HELP!!! No vacuum after head and intake swap.....

[1bad92lx]

I just finished a head and intake swap and now the car has no vacuum and will hardly run. I have to keep giving it gas to keep it running. If you hold the gas pedal at a constant spot then the rpms go up and then down repeatedly. I'm running a holley systemax intake with performer rpm heads. I have an autometer vacuum/boost gauge and it's reading 0 at idle and barely moves when I give it gas. The car also has a Novi 1000 on it. Any suggestions or comments? I barely got the car from the shop to my house.

thanks,

Matt

 

[dastang2]

do a compression test, i think you need to shim your rockers or check the pushrod lengths with the new heads. something like this happened to me and i shimmed the rockers and they work great. i got a shim kit if you wanna buy or trade

 

[1bad92lx]

I've got stud mount rockers and I have the right length pushrods. When I first started the car I had about 10lbs of vacuum at idle and after about 20 or so minutes of letting it run it started to get less and less. The rockers are adjusted right. I already readjusted them just in case I had one or two that might have been too tight. I'm wondering if its an intake gasket problem? It run okay at wot last night and after a while it got worse and worse. The car is not smoking at all. The air/fuel gauge keeps reading extremely lean and that could be a sign of a big vacuum leak I would think. But the exhaust smells rich. It is also popping through the intake at idle no matter where the timing is set at. It's really confusing me. Any more ideas..........?

 

[Black1987Stang]

Maybe a vacuum leak, try pulling codes?, i was gonna say wrong rocker adjustment but seems like u did them right. ....Ive had the same problem when i held it at an rpm and it would just start revving up to like 4k and down to like 1k or something....that was when my battery was going out and my lifters were bad too but my main problem from that was my maf was bad, check ur maf, clean it whatever and try a visual check make sure everythings hooked up. my vote is the maf

 

[jrichker]

If someone else did the work & you paid for it, take it back & tell them to fix it... for free...

If you did the work yourself, then, here are some resources:

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/

You'll probably need to remove the upper manifold to do the next step. It will give you the
opportunity to check the torque on the lower manifold bolts and the vacuum hose routing
while you are at it. See http://www.veryuseful.com/mustang/tech/engine/images/FordIntakeTorqueSequence.gif
for the lower manifold bolt torque squence

To set stud mount rockers, follow the following procedure. Start the car and get the engine
warm if possible. Then shut it off and pull both valve covers off and start the engine. Then
back each valve adjustment off until the valve clatters. Then tighten down until it stops
clattering and SLOWLY turn 3/4 tun more and set the lock, if it has one. Repeat the process
until you have done all the valves.

You will have a big mess to clean up because oil will squirt everywhere, but the valves will be
set precisely where they should be. Don't do it in your drive or on the lawn, the oil will
make a mess.

 

[1bad92lx]

I was wondering if maybe I have an intake leak at maybe the front or the back of the intake where I used silicone. The car did perfect for over 30 minutes of letting it idle and just playing with the fuel pressure and timing. Then the car started missing and cutting off. Thats when I lost most if not all of the vacuum. My brakes wouldn't work and the air/fuel was reading extremely lean. While I was driving it home the car was surging real bad at 2,000 rpms and unless you put the pedal to the floor it wouldn't clear up. I have went over all the vacuum lines about 10 times this morning and replaced all of them and made sure they were all tight. And there was no change whatsoever. It's still popping through the air filter and has 0 vacuum at idle. When you give it gas it will rev up and stay high for a couple seconds and then it will come back down. I'm really thinking that I might have an intake leak now. Thanks for the diagriam Jrichker. I have no smog pump so that vacuum line is gone.
I have:
fuel pressure regulator to the intake.
The S from the vacuum log on the firewall to the intake
The smog canister is tee'd into the pcv valve line and is running to the intake.
And the Egr valve vacuum is hooked up and the black plastic line from the vacuum bundle is hooked to the intake.

Thats the only way I know to have the vacuum lines. They are all new and all are tight. I am scared I have an intake leak.

 

[Grn92LX]

You definatly have a vacuum leak. Big vacuum leaks = a lean condition hence your popping through the intake. I had that problem when I first got my 347 running. I ended up having a leak at the lower to head and I also forgot to plug one of the many vacuum ports on the upper manifold.

Spray carb cleaner around suspected area's especially around the lower manifold to head. I have a wideband and we were watching it as we sprayed carb cleaner and when we hit vacuum leaks you can see the a/f change

I was making like 2-3" of vacuum at idle, car drove like dog shiit bucking and stuff and the brakes sucked. Now I make appx 10" at idle.

