Stuck on Manifold choice Sniper vs. 302

[zaquhree]

I have some videos of my car on the 3.6" making 11-12psi and the 3.33" capped at 11.6psi. It was a different type of feeling. The car felt faster on shifts with stock converter cause the rpm dip but felt soft up top. You get the IATs of someone running 15-17psi but only power from 11.6 or whatever spring you run...

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[MyLilPony]

I have some videos of my car on the 3.6" making 11-12psi and the 3.33" capped at 11.6psi. It was a different type of feeling. The car felt faster on shifts with stock converter cause the rpm dip but felt soft up top. You get the IATs of someone running 15-17psi but only power from 11.6 or whatever spring you run...

You ever dyno before and after?

 

[zaquhree]

Unfortunately no but I was pretty intimate with that car. Midrange gains is what I felt and soft up.top

 

[3beeps]

I messaged this to you on IG, but I'll put it here anyway.

In your log, the MAF looks to have an issue right at 6400 RPM. It hits 86.688 lb/min and caps out. Seems to be right where the graph starts going downward.

 

[Chummel]

I messaged this to you on IG, but I'll put it here anyway.

In your log, the MAF looks to have an issue right at 6400 RPM. It hits 86.688 lb/min and caps out. Seems to be right where the graph starts going downward.

All my logs cap at 86.688 as well, I don't think that's an issue.

 

[SolarFlare]

I messaged this to you on IG, but I'll put it here anyway.

In your log, the MAF looks to have an issue right at 6400 RPM. It hits 86.688 lb/min and caps out. Seems to be right where the graph starts going downward.

I think someone in another thread said that's the cap of what the maf reads, after that the tuner has to calculate flow. But don't quote me on it.

 

[whatsup62]

I think someone in another thread said that's the cap of what the maf reads, after that the tuner has to calculate flow. But don't quote me on it.

Yes that's the case. Mine does it also. i was concerned when I saw that and asked Lund. That's as high as the value goes. I am a believer that the intake fixes the flatline. My swap did...pulls up top as far as you have the balls to take it.

 

[markmurfie]

Mylittlepony

your long term fuel trims are indicating an issue. 20%+(rich) fuel is being pulled during your pull to maintain target AFR. under non boost conditions LTFT are indicating 15% (lean) fuel is being added.

MAF lb/min will cap at 86.68, but you can look at MAF frequency and confirm LB/min is still going up, you just cant see what values the ECU is using. the LB/min is a value manipulated by the tuner. Frequency is what the sensor is reporting. With intake air temps shooting up seems normal airflow is starting to level off.

your goal would be to find the cause of the LTFTs. unmetered air while manifold has vacuum, leaking air while it has pressure. Leak will most likely be some where from the throttle blade to the heads.

 

[MyLilPony]

Mylittlepony

your long term fuel trims are indicating an issue. 20%+(rich) fuel is being pulled during your pull to maintain target AFR. under non boost conditions LTFT are indicating 15% (lean) fuel is being added.

MAF lb/min will cap at 86.68, but you can look at MAF frequency and confirm LB/min is still going up, you just cant see what values the ECU is using. the LB/min is a value manipulated by the tuner. Frequency is what the sensor is reporting. With intake air temps shooting up seems normal airflow is starting to level off.

your goal would be to find the cause of the LTFTs. unmetered air while manifold has vacuum, leaking air while it has pressure. Leak will most likely be some where from the throttle blade to the heads.

I am assuming the wastegate opening to hold Boost back wouldn't be causing the LTFT issue since it is Pre MAF correct? It is a major leak obviously when it opens which it starts to creep at 10#.

I'll check all lines but there are only 3 post throttle body, egr, vacuum block and brake booster. Unless the throttle body is leaking post plate.

 

[MyLilPony]

I checked all lines and hoses and tubes post MAF and didn't find anything that was venting. The only thing I can think of that is post throttle body and is not metered is the Purge line I have circled in the picture. It would allow for un metered air to enter when the valve opens to dump fuel vapors.

