Hi everyone... I'm new to this site. Actually my first membership to any forum ever. I was really hoping you guys could help me out with this issue. I bought this 05 TB I6 4.2 about a week ago for 1500. Only 78k miles. I considered it a steal. He said it wouldn't start... I was able to start it but it stalled 3 seconds later, if that. Saw that the gas gauge was Empty with light on. He told me he put gas in it and that it wasn't completely Empty and it had been broke for a while. I know about the recall for the fuel pump/fuel gauge so I figured it was an easy fix along with the RPM gauge(needle stuck at 6oclock position) and oil pressure gauge. I was wrong. 55PSI on the fuel rail... I have good spark. Found 2 pressure switch sensors installed... One installed in the block acting as an oil plug and another one connected to the ECM with a screw in it, like someone tried bypassing the system... I pulled both plugs and installed a brand new one. The only code it throws is P0068. Checked MAF. Vacuum lines. IACV. Pulled and cleaned the Cam Sensor. Everytime I go to start it, it does the same thing. No more, no less. Everyone is telling me to check for compression... It only has 78k miles on it though. Isn't it a little too early for bad valve seats and rings? And even if I had a dead cylinder wouldn't it still start and run for me than 2-3 seconds? Any comments, suggestions, or questions for me would be greatly greatly appreciated. Thanks everyone.
2005 Chevy TB LS I6 4.2 starts but stalls 2-3 seconds later
- Thread starter Sean
- Start date
SmokeyMcBlazer
Member
- May 5, 2013
- 434
Welcome aboard.
It might be a long shot but did you check the throttle body? If its terribly dirty and the battery was disconnected long enough to reset the PCM, the truck might not want to start and it surly wouldn't want to idle.
Hopefully its something simple like that...
It might be a long shot but did you check the throttle body? If its terribly dirty and the battery was disconnected long enough to reset the PCM, the truck might not want to start and it surly wouldn't want to idle.
Hopefully its something simple like that...
Thanks for replying... Please continue to do so... The TB came with 2 batteries in it. Both were pretty much shot. I had to jump it the first time I tried starting it. Only ran 2-3 seconds then died. Bought a new battery. Each time I finish working/diagnosing I disconnect the battery so it doesn't die. The throttle body seemed like it was functioning correctly but I pulled it yesterday to clean it just incase. What's the chances of the motor going bad it?
Mounce
Member
Not very high.
This is interesting. Have you inspected the MAF and maybe thought about replacing it? Might wanna follow it's wires and make sure they're intact and/or check to see if it's getting power at the connector.
You'll get more advice throughout the day, don't have to worry about us not replying.
Btw, welcome to GMTNation! You couldn't have found a better forum.
This is interesting. Have you inspected the MAF and maybe thought about replacing it? Might wanna follow it's wires and make sure they're intact and/or check to see if it's getting power at the connector.
You'll get more advice throughout the day, don't have to worry about us not replying.
Btw, welcome to GMTNation! You couldn't have found a better forum.
linneje
Member
- Apr 26, 2012
- 404
You are covering the technical bases, but you should eliminate some of the more obvious stuff too, since it wasn't your vehicle you don't know what the last person did.
My dad was a mechanic by trade, and couldn't start my car as it died on my mother pulling away from the farm. He could get it going for a second or two, but it would keep dying. After about an hour he realized he was smelling diesel ...(it was the first time Mom had ever filled it herself)
So you should rule out bad gas (I doubt diesel in this case!) or fuel filter.
My dad was a mechanic by trade, and couldn't start my car as it died on my mother pulling away from the farm. He could get it going for a second or two, but it would keep dying. After about an hour he realized he was smelling diesel ...(it was the first time Mom had ever filled it herself)
So you should rule out bad gas (I doubt diesel in this case!) or fuel filter.
Mounce
Member
I don't think his will have a serviceable fuel filter, those were done away with in either 05 or 06. He can look to see if there is one though. Pull gas cap and take a whiff, it's worth a shot but highly unlikely since a diesel nozzle won't fit through the filler hole.
Lol. Good times. My mother did the same thing... Yea I did make sure it wasn't diesel... I work for Metson Marine as a diesel Technician. Love the smell but I couldnt smell it on the TB. I did check the MAF... At the connector I got a solid 5v. I've been reading all the posts before I even thought about buying the TB and the information and solutions yal have is amazing. I figured I'd find someone this has happened too in the past with 05-07s having all the problems they've had. The "mechanic shops" here on HI is a freaking joke and the dealerships are shit. The only thing they would be good for is checking the Cam and Crank sensors signals as I do not have the correct equipment to do it myself. I really do appreciate yal helping though.
