in desperate need of help

[wloy7]

I don't know what to do.

I have a 1994 jimmy, 4 doors, v 6 vortec engine. It has 138 000 miles and is running like crap. It is blowing black smoke durning idle while increasing in density and a red flag to the cops when accelerating. Also, it idles rough (feels like it misses or skips), gets terrible gas milage, and won't pass emissions. I have changed the pvc valve, throttle position sensor, spark plugs, lines (myself), o2 sensor (which i found after the cat, i can't find another one), oil, fuel pump is 6 months old, exhast from cat on (not cat though), and i think that is it.

I am a student with a part time job. I have no money. I need this car to get to work (although I hate my job) and school (more important). If anyone can give me some advice, other than drive it off a cliff, i would be very grateful.

thanks

[drdd]

with all that going on ... does your "check engine soon" or "service engine soon" light come on? If so, take it to Autozone and have them read the trouble codes for free. Report those codes back to the forum.

Also, can you be more descriptive than 'running like crap'? What exactly is happening? When? tied to acceleration? deceleration?

had an engine cylinder pressure check lately? ... leakdown test?

is there oil in your coolant? is there coolant in your oil? look!! check!! smell!!

anybody else on the forum?? carbon in egr?

report back.

Originally Posted by wloy7

I don't know what to do.

I have a 1994 jimmy, 4 doors, v 6 vortec engine. It has 138 000 miles and is running like crap. It is blowing black smoke durning idle while increasing in density and a red flag to the cops when accelerating. Also, it idles rough (feels like it misses or skips), gets terrible gas milage, and won't pass emissions. I have changed the pvc valve, throttle position sensor, spark plugs, lines (myself), o2 sensor (which i found after the cat, i can't find another one), oil, fuel pump is 6 months old, exhast from cat on (not cat though), and i think that is it.

I am a student with a part time job. I have no money. I need this car to get to work (although I hate my job) and school (more important). If anyone can give me some advice, other than drive it off a cliff, i would be very grateful.

thanks

[94 Jimmy]

Read the posts here about the Jimmy and its CPI (Central Port Injector) problems. It's for multiport injector systems, the throttle body injector systems is different. The CPI takes the fuel from the tank mounted fuel pump and regulates the pressure then distributes it to the 6 injectors. Each output line has a poppet valve which opens at 45PSI or so, this insures that there is a supply of pressurized fuel at the input of each injector when it is given the command to open.
Great system right, well sort of. The problem lies in that the CPI is mounted in the upper intake manifold and the fuel regulator has a tendency to leak and dribble fuel into one side of the manifold. This runs one bank of cylinders rich, and when the O2 sensor reads this rich exhaust it tries to shorten the injector time which leans out the other bank of cylinders, not conducive to a smooth idle.
Check out:
http://www.asashop.org/autoinc/feb2000/techtotech.htm
for an explanation and photos.
If you’re handy you can just pull the upper manifold, it's not a bad job and will give you a birds eye view of what's going on. If one side, usually the passenger side, is clean with a slightly yellow brown color and the other side is dirty from the crankcase vent then you have a leak and the fuel is acting like a solvent to clean the manifold.
EBay has CPI units for sale; try to find the updated ones which have a better fuel regulator. Their not tough to install, just be careful not to get any dirt into the injectors when you remove the poppet valves.
Good luck
94

[wloy7]

Thank you all for the responses. Im going to take a chance and try to take off the manifold myself to check for a leak. I am also going to check my pvg valve. About my check engine light. The light dosn't come on till about 10-15 min after i start travelling. When i stop and restart my car, the light is not on. recently though after i replaced the o2 sensor, the light has been coming on the shutting of while it;s running.

Wish me luck, and thanks again.

[94 Jimmy]

Check the web site I suggested, it has an alternate way of checking the inside of the intake maniford. It's much easier than pulling the whole manifold. So check: http://www.asashop.org/autoinc/feb2000/techtotech.htm
pay close attention to the discussion of the cross manifold valve and how it can be removed with 2 bolts to allow access for a visual of the inside of the manifold.
Also check the computer codes, with your car running this bad the computer is sure to have set some codes. If you don't know how to access the computer, repost and we can give you some instructions. The access plug is mounted on the bottom of the dash below the steering column.
You said you replaced the plugs and "lines" do you mean the spark plug wires? If you did, did you get them back on in the right order? If you didn't, then it might be time, they last a long time, but not forever. If you have access to an ohm meter check the resistance of each wire. They sould all be roughly the same reading, with the longer wires having proportionately higher readings. If you have any that are way off, time for new wires.
I don't know what your tool situation is, if you need tools, check Harbor Freight on line, they have fairly fair tools at very reasonable prices.
Well let us know how it's going.
See ya
94

[wloy7]

Ok guys, I found the codes that were registered in my computer. They were 32 35 38. I really think the egr valve is shot. the more I read abou the more it sounds like the problem. The other codes are for the idle ( i increased the idle to get ride of the miss at idle), and a tranny problem ( not really a priorety). I am going to get a guy i know to fix the egr this week. I still am going to check the manifold for leaking gas, with my luck this will be a problem. All that I want is this thing to pass emissions. I am not planning on keeping this thing for too long, so the the less money I put in the better.
I can't thank you guys enough. You guys have saved me alot of money to find what is going on. I will let you know how things are going.

[wloy7]

Hey folks, well i changed the egr valve and things have changed. The car is running smoother, but it is still running really rich. I mean it smells like complete gas. Can you give me anywhere to look.