Tahoe issue??

[macojoe]

When I start it in the morning, it runs real ruff, after it warms up it runs great! In the old carb days I would say it was the choke. Today I say its TPS or something like that?? OI not up to all this computer crap!

Thanks Joe

[THEFERMANATOR]

My bet is the throttle body and IAC are carboned up. VERY common issue on trucks with over 100K miles, and is relatively easy and cheap to fix. Get you a can of carb cleaner or throttle body cleaner(there both about the same stuff, but carb cleaner is normally cheaper), remove the intake tube from the throttle body, open the throttle and spray the throttle body down and wipe it out real good with a rag to get all that black gunk out, and if you have some torx bits remove the IAC from the throttle body and spray it off and teh throttle body where it goes in to get as much of that black gunk out as you can. Also you may want to check the fuel pressure regulator out, but that normally causes issues with a hot start.

[aussie]

have a look at the exhaust when you start it see if its got black smoke comming out of it ---that will tell you if its over fueling --leaky injection can cause that on cold start up or when the car has sat for a few hours
check your exhaust to eliminate fuel alot of other things can cause it but lets not jump the gun

[macojoe]

Thanks guys!! I bet the carbon is it as the person driving the thing was a women with 2 small kids its who life. The kids looked like they were 10 and 12 now and thats the age of the truck and they have had it since new.
I will have to get my son to look at it as I can't see my left han most of the time, LOL!
Any pic's of the area to look at?? He has no patience, and gets pissed fast!

[THEFERMANATOR]

The throttle body is dead center behind the fan. It has the black plastic tube coming from the air filter box over to the engine. This is a VERY common issue with cold starts. They're supposed to be cleaned every 30K miles to prevent them from gumming up, but most people don't know to do it, and most shops are to lazy to open them up and clean them out hwen they charge you to do an induction service. It doesn't take that long to clean it out, the hardest part will be getting the plastic intake tubing out of the way so you can clean it out. Just be sure when you put it back together to get the plastic tubing all put back together or else it won't run for crap afterwards.

[aussie]

if you have a phone take pictures of things you take of in stages and mac if you were close by i would came and fix it for you free off charge-- i do this for all my mates-- im sure there will be videos on you tube showing how to do it and maybe someone on here can video it and send it to you

your saying it runs rough on idle when cold and once its hot its good--yes it could be the throttle body blocked not allowing enough air at idle cause when the engine is cold the coolant temp sensor tells the computer the engine is cold so it alows injectors to stay open longer so if you not getting enough air due to a blocked throttle body it will run like have the choke pulled too hard on a carby engine

when you start the engine cold if you hold your foot on the gas just i tiny bit does it run better---


theres 3 things that can cause rough idle when cold

too much fuel
not enough air
vacum leak
head gasket leak or cracked head

i dont know too much about these engine and what they suffer from but they all work from the same princeable

with the crack head or gasket what happen when the car sits for long peroids water leaks back into one or more cylinders so when you start it will missfire till the water vapours are pushed out --once its hot the water that leaks in turns to a steam which dosent effect the cylinder just like old school water injection

there 2 ways i check for this
one--if its a v8 get 8 screw drivers remove all spark plugs while the engine is hot keep each spark plug in order to cylinder and check for difference in color of the spark plug usuall the one missfiring will look different colored --place a screw driver down each spark plug hole for 30 sec then remove one and check if there any water on the screw driver check all if there all dry then there no leaks

two you need some one who has a exhaust gas analizer --you remove the radiator cap you may need to empty some coolant from the radiator start the engine --place the probe in the radiator filler and cover with a rag and run the engine if you get a reading then you have exhaust gases on your cooling system

[macojoe]

I am going to try Ferms fix before getting into anything to deep, But going to have to wait a few days as we are going to get a HUGE SNOW STORM here tomorrow they are saying up to 2 feet!! I am also busy trying to get the new house ready to move in. I got all the ceilings painted today along with 2 walls, got a new vent in for the dryer , washed all the curtains, still have to paint the living room and kit chen and steam clean all the rugs. Busy Busy Busy!!

Wife still in the hospital, they say she doing good and will go back to the rehab place for 2 weeks after this, that will be 2 months since she will be home, and I should have us all moved by then??

[THEFERMANATOR]

You will know REAL quick if it is the throttle body carboned up. The colder it gets the worse it will be. When the engine is cold it needs more air, and if teh throttle body and IAC are carboned up it cannot get enough air in. Think of it like a choke on an old carbed engine. If the throttle body is carboned up, then the choke essentially can't work to allow it to stay running. If it doesn't want to stay running, give it a little throttle right after it starts to keep it running. After a minute or so it should idle on it's own.

[aussie]

mj hope your wife has a speedy recovery

[macojoe]

Thanks ferm thats just what it needs a little gas to keep running for a few min.!! Thanks aussie I will tell her!