Rough Running Only When Cold - Chevrolet / GMC 5. 7 Vortec
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Date: 2020-08-05
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Comments and reviews: 10
Benjamin
Hi good very good video. How would I check my 94 454 tbi. It's in an 2500 2wd suburban Silverado trim.
Not sure if all that matters.
Huge rough high idle at cold start up.
I've sprayed it left right. Around tbi. After warm up and cold. I couldn't tell any difference.
Has new gasket on tbi. All of them a rebuild kit fixed a injectors house leak. And replace everything at once. But now
It's doing it again.
Rougher though. shuts off almost immediately after cold start like it's being drug down.
Had most original parts on it still. Say all GM. And very Very fragile. Plastics keep breaking if I check connection. Omg.
So I have replaced pig tails and on some with new tps iac map and Temp sensors. All temp sensors (3. No vacuum leaks I can see. Hoses are most new from previous vacuum leaks.
Engine temp runs about 200, 190
Spray pattern looks good on inectors.
After I Keep it running and drive it by tapping throttle to get going or will turn off. (Stall. It seems to run smoothly. And last shift about 45mph -50 mph feels stumbly. .if that's a word sloppy last shift. But runs strong so confused.
At times when I do get it running and drive. when I accelerate from a stop ( not stalling) will bogg down a smidge and take off.
Has rebuild early 2000's 4l80e. From AAMCO out of their warranty. 4 years ago.
First trans broken house and no reverse, high 2nd then shifted after 3000rpm.
Has new distributor. Was going to rebuild old. But almost same price either way.
New acdelc wires and plugs. .
Timing 4degree btdc
Timed with connection disconnected. Ran great. Then this very confusing issue
reply
Hi good very good video. How would I check my 94 454 tbi. It's in an 2500 2wd suburban Silverado trim.
Not sure if all that matters.
Huge rough high idle at cold start up.
I've sprayed it left right. Around tbi. After warm up and cold. I couldn't tell any difference.
Has new gasket on tbi. All of them a rebuild kit fixed a injectors house leak. And replace everything at once. But now
It's doing it again.
Rougher though. shuts off almost immediately after cold start like it's being drug down.
Had most original parts on it still. Say all GM. And very Very fragile. Plastics keep breaking if I check connection. Omg.
So I have replaced pig tails and on some with new tps iac map and Temp sensors. All temp sensors (3. No vacuum leaks I can see. Hoses are most new from previous vacuum leaks.
Engine temp runs about 200, 190
Spray pattern looks good on inectors.
After I Keep it running and drive it by tapping throttle to get going or will turn off. (Stall. It seems to run smoothly. And last shift about 45mph -50 mph feels stumbly. .if that's a word sloppy last shift. But runs strong so confused.
At times when I do get it running and drive. when I accelerate from a stop ( not stalling) will bogg down a smidge and take off.
Has rebuild early 2000's 4l80e. From AAMCO out of their warranty. 4 years ago.
First trans broken house and no reverse, high 2nd then shifted after 3000rpm.
Has new distributor. Was going to rebuild old. But almost same price either way.
New acdelc wires and plugs. .
Timing 4degree btdc
Timed with connection disconnected. Ran great. Then this very confusing issue
reply
Walter
My 5. 3 avalache is doing the same thing except I live in northern canada and when it below about minus 12 degrees centigrade it runs rough at start up the when I go about 5 miles and engine temp comes up to almost normal it start bucking and kicking and instant fuel economy goes to 5 miles per gallon. If outside warms up to minus 10 or more it doesn't do it but fuel economy is only 15 miles per gallon. I changed the spark plugs and the drivers side bank were normal tan color but passenger side bank were black. On a really warm day plus 10 it runs quite good after about 5 miles and fuel economy goes to 17-18 mpg. I've had random miss fire codes. One option is to wait for summer. I was thinking intake leak as well and after watching your video I'm convinvced
reply
My 5. 3 avalache is doing the same thing except I live in northern canada and when it below about minus 12 degrees centigrade it runs rough at start up the when I go about 5 miles and engine temp comes up to almost normal it start bucking and kicking and instant fuel economy goes to 5 miles per gallon. If outside warms up to minus 10 or more it doesn't do it but fuel economy is only 15 miles per gallon. I changed the spark plugs and the drivers side bank were normal tan color but passenger side bank were black. On a really warm day plus 10 it runs quite good after about 5 miles and fuel economy goes to 17-18 mpg. I've had random miss fire codes. One option is to wait for summer. I was thinking intake leak as well and after watching your video I'm convinvced
reply
Carlos
I tried your technique and could find no leak. It's a 98 Tahoe, idles a little rough for 5-10 secs when the engine's cold (starts right up and the miss isn't real bad, but it's never really cold around here (maybe 60F at night. Sometimes still seems slightly rough (not perfectly smooth) at warm idle. I tried:
1. Cleaned mass air flow sensor, snugged 3 hose clamps downstream of the air filter that weren't real snug. No change.
2. Changed air filter, replaced airflow indicator that had a crack in the rubber. No change.
3. Replaced fuel filter. No change.
4. Ran 3 tanks of fuel system cleaner (Techron, STP & Gumout. No change.
Any ideas?
