Idle Problems After LT Header and O/R Hpipe Install

tangtang · Nov 21, 2011

Ok so me an a friend decided to tear apart the car this weekend and put on a set of BBK LT and a BBK O/R h-pipe without cats. After finally getting everything back together after many choice words....the car is 5x as loud (for obvious reasons i know) and will not idle properly. I know this sounds funny but...sounds like it has a cam now the way the car is rising and dropping in RPM's. It sounds like the ECU is trying to settle itself but cant. The O/R h-pipe has all four O2 sensors in it. I had to fabricate my own extender for the rear O2 sensors. I have already contacted Bama to get my new tune to bypass the sensors but im not sure that this is all the problem. That should just kick a code rite? It also sounds like a drag car when under acceleration. Any ideas?

mustangjoe02 · Nov 21, 2011

i have the same exact problem but with mac lts and bama keeps sending me a tune that makes the idle worse. hopefully someone knows whats going on.

wmburns · Nov 21, 2011

The rising and falling RPM's indicates to me the vacuum is changing. What could cause this? Look for vacuum leaks at the PVC value, PCV grommet, PVC lines, and valve cover gaskets.

Check the throttle return spring. Is it in place and strong?

Deleted member 38176 · Nov 21, 2011

Same problem here. No leaks anywhere and I've had several retunes without any luck. Mine is somewhat minor so I just deal with it.

mustangjoe02 · Nov 21, 2011

so nightfire, the tune never helped with your problem? mine barely fluctuates without the tune, but with the tune its horrible. i dont think its the pcv because it didnt do it before the install. maybe a small exhaust leak that you cant hear but its there?

Deleted member 38176 · Nov 21, 2011

mustangjoe02 said:
so nightfire, the tune never helped with your problem? mine barely fluctuates without the tune, but with the tune its horrible. i dont think its the pcv because it didnt do it before the install. maybe a small exhaust leak that you cant hear but its there?

It might have helped a little but not much. It only surges maybe 100rpm at the most and does so rather slowly. I've learned to just ignore it really.

It never did it before the LT install and the vacuum lines (and similar accessories) were never messed with (I dropped the motor slightly for the install). I suppose that a small exhaust leak could be possible but the issue isn't big enough for me to investigate every inch of it.

tangtang · Nov 22, 2011

yea i will check all the vacuum lines today an make sure nothing came loose. i dropped the motor as well an never removed any vacuum lines. at least not intentionally. who knows...maybe one came off. when i talked to Bama performance they said that it sounded more like a leak an that was causing it to go rich an lean since it was gettin fresh air to the forward sensor. glad to know im not the only one having this problem

tangtang · Nov 22, 2011

did anyone else have problems gettin the dipstick tube back in? mine was such a pain. i think im going to have to change it out for a flexible tube. that an jus an fyi for everyone. i disconnected the spindle from the ball joints when doing this an somehow managed to get a little PB Blaster on the joint. that stuff works so well that the spindle an ball joint could not create enough friction to put the nut on that goes on the top of the ball joint....DEF A STRONG SUPPORTER OF THAT STUFF IF IT CAN DO THAT! THATS A RIDICULOUS AMOUNT OF PRESSURE!

Deleted member 38176 · Nov 22, 2011

tangtang said:
did anyone else have problems gettin the dipstick tube back in? mine was such a pain. i think im going to have to change it out for a flexible tube. that an jus an fyi for everyone. i disconnected the spindle from the ball joints when doing this an somehow managed to get a little PB Blaster on the joint. that stuff works so well that the spindle an ball joint could not create enough friction to put the nut on that goes on the top of the ball joint....DEF A STRONG SUPPORTER OF THAT STUFF IF IT CAN DO THAT! THATS A RIDICULOUS AMOUNT OF PRESSURE!

PB Blaster was used in excess during my header/midpipe install

mustangjoe02 · Nov 22, 2011

i didnt have any issues except with gettin the egr fitting off the old pipe. im just wondering if it was an exhaust lak, wouldnt you hear it? i had one the first time i installed because the pos gasket blew out an it was definitely noticeable.

tangtang · Nov 22, 2011

mustangjoe02 said:
i didnt have any issues except with gettin the egr fitting off the old pipe. im just wondering if it was an exhaust lak, wouldnt you hear it? i had one the first time i installed because the pos gasket blew out an it was definitely noticeable.

yea but i dont think thats it. it was like that from the moment we fired it up an would that change the rpms so much an cause it to go lean then rich? when u drive it an you go to neutral...it likes to stay at 2000rpm too.

AMChrisYoung · Nov 22, 2011

tangtang said:
Ok so me an a friend decided to tear apart the car this weekend and put on a set of BBK LT and a BBK O/R h-pipe without cats. After finally getting everything back together after many choice words....the car is 5x as loud (for obvious reasons i know) and will not idle properly. I know this sounds funny but...sounds like it has a cam now the way the car is rising and dropping in RPM's. It sounds like the ECU is trying to settle itself but cant. The O/R h-pipe has all four O2 sensors in it. I had to fabricate my own extender for the rear O2 sensors. I have already contacted Bama to get my new tune to bypass the sensors but im not sure that this is all the problem. That should just kick a code rite? It also sounds like a drag car when under acceleration. Any ideas?

tangtang said:
yea but i dont think thats it. it was like that from the moment we fired it up an would that change the rpms so much an cause it to go lean then rich? when u drive it an you go to neutral...it likes to stay at 2000rpm too.

