'06 SV6 starts then stalls sometimes.

UPDATE: Please read further to find out about the C305 connector that can cause this, and many other, symptoms that my van had. But in the end, my starting issue was fixed by simply cleaning the Mass Air Flow (MAF) sensor and electronic throttle body (TB) with their specific cleaners.

I've got an '06 SV6 that always turns over but about 1 in 20 times will immediately stall right after starting. When it doesn't stall, the RPMs still dip pretty low at first before going to normal. I can hear the fuel pump priming.

If my 3800 Grand Prix was doing this I'd check the idle air controller, but I don't see one anywhere obvious with this 3.5l engine. Could it be a fuel pressure problem or something with the MAF? The car is showing a 0442 - small evap leak code but I can't imagine it's related. Any ideas what to check?
-Doug

I've got an '06 SV6 that always turns over but about 1 in 20 times will immediately stall right after starting. When it doesn't stall, the RPMs still dip pretty low at first before going to normal. I can hear the fuel pump priming. Any ideas what to check? -Doug

I did a quick google search and following items were found:

A - Replace Gas cap. Sometimes, even a new gas cap is defective. Test with new one, or different used one that is rated for your specific vehicle model.

B - I used to have a similar issue and a change of the fuel filter seemed to do the trick. It wasn't as rough as your describing though.

C - The 442 code is a very small leak in the evap system, it could be a cracked hose on the system or a bad connection at one of the hose's 0-rings or a leak at the fuel filler tube, this type of leak is difficult to locate, the evap system should be pressure tested or tested by injecting smoke with a special machine, the smoke will exit into the air and can then be located, most dealers or smog test stations have this machine, this would be the most reliable way to find the leak instead of just putting more parts on that may or may not fix this leak.

D - I had this problem before, the dealer replaced the maf sensor and reprogrammed the ecm, it wasnt the gas cap.

E - They said that they manually checked the throttle actuator and that once they started fiddling with it that it started running fine...

Hope some of these suggestions help...

.

I did a quick google search and following items were found:

A - Replace Gas cap. Sometimes, even a new gas cap is defective. Test with new one, or different used one that is rated for your specific vehicle model.

I already bought a new locking gas cap. It didn't solve the evap leak problem or the starting problem. It wasn't a waste though, I wanted a locking one with such a large tank and my wife having the van at the school she teaches at.


B - I used to have a similar issue and a change of the fuel filter seemed to do the trick. It wasn't as rough as your describing though.
Good idea since I don't know when (or if) any previous owners did this.

C - The 442 code is a very small leak in the evap system, it could be a cracked hose on the system or a bad connection at one of the hose's 0-rings or a leak at the fuel filler tube, this type of leak is difficult to locate, the evap system should be pressure tested or tested by injecting smoke with a special machine, the smoke will exit into the air and can then be located, most dealers or smog test stations have this machine, this would be the most reliable way to find the leak instead of just putting more parts on that may or may not fix this leak.

Now that the weather is nicer, I'm just waiting for the rain to stop so I can get under the van and check all the hoses for obvious problems. I'd bet I'll have to end up getting the smoke test done. I wouldn't think this could be related to the starting problem, but who knows?

D - I had this problem before, the dealer replaced the maf sensor and reprogrammed the ecm, it wasnt the gas cap.

That would be my last resort because of the $$$!


E - They said that they manually checked the throttle actuator and that once they started fiddling with it that it started running fine...

That's interesting, because if I react quick enough, I can usually stop the engine from stalling by giving it a little gas. If I always give it a little gas, it never dips to low or stalls. But that's no long term solution. I'll have to check the throttle.

sisson d,

Stalling is sometimes caused by a faulty IAC (Idle Air Control) system.

There is a valve attached to the side of the throttle body and may have a loose wiring connection OR the valve may be defective.

Cleaning the throttle body usually fixes a few idle issues.

I've got an '06 SV6 that always turns over but about 1 in 20 times will immediately stall right after starting. When it doesn't stall, the RPMs still dip pretty low at first before going to normal. I can hear the fuel pump priming.
-Doug

Does it always have difficulty starting, or just 1 in 20 times? My wife's van started this behavior and it eventually turned out to be dirty injectors that were leaking fuel into the engine. Hers would have difficulty starting only when it had been shut down for a short period of time, from say 10 minutes to a couple of hours. An early morning start always worked good.

sisson d,

Stalling is sometimes caused by a faulty IAC (Idle Air Control) system.

There is a valve attached to the side of the throttle body and may have a loose wiring connection OR the valve may be defective.

Cleaning the throttle body usually fixes a few idle issues.

That is the very first thing I thought of when we first got the van a few months ago. Then I looked around and didn't see anything that was obviously the IAC and, apparently, completely forgot about that.:eek7: I have replaced the IAC on my '98 Grand Prix years ago for an idling problem that turned out to be a vacuum leak. I will take a better look for it tomorrow. Strangely, I don't see replacement IAC valves listed on autozone or napa's websites. Thanks for the reminder. Of course, I'm sure it won't be that easy.

Does it always have difficulty starting, or just 1 in 20 times? My wife's van started this behavior and it eventually turned out to be dirty injectors that were leaking fuel into the engine. Hers would have difficulty starting only when it had been shut down for a short period of time, from say 10 minutes to a couple of hours. An early morning start always worked good.

Also a good idea. I'm not not sure about the first start of the day since my wife takes it to work in the morning and I get it for work at night. She hasn't mentioned it happening to her. Plus it happens infrequently enough that I can't seem to pick up on any pattern. Although it always seems a little weak for a few seconds when first started even if it doesn't stall. How did you figure out that it was the injectors?

How did you figure out that it was the injectors?

