TBI 350 emissions help

[GMCJason]

I need some help getting my Suburban to pass emissions. I took it in the other day and it failed; CO and Hydrocarbons way to high at both idle and 2500 rpm. I figured it may not pass because it just smelled rich. I was right.

We took it camping over the weekend and it just didn't sound right at idle or at a higher rpm so I started digging around. I found one of the plug wires laying on the exhaust manifold and the insulation had been burned through and you could see the wires. Moving it and wrapping the exposed area in electrical tape seemed to help, at least as a temporary patch until I got home. When I got home I replaced all the plug wires and took it in again - failed again with the same problem.

Now, I had problems last inspection time (2 years ago) and at that time I replaced the O2 sensor, all the plugs, and put in a new air filter. Before I tested it the second time I changed the oil and got it nice and hot and it passed. All that is 2 years old but it only has about 4000-4500 miles on them so I wouldn't call them old.

What else should I do? The check engine light hasn't come on so I assume there are no codes but I haven't checked. If I were to take it to a shop what would they do besides tune it up? Since the CO and HCs are so high it's obviously not completing combusting the fuel but I'm not sure what else to do. I hate just replacing parts because they might be bad. Is there a way to tell if it might pass without actually testing it? How do I know if it's fixed without forking over another $25?

For the record the engine is supposed to have about 40-50k on it and when it passed 2 years ago it seemed to do so with flying colors, not squeaking by. The engine is, as far as I know, a stock replacement.

Thanks for any assistance.

Jason

 

[doonjumper]

Try checking your TPS switch. You will have to get a manual less u have 1 to see what the ohms should be . You can test this yourself pretty easy with a multimeter. Just make sure that the readings are within specs. specified in the manual. You can prolly find the specs online aswell. The ohms will raise and lower when the accelerator is applied. Thats just 1 area there are lots of variables unfortunatley.

 

[Thunder]

Just because the CEL light is not on does not mean there is something wrong.
Check for trouble codes.
Might be time for a tune up Cap and rotor? Fuel filter? Dump some lucas fuel treatment in the tank to clean the injectors.
If you dont have a scanner take it to AZ or somewhere where they will scan it for free. Check the TPS output as said above and the coolant temp sensor to see if they are reading right.

 

[Cricket]

Is there a way to tell if it might pass without actually testing it? How do I know if it's fixed without forking over another $25?

Jason, if your dealing with Envirotest you should get several free retests, unless they've changed their policy.

Have you looked at your injectors, any dripping or excess fuel. You should have a nice even cone shaped pattern.

 

[GMCJason]

Thanks guys, I'll see about checking the items you mentioned and see what I can do about getting it running right.

And James, it is the shop down off Airport Rd. and you get one free test.

 

[Col_Sanders]

So do any of those "Guaranteed to reduce emissions" things they sell at parts stores work?

 

[doonjumper]

I have learened several things as I've gotten older and hopefully wiser, one of which being there is no "cure-all" in can...... unless its beer!

 

[cabledawg]

Having the engine hot will help reduce some of the emmisions. Should be around 210 when you take it in. The engine will run rich when its cold, which is why you might check the manifold temp sensor. If the sensor shorts out when hot, the ECM thinks the engine is cold and will dump tons of gas in.

 

[GMCJason]

Some great stuff here guys. I'll check it out this weekend. If I can't figure it out maybe I'll just drink a few "cure-alls" in a can and contemplate swapping in 104 more cubic inches under the hood and starting there.

Thanks for your input.