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Master Auto Tech.
Master Auto Tech., A.S.E. Certified Master Technician
Category: Chevy
Satisfied Customers: 598
Experience:  Over 20 years working on imports and domestic cars
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I have a 01 S10 with the 4.3L. On a moderate to cool day

Customer Question

I have a 01 S10 with the 4.3L. On a moderate to cool day (less than 80 outside) I can start the engine and it runs perfect. If it is a warmer day 80+ I go to start it, it will start just fine and run for about 30 seconds and then start to idle rough. If I put it in gear it has little to no power. After about 30 seconds of no power and rough idle it goes away. Again this only happens on hotter days. It will also happen if it is a moderate cool day and I ran the vehicle good and hot then shut it off. Later to start it, it has the same issue as it does on a hot day.
Submitted: 9 months ago.
Category: Chevy
Expert:  Cary York replied 9 months ago.

Hi, I’m Cary and I’ll be helping you today.
Please understand that I can't smell, hear, or touch the vehicle either, so patience is appreciated. I work part-time here on JustAnswer to help you and others repair their own vehicles, and I get credited by your ratings. So before leaving the site make sure and leave me a rating. You can still reply to me as many times as needed, even after the rating..

Is the check engine light on?

Customer: replied 9 months ago.
NO. Although one time it did but, it was only a code for misfire cylinders when it was a real hot day. I have had the code reset and have not had the light on since.
Customer: replied 9 months ago.
This has everything to do with how hot it is under the hood. If I leave it in the sun it will act up even more. In the colder months this pickup has no issues at all. It never gives me any other issues. Good fuel mileage and power all of time (except for that 30 seconds after startup when it is hot out)
Expert:  Cary York replied 9 months ago.

This engine has a fuel injection assy under the intake. It sounds like the engine may be running rich due to an injector leaking. Loading the intake the fuel while it sits. Here is a bulletin on the issue. Cleaning may help. But replacement may be needed. To know for sure we need to have a scan tool to see O2 sensors and fuel trim readings.

Expert:  Cary York replied 9 months ago.

Here it is

Expert:  Cary York replied 9 months ago.
Expert:  Cary York replied 9 months ago.

You may try adding fuel cleaner to the gas tank. I would double or triple dose it. May take several times.

Customer: replied 9 months ago.
OK. So why does it not have a problem when it is a lower temp outside? I would be inclined to agree with that except temperature has everything to do with it. And also why does it run good for about 30 seconds first and then have the issue? One bit of additional information. When it is really hot out 95+ and it is in the sun, even it I have not started it for a day or two, I go to start it and it will do the same. And yes I have ran fuel injector cleaner through it a couple of times.
Expert:  Cary York replied 9 months ago.

When the ambient temp is cold it requires more fuel on start-up. Hence choke on a carb. When hot less fuel. More fuel hot then it loads on start-up and take a few seconds to clear the intake and smooth out.

Expert:  Cary York replied 9 months ago.

If you have ran fuel cleaner through it with no results, I have also seen the fuel pressure regulator leak on these fuel injection assy. The regulator come with the assy or can be paused separately.

Expert:  Cary York replied 9 months ago.

Sorry. Purchased separately.

Customer: replied 9 months ago.
hmm....So I get why when hot with that description now but, why does it run good for about 30 seconds first? Here is how the order of events go. Assuming it is hot out, I start the engine the engine naturally is going to idle a bit higher as they all do when they just get started. Next it will idle down to a near normal warm idle RPM 10 seconds later or so it then starts to have its issue.
A few times when it has been near 100 outside, I started it, it had it normal weird power/idle issue, I pushed through it, only to have it come back about 30 seconds later.?? I was leaning to more of a EVAP issue except I know that EVAP issues almost always pop a code.One last description / example for you:
I start it when it is hot out. I put it in gear (no issues yet) but, 30 seconds of being on the road it then looses power. I push through it by giving it more accelerator. It is really sluggish but I am going down the road (10-15 mph or so), then all of a sudden the power comes back and my tires chirp. It is that sudden the power comes back.
Customer: replied 9 months ago.
Just today I had a mechanic monitor the fuel pressure when it was doing it and they said it was fine.
Expert:  Cary York replied 9 months ago.

