Engine suspected lower intake leak into the lifter valley... any tests to confirm out there?

[Blucifer99]

i suspect i have a lower intake leak in the lifter valley.. i just replaced my whole top end . the car was running decent, but slowly a few problems have popped up.. which were probably present the whole time but ive been tuning my car with megasquirt and i belive my idle advance was masking this problem.. because if i shut off my idle advance the car idles high on start up, this is why i suspect its a leak somewhere

cars pulling steady 12inches of vac (60map) at 825rpm and 15 degrees timing.. trickflow stage one cam,,
tests ive done so far is blocking the pcv to see if theres vaccum in the engine, there is vac when the pcv is hooked up but nothing when its blocked off very Minimal blowby, ive also done the carb cleaner spray all over the top side to make sure its not leaking there which its not.. Ive checked my oring seals on my injectors by using a eye dropper with oil on the oil rings to see if it sucked in,and they're all sealed. front and rear of the lower intake isnt showing any signs of coolant leaks or oil leaks. theres no coolant in the oil either. Plugs are new and have barely 150kms on them so they arnt much help showing any signs. theres no oil smell or coolant smell from the exhaust either, also no smoke. i have done a smoke test which showed the egr diaphram was leaking so i blocked that off... also im not running any emissions stuff so thats not hooked up and half of the vac lines are not in use or hooked up.

so if theres any other tests that you might know about Im all ears before i go tearing the lower off to see..

 

[Mustang5L5]

Smoke machine. Build one

 

[jrichker]

Vacuum leak due to slipped lower intake manifold gasket...

Ask Nicoleb3x3 about the intake gasket that slipped out of place and caused idle and vacuum leak problems that could not be seen or found by external examination. I don't care what you spray with, you won't find the leak when it is sucking air from the lifter valley. It simply isn't possible to spray anything in there with the lower manifold bolted in place.

Determining if you have a leak due to a slipped intake gasket as shown above. This test is only good if you can get the engine to run somewhere in the 1000-1700 RPM range
If your valve cover oil filler & PVC systems are still in the original configuration, try this:
Cap or plug the hose from the intake manifold to the PVC valve with a bolt.
Cap or plug the PVC valve with a piece of hose with a plug or bolt in it.
At that point the only vent for the crankcase is the tube from the oil filler neck to the throttle body.

Disconnect the tube that runs from the oil filler neck to the throttle body. Make sure the oil filler cap is on securely. Start the engine and put your thumb over the end of the tube that comes from the oil filler cap. If you feel suction, there is a leak. Another thing to do is to extend the tubing from the filler neck so that there is enough to stick the end in a jar or cup filled with motor oil. If it sucks up the oil, you definitely have a leak at the underside of intake manifold.

This isn't necessarily the definitive test, but it is the best thing I could come up with on short notice. If there is a lot of blowby, this obviously won't be of much help.

See the picture below to see the breather tube where in connects to the throttle body. It is close to the TPS and runs over the top of the IAC.

The following are diagrams courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout

http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

 

[Blucifer99]

Smoke machine. Build one

I guess you didnt read my whole post. It says i already did that. Nothing else is leaking besides the egr diaphram.. I made my own smoke machine with a 2l bottle and used a cigarette. No visable smoke.

 

[Blucifer99]

Vacuum leak due to slipped lower intake manifold gasket...

Ask Nicoleb3x3 about the intake gasket that slipped out of place and caused idle and vacuum leak problems that could not be seen or found by external examination. I don't care what you spray with, you won't find the leak when it is sucking air from the lifter valley. It simply isn't possible to spray anything in there with the lower manifold bolted in place.

Determining if you have a leak due to a slipped intake gasket as shown above. This test is only good if you can get the engine to run somewhere in the 1000-1700 RPM range
If your valve cover oil filler & PVC systems are still in the original configuration, try this:
Cap or plug the hose from the intake manifold to the PVC valve with a bolt.
Cap or plug the PVC valve with a piece of hose with a plug or bolt in it.
At that point the only vent for the crankcase is the tube from the oil filler neck to the throttle body.

Disconnect the tube that runs from the oil filler neck to the throttle body. Make sure the oil filler cap is on securely. Start the engine and put your thumb over the end of the tube that comes from the oil filler cap. If you feel suction, there is a leak. Another thing to do is to extend the tubing from the filler neck so that there is enough to stick the end in a jar or cup filled with motor oil. If it sucks up the oil, you definitely have a leak at the underside of intake manifold.

