Pirate air leak (Arrgggggg)

[7thousandpiecesMGTE]

setup: fully rebuilt 7m, t61 turbo, stock 440cc injectors, afpr, walbro, 6 lbs of boost, 2.5" hardpipes, spearco replica, custom intake pipe, external wastegate, open dump tube, 3" back.

Car has been running with a very high idle, did some break in runs and drove it for a bit to try and seat the rings before hunting down the idle issue. Drives great, boosts well (too well, hits fuel cut for various reasons).

Starts up at about 1700 rpms, gradually drops to about 1100ish rpms steady after fully warm. Vacuum is about 14inhg steady at this rpm. No loping or vacuum . When engine is cut off the ISCV tick tocks. Due to the gradual reduced rpms during warmup I think the ISCV works.

Cant set base timing yet as the motor will not idle at 650. Tried to check for vacuum leaks with starter fluid with no luck. Then I plugged all ports into the intake manifold: ISCV, PCV, brake booster line, boost gage line on the back, and the port on the front that supplies a vacuum tree. The damn motor still runs... and actually pretty close to where it should be around 600-700 rpms.

So I have a pirate on board!

My question is what is the best course of action to take next? The leak must be in only a few places:

tb/intake mani gasket, iscv gasket, egr, upper intake to lower, lower intake to head. Like I said I sprayed the shit out of the manifold with no increased idle.... if there can be another pirate air leak location please let me know.

Should I just disassemble the whole intake side and start over piece by piece?

 

[hvyman]

Have you tried setting the cps to 10*btdc?

 

[7thousandpiecesMGTE]

Cant set timing (correctly) until I fix the vacuum leak.... the cps is inserted correctly with the crank at 0 and cams at 0 but i cant set timing to 10° btdc until it idles at 650

 

[IJ.]

Spray some "aerostart" around the intake with it running and note any change in RPM.

 

[7thousandpiecesMGTE]

I did this with almost a half a can and could not hear the idle increase....

 

[IJ.]

Hose for the Pwr steer idle up connected?

 

[7thousandpiecesMGTE]

Hose for the Pwr steer idle up connected?

Yes sir it is but as stated above I plugged ALL ports to the intake manifold, every single one, trying to choke it to death and it wouldnt die....

 

[Jimbo]

Try plugging one port at a time and see which one makes a difference.

 

[IJ.]

Might just be a timing issue Andrew.....

If it's running advanced it's going to idle fast, any codes?

 

[7thousandpiecesMGTE]

I plugged them all at the same time, trying to choke the motor down but it didnt die. The leak is on the manifold itself as I have isolated all hoses and connections outside of the intake manifold out of the picture.

---------- Post added at 03:36 PM ---------- Previous post was at 03:33 PM ----------

only code is code 31 (afm) which is odd becuase it ran fine. I did spray starter fluid into the filter.... i hope i didnt hurt the afm by doing this.

Ian, shouldnt the motor die if I cut all of its air supplies to to cylinders off?

 

[hvyman]

Usually vacuum leaks wont raise the idles 300rpms+ and idle smoothly. More of a lopey.

Try adjusting the cps and see if the idle changes.(with te1 and e1 jumped.)

How are your idle screw and tps set?

 

[IJ.]

Try running it with the AFM unplugged and see what it does.

Have a look at the TB blade.

 

[7thousandpiecesMGTE]

I can move the cps up and down with t1 and e1 jumped and rpms fluctuate when i do this but it still doesn't get to 650 rpms. The tb screw is not a factor as i have an 89+ tb and its not on there ( I meant to mention that in the first post).


Ian I have thought about the tb blade (I looked and the throttle cable linkage but it is too loose, not tight enough to hold it slightly open, but I will inspect the tb blade itself. And try running it with the AFM unplugged.

 

[hvyman]

I wasnt talking about the air screw but the one on the linkage. That air screw shouldn't be touched with.

 

[7thousandpiecesMGTE]

I wasnt talking about the air screw but the one on the linkage. That air screw shouldn't be touched with.

Exactly, I just misunderstood you. I did look at the linkage, and its not keeping the tb open.

 

[hvyman]

Is the tps adjusted correctly?

 

[7thousandpiecesMGTE]

yes, per tsrm with ohm meter and feeler gage. and its new. I get a code 51 when i tap on the gas idle contacts are good. also the tems engage with WOT

 

[3p141592654]

Check the throttle plate first. It should be fully closed. There is a screw on the 87-88s that can keep it open.

 

[7thousandpiecesMGTE]

Check the throttle plate first. It should be fully closed. There is a screw on the 87-88s that can keep it open.

will check throttle plate. I have an 89 + tb with no adjustment screw.

 

[hvyman]

Try backing the tps down by hand. That can raise idle as well. If you get it down some you should be able to adjust the rest with the cps.