires.

+1 on that.

Your talking about a moist environment. When is the last time the van had a full tune-up? Cap, rotor, wires, plugs.
The "Crab" style caps that GM used for the later distributors will cause problems like this. Condensate will compound the issue. Once the engine warms up and burns all the moisture off the secondary ignition stuff, its no longer an issue.

I have my doubts that the idle circuit has anything to do with this. Think about it, once you crack open the throttle blade, the idle circuit doesn't matter much. We're not dealing with a carburetor here. You can compensate for a D.O.A. IAC valve by opening the throttle. If your opening the throttle more, and the van stumbles more than it's more than likely not an IAC problem.

A TPS issue would likely haunt the van most of the time too, unless it's a moisture intrusion issue. This van does not use speed density for fuel control. The MAP sensor on this rig is present for monitoring the EGR valve opening. The MAF meter is what is primarily used for fuel control along with the primary O2 sensors.

Same with a fuel pump. Key switched on, engine starts, you have fuel pressure. If it were a pump or filter issue, I would expect a loss in over-all performance, and the fuel pump doesn't really care what the time of day is, or how moist it is outside.

Just my 2?......

 

[bigdee]

Re: Engine only stutters at 7:00am

You could just ignore it. I had an s-10 that started that studdering thing like it was intermittently losing a cylinder. I never got around to fixing it and drove it back and forth to work for 3 years. A couple months ago I gave the truck to my son-in-law. Before he came to pick it up I was going to try and find the problem for him......I found a deteriorated vacuum line that operates the heater dampers. After fixing the leak the truck has not skipped a beat.

 

[BlkY2k]

Re: Engine only stutters at 7:00am

I think Jetboat about covered this one, Good Job. You guys can laugh about leaving at a different time but I`ve seen some strange things over the years with different vehicles, father-in-law had a ford pickup that would NOT start at 30* it was in the shop more in the first year than he got to drive it. The techs never did find the problem, he got to the point he just carried a propane torch to heat up the control box and fool it into starting. Worked every time.

 

[Tim Frank]

Re: Engine only stutters at 7:00am

I leave for work at 7:00 am. I idle out of the drive way with no problems. As I push the pedal to accelerate onto the main road the engine slows, misses and stutters for about 5 seconds. After that it runs perfectly fine. This never happens at any other time, it only happens when I leave at 7 am. Any ideas? I have a 2002 chevy astro van


thanks for the help

From the responses I have still not figured out whether you are saying that you HAVE actually left at, say, 7:15, and there has been no malfunction at all.

 

[dolluper]

Re: Engine only stutters at 7:00am

Bad disy cap.....dirty mass air flow sensor

 

[puddle jumper]

Re: Engine only stutters at 7:00am

I think Jetboat about covered this one, Good Job. You guys can laugh about leaving at a different time but I`ve seen some strange things over the years with different vehicles, father-in-law had a ford pickup that would NOT start at 30* it was in the shop more in the first year than he got to drive it. The techs never did find the problem, he got to the point he just carried a propane torch to heat up the control box and fool it into starting. Worked every time.

I will second that. Some things are just left best to the witch doctor to do his voodoo on.

 

[jimr]

Re: Engine only stutters at 7:00am

depending on the year it could be an intake air temp sensor or coolant temp sensor reading hotter or colder than it is