 

[1bad92lx]

Ok thanks for seconding my notion of it being the intake. The car pulled so hard last night at WOT until this leak developed, I can't wait to get this thing fixed. I remember that I didn't make as much of a bead at the front and back of the intake as I usually do. I was really rushing to get the car out of the shop before today. I think I might try the carb cleaner trick tomorrow and see what happens. Was yours leaking at the front and back or at the actual mating spot from the intake to the heads? What did you do to fix it? My forgetting the correct torque sequence might have had something to do with it too. I'm so mad because I know what the car will run like when it's fixed and I can't wait to find the culprit. My car at idle is actually reading dead on the 0 right now, so I know I got a BIG leak. Thanks

 

[Grn92LX]

Mine leaked from where it meets the heads. The main leak was the 1/8" npt plug I forgot to put in on the upper manifold. All I did for the lower manifold was retorque it. I would loosen every bolt a little and go through the sequence again. Keep going until the tq wrench just clicks. When I first installed the lower I kept going around the tq sequence until the wrench just clicked on 22 ft/lbs.

I wouldn't be going WOT getting into boost just yet knowing you have a lean issue due to a vacuum leak. I know it must be tempting though.

Here, this link has the proper tq sequence for the manifold and other stuff-

http://www.hardcore50.com/technical_articles/cleances&torque_specs.htm

 

[1bad92lx]

Yeah I shouldn't have floored it just yet, but the car was getting on my nerves with this leak. I wonder if I should just take the upper and lower off and replace the lower gaskets with new ones and silicone the crap out of them. I made sure to use both pipe plugs on the upper and lower and I sealed them with lots of thread tape so I shouldn't have a leak there. The fact that it run perfect for 30-45 minutes and then all of a sudden started dying really gets me. I would think that if the gaskets were to leak they would have done it on startup also. I don't know. I just know that it got worse as I drove it.

 

[Black1987Stang]

I had the same problem somewhat...I had replaced my lifters, started her up ran pretty good, took it around the block etc. after 20 minutes it started bugging out, as long as i was accelerating it was OK but if the motor was at idle or had no load it was soo screwy...and my vacuum was changing from like 3 to like 10 somehow ...i had disconnected the battery for 20 minutes and it worked awesome for a few start ups then went back to being like before and was going back and forth for a while...put a different mass air flow sensor on and it was perfect...im still wondering how the maf was changing the vacuum , but that was my culprit anyways

 

[1bad92lx]

I just sprayed carb cleaner around everything in hopes of finding a leak and it didn't do anything at all. I sprayed directly where the lower intake meets the heads and it seemed as if the idle raised whenever it wanted to without any relation to where I was spraying. I guess the next step is to pull the upper and lower and put new gaskets on and use the correct torque sequence and see what happens. I just hate to start pulling everything back apart so soon. It's still reading 0 vacuum at idle. And the rpms will hang up high if I give it any gas at all. It will maintain a very rough and erratic idle but it's still pulling 0 vacuum. I just wanna figure this thing out. Any more suggestions?

 

[HISSIN50]

One can:

disconnect all vac fittings to the intake and plug them, except one. On this one fitting, install a vac gauge.

Disable the fuel system and the ignition, and crank the motor. Look for 3-6" of vac while cranking.
If the gauge reads zero, recheck that the intake's bungs are all sealed and try again. If still no vac reading at the gauge, that suggests a mating surface/housing leak (assuming everything under the valve covers is good-to-go).

Good luck.

 

[dastang2]

you would hear the vacuum leak of that size for sure, i still don't think it is a vacuum leak.

 

[Black1987Stang]

you would hear the vacuum leak of that size for sure, i still don't think it is a vacuum leak.

Hisson's idea is a good idea, try that and go from there.

I agree with dastang too, i dont think its a vacuum leak either, I forget did u try pulling codes?

 

[TomCat]

I remember some guy on here had a bad leak and he just covered the TB opening with his hand. I guess it might start sucking through the leak really hard and you'll be able to hear it.

Good luck!

 

[1bad92lx]

Guys I think I have some blown head gaskets. The plugs fouled out and I have went over everything. I retorqued the lower intake and sprayed carb cleaner on everything in sight searching for a vacuum leak and found nothing. I think that I ran way too much timing when I first got it running saturday and when I put my heavy right foot down all the way, that I blew the head gaskets. After I backed the timing down, I believe it was too late. I'm ordering some more head gaskets tomorrow and tearing it back down this weekend.

 

[jrichker]

Borrow or buy a compression tester before going through all the effort to change the head gaskets.

 

[dastang2]

ditto, you got water in the oil

 

[1bad92lx]

I've got a snapon compression gauge and the 14mm extension for it won't tighten all the way down on my heads. When I cranked it over I got about 65lbs of pressure and that's it. Either the gasket is blown or the gauge was leaking. I unplugged the mass air meter and it didn't make any difference. I have went over everything. I've checked every vacuum source, every electrical connection. The fact that the car did run perfect for almost an hour until I put my foot in it with WAY too much timing makes me think I've killed the head gaskets. Theres really nothing else it could be that would make it do what it's doing. I put new plugs in it last night and all of them except for two were drenched in fuel. I tried to restart the car after the new plugs and it still wouldn't run any better. I know I have got to have a big time gasket leak. I'm going to tear it down this weekend and check it out real good. And there is no water in the oil. That would only happen if the gasket leaks towards a water passage. You can blow them from cylinder to cylinder and not get any water in your oil. I know from experience. My ex g/f blew a head gasket on my 92 when she kept driving through traffic without the electric fans on and there was no water in the oil.