Does anyone have a schematic of the ECM laying around by chance? I just wanted to double check all the sensors and make sure there's no opens in their circuits.
Mounce
Member
Look up Mooseman on here. He's a member and has a link to free service manuals in his signature (the text below his post) I think they should be in there.
Mounce
Member
I'm just unsure if the maf being disconnected would cause such a problem though.
More ideas are definitely coming though, you're doing excellent at troubleshooting, Sean, especially being a new guy.
More ideas are definitely coming though, you're doing excellent at troubleshooting, Sean, especially being a new guy.
I've already done and been through the pass lock. As soon as I heard about pass lock I automatically jumped in and turned the key to the "ON" position. Security light did go off but I still cranked it over just for the hell of it. It started and then of course died and I watched the security light. It went off again so Passlock is ruled out. Too easy I reckon. Lol. If I had a live data scan tool I would have checked the Cam and Crank sensors. I don't have one though. None of this is making sense to me though. The symptoms don't add up to any of the sensors acting up... Fuel system components would cause this kind of problem... Maybe a bad ECM... Everything that would cause it to start and die immediately are all coming out SAT... This thing is just kicking my ass.
How about the ignition yal? I'm not sure what it is but someone did connect something like a remote start or keyless entry up underneath where the OBD2 connector is... I hear the ignition switches go out on the 05s as well? The problem is, the guy I bought the vehicle from said nothing about what was installed though... I saw it yesterday when I hooked the scan tool up. I'll find out what it is and let yal know as soon as I do... If someone were to cut an ignition switcha negative and positive wires at the same time could that damage anything in the circuit?
Idk man. That's why I was asking you all... I'm really trying NOT to start just changing parts cause it could be... I've the got the IAC cleaned up and I'm going to clean the MAF tomorrow and check for more vacuum leaks and make sure the intake manifold is tight... If I can get to it. I'll also start going through all the sensors tomorrow and making sure I have no resistance or opens in my circuits. Mooseman... Thank you for the service manual and thanks to all those who are trying to assist me with this pain in the ass. Night.
Mounce
Member
BlazingTrails
Member
- Apr 27, 2014
- 19,409
This is sounding like a fuel delivery problem. Do you have any records of the fuel pump being changed? It ounds to me like the fuel pump is shot.
Thanks Mounce... That's what I thought when I originally bought the vehicle... I saw that the fuel gauge was not working and he also told me it hadn't been working for a while and Ive read all the fun reviews about the Fuel pump/gauge recalls from GM... I hooked up a fuel gauge and turned the key on... Pressure went up to 60PSI and then when I started the vehicle pressure was between 55-60PSI. If the damn thing would run longer than a few seconds I could probably diagnose/troubleshoot more.
BlazingTrails
Member
- Apr 27, 2014
- 19,409
So the tb is getting 5 volts. What is the signal looking like? I just read through the posts again and it sounds like you need a new throttle body 2002-2005 does not have a maf sensor. The pcm uses the tps sensor and map sensor to calculate a fake maf number. You may have an issue with the map sensor or the tps sensor.
yeah. Your right. I didn't do enough research evidently... As soon as I saw the P0068 code I automatically assumed MAF sensor. I will have to check it again tomorrow. How can I tell if the TPS is bad? And if it is bad that means the whole Throttle assembly is bad correct? Doesn't the TPS sit inside of the assembly? And as for my Oil Pressure and RPM gauges not working... I've heard that gauges malfunctioning is a telltale sign the ignition switch is going bad but wouldn't throw a code because the ECM does not monitor the ignition switch... But would the vehicle even start if that was the case? Sorry so many questions.
Mounce
Member
I think you'd need a decent scan tool to diagnose the tps, to see what it's telling computer, maybe hit up a junk yard and get a throttle body cheap and see if it works then you can buy new if you find it necessary.
Ignition switch failure is normally characterized by the abs and brake light randomly coming on, and normally they still function when bad, the lights are just annoying. But in your case it's not running long enough to show that.
Ignition switch failure is normally characterized by the abs and brake light randomly coming on, and normally they still function when bad, the lights are just annoying. But in your case it's not running long enough to show that.
Alright yal... Cleaned up the IACV and reinstalled. Checked for more vacuum leaks... Tested MAP sensors with key ON. I'm getting 0.3volts... I don't have anything to test the TPS sensor in the throttle assembly... Everything else seems to be fine... I guess I'll try to grab 1 from the junkyard and see if does anything different.
