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Discussion Starter · #1 ·
Again the wife's 2001 Silverado is acting up. engine 177,900 mi now or a bit more. 4.3L engine, automatic, 2wd. After correcting fuel system issues and a full ignition tune it has been running fine. Till today when it died on her for no obvious reason. Twice while stopped and once when backing out of a parking spot. No real warning 2 times, shuddered 1 time in the parking lot idling.
When she got home I went out after about 30 minutes. It started right up and idled fine for about 30 minutes, shuddered and almost died but caught itself and smoothed out about 5 or so minutes later it stumbled and quit like I turned the key off. In less than 5 minutes it started and idled fine for a few minutes and I shut it down. There is no check engine light so I don't know if it has any codes stored.
I am wondering if it could be the coil opening when it gets hot. The quick restart has me questioning that though.
We are getting ready to leave SE Louisiana for Florida but I need to know it's going to be reliable for the trip.
Any ideas out there?
 

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It's fuel, or spark.
When it shudders, is it the same shutter as when you turn the key off; or is it a longer shudder?
 

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Discussion Starter · #3 ·
First time it shuddered in front of me a bit longer but not like a fuel issue. Was more like a ignition miss. When it came back to a normal idle there was no hesitation. When it actually died on me it definitely acted like loss of spark. Stuttered and died almost instantly.
That's why I thought coil. Restarted and idled smoothly pretty much right away.
The fuel pump is relatively new. Was changed by the previous owner ( my brother in law) I replaced the fuel filter and the spider injection system in the last month. Fuel pressure cranking was 62 psi at that time.
 

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I agree, sounds like electrical, maybe a worn ignition switch. Is she like my wife (and I'm guilty as well), does she have a lot of keys/etc on the key ring?
 

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Discussion Starter · #5 · (Edited)
No actually she only has 3 keys on the ring and 2 are for the truck. But it could be the switch. I recently replaced the steering Column with the switch in it so have no history on that. It is a bit sticky to turn sometimes.
Is there an easy way to verify that. Are we talking the complete switch or just the lock cylinder?
I Have another good switch with key as well so maybe I will try that.
Thanks for the input
 

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The switch is on the column; but under the dash end of the column.
The part you see, the part the key goes into, is just the lock cylinder. There is a rod that goes from the cylinder to the switch, the rod moves up and down as the key is turned.
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Check your fuel pressure. New fuel pumps don't mean quality. I've done 3 in relatively quick succession because I installed cheap parts.
 

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Discussion Starter · #9 ·
So before blindly changing the ignition switch this morning. Went for a ride with the wife and got some new symptoms. Rich stumble at cold idle, better hot but coming to a stop rpm dipped below 500 then came back to normal. I decided to go get it checked for codes. Got MAFF and O2 sensor codes. Changing both primary O2 sensors and the Maff now. Amazingly I suspected both before the codes verified my diagnosis. Will update the Post when it's done.
Fuel pressure still checks out but thanks for the idea on that. I have been turning wrenches for many years so I also know New does not always mean good 😊.
My last duty in the Navy was as a Fleet Diesel Inspector (Trouble shooter/ tech guide for the US Submarine Fleet) so troubleshooting is a strong point. Just not great with the comuterized systems in modern vehicles though I am learning. This Forum has contributed greatly to that. Thank you all.
 

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Discussion Starter · #10 ·
Update.
Changed the MAFF. Got a wrong O2 sensor so have not changed them. While out correcting the O2 sensor discrepancy, It ran better cruising, but when sitting at idle, once after a bit it stumbled a few times at inconsistent intervals then stumbled lightly and died.
Restarted immediately and was ok.
Wife says while driving it does not feel right. Poor acceleration and seems to me to intermittently stumble for just a second. Almost unnoticeable if you're not looking for it. Kind of like a misfire but not, if that means anything. I am also seeing poor mileage, like about 13 mpg on e10/87 octane fuel.
Have been told changing the O2 sensors (pre cat) is a waste of money, but I am not sure about that even though it comes from someone with experience.
The plan is let it cool down overnight and see if the crappy cold idle is still there. If so I am leaning towards changing the O2 sensors.
any other input out there?
BTW I hope the abundance of information is more help than hinderance but in my experience the more information you get the better for troubleshooting.
Thanks in advance for any advice.
 

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Discussion Starter · #11 ·
So today I got the upstream 02 sensors changed. Still have the stall at idle issue and it actually is a little worse. Engine hiccups when driving too. Cold idle is better (after MAF, Before sensors) checked EGR and looked for possible vacuum leaks as well. Cleared codes but the check engine light is back. Any ideas out there.
 