Thanks
reply
I tried your technique and could find no leak. It's a 98 Tahoe, idles a little rough for 5-10 secs when the engine's cold (starts right up and the miss isn't real bad, but it's never really cold around here (maybe 60F at night. Sometimes still seems slightly rough (not perfectly smooth) at warm idle. I tried:
1. Cleaned mass air flow sensor, snugged 3 hose clamps downstream of the air filter that weren't real snug. No change.
2. Changed air filter, replaced airflow indicator that had a crack in the rubber. No change.
3. Replaced fuel filter. No change.
4. Ran 3 tanks of fuel system cleaner (Techron, STP & Gumout. No change.
Any ideas?
Thanks
reply
autorepair
Mine starts and idles fine. I let it warm up
But every morning. when I'm on the throttle it will lose power almost to the point of stalling and if it doesn't do that it surges
But it will run fine in the afternoon.
I know it has spark
I've redone the entire ignition system
It's getting fuel I replaced fuel filter
Cleaned throttle body.
Idk what the hell it is
It acts like the distributor cap is fowled but it's not.
fuel pressure
Vacuum leak
Sending units?
Sensors?
reply
Mine starts and idles fine. I let it warm up
But every morning. when I'm on the throttle it will lose power almost to the point of stalling and if it doesn't do that it surges
But it will run fine in the afternoon.
I know it has spark
I've redone the entire ignition system
It's getting fuel I replaced fuel filter
Cleaned throttle body.
Idk what the hell it is
It acts like the distributor cap is fowled but it's not.
fuel pressure
Vacuum leak
Sending units?
Sensors?
reply
Doug
Where's the follow up video. I would like to see the rnr, the bad gasket, and the estimate process (time parts etc. I thoght I could i try retorq the intake maybe add a couple ft/lbs before try do the whole thing myself. If its not to expensive i could have a shop do it. I was hoping that actually seing the job done would help me determine if its something my current disabilities would not allow me to complete.
Cheers
Doug
reply
Where's the follow up video. I would like to see the rnr, the bad gasket, and the estimate process (time parts etc. I thoght I could i try retorq the intake maybe add a couple ft/lbs before try do the whole thing myself. If its not to expensive i could have a shop do it. I was hoping that actually seing the job done would help me determine if its something my current disabilities would not allow me to complete.
Cheers
Doug
reply
JSN
Hey thanks for your videos so helpful. I have a 1990 Toyota pick up 3vze engine and the problem I'm having is when the truck is cold if I attempt to drive it it runs but it feels like it had a fuel cut when you accelerate it acts like the accelerator does respond and it doesn't want too when you step on the gas when its reaching O/T problem go away. by the way fuel pump is new
reply
Hey thanks for your videos so helpful. I have a 1990 Toyota pick up 3vze engine and the problem I'm having is when the truck is cold if I attempt to drive it it runs but it feels like it had a fuel cut when you accelerate it acts like the accelerator does respond and it doesn't want too when you step on the gas when its reaching O/T problem go away. by the way fuel pump is new
reply
Puticio
Thanks for sharing your knowledge. My 2001 f150 4. 6 has the same symptoms. Followed your instrutions and found the leak at intake manifold gaskets. Out of curiosity i hooked up a homemade smoke machine to intake to see if there where any other leaks. Smoke verified the intake manifold gasket leak. But is it normal to see a little smoke out iac valve and egr valve?
reply
Thanks for sharing your knowledge. My 2001 f150 4. 6 has the same symptoms. Followed your instrutions and found the leak at intake manifold gaskets. Out of curiosity i hooked up a homemade smoke machine to intake to see if there where any other leaks. Smoke verified the intake manifold gasket leak. But is it normal to see a little smoke out iac valve and egr valve?
reply
Jay
Man i been going nuts over this problem my 03 avalanche was getting a p0300 code random misfires so i change all my spark plugs and wires ran good last night now this morning i went to turn it on and nope rough idle again once it warmed up it went back to normal so im just gonna do the gasket swap and see what happen thanks for the video
reply
Man i been going nuts over this problem my 03 avalanche was getting a p0300 code random misfires so i change all my spark plugs and wires ran good last night now this morning i went to turn it on and nope rough idle again once it warmed up it went back to normal so im just gonna do the gasket swap and see what happen thanks for the video
reply
James
Im working on a 2016 Chevy 2500 6. 0 gas 4x4 high country I rebuilt the front diff and was driving went to limp mode sounded like a intake manifold leak so I replaced the gasket the valley gasket injector o rings fuel rail side and manifold side throttle body gasket and now its still roaring what could it be
reply
Im working on a 2016 Chevy 2500 6. 0 gas 4x4 high country I rebuilt the front diff and was driving went to limp mode sounded like a intake manifold leak so I replaced the gasket the valley gasket injector o rings fuel rail side and manifold side throttle body gasket and now its still roaring what could it be
reply
dhontschang
Hello I have 2011 ram 1500. my engine stall or stop on a intersection, when engine is cold in the morning. ones it's warm up. it's runs good. any advise. thanks. took it to dealer couldn't find any cord. they said engine misfiring. so change coil but still have the same problem.
reply
Hello I have 2011 ram 1500. my engine stall or stop on a intersection, when engine is cold in the morning. ones it's warm up. it's runs good. any advise. thanks. took it to dealer couldn't find any cord. they said engine misfiring. so change coil but still have the same problem.
reply
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