[FIXED] 02 GM 3.1 403-5 DTCs

02 Buick 3100sfi auto 54K
Current DTCs
P0403,
P0404
P0405
pending P0404

the Campbells soup version

Parts Swapper here... at least it feels that way.
New to New OBD ii my prior experience has been learning EFI for a 88 Toyota.
DVOM stuff.

Hoping to save my friend a few $$$ befor a planned trip this summer I wanted to do a tune up on her car.
I started out changing the spark plugs, wires, air filters and an oil change.

It went from poorly running couldn't find WOT because it fell on it face before it hit third gear and needed an egg under the pedal... to a no start.

I finally found a loose connection to the ICM but not before becoming the PS of lore

Along the way I did get an OBDII scanner from some nameless entity and then one for my laptop from CHINA to book. Cheaper AND BETTER...
Originally I saw a random miss fire code and a couple others I failed to log before I hit that stupid button.

My cousin directed me to 'the box' and also here after I hit the stupid button.
I now know all is not lost but some of it may well return.

After wiping the codes and eventually getting the thing to fire I was able to take it for a test drive.
As bad if not worse but over the course of a dozen or more 0-40mph cycles ran good enough to hazzard a shot at highway speeds.
Next did a GM cold start reboot drive cycle and things eventually reached original drivability... i.e. it was gutless.

Back home, key off back on DTCs P0403, P0404, P0405 are shown.

While looking up P0403 I find the How to test for restricted exhaust (catalytic converter).

First thing this AM I'm at AZ to rent a tester. Nope. They can order one
O'Reilly and 2 NAPAs same story.

Deep in the comments section were some alternative tests I could preform in the mean time.

Other test methods:
1. use vacuum gauge (0,65 bar): § WOT : zero vacuum.
§ If restricted: 2000 RPM -> vacuum drops more and more
2. infrared thermometer test on cat (@ 2000 RPM, outlet 60° hotter than inlet)
3. scantool: 2nd O2-sensor steady voltage (±0,5V)


Hooking my Vac to the brake booster line and watching for gradual vac loss while @ 2500rpm it didn't happen.
No Vac loss.
At the same time watching the 02 V signals 02#2 varied +or- .4v from 0.5v

I wasn't ready to put it up on jacks to take the cats temp. at that moment, but surely can.

I'm looking for direction, suggestions or ideas and in the I'm going to go ahead and start looking at making my own Exhaust pressure tester.


thanks

Just a heads up, I moved this from the Welcome Mat to the Repair Questions section.
No harm, no foul.

I'm late for work or I'd search out a video for you.
Look on the Scanner Danner YouTube page for a wide open throttle O2 test.
Your symptoms make me feel like you could be looking at a fuel delivery issue, and this test will help point us in the right direction.
Basically from a stop, do a wide open throttle pull through first gear while watching the upstream 02 sensor data.
If the fuel system is good and the mass airflow sensor is operating correctly, the upstream 02 should be rich the whole time you're at WOT (wide open throttle)

Noah has the right idea , start with the test he described with your b1s1 oxygen sensor , I suspicion your going to see it go lean , the next step would be to check the fuel pressure. Back to your codes these deal with the egr valve and do not point to a plugged exhaust, if the pintle is stuck open it will run horrible at idle and try to stall it didn't sound like that is what's going on so let's concentrate on getting the engine running right . Is it missfireing below mid throttle? Or only over?

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Another vote for starting with the WOT O2 test. Very easy to do, and gives great direction for low power issues. Is this the video you've seen already? If not, it's a fantastic place to start.



Take a picture of the WOT run if you can, and post it here. Seeing a rich O2 during WOT tells us there's no fuel delivery issue. Seeing lean says there IS a fuel delivery issue.

A backpressure tester would be cool, but you can also do the same check at the EGR valve itself. Remove the valve, plug the port that goes to the intake (as it'll have full manifold vacuum with the engine running), and jam your vacuum gauge into the exhaust port. If needed, run the engine to find out which is which.

Check the pressure at idle and 2500 RPM just like in the video. Don't worry about the limited scale on the vacuum gauge - if any of your readings max the gauge, then you've already found the problem. The gauge and hose will survive exhaust temperatures temporarily, but don't do this test longer than necessary to get your readings.

OK I have some of what you ask for.

RE Fuel Pressure. Not supported so I hooked up the gauge and watched through the windshield.
50-55psi the whole time.

This photo is the data as it read on the 'dashboard' of the scanner.
I could also post the Strip Chart view but this view shows the most data in one shot.

On 100% throttle it bogs bad
@25% it accelerates fairly smooth up to 30mph.

To be honest I'm not sure I fully grasp which reading of the STFT indicates rich or lean.
I'm going to guess Higher O2 readings indicate leaner fuel ratio?

I am much more inclined to do the EGR exhaust pressure test than the up stream O2. I had to pull the EGR to make enough room to get down there anyway!
I'm going to wait until I see the feedback from this post

Wow is this a maf engine? Your only getting load to 44%! If this has a maf get it's reading at idle and at wot

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Thanks for the update! Just curious, what program are you using for the scanner?