This isn't necessarily the definitive test, but it is the best thing I could come up with on short notice. If there is a lot of blowby, this obviously won't be of much help.

See the picture below to see the breather tube where in connects to the throttle body. It is close to the TPS and runs over the top of the IAC.

The following are diagrams courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout

http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Also. Yesturday i tried your little test of blocking the pcv valve off and capping the port on the intake for the pcv valve. There was no suction in the throttle body tube that goez to the oil filler neck. I even gave it throttle to see if it would have suction. And it had zero suction at the throttle body tube...

 

[a91what]

Is the map signal steady at 1k rpm?

 

[Blucifer99]

Is the map signal steady at 1k rpm?

Pretty steady. Fluctuation between 59.3-60.1. On cold start. But like 10seconds after started its steady at 59.8- 60kpa. Its just my idle advance kicks in soon as i start it.. So i added a 5 second delay to see what it would do. And it reved up to like 1300ish then fell off quickly to cold idle. Didnt hang or nothing. And i havnt moved the cranking duty steps from what it was originally set at.. the only thing that caught my attention was i had vaccuum in the crankcase with the pvc hooked up... zero vac with it unhooked.. but then again the cobra intake has 2 pcv hoses in the upper.. so double the sucking force.. but if i block the pcv theres zero vac in the crankcase.. tiny bit of blowby thats barely noticable... im just tryin to rule stuff out before i get pissed of enough to pull the lower.

 

[Blucifer99]

i think ive found my problem.. after looking at all my tunes from may 3rd up till now ive noticed duty steps were changed when we did the class... 44% was gettin me 1200rpm on startup when i was using closed loop pid.. but since we changed it to manual.. we bumped it up to 56%.. and 56% is reving way to high on startup. making it seem like i had a vac leak and it was reving up because of it.. which isnt the case.. the 56% was overiding the idle advance from stopping the revs climbing on startup with more air being added.. so hopefully if i change my Kpa activation to say 42kpa and add a delay of 1second it should stop the problem im having... considering im idling at 1000 when cold.. and at 1200 and 43kpa thats about 1kpa higher then my startup revs.. so im gonna try that out and see what happens, i hope this makes sense lol

 

[a91what]

On what table? Overshooting rpms on startup look at the cranking duty% alter this in 5% steps first.

 

[Blucifer99]

On what table? Overshooting rpms on startup look at the cranking duty% alter this in 5% steps first.

well what im talking about is that my cranking duty steps were high enough (56%cranking duty) for the idle advance to see a false load on the motor on start up.. so it was making the idle advance remove -4degrees on cold startup.. thats even with a delay added of 1 sec.. when i added a delay of 3 seconds.. the car started and reved up to 1300 and the revs fell down to about 1080 and then idle advance kicked in.. thats why i originally thought it was a lower intake leak or something,. until i noticed that in my previous tunes before our class that my car was starting just fine with a cranking duty % of 44 cold and with closed loop idle PID on instead of manual.. but before i tried to lower the cranking duty and the car would struggle to start because the idle advance would see the load and pull 4degrees.
ever since we changed it to manual. my cold starts have been a problem. but ive been slowly gettin it narrowed down to whats causin it. and to me its to high of a cranking%duty and a super sensitive idle advance settings, so tomorrow i may just add a clt temp condition of 80* and set the cranking duty to 44. and see how it acts. cause the cold start issue is my only issue. im just glad ive kind of ruled out a dam vaccuum leak. cause ive had it with chasing those dam problems. lol

 

[a91what]

Not everyone car responds well to idle advance when they're cold all you can do is a just a temperature setting to stop the idle advance from occurring when the vehicle is cold I haven't looked at the data logs you posted but I'm assuming the issue that you're having is that the rpm overshoots its value that you're looking for and then sharply drops past what you want You could lengthen your run start taper time as well. Don't adjust any load parameters In the idle advance that's also going to affect its activate when the car's hot the time delay you put in is also going to affect it when it's hot you'll have to see how the car likes that once it's full warm. If this issue is only occurring at a full cold start then said the temperature value to something in between cold and hot you could try a temperature of 120 to 140 and see if that fixes the problem that you're having then adjust your cranking duty percentage. This is the fun part about tuning a cold start You only get one chance a day to get it right

 

[kjohnson1]

baby oil works better for a smoke machine. I poke a hole in an empty spray paint can, add oil..then heat. Through a second hole I attach a hose.

