Code 32 with a high flow exhaust.

[Nick88]

Just put up a post on fuel economy

 

[Nick88]

Very interesting, now I’m stumped, I was driving with the exhaust cutout fully shut today and it popped code 32 getting off the parkway when I was going around 40mph. What should be my next step? I verified solenoid operation, verified egr operation, and I verified the ports aren’t extremely clogged as running with no egr creates a massive vacuum leak and shoots exhaust out of the intake from exhaust side. Any ideas??

 

[Road Trip]

Very interesting, now I’m stumped, I was driving with the exhaust cutout fully shut today and it popped code 32 getting off the parkway when I was going around 40mph. What should be my next step? I verified solenoid operation, verified egr operation, and I verified the ports aren’t extremely clogged as running with no egr creates a massive vacuum leak and shoots exhaust out of the intake from exhaust side. Any ideas??

Hello Nick88,

When dealing with any function like this, from my troubleshooting perspective they fall into 3 distinct categories:

* ALWAYS works (Never throws a Code 32)

* Intermittently Works / Fails (Periodically throws a Code 32)

* NEVER works (Can't get Code 32 to clear)

****

Intermittents can be tough, for oftentimes you need a lot more info about the failing function when it's almost working
as advertised vs. a function with a single hard-broke part in an otherwise robust, like-new circuit.

But I like your hands-on style, and willingness to carefully observe the vehicle in use while the SES light was in Field Service mode.

Given this, I'm going to outline how we can learn more about this whole TBI Code 32 thing, and by the process of elimination
we'll figure out how to fix the intermittent Code 32 failures with the least time, parts, and effort expended.

OK, the Golden Rule of troubleshooting intermittents is that you can't fix an intermittent until you can first break it at will.

The big players in this Code 32 testing are the EGR Valve, EGR solenoid, O2 sensor, the computer orchestrating all this, and of
course the wiring and vacuum line interconnecting these items.

I'm going to approach the problem from the perspective that everything involved *can* work, but we may have a performance restriction
somewhere in the circuit (from all the accumulated miles) that has made the test sometimes pass, other times fail.

From this perspective, let's look at each individual part:

EGR Valve

* Newly replaced EGR is correctly calibrated for your particular engine?(gas flow vs input signal)
* Passages to/from valve are flowing as new. (Can you affect the idle by opening the EGR valve with a small hand vacuum pump?)

EGR Solenoid

* Does the solenoid pass the electrical checks in the FSM?
* Via the existing wiring, can the computer reliably turn off the Solenoid 100% of the time? (ie: are there intermittent connection(s) in the
wiring harness where signals work most but not all of the time...leaving the EGR solenoid in the wrong state, and causing the test to fail?
Refer back to my previous post for the associated color codes of the wires involved.)

O2 sensor

* Is the O2 sensor able to feedback the state of the exhaust to the computer so that the small amount of fueling
changes associated with the EGR being turned off during steady state highway cruising occur?
* Is the wiring to the O2 sensor in good condition? And the engine/computer grounds healthy?

NOTE: Given the recent O2 sensor replacement (and lack of Code throwing for O2 performance) this is not my current focus.

Computer (ECU / PCM)

* Is it passing it's own self-tests failure free? (No Code 51 / 52 / 53)
* Is it running the correct code/calibration for the engine in your engine bay?

NOTE: The history of this engine bay is interesting, for in your OP you detailed that the EGR system wasn't working,
and that you had to change the ECU as part of the repair effort? Was there an issue that the PO couldn't sort out
by changing parts so he had the EGR test bit cleared in the operating system? (No news is good news mindset?)

****

Ok where to go with all this? If I was your neighbor, I'd want to see how often the failure is stimulated by your
driving schedule with the EGR temporarily disabled. In other words, if I disconnected the vacuum line to the
EGR valve and plugged it, would this test fail every single day you drove? Or would it only fail when you are on
the parkway, but once on the parkway it would fail every single time? Or would it only fail once every 4-5 trips or so?

As a troubleshooter I need to know this so that I don't erroneously declare a fix, only to have it fail again unexpectedly.
(That is a troubleshooting roller coater to avoid. :0) Actually, the rules I used when I did this for a living was that I wouldn't
declare a victory after a repair effort until the SUT (System Under Test) would run at least TWICE the previous observed
failure interval. So, if it originally took 4-5 days to show, I would wait at least twice that before declaring victory.

For what it's worth I've added a quick & crude hand-drawn illustration of how a varying test signal can be set up to
never fail with all new parts & the truck just rolled off the assembly line. The Code 32 test is run at least once every
driving cycle where the driver's demands fall within the load parameters needed by this test routine. And on 99%
of the TBI trucks this test runs unobtrusively in the background literally thousands of times over the years and never
kicks a SES light because of a Code 32 failure. (!)

But as the dashed red line shows, once the ability of the overall EGR circuit to move an adequate amount of inert gas
back into the intake degrades over time, then the ability for this test to pass becomes intermittent. And as the
weak link/performance bottleneck in the test setup further degrades over time, the once a month intermittent eventually
becomes an 'every other trip' intermittent.

And so on and so forth.

So if you could temporarily disable the EGR valve and report how often your driving schedule causes this test to
fail, then we will have a good baseline to work from. And if your local parts store's tool loaner program has a
hand vacuum pump available, then we can test the EGR in place for how much inert gas authority it is currently
bringing to the party. And of course bonus points for verifying the electrical side of all this as well.

And if we follow through with all this and report the findings, then TBI owners battling Code 32 failures will gain valuable insight
into all this.

Let us know what you discover.

PS - And if you want to read a little more on all this, a fellow GMT400 member took the time to write about this awhile ago:
Found this first: (Someotherguy on TBI Code 32)
Found this second: (Someotherguy referencing the above in this forum) < This thread has a declared fix at the end FWIW.