[ChevroletSS]

Hey guys my truck just started acting up. When Im driving and come to a stop the idle is unstable and sometimes stalls. When I go to take off it falls completley on its face and then takes off. Sometimes it stalls and takes awhile to start back up and I have to have the pedal all the way to the floor to start it. I unhooked both sensors that my egr vaccum lines run in. I think one of the them is the map or maf or something. I could be wrong. Whatever the sensors are I unhooked the ones with vacumm lines coming from egr. The truck runs almost like it should. So I have to drive it with those unhooked. I dont want it that way even tho I plan on taking this engine out I still want it right for right now. Only problem I have with the engine this way is it still hesitates a little on take off but not to bad. Its my 94 chevy. Everything stock.

[hcompton]

Have you tried to take the egr off and clean it. Sometimes you can clean them and get them to seal a little better and last another few thousand miles.

Usally if its just the sensor of valve it will still run ok sometimes or until it gets hot. Leaking egr will run like crap all the time. You can pull the codes and see of the egr sensors are not responding.

Replacing the egr is not that expensive. Try rockauto.com if all else fails they usally sell a cheap one.

Has the mpg gone way down usally a sure sign the egr is bad. Even unhooked it may still be causing bad milage.

[Richiehd]

Codes? Well now you have vacuum lines disconnected, you will have multiple codes. Scan it, connect lines, clear codes and road test. Rescan it.

[1Gary]

You want to use a dentist pick and clean out the carbon out of the piddle valve.The gasket replacement is a screened gasket from the help section at your local parts store.That helps keep the carbon out of there.

[ChevroletSS]

The problem occurs when it get hot. When cold it would be fine. Also I have all the vaccum line still hooked up. As far as gas mileage goes. It doesn seem like it is or was effected. I hate TBI. Ill see what I can do. My engine light bulb was tken out or blown so I guess I need to replace thst first and get codes.

[Richiehd]

Originally Posted by ChevroletSS

The problem occurs when it get hot. When cold it would be fine. Also I have all the vaccum line still hooked up. As far as gas mileage goes. It doesn seem like it is or was effected. I hate TBI. Ill see what I can do. My engine light bulb was tken out or blown so I guess I need to replace thst first and get codes.

Buy a cheap code reader, forget the light

[ChevroletSS]

I have a code reader but I need the light to flash the code. (OBD1)

[hcompton]

Originally Posted by ChevroletSS

I have a code reader but I need the light to flash the code. (OBD1)

Got ya! Check thefuse and make sure none are blown. Its a pain to pull the dash and replace the lights in most cars some trucks are easy but not sure about yours. Bulbs a a buck or two usally.

Maybe autozone or another parts store can code scan it for you. They usally have code scanners with display screens. Its also easy to test the egr valve. I think its 12 v it flows air no volts its closed. If you have a vacum pump for brakes you can use it to test the valve and the egr. Egr should open on vacum and hold air if it leaks down its broken and needs replaced. Other than that its carbon build up.

[scholman]

hcompton,

In California parts stores are no longer allowed to "read codes" Either the owner of the car can buy a reader and do it on their own or the owner must take the car to a smog repair shop and pay to have it scanned. Even AAMCO is only allowed to read the codes NOT erase them unless they repair the problem. They will read the codes for free.

Scholman

[dsraven]

to check the egr, remove it, flip it over and secure it with the gasket surface level. now fill one of the two chambers you see with solvent. it should hold the solvent in the port for awhile. if it starts to fill the other port then it is leaking and will cause exhaust to leak into the intake manifold when it is supposed to be closed. this will cause the stall and hard start, poor fuel mileage etc. they will sometimes stick in the open position if the vehicle is not used for awhile and then taken out for a run, especially when you coast down a hill or go from high speed roads to a low speed road. that is when the valve is supposed to open and burn up some of the unburned exhaust gasses. the problem is that the valve can open further than it normally is used to, and then stick there. or the valve can just plain be worn out.
check it, the solvent shouldn't go anywhere.if it does the valve is toast and you are on borrowed time if you clean it and stuff it back on.

[1Gary]

Yeah I wouldn't wait about getting a code from it.It is a easy fix with only two bolts and the screened which is cheap.Just clean it.

[4 Jaw Chuck]

Why not just replace the valve, a 1994 engine would need one by now...they don't last forever and the sensor that reads the valve position would be worn out. Easy enough to measure the resistance of the sensor with a DVOM if needed but I doubt you will find its any good, those diaphrams that actuate the valve are just a type of synthetic rubber and crack which causes all kinds of issues.

In my experience cleaning them is a waste of time, its almost never the valve itself...its either the sensor or the diaphram. Another option is the junkyard, you never know you could find a recently replaced one on another vehicle...any vehicle with that engine would be a candidate for a swap.

[Richiehd]

Test dont guess. Then you only change the parts that are broken.

[ssmonty]

X2... I'm with Richiehd. Your IAC(idle air control motor)valve may be sticking or defective, MAP may be bad, Throttle position sensor bad, intermitten harness connectors,...quite a few things or combinations could be the problem. With out reading the codes your just guessing. Not that the codes will tell you exactly whats wrong, but it will tell you what the computer says is the resulting symptom.
If the computer senses a low MAP value, it dosen't necessarily mean the MAP sensor is defective, it could be a loose hose going to the brake booster causing a vacuum leak. The codes can narrow down the fault, but don't always tell exactly whats the defective component.
Please forgive my spelling.
FWIW,
Good luck,
ssmonty

[ChevroletSS]

Well I guess Ill take myy dash off and put a bulb in it. The dash seems easy to do. Right now the map sensor and egr evap sensor is unplugged and it actually runs like it should but thats the only way I can drive it and I dont want it that way. Its pretty basic under the hood, its just like looking at a carb engine, theres not much to it so I cant see nothing else that could be wrong. There is one pigtail that has been unhooked sinse I have owned this truck and There is nothing to plug it into. It reaches about eight inches. Does anyone know what this plug is.