OP, it definitely sounds like you have an air leak. Try spraying some carb cleaner on the manifolds near the heads and if the idle changes, you have found your leak. Another way to test is to smoke-test/pressure-test your intake/vacuum line system. Most shops will have a smoke-tester/adaptor that works on Mustangs. Keep looking into it and let me know if you continue to have issues/need assistance.

I hope this helps!
Good luck!
Have a wonderful/happy holiday!

mustangjoe02 said:
i have the same exact problem but with mac lts and bama keeps sending me a tune that makes the idle worse. hopefully someone knows whats going on.

A tune isn't going to make an idle worse unless there is a leak somewhere. Have you smoke-tested/pressure-tested your intake/exhaust system?

tangtang · Nov 22, 2011

AMChrisYoung said:
OP, it definitely sounds like you have an air leak. Try spraying some carb cleaner on the manifolds near the heads and if the idle changes, you have found your leak. Another way to test is to smoke-test/pressure-test your intake/vacuum line system. Most shops will have a smoke-tester/adaptor that works on Mustangs. Keep looking into it and let me know if you continue to have issues/need assistance.

I hope this helps!
Good luck!
Have a wonderful/happy holiday!

A tune isn't going to make an idle worse unless there is a leak somewhere. Have you smoke-tested/pressure-tested your intake/exhaust system?

Thanks for all your help. i am hearing a whistling from the drivers side near the rear of the headers. i dont know if its the headers or the egr but looks like im gonna have to spend some more time. ill keep you updated

tangtang · Nov 25, 2011

I found an exhaust leak where the driver side tailpipe meets the H pipe. After fixing this I am still having the same problem with my car pulsing. I still think it could be the o2 sensors. Any ideas?

tangtang · Nov 25, 2011

Thanks for all your help guys. I just figured out the problem. The vacuum line had come loose and after reconnecting it immediately started idling better. I'll take pictures so if anyone else had the same issue they can check where to find it.

mustangjoe02 · Nov 26, 2011

which vacuum line was it?? maybe i should have mine smoke tested cuz ive tried the carb cleaner trick and cant find anythin. maybe a hose is cracked somewhere or maybe i have a small enuf leak to where i do not ear it.

tangtang · Nov 26, 2011

mustangjoe02 said:
which vacuum line was it?? maybe i should have mine smoke tested cuz ive tried the carb cleaner trick and cant find anythin. maybe a hose is cracked somewhere or maybe i have a small enuf leak to where i do not ear it.

its one on the back side of the throttle body right below the throttle cable

mustangjoe02 · Nov 27, 2011

where does the other end lead to? i just want to replace the right one cuz i know those hoses back there are old

BlackArtemis · Nov 28, 2011

OK same problem here.
Installed BBK headers and catted H
Removed EGR and DPFE
used the Lethal Performance EGR block plate and header cap.
Deleted 1 red vacuum line and the green one.
Now the red vacuum goes from passenger side to plenum to fuel
Checked PCV, bearing moves w/o problem
But the PCV valve hose was collapsing. I replaced it with some heater hose from ACE and tightened it with a clamp.
Told Bama tuners I removed EGR and to account for that in my tune (no more check engine light)

But I still get a drop in RPMs from 1100 to 500. When it idle it gently goes up and down. After a rev it comes down smoothly, hits 1100 and does a sharp drop, sometimes it sounds like it will stall out.

What else can I check?
Clean MAF?
O2's were brand new and have under 500miles on them
Smoke test (how could I do this?)

thanks all

tangtang · Dec 1, 2011

BlackArtemis said:
OK same problem here.
Installed BBK headers and catted H
Removed EGR and DPFE
used the Lethal Performance EGR block plate and header cap.
Deleted 1 red vacuum line and the green one.
Now the red vacuum goes from passenger side to plenum to fuel
Checked PCV, bearing moves w/o problem
But the PCV valve hose was collapsing. I replaced it with some heater hose from ACE and tightened it with a clamp.
Told Bama tuners I removed EGR and to account for that in my tune (no more check engine light)

But I still get a drop in RPMs from 1100 to 500. When it idle it gently goes up and down. After a rev it comes down smoothly, hits 1100 and does a sharp drop, sometimes it sounds like it will stall out.

What else can I check?
Clean MAF?
O2's were brand new and have under 500miles on them
Smoke test (how could I do this?)

thanks all

ok i had to take in to account that when installed my LT BBK's i had to raise an drop the motor to get them to go into place. when doing this i pulled a vacuum line off the backside of my throttle body rite under the throttle cable where it meets the throttle body. i would check all your lines to make sure they are connected an look for any place that looks like it needs a hose connected but there isnt one. thats most likely your problem. i had the exact same symptoms. the smoke check....well i jus lit a cigarette an blew the smoke on the exhaust. if there is a leak (epecially with the way your changing RPM's) you will see the leak push the smoke away. good luck

Idle Problems After LT Header and O/R Hpipe Install

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