Hey all - 2009 alpha with 130k miles has been throwing an intermittent P0328 the past two weeks. I’ve been towing a camping trailer across the country during this time but the code gets set with and without the trailer. I clear the code when it trips and it usually stays away for a few days before coming back. I’ve also occasionally seen reduced power on hills, and today saw ignition retarded to -10 deg when experiencing the power reduction followed by the check engine light and P0328.

Codes are coming from my Scan Gauge II. I’m away from home and don’t have my scanner with me.

So, is this just a bad knock sensor or is there something else I should be looking for? Appreciate the help!

NMH3

 

hopefully you just got some bad gas on your travels. try adding a bottle of gas drier of some sort and maybe an octane booster.

 

That was my first intuition so I switched to premium about 5 fills ago, all in different towns. I thought it made a difference at first, but all the symptoms have come and gone (then come back again) since then so I’ve pretty much ruled out gas as the problem.

In the morning the truck seems to work fine, but after driving a while is when the symptoms show up, suggesting some heat dependency. Water temps have consistently been in 210-220 range, up to 230 on extended steep grades in the mountains but comes down again once we reach the top of the hill.

 

What are your Trans Temps? Coolant still look good? When the Aplha's get over about 227-230F for a few minutes, that will trigger the PCM into falling back to reduce power and heat soak, but that should be temporary.

Easy stuff first.... bad knock sensor or wiring to it.

 

Thanks doc. Transmission was good - below 190 when this last happened. Coolant has been running 200-220 and TFT 180-220 as I move across the country. Some of the long 6% grades pulling the trailer has seen coolant and TFT climb as high as 235 until I crest the hill, but comes down right away when we get to the top. It’s also stable in the hill climb if I stay in 2nd gear and 50 mph during the climb. Combined weight of truck and trailer is 10,000 lbs.

The latest power reductions have happened with just the rig, no trailer. Yesterday, the V8 drove like a beast in the morning, but then I parked it in the sun for 4 hours and it drove like a dog on the way home. This time it threw the P0328 at the same time as symptoms. Coolant temp was 225 when this happened. I wasn’t monitoring IAT at the time, but read that can also be a factor. Previously the code was getting set immediately at engine start (hot and cold) with no noticeable symptoms at the time the code set.

I’m going to try and get a new sensor today (it’s a holiday here in Canada) and see if that resolves it. Appreciate ideas for other things to look for.

 

 

Replaced the driver side knock sensor today and cleared the P0328 code. Removed the skid plates to get better access, then an easy 10 minute job to replace the sensor. Code has not returned and PCM is no longer retarding the timing every time I give it gas. More or less feels like a brand new truck with a bigger engine now!

Checked out the passenger side while I was down there in case I had to do that too. It will definitely be harder to get at, but still looks doable without having to remove anything but the skid plate, but it will probably require a few more swear words when trying to contort hands and arms to get tools on the part. :-)

 

Thanks for completing this Thread by reporting your solution. KUDOS!

 

Well, false victory it seems.

I’ve put 100 miles on the truck since replacing the knock sensor and all was great for the first 90 miles, then today after a 20 mile drive we parked it for 3 hours in the sun, after which the power reduction issue came back with a vengeance and was experienced for the full 17 mile drive in city traffic to our destination.

During this drive the ignition advance would retard to -10 deg whenever I tried to accelerate at low speed/rpm. Once the rpm’s built up a little the negative advance rolled off, but power is not like before and the tranny kept kicking down into low gear and higher revs on the drive.

There are no current or pending codes showing on the scan gauge. IAT was 100-130, coolant 210-225, TFT around 200-215 and outside temperature was 86F. If the engine is in neutral or park we don’t see any negative advance numbers, which I suspect is normal behavior. All of the temps on the drive today seemed a little high to me based on what we saw during our trip here.

I’m still away from home without my scanner. We are meant to leave on Monday for the 1800 mile cross-country return journey pulling the trailer so really appreciate all and any ideas people have on what might be going on here.

TIA,
NMH3

 

I was reading your post and came across a interesting (to me anyhow) statement/observation you make.
Each time vehicle sat in sun for hours!
I'm going to deviate from others and recommend to start with basics.
What is the value??
ppm/grams readings Maf
iac
requested TB
actual TB
Now gas tank....
value for pressure when evap sel closed, open??
pressure should build when requested closed... conversely when open should fall. If valve is stuck pressure when heated in hot sun of day could be building to high.
What are your actual trims while driving??

what are the knock sensors actually reporting??