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Ok, let's back up; opening post you said no CEL, then part way through the posts, you said going to check for codes and you reported O2 and MAF codes, was the CEL on?
And now your saying "cleared codes; but check engine light is back", I'm having a little trouble following that.
Front O2s are not a waste of money, they can effect engine performance. If you have a problem with a front O2, the engine computer will use built in fuel tables to mix the air and fuel. This will result in poor gas mileage and some driveability problems; but not enough to kill the engine, the MAF is the same. They all have fail safe backups to get you off the road.
Have you looked at the throttle body? If it was only dieing at idle, I'd suggest TB; but your saying it also does at speed, the throttle body shouldn't cause that.

If the CEL is back on, get it read and let us know the codes.
 

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Discussion Starter · #13 · (Edited)
Ok to clear the cell issue up, there was actually a cel but I didn't realize in this truck it simply says service engine soon and I in my ignorance took that to mean "Service" not check engine. Once I got that cleared up I took it to the parts store to have the codes checked. That resulted in 2 codes. MAF and upstream O2 sensors. I replaced the MAF and both upstream 02 sensors. No change occured. Had the codes cleared and in less than 30 minutes the cell was back on. Same codes so for right now I am ignoring them.
Today my wife had codes checked again and they are again MAF and Upstream O2 sensors.
Got to speak to a knowledgeable tech this afternoon who told me to disconnect the neg battery cable for a minimum of 15 minutes to clear the codes.
Also told me to check out the ect sensor (he said "ecm temp sensor") I only get engine temperature sensor when I Google that term.
I am getting ready to do that now.
Sorry about the confusion. I am just getting brain overload with this problem which by the way is getting worse. Engine stalls more often as of today and the burp/misfire? is still there but more noticeable now. Fuel mileage is worse as well. Trucks running quite rich.
Also checking the wiring through out, at least where I can for any abrasions, breaks ectetera. If the cell returns after disconnecting the neg terminal I will have them read again and share that information.
Hope that clears it up for you and gives you more to work with.
Thanks again for the help.
 

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Disconnecting the battery does the same thing as the clear button on the OBD2 scanner, the codes will return
Please provide the codes.
If your running rich it's because the injectors are staying open too long
2 reasons, the computer is telling the injectors to open longer.
Or, the injectors are dirty and not able to close.
Ignoring the O2 codes will cause the computer to use it's fuel mix tables instead of using the data from the O2 sensors.
The tables tend to run a bit rich, add a leaking injector, or 2, and you could have too much fuel in the cylinders.
I think you need to solve the reason the codes are being set.
 

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Discussion Starter · #15 ·
I can agree with that. I am not currently worried about dirty injectors as the were all replaced about 600 miles ago. I also know does not always mean right. When I get the codes tommorow I will share them. My search from the beginning has been to determine why the codes are being set and to correct them.
If tommorow the codes are the same as the last three times, two times which have been after the components found at fault have been replaced I will be thoroughly confused. Currently the truck has become very unreliable and is the only vehicle that is even running after 2 other family members vehicles had given up the ghost entirely. Both today.
Thanks again for your time and the advice.
 

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Lots of times the sensor reporting the error code is not at fault, it's just doing its job and reporting. And changing the sensor won't fix the code, the new part will report the same condition.
 

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Discussion Starter · #17 ·
Got it. I did test the ETC sensor as recommend by someone else it is functioning properly. The stalling at idle got worse today and as of this event I now have a no start condition. After testing the ECT. and reinstalling the coolant ( test was done out of the vehicle) it started and would not idle under 1,000 rpm. When I tried to idle it it died and would not restart. If I can get it to run tommorow it's going the shop I guess. Will update here when I know more. Really starting to think fuel. Maybe the new spider injection unit is bad. Acted like a flooded engine last time it ran.
 

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What was the actual value of your fuel pressure? If I remember correctly, you said it "checked out", but I don't remember a number.
 

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See
Got it. I did test the ETC sensor as recommend by someone else it is functioning properly. The stalling at idle got worse today and as of this event I now have a no start condition. After testing the ECT. and reinstalling the coolant ( test was done out of the vehicle) it started and would not idle under 1,000 rpm. When I tried to idle it it died and would not restart. If I can get it to run tommorow it's going the shop I guess. Will update here when I know more. Really starting to think fuel. Maybe the new spider injection unit is bad. Acted like a flooded engine last time it ran.
Pull a plug and see if it's wet, or at the least very black and sooty.
That's an old school running rich check.
If the plugs point to a too rich condition, you have an injection problem.
 

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Discussion Starter · #20 ·
Thanks for the reminder. I do know that the tail pipe is black and has light sooting and mileage seem to be going downhill. Will check a plug this morning.
Fuel pressure was a solid 62psi.
There is the possibility that the recently installed spider injection system is failing. Nothing is being taken for granted at this point.
 
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