allos

I recently got a 92 firebird with the 305 TBI. The car runs good but I noticed that one of the lines on the throttle body unit was plugged.

According to the diagram I have it goes to the temperature sensor in the airccleaner, which is disconnected and the line running from the Temperature sensor to the VAC Motor is cut.

I would like to know why those are disconnected, and if thats actually what they are.

I am also receiving an error code 32 for the egr system, which from what I have read it means it probably just needs to be cleaned.

But I am also receiving error code 44 for O2 sensor lean, any information about this would be helpful. Do you think it is being caused by the hoses being disconnected or does it need to be replaced?

There is also some wires disconnected by the accumlator.

I have uploaded pictures here.
http://s1285.photobucket.com/user/al...?sort=3&page=1

Anything else you might notice that needs to be fixed would be appreciated.

Thank you.

RFmaster

Welcome to TGO

Thanks for posting photos which makes debugging a bit easier.

1) The themiatic vacuum valve (aka temperature sensor) controls vacuum application to the flapper. The flapper diverts some hot air from exhaust manifold to maintain warm inlet air. PO probably cut and plugged vacuum line when temperature sensor developed a leak. I do not remember part numbers, but I believe service parts are still available. Using a spark plug is world class solution! If you have emission compliance testing where you live you have to fix it - in CA this will be a visual failure.

2) EGR Code 32 is notoriously hard to debug in TBI systems, but since you have Code 44 it is likely stuck EGR might be causing lean exhaust ( and unstable idle). Like you said - remove and check EGR valve operation. Clear out EGR intake manifold passages from carbon build up. I am going to venture to say that you may still have original O2. Replace with AC-Delco unit, BOSCH does not have the same response curves.

3) Not sure about harness disconnect by the accumulator - need to find FSM. High mileage TBI tends to develop a vacuum leak right at the front flange, where vacuum ports are - just R&R the gasket, clean flanges and torque to spec.

//RF

allos

Alright, Thank you. I noticed one of the seals around the throttle body was bad when I was screwing the aircleaner back down so I'll probably get a rebuild kit and replace that sensor.

I think I'll leave the plug in for now, I don't have emissions testing here.

None of the parts stores near me have the Ac Delco sensor, do you know if Denso sensors are any good. Also I read something about upgrading to a 3 wire sensor is that worth doing?

RFmaster

Thermatic valve part number is 8997787 or SMP STANDARD MOTOR PRODUCTS ATS1. They are getting pricey - JY item in my book!

O2 Sensor are now mass produced commodity. 92 uses a single wire unit because it is screwed into cast iron (CI) exhaust manifold (driver side, just above oil filter). The three wire NBO will improve cold temperature operation, but keep in mind that ECM will not go into closed loop until CTS is above 45C and engine run time greater than 2 minutes from a cold start. Unless you have headers three wire is not really needed - CI manifold will keep NBO well above 600F. You really need 3, 4-wire unit if you have headers!

When rebuilding TB make sure to use two wrenches to unbolt fuel lines! This will prevent oh-**** moment when you realized that you have twisted the fuel line. Spray some WD-40, get some rugs to keep excess gas from spilling onto intake and unbolt fuel lines while TB is still held down to intake. TB's are easy to rebuild no special tools required - just take your time to clean years to grime off. Pay attention to the o-ring order - thin washer in the injector cavity! Most kits instructions are not very clear so you should note rubber o-ring, washer positioning during injector extraction. It is also a good idea to send your injectors for cleaning and flow testing. I use Witchhunter performance to service my injectors.

Single wire NBO:
AC-Delco AFS-21 -> DENSO Part # 2341001

//RF