2006 Cold Start: Jake Brake Sound; Cold Start (4 Viewers)

[2000UZJ]

Morning all — this just started after some recent maintenance.

My 2006 with 302K miles was getting terrible mileage (~6.1 MPG) and felt lethargic. P0420 popped up, so I replaced the O2 sensors, spark plugs (OEM), and Denso coils — all torqued to spec (plus a hair on the plugs).

The next morning on a cold start, I heard the Secondary Air Injection Pump run, shut off, then a few seconds later came a deep, two-beat rumble — like a distant Jake brake or a modern V8 switching to sport mode — lasting about 2 seconds. It happens randomly, but always only on the first start of the day.

I've ran back through my checklist, and vacuum hoses are good, and everything plugged in. This doesn't sound like the SAI Pump, however I guess it could be?

What says?

 

[OEMGUY0720]

Any error from your OBD scanner when you ran diagnostics during or after the symptom?

 

[2000UZJ]

Any error from your OBD scanner when you ran diagnostics during or after the symptom?

P0420, which was accompanied by terrible performance and sub-par fuel economy. No codes after, and doubling of fuel economy. I know sit in the 12's.

 

[Mike NXP]

I don't have any experience with that noise or SAI pump , but I know I've seen some folks talk about a small filter in the pump that can sometimes get sucked in. I doubt thats your problem, just trying to add any relevant info.

Since the noise never happened before and then started after maintenance I'd think to focus in on whatever you touched during repairs, but I don't see how plugs, coils, o2 sensor could lead to these symptoms...

What about like heat shield on the exhaust or something like that. Is it a rattle? Jake brake noise, hmmmm

 

[2000UZJ]

I don't have any experience with that noise or SAI pump , but I know I've seen some folks talk about a small filter in the pump that can sometimes get sucked in. I doubt thats your problem, just trying to add any relevant info.

Since the noise never happened before and then started after maintenance I'd think to focus in on whatever you touched during repairs, but I don't see how plugs, coils, o2 sensor could lead to these symptoms...

What about like heat shield on the exhaust or something like that. Is it a rattle? Jake brake noise, hmmmm

I think I may need to try to capture a video of it, it's a very unique sound, but the best I can describe is a jake brake sound. The engine RPM calms down, SAI cylces on>off, then this new induction sound happens. It's a very deep grumble, I guess induction sound might be a better term

 

[OEMGUY0720]

It could be the SAI, not discounting it. Usually for VVTi 2UZFEs, the SAI issue comes up during cooler months where it has to stay ON longer in respect to the O2 sensors warming up the catalytic converter temps. I’m curious what was the your outside temperature when you first got the P0420 dtc? And do you happen to have the Hewittech’s SAI kit on your truck?

 

[2000UZJ]

It could be the SAI, not discounting it. Usually for VVTi 2UZFEs, the SAI issue comes up during cooler months where it has to stay ON longer in respect to the O2 sensors warming up the catalytic converter temps. I’m curious what was the your outside temperature when you first got the P0420 dtc? And do you happen to have the Hewittech’s SAI kit on your truck?

It very well be the SAI Pump, potentially running at different RPM's and creating a hum, a bearing could be going out. P0420 came on when it was HOT, ~100*F, 90% Humidity, on the highway. I was coming back from the airport, so it had sat for a few days. It's in the 70's in the AM now, when this happens.

I do not have any SAI blockers, etc. This is, from what I can tell, the OEM equipment from 2006, with no replacement parts.

 

[OEMGUY0720]

On the bright side that’s 300k+ solid miles before it went out, pretty impressive to me. I have the Hewitt SAI bypass kit installed around 4 years ago and haven’t had any P0420 related issues since. It basically bypasses the SAI motor and alters the signal to run natural aspiration during startups especially when it’s cold. First time I experienced it was 4 winters back and it stayed on limp mode, no unusual blower sound. After the install engine operated normal again.