Very good data here, BTW. This is exactly what we needed. The low Load and low MAF readings are an indication of poor engine breathing. The upstream O2 is showing close to 1V (rich), which means the cause of the low power is not likely to be related to lack of fuel. Your fuel pressure reading tends to back this up.

The short term and long term trims aren't valid during this WOT test, as the PCM goes into open loop and stops trying to 'trim' fuel. Once you go back to just cruising along, closed loop will probably kick in, and the trims will start moving again.

I am much more inclined to do the EGR exhaust pressure test than the up stream O2. I had to pull the EGR to make enough room to get down there anyway!

Sweet! :lol: I'd say do that test next, as your WOT data is suggesting a plugged cat. A restricted intake is also a possibility, but less likely. If your backpressure test comes back negative, then let us know and we can suggest further testing.

Now added p0300 with FreezeF data 'Fuel sys in OLoop due to engine load'
stft 0% -
ltft 6.25%
Mass AF 6.21lb/min

GM- Cause
Engine runtime over 90 seconds at idle speed, ECT sensor input more than 132°F, fuel adjustment more than a calibrated amount in the PCM, then the PCM detected multiple misfires had occurred


Above 50% throttle for the most part.

6.21 lb/min is around the airflow rate that we saw in your screen capture during WOT, so it makes sense that the P0300 set around the same time. Poor engine response under heavy throttle, but acceptable acceleration under light throttle is another common symptom of a restricted exhaust.

Idle rpm 894

MAF @ 894rpm 1 lb/min @99 sec. ---- 0.9 lb/min @ 128 sec

---

Load 4-5

MAF @ 3893 rpm 7.4 lb/min ---- load 44 approx. = WOT

I'm fabing an attachment I can use on the EGR line. Basically a mounting plate to receive the copper line with a nut welded on the back side to attach my pressure gauge to with a hole for a through bolt like on the EGR itself.
So I hope to run the Exhaust pressure test tomorrow.

Sweet! Let us know what you find.

Did your vacuum gauge not come with a large adapter?



It's that big end that I usually shove into the exhaust port at the EGR for testing. Not saying you shouldn't make an adapter plate! Just didn't want you to go to the trouble if you didn't have to.

Tyler wrote: Thanks for the update! Just curious, what program are you using for the scanner?.

OBDWiz is the software. $32 for the connector includes the key to download the software and for another $40 or so you can upgrade to their 'pro' package which includes the ability to graph, run the EVAP test and stuff.

It took a while to sort out the capabilities and how to select gauges and such but in the end.... its just more software to figure out.

No adapters for my gauge so I went for something that let me mess with my lathes... that way I'm not thinking all I do is work on the car.

StepSide88 wrote: No adapters for my gauge so I went for something that let me mess with my lathes... that way I'm not thinking all I do is work on the car.

Lol any excuse is good enough to fire up the lathe !

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StepSide88 wrote: No adapters for my gauge so I went for something that let me mess with my lathes... that way I'm not thinking all I do is work on the car.

Sounds good to me! :lol: Wonder if anyone produces an adapter like that… If not, market it.

OK I have a result.

The adapter works with the exception of the phenolic plate (piece of scrap) I used as a backer for the rubber intake gasket.
It lets you know when you hit 3K rpm. Still I messed with the lathe and played with all my toys (scrap and spare junk from garage sales or just junk)
which was worth it if it clears a part from the 'to buy' list.

At best it maybe drew 2 lbs.

After talking with my cousin I decided to run the evap cold start this AM and in prep of getting O2 reading checked codes.
P0403
P0405

no P0404

I thought I"d posted this but don't see it so more info

EGR connector pins read:


A B C D E

KOff 7.8v 7.1v 7.5v 5.01v 12.8v
KOnEO 34.9v 34.9v 34.9v 5.01v 12.8v
KOER 3.7-7v vari +/- vari .961v 4.9v 2.9v - 7.9v vari



SO after close but not exact Drive Cycle and waiting for the 45 min
I No longer have
P0403 or P0405.

I do have P0404 back however.


All On Board Monitors now Pass

But Monitor Status shows the tests for Catalyst, EVAP, O2 sensor heater, and EGR sys are incomplete.

17hrs to next Key On.
So while I drift down this slow section of the river any suggestions?

StepSide88 wrote: OK I have a result.

The adapter works with the exception of the phenolic plate (piece of scrap) I used as a backer for the rubber intake gasket.
It lets you know when you hit 3K rpm. Still I messed with the lathe and played with all my toys (scrap and spare junk from garage sales or just junk)
which was worth it if it clears a part from the 'to buy' list.

At best it maybe drew 2 lbs.

Wow, highest reading was 2 lbs? What was the measurement at idle and 2500, specifically? I don't doubt your readings, just want to make sure I understand what you saw.

My gauge was a 60 lb test with 10 lb marks and 3 tick/hash marks.
the needle moved between .5lbs idle and 2lbs or maybe slightly more at WOT as best I could read while driving with the gauge laying outside against the windshield on the pass. side.

What sort of MAF readings are the normal range for this beast?