Lots cheaper then injector change......

 

We had to change the radiator out a few months ago due to the plastic cracking and pulling away from the metal portion of the radiator causing a leak. We also did a system flush and changed from the Dexacool (GM crap) to the regular green fluid. She runs a lot cooler now.....but the H3 is at the mechanics shop for the injector change....and while he was in there he said the intake gaskets had shrunk which was also causing an airflow issue. I hope this fixes it and luckily I love and trust my mechanic and I know he isn't messing around with me on the issues...I will never use the dealership for big ticket fixes! He even lets me use his garage for my own oil changes. If this doesn't fix her, then I'm assuming the crankshaft will be next. But the mechanic is hopeful and says so far she is running MUCH better! We get her back tomorrow so we'll see for ourselves.

And I want to say thanks to all you that have posted here and helped us learn a little more about cleaning up our H3!!!

 

Tina- make sure your mechanic changes out the thermostat before he digs any deeper into your idle problem.

I bought my H3 new in 2006 and had no issues with it until I found the radiator cracked last November. You seem to have exactly the same symptoms as my H3. My idle problems started getting worse right after the radiator change. My mechanic's theory is the thermostat is going bad first which is overheating the radiator and cracking it. He suggests changing out the thermostat at the first sign of an idle drop, he seen the thermostats fail as low as 50K miles.

Chicken or egg?

Doesn't matter, word to the wise for all you H3 owners; if you replace the radiator or have a shaky idle ... change out the thermostat. A faulty thermostat may actually be the smoking gun behind the idle drop everyone is experiencing with the H3 Hummers.

My H3 idles like a dream now.

 

I've got a stalling issue but only happens when my car is in full steering lock left or right. And only when I bleep the throttle ie. parallel parking, here is a video of my car stalling:

 

So finally got the word from multiple mechanics. The valve seats are bad. The valves are not sealing properly and the seats are being pushed down under idle. Losing compression in the cylinders. When the motor is under load, the compression is enough to temporarily overcome this problem, but the seats are continually being pushed further down. GM wanted to replace the head (at $1000 for the bare head casting PLUS all additional parts and labor). A local machine shop wanted to shave down the valves to keep them from pushing in the seats, but this is a hit or miss fix (uhhhhh, no). Found a machine shop in Odessa, FL that has dealt with this problem enough times that they knew EXACTLY what the issue was and how to fix it. Apparently, it's a semi-common problem with the 3.7. The machine shop portion is $450, plus the money I'm going to be in this thing to my mechanic for the labor. Not happy, but better than the $3000-4000 head job this was going to be. Should have it back within a week and I will let you all know how that works, but I've gotten a guarantee from the machine shop that it will be fixed.

 

I fixed this months ago on mine...problem ended up being the first 3 spark plug wells (from front of the vehicle) were completely filled with water..last 2 were dry. I suspect that this happened from splashing deep puddles (which I doubt) or from when my buddy decided to hit underneath of the hood with a powerwasher with the engine running (he said it was safe to do). I also cleaned the throttle body which was completely black...never did clean the MAF which I need to do one of these days. Truck has been good ever since....

 

I'm gonna throw my hat in the ring here. I've been having this problem for a week or so now. I replaced the plugs and throttle body 10,000 miles ago... I just did a little work to my truck and decided to clean my MAF and TB. It wasn't bad since I just changed the TB recently. I thought maybe I damaged the TB gasket so I replaced it ($4)... I checked the coil packs. One was way corroded so I replaced it. That didn't do it. I had the supersparkz spring deletes in and I put the original springs back in. Nothing. I did a coolant flush a month or so ago and replaced the thermostat at the same time. I'm at a loss. I have an appointment at the dealer in the morning. I really have no idea what it could be. Not sure if they'll have any idea either.

