High RPM control from computer

[liljoe07]

Understood.

Problem with rear main leaks is it will leak more while driving than just sitting in the garage not moving. So you may be leaking more oil than you think from the Rear Main seal. If the seal is not at fault, then its a crankcase pressure problem. To much pressure will force oil out in places it shouldnt be.


Do all your plugs look good? If your burning that much oil, it will show in the plugs.

 

[Nicoleb3x3]

i don't think it's the valve seals...wouldn't that show on the vacuum tester? steady vacuum seems to imply my valves are ok?

as for the rear main...I know it's leaking...I actually think it's the last main cap itself (I didn't use rtv on it and some say you're supposed to) I guess I don't see why the sudden change in oil loss, perhaps If I can get back to driving my stang daily I can get a better idea on how much I'm losing and how often.

so...I guess back to focusing on the whine/hiss noise and probably vacuum leak....

 

[jerryD]

where the heads new or used? maybe a leakdown test could help find out if you are getting crankcase pressure build up.

 

[liljoe07]

Valve seals wont show on the gauge since if really has no effect on vaccum. But valve guides will. But its usually shown by a slighty erradic needle, or a gradual increase as the Throttle is steadily opened.

Anyways, try spraying Carb cleaner around the Lower intake sealing surfaces while the Engine is running. If the idle raises, you have a vac leak in that spot.

 

[Nicoleb3x3]

heads are spanking new...along with everything else except the block (newly machined and cleaned) and the crank was done undersize but still the original.

I tried carb cleaner already...but I may try it again by the lower intake in the front.

what causes valves to not seal all the way?

 

[Nicoleb3x3]

forgot to mention my pcv valve is spanking new...including the supporting vacuum hoses

 

[liljoe07]

Not valve sealing...LOL Valve seals are actual seals. They go under the valve springs.

Valves not sealing, could be from a bad valve job.

 

[Nicoleb3x3]

..lol ok I get it now

new heads fully assembled from AFR...my seals should be fine!

 

[liljoe07]

..lol ok I get it now

new heads fully assembled from AFR...my seals should be fine!

You should be fine. More than likely your just leaking oil more than you think you are.

Try the Carb cleaner again in front if the Intake.

If no leaks are present with the carb cleaner. Then it may be your lower intake gasket. If it doesnt seal, and is open to Crank case pressure, the vacuum can be lower.

 

[Nicoleb3x3]

I didn't have much time tonight to check stuff, but I did check my tail pipes for blue smoke...no smoke at all at idle or 2k rpm at idle- cold or warm (160)

...will have to take it out on the highway and see if my boyfriend can follow me and see if he spots anything when the engine is under load.

 

[liljoe07]

Let us know.

 

[2000xp8]

I've had this happen before, turned out to be the TPS.

 

[jrichker]

See the "Surging Idle Checklist for help with all your idle/stall problems. Everything you need to find and fix idle problems is in there.

The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

 

[67coupe]

Nicole,

Next time the idle hangs high(1200 rpm+), cut the engine off and restart. If the engine returns to a normal idle, then your issue is with the TPS circuit. The "base idle" TPS value is reset after every ignition cycle.

See jrichkers post for details on cleaning the 10 pin connectors and the TPS connector. DO NOT buy a new TPS until this is done.

 

[Nicoleb3x3]

restarting does not make it go away...the symptom is the same...idles at 1k but hangs at 1800-2200 when driving and slow to return to 1k idle when stopped.

I'm not getting a code from the tps....and it's also spanking new (last year)

 

[Nicoleb3x3]

I've been through the surging idle checklist before...fixed my tps last year

...this time it's different....not a surge at all and it idles perfectly

 

[liljoe07]

Has it always idle at 1000rpms? That cam should be in the 800 range.

A list of codes would help here. Even the ones you don't think are important. Even the Continuous Memory codes

 

[mkk50]

Do you have an aftermarket throttle body? And have you cleaned/replaced the IAC recently?

 

[jrichker]

I've been through the surging idle checklist before...fixed my tps last year

...this time it's different....not a surge at all and it idles perfectly

The "Surging Idle Checklist covers all sorts of idle problems, not just a surging idle. Check it out, the answer is probably in it..

 

[Nicoleb3x3]

SOLVED...finally

Turned out to be a vacuum leak, which is what I was supecting after all the other checking I did last year...anyways we started to actually HEAR it and spent more time searching for it.

I never expected the lower intake gasket:

gotstang.com - Hanging Idle; FIXED! by Nicoleb3x3
Somehow it slid down...no way it was like that when we installed it.
Not sure if it slid down after dropping the intake on it...or if it's because we found the lower intake bolts actually had loosened up. I can't remember if we tightened the lower after warm-up or not....course with me anything is possible.

I can't beleive I had no other symptoms...considering it was blocking part of the intake ports themselves...AND leaking inside the lifter valley...and yet it still made 280 hp...interesting- time to go back to the dyno and check how my tune was affected. The problem started days after going on the dyno.