The title pretty much explains what's going on!

About, eeehhhh.... I dunno, 2 weeks ago? My Blaze' through a check engine light and has been stalling on me at random times. It doesn't do it while driving EVER, only at stoplights, stop signs and when the vehicle is not in motion. Hasn't done it in park though, only while in drive or reverse and in a stopped position. Odd thing is, it shows NO SIGNS of "puttering", rough idle or anything that you would expect - It simply dies. <--- and that's pretty much the face I make in the middle of a busy street, during rush hour!!! But MOST of the time it'll start right back up followed by me HAULING TAIL to the nearest gas station!

Now, my fuel gauge doesn't work (stuck on E) so 90% of the time I immediatly think I've ran out of gas which explains "The Gas Station 300" presented by "Stalled S10 Blazers" after it happens. (I'm planning to diagnose/fix this in the VERY near future! Honestly I believe I'm just going to bypass the "floater" and install this Auto Meter Cobalt Digital Series Fuel Level Gauge - P/N: 6910 and never have to worry about where I'm at on fuel again!)

Anyways, I was thinking low fuel was the problem until yesterday! I had just put $20 in the tank and as I was waiting to pull out of the gas station it did it: dead. I turned it over numerous times, only to look like the fool with the badass truck that'll turn over but not run! A nice homeless man came over and helped me push it over into a parking space, where I turned it over one more time and it started right up!?!? The guy looked at me like I was an ******* for making him push this truck with 35x12.50's for 100yd's when the thing would obviously run! Whatever... he got 2 bucks and went into the store for a beer.

Now the thing is, I've checked to see if the truck was stalling at only hot temp's via the on dash gauge - not the problem because it does it randomly at all different running at operating temps! It hasn't done it after sitting, EVER! (though it has stalled before the truck completely warms up) Some of the times it'll start right back up, other times I have to give it 5 mins. Sooo... I'm totally confused on what it could be.

After the incident yesterday I went immediately to (but dreadedly - I HATE THEM) Advanced Auto and had them run a scan to get some codes. The ECU threw a P0420 and a P1870 code. Now, I've looked up both and know that one is theoretically telling me that something is wrong with my transmission (I have the hard 1-2 shift) so I just assume that's why it gave me that code. But the other is a catalytic converter code, or O2 sensor I believe, from what I've read....

ALL of this being said... I don't think this cutting out is a fuel related problem: brand new fuel pump, brand new fuel filter and it just doesn't seem fuel related IMO. The ONLY thing I read about the P0420 code that didn't involve the cat or O2's is a gas cap that was not sealing right. Supposedly the guy fixed it and the code went away! (I actually think I read that on this site) With that, my gas cap is NOT RIGHT, a 1 day old infant could spin it off and it doesn't seem to "lock" on right. Again, don't think that's my problem though.

Here's my question... do you think the P0420 code IS my stalling problem? Will a bad O2 sensor cause the truck to run to rich/lean or something of the likes and cause a stall? Or do you think it could be my cat is clogged all to hell and/or getting to hot or something? (I plan to run the truck hard tonight and then check out my cat to see if she's glowing) But I would assume if that was the problem I would see an overheating problem. I'm just confused and need help from someone, I just think it's something simple and the codes are no contribution to the problem I'm having. I just don't understand why it'll start right back up sometimes and other times take a minute...

ANY INFO is greatly appreciated, I love my truck - I just want her right!

PS: At random times the truck will idle darn high, like going 30mph high. But it's very uncommon and only happens seldomly. Just wanted to throw that in there...

 

I would suspect the MAF sensor first, it'll cause issues just like you're describing.

Next would be the throttle position sensor for the random spikes at idle.

When my cat went bad / clogged, it didn't have any power and would buck like a bronco on his first ride so, I doubt that's the problem.
However when my TPS went bad it would idle at about 2000 RPM's randomly, mostly while at stop lights or when switching gears (5spd model), and the MAF will cause it to die at idle..

 

The MAF sensor make sense in every way, but the fact that it starts right back up or just takes a while to start back up. I just don't understand how the mas sensor could do that, work one min and not the next. But than again, the only thing I know about them is unplugging them on friends cars in high school - just to watch them freak out about how their 93 Geo Prism wont run! My truck DOES have SLIGHT hesition sometimes while gaining speed as your light on the throttle. Wide open, no hesitation though! Could it be a dirty MAF, short somewhere in the MAF? Just need an explination of why it wouldn't be a constant problem if that was the culprit! Also, wouldn't that throw a code?

