Trouble after secondary air disabled

[ElanS2]

Instead of replacing a seized secondary air injection valve on the drivers side at an abusive cost and with no guarantee I had the entire system disabled. The pump was removed, the drivers side injection valve removed and a cover plate installed, and the air piping to the other side was disconnected. The passengers side valve remains, although it is not operating, and the electrical connection concerning the atmospheric pressure sensor is supposed to be still operational.

During the job I was sold on the idea of installing a 3" catted downpipe which was done 2 weeks after the removal/disabling of the air injection apparatus. At the time of the DP installation the tuning was modified in a manner that was not explained to me, "you wouldn't understand".

Now I am plaged with strange noises on start-up that disappear, then reappear before trailing off to a normal engine sound. The timing of this sequence repeats in a manner that indicates to me that it is controlled by something. None of this happens when the engine is warm at start-up, only on a cold engine. The rpm at start-up is just over 2000 and trails off to +/- 1500. The noise seems to be coming from the drivers side on the top of the block below the intake manifold. The timing chain and the AC pump have been ruled out. I have heard a click preceeding the final trail-off but I have not been able to locate it's source although it is on the driver's side below the intake manifold ( not in the center) where visibility is poor for my old eyes.

The experts that did the work have not been able to hear the noise because the engine is always warm when I get there and I am 600 miles from them so I do not get to the shop very often.

My question is this: Is there a start-up routine controlled by the computer that could be behind this ? My experts say no, but I find that hard to believe. The sequence is so consistant I doubt their statement.

2007 Wagon GT, turbo, 100,000 miles, no oil consumption, daily driver. I love this car.

I have been looking for something similar to my problem without sucess here. I also searched NASIOC for something with a little bit of sucess, but I am not able to get back to it. It seems that some people have experienced a simliar situation after a DP/tune.

Edited September 11, 2019 by ElanS2
new info. and lack of replies like none !

[ElanS2]

NASIOC comments indicate that there is something called "stratified start up" going on that should be disabled to stop this. Anyone know what that is and if it affects a 2007, Legacy GT, 5EAT ?

[Code]

Could be TGV opening after car warms up a bit.

[ElanS2]

Monkey, Thank-you for your interest.

How long is a bit ?

The sequence is:turn ignition switch to on and wait +/- 15 seconds to allow gauges to stabilize, engage starter, immediately as engine starts loud roaring/growling noise and 2000rpm, less than 5 secs and loud noise disappears for +/- 3 secs and then returns to taper off and disappear for good over less than 30 secs as rpm decreases to +/- 1500.

Happens only when engine cold.

This has been happening since May meaning over the warm season here ( Sept-Iles Quebec along the north shore of the Gulf of St Lawerence ). We are about to enter the cold season and I am wondering what is in my future. Cold is down to at least 0ºF. Jumping to 2000 rpm does not sound good to me. Using 100% synthetic.

Edited September 12, 2019 by ElanS2
spelling error

[ElanS2]

Cannot find a list of abreviations !

What is TGV ? throttle gate valve ?

And where is it ?

I think I have heard a click when the noise restarts but I cannot identify where it comes from other than possibly the driver's side under the intercooler maybe.

[Code]

Tumble generator valve. It’s between the block and the intake manifold. It is a flapper that closes during cold-start. Emissions control BS. They can be removed, though it is a bit h to do so.

[ElanS2]

Thanks again. I now remmber having seen that somewhere !

Sounds like it causes turbulence to the flow, perhaps to improve fuel/air mixing.

Can I reach it with the rod on my stethoscope ?

 

Is it behind the alternator ?

There is a device/connector there that is buzzing when the ignition is on and inaudible after starting.

 

I will try and see if the buzz remains once the engine is warm.

That will have to wait until I finish changing some heat shields

Edited September 12, 2019 by ElanS2
new thoughts

[ElanS2]

Will a 2007 GT have a TGV ?

[ElanS2]

Will a 2007 GT have a TGV ? Answer Yes !

 

From the 2007 service manual:

 

A tumble generator valve is provided on each engine bank, between the intake manifold and intake air ports. The right bank tumble generator valve has butterfly valves for the #1 and #3 cylinders and the left bank tumble generator valve has those for the #2 and #4 cylinders. The two butterfly valves in each tumble generator valve are fitted on a single shaft that is driven by an actuator.

The tumble generator valves are controlled by the ECM according to the coolant temperature and the time elapsed after start of the engine.[/color] When the engine is started, the butterfly valves are moved to the closing ends. In this state, the intake air flows at very high speeds passing through narrowed passages in the directions determined by the individual intake air ports in the cylinder head. This creates tumbling air motions in the cylinders, which enables lean mixtures to be ignited and thus harmful exhaust emissions to be reduced during engine start. The tumble generator valves are fully open when the engine is operating at an ordinary driving speed, allowing intake air to flow without being changed in direction and velocity.

 

That certainly sounds like my situation.

Now I have to find out what my tuner did !

 

Monkey Thanks again for getting me onto the "TGV"

I am now a donating member thanks to you !

Edited September 12, 2019 by ElanS2
new info.

[ElanS2]

Another question:

On startup the valve must be closed to do its job of creating turbulence that improves fuel vapourisation. Does it open gradually ( moderation ) or is it on/off. If it modulations that would explain the tapering off of the noise at the end of the sequence, but it will not explain the abrupt disapearance of the noise 5 sec after initial start up. There is perhaps a click when the valve reaches full open and also at full close. I will have to listen attentively now that I know what is going on. If I can hear both clicks that will be great.

I will also try and hear it on each side of the engine.

[Code]

New Member, Quit calling me Monkey, my username is Code. Lol. Good luck with your funny noises.