I can pull the line and cap it as I have seen quite a few that are set up this way. But I am not sure if it will throw a code. Also, I think on the stock manifold it is plumbed and dumped post throttle body not causing issues... maybe I'm wrong on that...

 

[markmurfie]

Correct it is pre MAF so the air leaking out of it would not be measured and not affect fuel trims.

The 15% lean at idle is a sign air is getting into the manifold, as pre throttle body vaccum will be much less and air leaking in would be less noticeable.

What you circled would normally be going to the valve cover as its the PCV. Procharger moves this and the passenger side to a t fitting in the inlet tube. you now have breathers. This would be where your vaccum block would hook up since you no longer have IMRC vaccum lines.
https://farm6.static.flickr.com/5293/5475123794_7bab41dc04.jpg

The hose on the opposite side should be going to the evap purge solenoid. The hose for the fuel vapor vent comes from under the brake booster.

I guess you can swap and not have any issues.

below the evap purge solenoid hose is where your brake booster should hook up.

you also mentioned oring issues with your injectors, this can cause an air leak and would be my guess to what your issue is. The Boss intake the fuel rail bosses are too long and have to be trimmed to allow the id1000 injector to fully seat into the manifold.

Quote from shaun@AED:
"When installing the factory rails/injectors on the Brand New Boss IM I found the injectors were not fully seating in the manifold.
The O-rings were barely into the manifold and could easily cause a vacuum leak.

After some investigation I found the solution was to cut down the Aluminum Fuel rail spacers by .140". This allowed the injectors to fully seat in the manifold.

The Aluminum Rail spacers that came with this Boss IM were identical to the GT IM on the vehicle.
Back in 2013 when I was running a Boss IM I could have sworn the rail spacers were noticeably shorter for the Boss.

So be aware, if are experiencing what seems to be a vacuum leak after a Boss IM install, check how deep the injectors are seated into the manifold. To do this you can remove one of the Metal injector clips on an injector (#5 should be pretty easy to get to) then push the injector down into the manifold. If it moves significantly, you'll want to cut down the aluminum spacers to properly seat the injectors in the manifold."


The other thing would be the orings between the manifold and heads or the one for the throttle body.

 

[MyLilPony]

So this AM I am going to do the old "carb cleaner" vacuum seal check around the manifold/throttle body and see if I can find a leak there.

I did replace all of the O rings on the ID 1000's when I found the torn one. Since there is no clip I'll ensure they are all pressed in tightly. While running I'll use an air line to listen to each injector seating and see if I can hear anything. I would assume if there was an air leak cause by the injector I would also see some sort of visible evidence which I did not see like last time.

Current vacuum set up is left side Purge Valve left side, upper right PC vacuum Block, lower right side brake booster. I'll cap the left, vent the purge and see if i get a code. For some reason I think the purge is the issue but we will see.

I'll also do a KAM reset once this is over.

 

[MyLilPony]

1 leak found so far. The hose coming off the manifold and connecting to the vacuum block had a small leak. I made a new, smaller, tighter fitting line and tested it; solid now.

That leads me to the question of how large of a leak does it need to be to cause the LTFT issue you see in my log? Would something as tiny as a small leak coming off the vacuum line cause it? And at that would something that small cause the major drop off I am seeing on the dyno? [MENTION=16352]markmurfie[/MENTION]

 

[zaquhree]

It can be quite a small leak. You will only throw codes at 25% swings which are huge. Anything over 5% consistently is an issue IMHO

Didn't you have this issue pre-BOSS? I would try to borrow a smoke machine

 

[MyLilPony]

It can be quite a small leak. You will only throw codes at 25% swings which are huge. Anything over 5% consistently is an issue IMHO

Didn't you have this issue pre-BOSS? I would try to borrow a smoke machine

Pre boss it was good just flat up top, during the boss swap I re-ran all the lines and replaced all of the lines with new lines. The exception was the main line feeding the vacuum block. I reused a stock line as it was Pre-bent moving the vacuum block under the manifold. That is the one that was leaking this go around.

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