I am going to opt out now. Thank You

Expert:  Tim's Auto Repair replied 9 months ago.

Hi, My name is ***** ***** for the delay.

I will do my best to assist you.

you still dont get an engine light?no codes?

Customer: replied 9 months ago.
No light and no code
Expert:  Tim's Auto Repair replied 9 months ago.

but it has gave a 300 code?

Customer: replied 9 months ago.
If the code for misfire is 300 then yes. I brought the truck in to my mechanic and he looked at the code and his said it was a misfire. Hopefully you can read the correspondence from the previous guy because I mentioned that before to him. That was only once that it came up with a check engine light and that was when it was 97+ outside and it was acting up much more than when it was cooler out. The mechanic cleared the misfire cylinder code and it has not come back since.
Expert:  Tim's Auto Repair replied 9 months ago.

ok

tell me,,did you give it a tune up?

Customer: replied 9 months ago.
If you mean new plugs, wires, cap, rotor, air filter, and fuel filter, then yes.
This has been a good running rig with just under 100k on it. It never has given me any other issues or troubles. And like I mentioned before, it has good power and mileage. Just this one issue which seems to be getting worse. By worse I mean it seems to be getting more sensitive to the temperature. An example of what I mean, it used to be only when it was 90+ outside but now it will even start to do it in the low 80's.
Expert:  Tim's Auto Repair replied 9 months ago.

yes i understand

Expert:  Tim's Auto Repair replied 9 months ago.

ok,,i will give you my thoughts on the matter if you like

Expert:  Tim's Auto Repair replied 9 months ago.

sense it isnt giving any codes and from the way you explain..

there are a few things that can do this

Expert:  Tim's Auto Repair replied 9 months ago.

first..

you need to remove a clean the egr valve,though most times when they stick,it will give a code,i have seen them not give a code..so remove and clean it,it is free and easy to do

Expert:  Tim's Auto Repair replied 9 months ago.

second..

replace the ect sensor,,[engine coolant tempeture]..this is what tells the computer the engines temperature and adjusts the fuel accordingly..these can go bad and not give a code..it can starve the engine of fuel or give it too much fuel when they are bad..

the ect ussally cost less than $25

Expert:  Tim's Auto Repair replied 9 months ago.

THIRD.

the crank sensor,these crank sensor can give a fit with temperature and not give a code.they can cause a missfire or completely stop the injector pulse when they get hot if they are bad..the crank sensor is located on the passenger side front of the engine near the crank pulley.

Expert:  Tim's Auto Repair replied 9 months ago.

and my final thought.

the catalyst converter,,

a clogged catalyst willl cause this problem also,you need to take it to a muffler shop to have them test your catalyst converter

Expert:  Tim's Auto Repair replied 9 months ago.

if i were going to pick one of those,,i would think your problem is the crank sensor

Customer: replied 9 months ago.
I have removed the egr valve on other vehicles in the past but I knew exactly what to remove first and where exactly it was. Do you have any documentation or website you can point me to, that will give me a step by step?As far as the engine coolant temp sensor I certainly can do that too but, do not that I did have my mechanic hook up the computer to the vehicle while it was cold to hot to make sure it was reading with in a normal range. He said it looked fine from what the computer was reading. Would you still replace the sensor?Catalytic converter...OK I could see that being the issue if it did it after it started up and then continued but trust me the truck runs fine after it goes through that short "phase" In fact I just got done putting about 800 miles pulling a camper with no issues (other than what we are talking about).
Expert:  Tim's Auto Repair replied 9 months ago.

stnd by,,i will upload the locations and tests/checks for the 300 code

Customer: replied 9 months ago.
OK I will start with the crank sensor (seems probably the easiest to start with). If that does not do it I will move on to the EGR valve. Still not convinced about the catalytic converter but I guess if none of the others work I will check that out too.
Expert:  Tim's Auto Repair replied 9 months ago.