BlazingTrails
Member
- Apr 27, 2014
- 19,409
I meant Throttle Body... The only code im getting is still the P0068 unless I unplug the throttle body then I get P0122, P2119, P0068, and P0223 all having to deal with the throttle... If the TPS was bad I wouldn't get a code?
Mounce
Member
Midnyteryder196
Member
Same deal Mounce... I'm torn bro. And yes I did try starting it with the MAP unplugged. It wouldn't even start... I did check the voltage from the Throttle Position Sensor wires coming out of the Throttle Body and got 2 different readings. I don't know a damn thing about the TPS or that throttle body and how it operates. Oreillys has 1 for 295 bucks and Napa wants 500... Im going to see if the junkyards here have 1. As for the MAP I have 5 volts to it and a 0.3v signal with the key on. What's the chances of it being bad as I don't have a scan tool that will tell me anything else.
Mounce
Member
I'm guessing that it's gotta be the TB. The code is from either the tps or the map sensor reading wrong. It can't figure out how much air is actually coming in so it can't tune it right.
When you cleaned the TB, did you cycle the butterfly? Any grinding? Also, when you turn the key to run (second click right before start) do you hear a clunk come from the motor?
-it's more of a click but it sounds like "clunk"... Any clicking/clunking noise, it should do it once.
When you cleaned the TB, did you cycle the butterfly? Any grinding? Also, when you turn the key to run (second click right before start) do you hear a clunk come from the motor?
-it's more of a click but it sounds like "clunk"... Any clicking/clunking noise, it should do it once.
Time to pick brains again... I have 2 TPS signal wires... Those are the wires I have 2 different readings on. Question is... Say I get 0.5 volts to one of the signals... If I open manually open up the throttle plate should voltage go up? Not exactly sure why I have 2 signal wires but goes to Pin 28 on ECM circuit number 485 and wire is dark green and signal 1 is goes to pin 30 circuit 486 purple wire.
Yea Ive heard if the TPS or the MAP is off the idle will be rough... I just can't figure out why it's only running for 2-3 seconds? I can't even tell how it idles cause it doesn't run long enough. But no I don't hear a clunk from the throttle body. Just the whine from the fuel pump...
BlazingTrails
Member
- Apr 27, 2014
- 19,409
The only other things I could think of that would actually keep it from starting would be the Cam Phaser, and the crank sensor both of which should trip the engine light. with the code you are getting I would say it is likely you just need the new throttle body. Have you checked every single fuse in the truck? sometimes even if it doesn't seem like something would effect what you are doing, it may be tied in with another circuit. For example if the lighter plug fuse is blown the OBD2 port does not work. I would use a DMM to check them for continuity.
Edit: usually to check the TPS you can check the signal wire to ground with your DMM and open and close the throttle plate slowly, you should see a smooth increase and decrease in resistance. If it drops out at any point or does not give a signal at it's rested position it is bad. You can also do the same thing with voltage to ground you should see a smooth increase and decrease in voltage. if it has no voltage in it's resting place or jumps to a weird number it is bad.
Edit: usually to check the TPS you can check the signal wire to ground with your DMM and open and close the throttle plate slowly, you should see a smooth increase and decrease in resistance. If it drops out at any point or does not give a signal at it's rested position it is bad. You can also do the same thing with voltage to ground you should see a smooth increase and decrease in voltage. if it has no voltage in it's resting place or jumps to a weird number it is bad.
I have checked all the fuses but I will check them again to be sure... I'll test the throttle body again as well... I have 2 signals for the TPS so I'll just check them both... Thanks man. I appreciate it.
Mounce
Member
Texan
Member
- Jan 14, 2014
- 622
In your first post, you mention two pressure switches, one with a screw in it.
Could you define these better. There is a oil pressure switch just above the oil
filter. This is for the oil pressure (fake) gauge. It tells the PCM that you have
at least 12 psi. oil pressure.
Could you define these better. There is a oil pressure switch just above the oil
filter. This is for the oil pressure (fake) gauge. It tells the PCM that you have
at least 12 psi. oil pressure.
No trouble code from the ECM Kaitlin... Why do you say the cam? Yes Texan, I'm talking about the oil pressure switches... One was in the block to prevent oil leaking everywhere but was not hooked up and another one which was hooked up but had a screw in the top of the head like someone was trying to bypass the oil presure system... I pulled both switches out and correctly installed a brand new one.