No power on hills, some power loss accelerating - Misc Codes

[sdamos]

I am thankful for all the folks in this forum, I have solved a few of my issues already and I am hoping with your help I can solve these last problems.

Symptoms:

It does not seem to matter cold or warm start, when I slightly press the gas pedal sometimes the engine will slightly stall then continue. Also, at idle, occasionally RPMs drop toward zero and the engine quickly recovers. Usually once per day when accelerating the engine bogs down like it wants to die around 20mph even when I continue pressing the pedal further down, then it takes off fine. Always when going up medium inclines I have a significant loss of power around 40 to 50mpg and if I get the pedal 3/4 of the way down it will eventually downshift, but sounds like it is struggling to climb. If I have a slight load, 1,000 lbs, my top speed is probably 40 mph up medium inclines. It "feels" like it is starving for gas, or air. The truck shifts fine on level surfaces and even seems to accelerate at a normal rate. One other caveat, we were sitting in construction the other day on a slight incline and waiting on a 4-way stop and the truck kept wanting to die and recover. It seems to have improved recently on its own.

What has been done:

When I bought the truck, not long ago, it had a P0135. It was stalling badly on every takeoff, but that was the only code I had. I replaced the upstream o2 sensor with a Bosch (now I know that was probably not a good idea). I found cracks on the exhaust manifold and exhaust smell in the cabin so I took it in. They replaced the exhaust manifold and also the thermostat (later found a code for that). Personally, I have cleaned the throttle body, replaced the spark plugs, replaced the fuel filter and air filter. I have also ran Techron through twice.

What codes do I have now:

Currently, I have the following codes: P0053, P0410, and P0455.

The truck is a 2003 4.2 I6 LT extended Trailblazer. I hope I have provided enough information and I look forward to your replies. Thanks again.

 

[The_Roadie]

Welcome! Wonderful detail in your post.

My 2004 shop manual doesn't mention a code P0053, but a quick Googling shows it might be the O2 sensor heater circuit is out of spec. That's exactly what a Bosch sensor will do. It won't kill anything to leave the code on, except you'll fail emission testing, the light is annoying, and may obscure a real problem code if you don't continuously monitor the codes. Change to an AC Delco sensor to fix it.

P0410 is the classicSAIS problem. Do you hear 30 seconds worth of a shop vac sound from under the driver's seat on every cold start? If not, the SAIS turbine pump or its power source connection has a problem. If the pump works, then the exhaust manifold mounted solenoid value is failed. Or the O2 sensor is not responding as expected to the SAIS diagnostic test. Depending on how you answer the question about hearing the turbine pump will determine how to proceed to troubleshoot this. By itself, this is not a worrisome code, since the SAIS system only reduced emissions on a cold start before the engine controls enter closed-loop operation. I would definitely get a code reader that can also look at real-time O2 sensor data, and see if it's wiggling as it should between 0.2 and 0.9 V (approximately) between 1 and 2 times a second. Plenty of youtube videos on what a good O2 sensor data looks like on various scan tools.

The last code is worrisome, since a leaky fuel supply EVAP system with a large leak can throw off your air-fuel ratio and cause driveability issues. Run a search for Purge Valve and look into the EVAP system. There is a thread here with manuals you can download, or you might find the Haynes manual of use. Or take it to a shop and have them diagnose this code and the EVAP system.

Also, loss of power behavior, combined with the P0128 thermostat issue, especially if it was driven by a scumbag cheap-ass previous owner who was motivated to transfer their problems to a new owner, would have resulted in driving with an excessively rich mixture. If driven long enough with a P0128, many owners have no idea that the second order effect (besides wasting a lot of fuel $$$) is that the excess fuel burns in the cat and will (no maybe about it) cook and kill the cat. You should also get the exhaust backpressure tested and be prepared to replace the cat.

Good luck. Glad you found us!

 

[The_Roadie]

Oh, and did you use Delco 41-103 plugs?

 

[Wooluf1952]

Welcome


In case you haven't heard:
http://gmtnation.com/forums/topic/218-welcome-to-gmtnationcom-heres-the-story/



Are you sure about the year of your truck?
My understanding was the SAIS wasn't used until the 2004 models. Unless it was installed in the end of year trucks? My 2003 Service Manual doesn't list a P0053 or a P0410.