PLEASE COPY AND PASTE the link below to your browser, I have uploaded more info on this there please copy and paste the link below to your main browser[INTERNET EXPLORER or FIREFOX]

.

https://www.dropbox.com/s/kxjfaqoeybzfjmy/0726-4.3-Locations%20View.doc?dl=0

.

if the link doesn’t work that way, try it this way

thanks

.

www.dropbox.com/s/kxjfaqoeybzfjmy/0726-4.3-Locations%20View.doc?dl=0

.

If you are satisfied with my answer, Please Rate my answer by clicking the rating button so I can get credit for my work. I’m not always going to be giving you good news, so please don't let this stand in the way of you accepting my answer. .it does not cost you more money and we will still be able to communicate, ,.please understand, i can not see, hear or touch the vehicle and only know what you tell me. Bonuses and positive feedback are appreciated.. if you are not satisfied with my answer, please do not leave bad feed back ,i will gladly opt out and let another expert handle the question. .if i have sent any diagrams, please print them. .sometimes you may need to right click the image [,then save picture as]to save it to your computer so you can open it with your picture program...Please ask if you need more help

Customer: replied 9 months ago.
thanks for the diagrams. I will give that a try. I would like to keep this conversation open for the time being. I will get back to you and let you know if the crank sensor and egr cleaning did the trick.
Expert:  Tim's Auto Repair replied 9 months ago.

please do

thanks

Expert:  Tim's Auto Repair replied 9 months ago.

please let me know

Customer: replied 9 months ago.
I have replaced the crank sensor but, unfortunately it has been cool and raining so I have not been able to effectively test it. I believe in the next day or two it is supposed to get warmer out and I will let you know the results then.
Expert:  Tim's Auto Repair replied 9 months ago.

ok

just let me know

thanks

Customer: replied 9 months ago.
The crank case sensor did not work. What are your thoughts on the timing control module? I have been thinking about it and wondering if this could cause the symptoms I am having. The EGR cleaning you mentioned would make more sense if it was doing it all of the time but it has to do 100% with the temperature. Like I mentioned before, I could have not started the vehicle for days but if it is in the sun and hot out, it will have the problem (and it only last for less than a min and then goes away). If it is cool out at all it will not do it. Knowing that I am not sure how the EGR needing cleaning would have such clear and exact symptoms related to heat. It would be a bit more consistent and not exactly related to heat?
Expert:  Tim's Auto Repair replied 9 months ago.

hi

if it wasnt the crank sensor

the ignition module is possible,,,,i would think it is for certain an electrical component breaking down with heat..yes,the ignition module is possible

Customer: replied 9 months ago.
Hi, please opt out I want an answer from a different expert. Thank you!
Expert:  Tim's Auto Repair replied 9 months ago.

no problem

thanks

Expert:  Master Auto Tech. replied 9 months ago.
I'm sorry you are having problems with your vehicle. I will try to help.I'm a full time mechanic and have been a mechanic for over 20 yrs and I work part-time here on JustAnswer to help you and others repair their own vehicles, and I get credited by your ratings.. So before leaving the site make sure and leave me a rating. You can still reply to me as many times as neeed, even after the rating.. I will need for you to be my hands and eyes since I'm not there.So are you still having this problem?
If you are and don't mind me taking a stab at it I'll try to help. Just let me know if you want me to try.I appologize that it's so early in the morning, I am on really early till 4pm easternThanks
Sonny
Customer: replied 9 months ago.
Still having the issue.
Expert:  Master Auto Tech. replied 9 months ago.
it looks like you have tried a lot of things. A lot of the most likely things too.
So I may have you try some unorthodox things if you don't mind.Here are two.
1) when your sure it's going to do it, try before you start it, unhooking the battery cables and touchinging them together for 10 seconds. Then reinstall and try running it.
2) if that doesn't work, unplug the o2 sensors and start and try. It will set codes that will need cleared later.I'm wanting to see how the computer reacts. I'm guessing something is throwing the computer for a loop.
The cable thing clears all adaptive memory. The o2 thing is just speculation.Let me know what happens.Thanks
Sonny.