 

Hi,
I have the same exact issue. And Yes!
I have changed every part mentioned in this entire thread.
You name it, it has been changed, Thermostats, mass air flow sensors, radiator, coils, spark plugs, water pump, gas pump, , Throttle body, EVERY DAMN THING listed in this thread has been changed.
The last thing changed was the thermostat and and engine coolant.
The car worked perfectly for two week. Yes, two weeks.
It is back at this god damn hesitation at low idle.
The only things that has not been changed, because I'm told the parts are working perfectly, are the valve seats and whatever is on top of the valve seats.
I am in three thousand dollars so far between work, parts, and opening up the entire engine.
Now get this: THE GOD DAMN DEALER SAID IT DOES NOT FIND WHAT IS WRONG! but they charged me 2000 dollars for checking the car.
When I called GM, they said they would only cover one hour of labor towards the 2,000 dollar bill i got.

IS there anyone in this entire website that would know what the hell is wrong with the H# 2007 stall issue at low idle, BESIDES anything that has been listed on this thread?
I am so pissed off, I cant even trade the damn car, because this damn stalling gives a red light to dealers and I still ow 10 K on it.

Again, Is there anything else besides everything that has been listed on this and other threads regarding stalling at low idle.

Please reply to gp1182@gmail.com

I am willing to give a reward to who ever can tell me 1,000 percent correct, what is wrong with the god damn car.

 

Hope you feel better after that rant?

Since you just jumped in to a 4 year old thread 78 posts in and claim to "have the exact same issue".... I have to ask what exact same issue?

Are you talking about acting like it wants to stall (false stall), or some form of the other banter in this thread, because for the most part this thread is pretty useless? False stall is almost always caused by a sticky (ie. god damned dirty) Throttle Body. I can explain why if you want, but it don't matter when it comes to correcting it.

I need an answer to this question before I can help: Have you cleaned your throttle body? If so, at what mileage, and how many miles do you have now?

I get that you chased parts all over, but you did not mention the ole cleaning the TB.

 

There's no such thing as a dead thread on the web!

From my experience a 4 year old thread is a "new thread" to anyone searching for answers. People that 'live' on the forums don't seem to understand that point.

H3 "acts like it wants to stall" ... yea that problem is plenty 'live' for anyone experiencing it.

However gp1192, your a member of this forum ... start a new thread ... a compression test would be pertinent in your case.



For those of you that stumble upon this thread and are suffering from the "acts like it wants to stall" problem ... this is a common occurrence with the Hummer H3's. Many times its a symphony of problems that combine to create this situation. You should see this symptom as an opportunity to perform some routine maintenance that has no doubt been neglected on your ride.

Below is a list of common items that can cause this situation in order of priority. Many times the stumble slowly improves but does not completely go away until you complete more ... or all of the routine maintenance.

#1 Clean the throttle body (And I mean properly clean it)

#2 Check the coil packs for corrosion. (Many times water gets inside)

#3 Remove, inspect, & even stretch the springs a little in the coil packs.

#4 Install new sparks plugs. (Don't cheap out, buy them from a GM Dealer)

#5 Clean the Mass Air Flow Sensor (Use a spray cleaner made just for this)

#6 Change the fuel filter (It may be slightly clogged affecting the idle)

#7 Change the thermostat (If your water temp reads below half ... it's shot ... the farther below half the more defective it is "i.e. it's stuck open")
Don't underestimate this one, this is what finally cured the last little ****le on mine)


Still a rough idle ... first thing first .. do a compression test to make sure your valve seats are not leaking. If the compression is good then you may have a weak coil pack, unlikely but possible. (A simple test at home it to pull off one coil pack at a time a see if the stumble is even) You may also have low fuel pressure, bad fuel pump!

If the idle stumble still has not gone away, you're now in need of some professional help.

Understand most mechanic's will start by a redo of everything you did, just to make sure you did it correctly. Carefully weigh your mechanical ability, tooling, and time available before you head down the DIY path. Finding a good mechanic, well, we all know how hard they are to find.
Sometimes ... and I hate to admit it ... the best option in the long run is to take is straight to the GM dealer.

Your milage my vary .........................