 

[sdamos]

Welcome

In case you haven't heard:
http://gmtnation.com/f5/welcome-gmtnation-com-heres-story-226/


Are you sure about the year of your truck?
My understanding was the SAIS wasn't used until the 2004 models. Unless it was installed in the end of year trucks? My 2003 Service Manual doesn't list a P0053 or a P0410.

Interesting that you mentioned that. Here is more information: This is indeed a 2003, but under the hood the ECM has 2005 hand written on it with what looks like white-out. So I am wondering if it really is a 2005 ECM and if that is causing issues with the fact that this is a 2003 truck? At Autozone there are two scanners there in the local store. If one is used they show these 3 codes. If the other is used it says my truck is a 2005, in which they go to manual selection and run with 2003, then they get like 29 codes, which are a bunch of wheel sensor codes, transmission codes, 4wd codes etc. Yet of all those the only 3 they can read are also the 3 I listed. So do I have a bad ECM or an ECM that is not compatible, or are all those nonsense codes that are in the history and possibly caused by the horrible driving conditions I am experiencing?

Also, you should know I replaced the exhaust manifold because it was cracked. There was also a code for the thermostat and it was replaced. So I also had the bad o2 sensor. Adding all that up in my head with the excessive power loss I am real curious how long it was like that before I bought it and if it fried the cat or not? It drove terrible today. The plugs I put in are Delco 41-103 plugs. That was asked earlier.

So what do you all think? Is it the cat, or maybe the fuel pump? It looks pretty rusted. Also, I just got home 30 minutes ago and the pipe on the engine side of the cat is warm, the cat was hot, and the pipe after the cat was cold. I can feel air coming out the tail pipe, but it sure makes me wonder with the cat being so hot that everything else was not even warm. Wondering if there is a huge restriction in the cat?

 

[SeductiveSound]

I would also recommend checking the MAF sensor.
My mother-in-law had a Montana with a similar issue.
Van would drive fine until you gave it a little gas or tried to drive up a hill, no power.
It was also throwing O2 sensor codes.

Have it checked, just to rule it out.

 

[The_Roadie]

I think MAF didn't come along until 2005, either. The vehicle seems to be a confusing mashup of years. Is the previous owner anybody you can call to get the truth about?

An exhaust backpressure test is the definite diagnostic for a clogged cat. Without getting that done, all we can do is guess by the symptoms, and that can lead to costing you money in the long run by useless shotgunning.

 

[budwich]

sounds to me like someone was either playing with "flashing" and / or replacement of the ecm with a different unit along with replacement of the engine.... maybe. Sounds like a desperate "frankenstein" attempt with less than adequate guidance and / or knowledge.

 

[Wooluf1952]

If that ECM is from a 2005, that could be why your getting the P0410. It's looking for the SAIS and you don't have one.
Does the VIN of the truck match the VIN in the ECM?

 

[sdamos]

If that ECM is from a 2005, that could be why your getting the P0410. It's looking for the SAIS and you don't have one.
Does the VIN of the truck match the VIN in the ECM?

I do not have a scanner to check that. I am told a 2005 ECM should not be a problem in a 2003 as long as it was flashed correctly. I suppose if my VIN is NOT in this ECM it probably was not flashed after install. Good assumption?

Also, my powerloss got a lot worse and more consistant today and I can smel some exhaust with the window down. I am really leaning on cat blockage. Wish there was a simple way to confirm without going to a shop. I have very little free time.

 

[The_Roadie]

As you know, sometimes you have to trade $$ for somebody else's time or tools. You could also just disconnect it for a while and annoy the neighbors with a high RPM test run.

 

[sdamos]

As you know, sometimes you have to trade $$ for somebody else's time or tools. You could also just disconnect it for a while and annoy the neighbors with a high RPM test run.

All joking aside, I did loosen up the converter and created about 1.5 inches of space between the manifold and the converter. Loud as hell, but does not make a difference in performance. I cannot rev the engine past 3k rpm really, even in park. Any suggestions on where to go from here given everything I have reported above?

Should I get a used ECM and try that, or try to have the one I have flashed? I am told a bad ECM or what that has not been programmed could cause this type of performance issue.

Thoughts?

