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Topic: vacuum leak? (Read 1404 times) previous topic - next topic

vacuum leak?

mornin, just put on my new cobra intake and now my car runs like dog!! starts right up, has a high idle,and i can't turn it down, idle screw is all the way out, not responsive at all, almost like its running off a few cylinders(kind of),not smooth, definatley not driveable.

  has new plugs, wires, sensors, just wondering if ya"ll use the front and rear gaskets for your lower intake to block?? or do you fill with sealent? i used the gaskets. all my vac hoses are new and for some reason(don't know why) i fill like i have a vac leak between the lower intake and block. and i feel like it's the rear

  timing is right on, tps good, car ran great before the intake swap. anyone have any suggestions, or experiance this before?? need help, got this week off and i have to have her running before sunday. Thanks for any help

  Thank, Joe

oh yea, 88 bird w/88 HO cam,1.7 rockers, stock E6 heads, 65mm throttle body,stang headers, 2 1/2" back
88 sport,TW heads, comp xe270hr, cobra u/Tmoss ported lower, 65 mm throttle body, under drives,smog delete,
1.7 roller rockers, cai, k&n, bbk adj regulator, 76mm Pro-m,all MSD ign. MSD dist,18° base timing, 3g alt.1 5/8 ceramic headers, 255lph walbro, 2.5" h-pipe, flowmasters, silverfox valvebody, 3.73 gear,
http://i216.photobucket.com/albums/cc154/flipnbird/DSCF0185.jpg ( RIP : ( )
 

vacuum leak?

Reply #1 –
Try spraying starting fluid along the gasket to see if that momentarly smooths it out. If so you have found your leak. Or just listen for the whistling.

And on installing the lower intake, I use the intake to head gaskets but chuck the cork pieces that go between the intake and block. By using a nice good bead of RTV there it insures that the intake is sitting down on the heads nice and tight.

Have you changed anything else other then the lower and upper intake pieces?

Bryan

vacuum leak?

Reply #2 –
88 Ho cam,88 SD comp(DA1),1.7 rockers,Ho fireing order,feels almost like some plugs are fouled, but they are not, just not responsive at all. non driveable.
88 sport,TW heads, comp xe270hr, cobra u/Tmoss ported lower, 65 mm throttle body, under drives,smog delete,
1.7 roller rockers, cai, k&n, bbk adj regulator, 76mm Pro-m,all MSD ign. MSD dist,18° base timing, 3g alt.1 5/8 ceramic headers, 255lph walbro, 2.5" h-pipe, flowmasters, silverfox valvebody, 3.73 gear,
http://i216.photobucket.com/albums/cc154/flipnbird/DSCF0185.jpg ( RIP : ( )

vacuum leak?

Reply #3 –
Ummm.. Can you put all those mod's (88 Ho cam, Ho fireing order, cobra intake) and run a SD computer?

I thought it required upgrading to MAF in order to modify the engine at all.
:birdsmily:   Objects In Mirror Appear to be Loosing  :birdsmily:

vacuum leak?

Reply #4 –
Yes,you can have an H.O speed density computer.I do.I agree with checking for a vacuum leak.Perhaps your TPS?
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

vacuum leak?

Reply #5 –
I would guess that you are close enough to stock to run the SD computer but you just might have just gone over the edge. With improved intake and exhaust you may be flowing more then it can handle causing the fuel maps to be wrong. Hard to say especially with the E6 heads as they are not known for their real good flow.

I would do a real good check of everything you just did and make sure no vacuum lines are cracked or loose and everthing is hooked up properly. Also run a scan toll on it and see if it kicks you any codes. If all checks out them I would be thinking it may be just too much for that computer. Best way to tell is to do the conversion to MAF. Or you could go back to your old intake just for a test to see if it solves your problem. If so, I am thinking the SD can not handle the Cobra intake with headers and 1.7 rockers.

Bryan

vacuum leak?

Reply #6 –
My first guess would be that the rear gasket shifted some when you installed the manifold therefore you didn't get a great seal.

That or the gasket is fine, but there is a leak between the thin gasket that runs along the back of the motor and the gaskets that go between the heads and the manifold.

I use the gaskets and also put a little gasket maker/sealant on. That helps hold the gaskets in place and when dries creates an air tight seal.

vacuum leak?

Reply #7 –
gotter fixed!! my son helped me and when he put my rockers on he had one of the rockers on wrong(the roller that the stud goes through was upside down),part my falt to for not double checking.

  anyway she is running but i can't get my idle to come down below 1200, idle screw is all the way out, checked tps, can't hear any vac leaks, gonna try the  starting fluid trick, any suggestions??
  Thanks, Joe
88 sport,TW heads, comp xe270hr, cobra u/Tmoss ported lower, 65 mm throttle body, under drives,smog delete,
1.7 roller rockers, cai, k&n, bbk adj regulator, 76mm Pro-m,all MSD ign. MSD dist,18° base timing, 3g alt.1 5/8 ceramic headers, 255lph walbro, 2.5" h-pipe, flowmasters, silverfox valvebody, 3.73 gear,
http://i216.photobucket.com/albums/cc154/flipnbird/DSCF0185.jpg ( RIP : ( )

vacuum leak?

Reply #8 –
check that the iac is clean that will cause idle problems

vacuum leak?

Reply #9 –
took off my lower intake and resealed everything, still a high idle(12-1500)took my tps off and the little shaft that goes up into the tps don't even stick out of the throttle body a 1/16 of an inch , so it don't even go into the tps (got the body off ebay and it was a 60mm and they bored it to a 65mm). my old one stuck out 1/4 inch or so, i am thinking then the tps isn't even doin anything, plus it was kinda F'd up also. i would try my 60mm throttle body but i can't get it loose from the intake. so you think this could keep my idle from coming down?? my iac is clean and sealed also
  Thanks for any input, Joe
88 sport,TW heads, comp xe270hr, cobra u/Tmoss ported lower, 65 mm throttle body, under drives,smog delete,
1.7 roller rockers, cai, k&n, bbk adj regulator, 76mm Pro-m,all MSD ign. MSD dist,18° base timing, 3g alt.1 5/8 ceramic headers, 255lph walbro, 2.5" h-pipe, flowmasters, silverfox valvebody, 3.73 gear,
http://i216.photobucket.com/albums/cc154/flipnbird/DSCF0185.jpg ( RIP : ( )

vacuum leak?

Reply #10 –
she's totally fixed and runs strong!! the throttle body i bought off ebay was the problem, the guy had it honed out to a 65mm(60 originally) and he home made the butterfly for it so it wasn't the greatest circle, plus where the shaft comes up for the TPS didn't hardly stick out the body.
  bought me a new one off summit(sum-22703, nice to)and presto, works great!! really nice piece for the money. i like how you can adjust the tps without undoing the tps itself.anyway my car is running and running good.
  Thanks for all the help,Joe

will try to get some pics of the whole car in a few days if someone would like to post them for me.
88 sport,TW heads, comp xe270hr, cobra u/Tmoss ported lower, 65 mm throttle body, under drives,smog delete,
1.7 roller rockers, cai, k&n, bbk adj regulator, 76mm Pro-m,all MSD ign. MSD dist,18° base timing, 3g alt.1 5/8 ceramic headers, 255lph walbro, 2.5" h-pipe, flowmasters, silverfox valvebody, 3.73 gear,
http://i216.photobucket.com/albums/cc154/flipnbird/DSCF0185.jpg ( RIP : ( )