Remote tune with prestige motors

Today I had my first remote tune session with Doug at prestige motorsports to check everything. As i mentioned before they are a pleasure to deal with, Doug FaceTimed me and talked me through linking up computers so he can access my computer. I went over everything on motor and found no exhaust leaks prior to session. Once he was logged on and I started car he Immediately shut the motor down and told me i had bad exhaust leak,computer was dumping 50% more fuel than needed to try and correct itself. He than shut off the o2 sensor and car was perfect. He than told me how to pressure test exhaust with a shop vac and soap/water to find leaks without starting car and it worked lol needless to say “slip fit” is no good as a few mentioned to me previously lol. Its crazy what 2 small pipe leaks can cause. Doug told me to fix leaks then call him to link in again and check. Their engines, customer support, and knowledge is amazing.
 
Yep. It only takes a trace amount of air leak into an exhaust to make the AFR gauge think you're lean when you're really pig rich.

Don't know what Doug suggest, and take the guys advice you're paying, but I would say get it tuned then leave it open loop. Or at least limit the ECU to 10% correction at most. With my Cobra, I have it as a gauge and tuning aid, but exhaust leaks creep up and will wash your cylinders with fuel.
 

Markus

SPRF40
Lifetime Supporter
....... He than told me how to pressure test exhaust with a shop vac and soap/water to find leaks without starting car and it worked lol needless to say “slip fit” is no good as a few mentioned to me previously lol. Its crazy what 2 small pipe leaks can cause. Doug told me to fix leaks then call him to link in again and check. Their engines, customer support, and knowledge is amazing.

Hello Joe,
can you elaborate with some more details (pics ;)) how you pressure tested your exhaust with the shop vac + soap/water?
I'm fighting small leaks ever since, at least I suspect some leaks I have not yet found.....
How did you fix the leaks e.g. at the slip joint?
Thanks in advance,
Markus
 

Chris Kouba

Supporter
Markus,

I'm going to guess it's a shop vac where you can plug the hose into the fan output side (pressure) instead of the intake side (vacuum). Take that output and run it into your tail pipe and tape it shut, then spray it down with the soapy water.

Just a guess, but seems pretty plausible.
 

Phil G

Supporter
Markus
Exactly what Chris said. Tape the vac hose good at the tail pipe and use watered down Dawn soap. It works great! I have a video I will try and dig out.
 

Randy V

Moderator-Admin
Staff member
Admin
Lifetime Supporter
Bigger question, how can you "fix" a leak in a slip joint?
I’ve not had any trouble with using the red or copper hi-temp RTV on the joints. Of course they no longer just pull apart easily, but they will separate With some concerted effort.
 

Ian Anderson

Lifetime Supporter
Bigger question, how can you "fix" a leak in a slip joint?
I have read just plain grease. Liberally applied then assemble.it will seal the joint and even if it cook hardens you have some chance of separating the parts later.

ian
 
I would think Doug would have some advice on sealing the slip-fit exhaust...since they build some motors for Superformance cars. After going through the same problem with the ball and flange collectors on my '66 mustang, I've been scratching my head on how a bundle system would seal properly. I ended up finding leaks on each collector that made my ProFlo injection system very upset after initial startup.
 
As mentioned above by Chris,that’s exactly how to test. also mentioned above lol,Doug recommended high heat copper sealant. I’ll update post once I address issue.
thanks
 
Update
Exhaust all back together and leak free. Used remflex extra thick exhaust gaskets that allow 50% crush factor for any flange imperfections. For AFR heads its part # 3096 (3” bolt space, for 2” its 3084) I than marked each tube once in collector to see how far they go in then took apart,cleaned and ran a bead of permatex ultra copper extreme temp (700+ deg)around inside of collector 1/2 the distance of mark on tube so it seals deep inside towards the end.
6C8CF8FF-765E-450B-9707-A57B8B2F0239.jpeg
 

Markus

SPRF40
Lifetime Supporter
Markus,

I'm going to guess it's a shop vac where you can plug the hose into the fan output side (pressure) instead of the intake side (vacuum). Take that output and run it into your tail pipe and tape it shut, then spray it down with the soapy water.

Just a guess, but seems pretty plausible.

Hello Chris, Hello Joe,

Thanks for your reply's (also to all other fellow's here).....

@ Chris, thanks for the 101 workshop lesson...... yes the fan output side (pressure)..... how embarassing;). When using a tool always only one way then you forget other functions (at least me, it seems):eek:.

How did a former colleague used to say: "human stupidity always outperforms human ingenuity"

Regards,
Markus
 

Markus

SPRF40
Lifetime Supporter
Markus
Exactly what Chris said. Tape the vac hose good at the tail pipe and use watered down Dawn soap. It works great! I have a video I will try and dig out.

Phil G,

Thanks to all reply's I now understand how it works - however, if you could post that video? :rolleyes:

Regards,
Markus
 
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