 

[The_Roadie]

You have to drive it for the test. In PARK and NEUTRAL, there's a 3K rev limiter built into the computer to prevent idiots from revving up and then dumping the transmission into DRIVE to chirp the tires.

 

[sdamos]

Ok, here is an update: I took it to the dealer and found that the program was indeed the wrong program on the computer. They flashed it to my VIN and told me the back pressure tests failed under load, but not low speed. So they suspect the converter is bad. Driving for two days now I have codes again, here is what I have:

P0172, P0440 and P0442. There were other codes, but they were all ABS related and on the left side (who knows?).

So I plan to determine if the cat is cooked, but could use some help on these codes.

Thanks!

 

[The_Roadie]

P0172 indicates excessively rich mixture and tries to determine if excess fuel vapor is getting into the intake from a saturated EVAP canister. The code sets if it is NOT due to an EVAP problem. It could also be coming from a bad diaphragm in the fuel pressure regulator (been discussed before here and how to smell the hose).

My 2004 shop manual doesn't list a P0440, but for P0442 it also involves a vacuum-pulling diagnostic on the EVAP system and its two valves (purge and vent).

Common item here might be the FPR. And if it leaks fuel into the intake manifold and causes excessive richness, that could clog the cat.

 

[sdamos]

So I straight piped the cat, it is gone. It was excessively clogged. The truck runs fantastic now. I took the Bosch sensor out and put in an NDK I think it was. I reset the PCM by the 10 and 28 fuses and I am going to see what comes back up now. It is possible that the clogged converter could have kicked back pressure back into the engine and caused any of those codes above?

 

[The_Roadie]

Thanks for the report. I can't make a guess on what the backpressure could have for side effects. Sorry.

 

[sdamos]

Ok, so after 3 days I got another check engine light. Only one left!!! It is a P0440. This has been mentioned several times on the forum, where do you recommend I start?

Thanks.

 

[The_Roadie]

Read all the threads that contain that code. Large Evap system leak can be a bad gas cap, cracked filler neck, or a fault in the solenoids or any of the hoses.

 

[sdamos]

Ok, so now I have a P0420. "The Roadie" I found your old reply to another user:"

"P0420 comes from "low cat efficiency". The PRE-cat O2 sensor wiggles from low to high voltage around once per second or sometimes 2 times a second as the PCM adjusts the fuel-air ratio

The POST-cat O2 sensor is much steadier, since the cat is supposed to burn any excess fuel and cause the output exhaust stream to be predictable and non-polluting.

A good scan tool that can look at the PRE and POST cat O2 sensor readings can tell in an instant if the cat has "low efficiency" for being broken or missing. I had an intermittent P0420 and troubleshot it this way. My POST-cat sensor readings wiggled up and down at the SAME rate as the PRE-cat sensor. That wasn't right, and will trigger the P0420 code.

Looking closer at the cat canister and I found a dent put there by an offroad rock. The ceramic cat element inside had broken up and bounced around until it was all broken and 1/3 of it had departed the canister.

A cat that has "low efficiency" for being clogged will show itself by high backpressure as measured in the PRE-cat O2 sensor hole."

Being that I cut my cat out, and I straight piped it, I used exhaust clamps so there is a tiny bit of air escaping at the joints. I will be welding it soon to seal that up, but will this code go away after a few cycles, or do I need to do something with the downstream o2? Or will this not go away until I install an actually converter in the path?

 

[The_Roadie]

A missing cat is the very definition of low efficiency.

You need to replace it, change the sensor out with some resistor that simulates the steady signal the PCM is looking for, or get a PCM tune that removes that DTC code so your SES light will turn off.

 

[Envoy_04]

One other option: go the spark plug non-fouler route. You can space the rear O2 sensor out from the cat pipe with common and cheap spark plug non foulers from an auto parts store. This let's the rear O2 sensor "sniff" less exhaust therefore thinking it is clean and tricking the PCM into thinking the cat is still working properly. I did it on mine and it worked like a charm until I could get my PCM custom tuned. You want the non tapered ones, they are the ones that have compression washers with them. You have to drill one of the two in the pack out straight down the middle, I think 1/2 inch. Screw the O2 sensor into the drilled out one, the drilled out one with the O2 sensor installed into the remaining normal one, and the whole thing into the cat pipe. Cheap way that worked for me to turn off the CEL thrown by a missing cat.