 

[Blucifer99]

baby oil works better for a smoke machine. I poke a hole in an empty spray paint can, add oil..then heat. Through a second hole I attach a hose.

Yea but a lower intake leak in the lifter area wont really show up during a smoke test. Unless u block off every passage on the engine. Including open valves to see if the smoke comes out the oil fill hole.. Basically the only way to find it is. Burning coolant. Burning oil. High map reading or low vaccuum reading.. Im just gonna probably pull the lower and quit guessing lmfao. The joys of owning and workin on foxes..

 

[Blucifer99]

Yea but a lower intake leak in the lifter area wont really show up during a smoke test. Unless u block off every passage on the engine. Including open valves to see if the smoke comes out the oil fill hole.. Basically the only way to find it is. Burning coolant. Burning oil. High map reading or low vaccuum reading.. Im just gonna probably pull the lower and quit guessing lmfao. The joys of owning and workin on foxes..

Well alil update.. Took the lower off. And it was definitly leakin in the lifter valley. Oil up the gaskets on a few cylinders. It seems some of my intake studs bottomed out when i torqued them aswell. So they tweaked the gaskets. my valves seemed to be out of spec too. 3 lifters werent pumped up.. So that explains the low map and ty driveability and stallings.. So new gaskets tomorrow and back at it ill be

 

[a91what]

that sucks keep at it you'll get it figured out.

 

[Blucifer99]

that sucks keep at it you'll get it figured out.

Hey steve. I dropped my dizzy in and it lined right up. Maybe a .5 difference from what i had before. So can i just warm the car up and fix timing to 20. Then adjust the dizzy to match 20. Instead of messing with the offset? Basically like we did before?

 

[a91what]

yup

 

[Blucifer99]

yup

K so ive got it to matching 20.. But for some reason it stays on 20 for a min. Then surges up and down. Is that the idle advance causing that u think? Seems like it holds good. Then jumps alittle. Then falls and then levels back at 20.. Just seems weird it dont hold steady. But im pullin a steady 58 map at 825rpm and 190temps.. So im seeing a improvement from before. Plus it does sound alot better. Has the thump back for sure

 

[Blucifer99]

yup

So i gather i had quite a big vacuum leak.. Before i was running inbetween a 13.9-14.3afr hot idle , pulsewidth of 4ms and 33idle valve value. And now at full hot im running at 13.2-13.6afr, pulsewidth of 3.8ms and a 26idle valve value. I didnt change nothin in the tune either so it Looks like im gonna have alot of work to do gettin back to a decent table again..

 

[Ptstew]

Vacuum leak due to slipped lower intake manifold gasket...

Ask Nicoleb3x3 about the intake gasket that slipped out of place and caused idle and vacuum leak problems that could not be seen or found by external examination. I don't care what you spray with, you won't find the leak when it is sucking air from the lifter valley. It simply isn't possible to spray anything in there with the lower manifold bolted in place.

Determining if you have a leak due to a slipped intake gasket as shown above. This test is only good if you can get the engine to run somewhere in the 1000-1700 RPM range
If your valve cover oil filler & PVC systems are still in the original configuration, try this:
Cap or plug the hose from the intake manifold to the PVC valve with a bolt.
Cap or plug the PVC valve with a piece of hose with a plug or bolt in it.
At that point the only vent for the crankcase is the tube from the oil filler neck to the throttle body.

Disconnect the tube that runs from the oil filler neck to the throttle body. Make sure the oil filler cap is on securely. Start the engine and put your thumb over the end of the tube that comes from the oil filler cap. If you feel suction, there is a leak. Another thing to do is to extend the tubing from the filler neck so that there is enough to stick the end in a jar or cup filled with motor oil. If it sucks up the oil, you definitely have a leak at the underside of intake manifold.

This isn't necessarily the definitive test, but it is the best thing I could come up with on short notice. If there is a lot of blowby, this obviously won't be of much help.

See the picture below to see the breather tube where in connects to the throttle body. It is close to the TPS and runs over the top of the IAC.

The following are diagrams courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout

http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

I am trying to source Qt/600 mile oil consumption in a newly rebuilt engine using a BluePrint 302 long block. I ran this test to check for a sucking intake leak. I get several psi pressure. Is that normal?
PCV is dry and compression is 132 to 144. Engine idles smoothly at 750rpm and pulls strong but smokes from both sides when goosing at idle. What would be a good test for valve seals?
Thanks