Boost Pressure

spithead051 · Apr 17, 2014

I've had a TRD S/C installed on my truck for almost two years now with a boost gauge and I am used to seeing 6 PSI under WOT. This morning I punched it to merge onto traffic and my boost gauge read 8.5 PSI which seems abnormally high.

The only changes I have made around the S/C are the URD fuel pump, Dynomax catback exhaust, and an aFe Stage 2 Si intake (which is only a month old).

I live near sea level and it was 45F this morning. AFAIK intakes do not allow more boost pressure unless I am misinformed.

I was planning on putting a URD 2.85 pulley on the S/C but now I am worried that it will produce too much boost and blow up my motor. AFR's were right around 10 as well so it was not running lean either this morning.

Is this normal behavior or something I should be concerned about?

sailingengineer · Apr 17, 2014

Just from my expierence boost press will change with air temp. My URD stage 3 setup will be around 10psi in the summer and I have seen 12+ in the winter months.

STONER-X · Apr 17, 2014

With a sc you will see different boost levels when the weather changes.... The cooler the air is the more dense it is so the charger is compressing more air... When it is hot outside the air is less dense so it will compress less air....

The challenge get you are seeing is normal...

Unless there is restrictions... like a bad cat causing the system to build pressure because it can't get it all out

trdtoy · Apr 17, 2014

IMO from 6 to 8.5psi is too much of a change due to weather conditions as a factor with issues you are experiencing. If you see 8.5psi at 45 degrees ambient it would have to be over 106 degrees to see 6psi based on the math. Also if you see 8.5 psi and afr still at 10 or richer likely in your case is unbelievable on trd tune especially if you have normal or free flowing exhaust. Guys running this much boost on trd tune seem to be high 10 at worst from what I have read. My vote is cat/s plugged causing you to see abnormal high boost but not actual more flow or power and trd tune making it stupid rich do to this condition. Get this checked out asap as you do not want to start fouling plugs, killing o2 sensors, thinning oil out ect..... Try not to get it in therich zone too much untill you get it squared away.

spithead051 · Apr 18, 2014

What are the chances of my truck having a clogged cat(s) considering it is only 4 years old with 41k miles on it? Seems way too early to be facing issues such as that. Also, fuel mileage and power are perfectly normal which are generally symptoms of a clogged cat.

Eraser · Apr 18, 2014

There are a lot of reasons from your listed set up that may cause early fouling cats (not nessecarily bad). And even if it is nothing to worry about you will feel a lot better knowing your engine is not about to melt than fronting the bill for a new engine.

In my opinion, get a pair of headers and a new Y pipe... great excuse to get new parts, you are probably going to have to wrench anyway. I would love a pair of the new URD headers.

justin13703 · Apr 19, 2014

Eraser said:
There are a lot of reasons from your listed set up that may cause early fouling cats (not nessecarily bad). And even if it is nothing to worry about you will feel a lot better knowing your engine is not about to melt than fronting the bill for a new engine.

In my opinion, get a pair of headers and a new Y pipe... great excuse to get new parts, you are probably going to have to wrench anyway. I would love a pair of the new URD headers.

If you are looking at doing new exhaust components in the near future, then it wouldn't be a bad idea to just do it now and see if it fixes it. However, I wouldn't just throw parts at it like headers and a y pipe and just hope it fixes it if you had no plans of doing it. Do some troubleshooting and try to narrow down what the issue may be before spending over 1k hoping it takes care of it.

Obviously you have a boost gauge. Rev your motor up to like 2k rpms. The vacuum should move towards 0, then quickly go back down near where the needle was at idle(my truck was around -22). If you have a clogged cat or a restriction in the exhaust system, the vacuum will stay near 0 as you hold the rpms up. If it passes this vacuum test, and you have no drivability, power, or check engine light issues, I would not jump to the conclusion that your cat is clogged.

spithead051 · Apr 19, 2014

justin13703 said:
If you are looking at doing new exhaust components in the near future, then it wouldn't be a bad idea to just do it now and see if it fixes it. However, I wouldn't just throw parts at it like headers and a y pipe and just hope it fixes it if you had no plans of doing it. Do some troubleshooting and try to narrow down what the issue may be before spending over 1k hoping it takes care of it.

Obviously you have a boost gauge. Rev your motor up to like 2k rpms. The vacuum should move towards 0, then quickly go back down near where the needle was at idle(my truck was around -22). If you have a clogged cat or a restriction in the exhaust system, the vacuum will stay near 0 as you hold the rpms up. If it passes this vacuum test, and you have no drivability, power, or check engine light issues, I would not jump to the conclusion that your cat is clogged.

I went out and followed your steps to the letter. Vacuum moved to about 9 and then dropped back down to 21 after a second or so. Looks like the cats are fine.

STONER-X · Apr 19, 2014

Here is how you can check the cats for sure.....

You just have to get past the cheesy video .... lol
[ame]http://m.youtube.com/watch?v=IzyvL5tQLzU[/ame]

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Boost Pressure

spithead051

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sailingengineer

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trdtoy

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spithead051

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Eraser

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