I'm not to worried about the throttle spikes, that only occurs usually when first started and then I take right off.

I'm beginning to think coil(s) or coil packs... not really sure which (if not both or neither) my blazer has. Do we have like an ICV (IDLE CONTROL VALVE), something like fords have? Even or, the coil doesn't seem like it wouldn't cause a CONSTANT problem and an ICV would hardly let it idle AT ALL.

Again... I'm confused. I just drove the truck about 10 miles, making one stop and constant driving - not one die, hesitation, stumble or anything. It drove powerful and purred at idle, like it came off the show room floor. I'm lost! It's random times and most of the times: nothing!

 

sounds similar to the problem I just had...stalling at stop lights, and sometimes a high idle. There were times I'd have to two foot it at a stop light, and if I didn't keep it above 500 rpm, it stalled...no sputtering...no warning...just stall.

I did some research on here and on the internet, and took it upon myself to remove and disassemble the mass air flow sensor, and clean the heck out of it with mass air flow sensor cleaner. Next, I removed the intake from the throttle body, and sprayed the throttle body with throttle body/carb cleaner, scrubbed off the carbon deposits (which coated most of the throttle body) with a tooth brush, sprayed it again, and repeated the process. Then, I removed the IAC valve which is located behind the throttle body attached with two #20 torx screws and has a plug at the top. Took that part out, and cleaned all the carbon off with the throttle body/carb cleaner. Sprayed it until no more dirty liquid dripped off. Reassembled everything. Runs fine, but the stalling problem was intermittent, so I won't know if the problem is fixed unless it starts stalling again.

 

Again..... how would any of this keep it from starting right back up after a stall?! I'm not trying to say your wrong or ANYTHING like that, but that's the part that baffles me! Sometimes yes, it'll start right back up and run like a scolded dog. Other times, nothing... and I have to wait (various times) before it'll start back up. Either way, when it starts back up, it runs perfectly normal for the rest of the day(s).

Anyone....?

This stalling is not a HUGE issue, but one I'd love to figure it out so it doesn't happen again! It does it MAYBE once a week and sometimes it'll start back up, other times it has to sit for 2+ mins before it'll fire back up. I appreciate the MAF sensor idea, cleaning it and everything but why would it start back up after sitting if I NEVER have to go and mess with the MAF?

Maybe the MAF is overheating? If that's even possible? To me that's what it seems like it is, SOMETHING (not necessarily the MAF) failing due to getting too hot. Maybe I'm just getting lucky and hitting that "sweet spot" of it not being TOO hot when it DOES fire back up after stalling. And other times it just takes a minute or two for it to cool back down before working again....??

I don't know I'm just throwing IDEAS out there... I don't know ANYTHING about MAF sensors!! Has anyone every had a dirty/bad one and it have the same symptoms as mine? Could you please explain why sometimes its an immediate start back and other times not?


Let me know how that works out, if it fixed your problem! I'd like to know. Also, did/would your truck not start right back up sometimes? Or was it just a stall followed by you firing it back up with no problems?

 

Guess there's no answers? I haven't had it happen in the past few days (knock on wood!), guess I'll try to find some more answers if it starts to happen again and continues to be a problem....

 

If the IAC is getting stuck or IS stuck at a certain position it can cause this at times. I have a dodge van at work that we just replaced the IAC on. It wouldn't start without giving it some pedal when it was cold. but if you kept your foot on the pedal untill it warmed up it would run fine. I'd suspect MAF or IAC or TPS if both of those prove good yet.

If the MAF is dirty or failing it would cause a no restart because the computer won't show flow coming through the intake. If the iac is failing/stuck it would cause too much/too little airflow during cranking/idling to allow it to run (this can be overcome by giving it some pedal when cranking if it is in fact the case). TPS shows the computer throttle position and if you get a voltage spike/dropout at any position it can confuse the computer into either cutting fuel or dumping too much and cause a stall.

as far as the P1870 go it's a common problem involving valve bore issues in the valve body of the trans. Commonly the overdrive apply valve. I had my valve body redone at a shop (although if you're mechanically inclined you can do it yourself with some research) because i'm lazy and had $500 to burn :\

the p0420 is probably completely unrelated to this problem as well and i don't think would cause any major running issues. Minus maybe some crappy fuel mileage.

 

Thanks for the reply and the reasoning behind the no start after stall.... I think I will go with just cleaning the hell out of the MAF, IAC and throttle body -see where that leaves me! If it continues, I will do more research. Again, thank you for the explination, exactly what I was looking for!

 

No problem.