I went through a long period of part swapping and internet research. I eventually put a fuel pressure gauge on the fuel rail and watched the fuel pressure from the time the engine was running to 10 minutes after I shut it off with the key. It dropped significantly during that time. It's suppose to hold pressure for quite a while. I also did an experiment where I started it and let it run for a minute and then shut it off and let it sit for 10 minutes. Then I tried to start it. It was difficult to start. I then let it run for a minute and then shut it off and let the fuel pressure out of the fuel rail, thus not allowing any fuel to leak into the engine, and then let it sit for 10 minutes. It was easy to start. Changed the injectors, problem solved.

Also...

Do inspect the vehicle's C305 Connector as well. re: "Starts then suddenly stalls" behavior.

For more details, surf entire contents of:

http://ww2.justanswer.com/uploads/GMGreatWrench/2009-02-07_013436_updated_Venture_connector_bulletin.pdf

Hope this helps as well....

.

Also...

Do inspect the vehicle's C305 Connector as well. re: "Starts then suddenly stalls" behavior.

For more details, surf entire contents of:

http://ww2.justanswer.com/uploads/GMGreatWrench/2009-02-07_013436_updated_Venture_connector_bulletin.pdf

Hope this helps as well....

.

Well...spike88...I think you just answered a question I never would have asked. How are most of my Montana's problems interconnected? Wow. I intermittently have almost all of these problems listed in that bulletin. In addition to the starting issue, that is frequent, I occasionally have the fluctuating fuel gauge, the ABS light, AWD disabled light, and the SES light.

I'm actually very excited about getting under the van soon to check this out. To think that I could solve most of the vans problems with one connector is great. I never thought that the problems could be connected. I wonder about the SES light though. I show a 0442 (small evap leak) code and I wouln't think that it would be related to that connector, but who knows. Before a search for that evap leak, I'll be checking that connector.

Spike88, I have a feeling I'll be sending you a thank you message soon.

I think Spike88 pointed me in the right direction. Here's the connector in question:
http://www.dougsisson.com/pics/c305_connector_sm.jpg

Yeah...it looks like there were problems in the past and a DIYer hacked away at it. I would use those connectors to hook up some car speakers, but these connectors are not meant to be exposed to the elements. No wonder there are problems. I'm surprised that the problems are intermittent and that the van runs at all.

Anybody have any advice on how I can fix this? I have a 2006 SV6, does anyone know if the older generation GM minivans use the same connector with the same pin outs? I already know that there aren't any of the newer generation vans at the local junk yards, but there are some of the older ones. If I can find a used connector, I could splice the wires and seal the connections with some heat shrink wrappers.

Again, thank you Spike88!

Well...much time has past since I discovered the bad C305 connector. But I recently finished most of the work on my new 2-car garage and actually have a place to work on my vehicles now. So, I went out to the local Pontiac dealership and the parts counter guy found a replacement connector with pigtails to be spliced to the existing wires and weatherproof heat-shrink connecotrs. He was great and actually spent close to 15 minutes on the phone with a help desk to track down this awkward part. It was $70, but was much less than a whole new wire harness. The only annoying thing is that the pigtails and the connectors were 10 gauge while the wires they had to connect to where either 14 or 18 gauge. Thankfully I have different connectors of various gauges and it was only a small nuisance. I ended up having to get all new female connectors for the body harness that the new harness plugged into.

I have driven the van around a bit and, so far, the ABS and AWD disabled lights have not come back on. The first day the engine never stalled during starting multiple times, but today that happened again twice. And the SES light with DTC 0442 remains. Strangely, before I replaced the connector, the code would take at least a few hours of driving to reappear when reset. Now I can reset it and it will immediately reappear before I even drive the van. So, I think there is still an issue with that wiring and will have to check it out more thoroughly.

Thanks again to Spike88.

Wait hold on....after writing this post I had to go out and check that DTC again because for some reason I thought it might have said 0449 when it used to say 0442 (small EVAP leak). Sure enough it is 0449 which is a problem with the EVAP canister purge solenoid circuit. Which, IMO, is a problem with my wiring since it started happening right after repairing the wiring. I have to check that again.

have you tryed putting sea foam in it to clean injectors? may not help your problems but will clean them. almost sounds like maf sensor also.

Final update:
It was in fact DTC 0449 after I replaced all the wiring. Ends up that, while I fixed the ground from the ECU to the evap purge solenoid when rewiring, the 12v power source was bad too. Apparently, in an attempt to make the evap system work again, some hack had cut the wire at the fuse box and ran it directly to the battery with an inline fuse. While the fuse box fuse was fine (because it was no longer hooked up), that hidden inline fuse had blown.

So, I rewired it through the fuse box again, cleared the DTC, and the check engine light has not come on since.

The ABS/Traction control light has come on a handful of times after backing up in slippery conditions. Although it comes on MUCH less than it did and never comes on in dry conditions anymore.

I eventually gave up on the hard start condition being from the bad wiring harness. So, I cleaned the MAF and the electronic throttle body with their respective cleaners from CRC. The MAF had no visible build up on it, but I thoroughly cleaned it anyway. The TB was very dirty and the valve seemed gummed up. It didn't move as easily as it did after cleaning and it didn't seem to close all the way either.

After the cleaning, the car starts strongly every time. And, as an added bonus, the MPG has gone up. On a recent 200 mile trip (almost all highway through the Berkshires and Taconics) that we've made numerous times before at 17-17.5 MPG, we got 20.5 MPG!

I'm kicking myself that I didn't just do that earlier. In the past I've had problems with other vehicles that could have been MAF related, and when I did the MAF cleaning, nothing happened. So, I guess I've just been conditioned to not even try it. But that said, considering how cheap and easy it is to do, everyone should give their MAF and TB a good cleaning for the potential MPG boost that it could give you.