Quote:
Originally Posted by Boydness
I just purchased an '87 V10 4x4 with the 305 TBI and on the first long trip the Check Engine light came on...
I was driving for about 15 minutes (maybe 13 miles) and the light came on. After turning off the engine, the light cleared and did not come back immediately when restarting the engine. It seems to only come on after 15 minutes or so of driving. There does not seem to be anything wrong with the running condition of the engine as there is no visible or audible performance issue when the light is on...
When I disconnected the battery to clear the code, it was 3 or more driving trips before the light and the code returned.
Any ideas?
Code 32
EGR system
Faulty EGR valve.
Faulty or loose wiring and/or connections at the EGR solenoid.
Faulty, loose and/or leaking vacuum hoses to EGR valve.
I would appreciate any suggestions.
Steven
|
Steven you have a TBI system in your '87 and to troubleshoot that pesky Code 32 you may want to perform the following functional check:
Manually open the EGR by lifting the diaphragm by hand at idle and see if you can observe idle stumble. Be careful not to burn your figures or get them caught. If the passages are plugged there will be no difference in the idle when you manually push the EGR valve. Verify that EGR diaphragm is not blown with a MitiVAC hand pump - EGR should hold vacuum.
This code usually gets set because the EGR does not work or if EGR passages are obstructed with carbon. Code 32 also rears its presence when exhaust system is modified since exhaust back pressure determines amount of exhaust gases entering intake manifold. Depending on application there are several different kinds of EGR valves used. - Another subject all together.
The following is the test criteria that must be met for EGR DTC 32 test to take place. Information is for a 1993 C/K TBI 5.0, 5.7 and 4.3L (s/t), but 1987 used a similar ECM logic:
The actual test that sets the DTC code 32 is done when:
-Throttle position is between 10% and 25% angle
-Steady throttle with no more then 2% change in throttle
-Above 32 MPH closed loop operation
-Max short term fuel trim (integrator) is less then 6 counts for 3.2 seconds
-desired EGR command greater then 40%
-MAP above 47.5 kPa or less then 15 kPa.
Basically the ECM shuts off the EGR and expects to see a predetermined outcome.
The ECM monitors the EGR effectiveness by momentarily de-energizing the EGR solenoid which in turn shuts off the vacuum to the EGR valve. With the EGR closed, the fuel integrator counts must fall (mixture gets richer as exhaust gases are no longer diluting intake mixture) within calibrated window. The fuel mixture called for must change by an expected amount. After failing the test twice a code 32 will be set. This test is usually done during long, steady state cruising.
Your ECM should have service number 1227747 (unless replaced with later service unit) and probably has a four letter broadcast code (BCC) = ASDZ, ASDU or similar. If you can post you BCC code specifics of your calibration can be found (or not).
//RF