Need troubleshooting help - vacuum leak

[grandwazoo]

O.k. hoping for some help.

I acquired my GN a few months ago, a beautiful 1987 beast of a machine. Unsure the details of many of the mods, but it's my baby and I am doing my best to figure out exactly what was done to her before she came into my life. I know it has a modified turbo, and a larger cam.

I just installed a Magnaflow 3 inch performance catilytic converter and I am about to do an exhaust rebuild, but first I need to get it licensed, my temp tags are expiring, and to continue working on it, I'll need to at least drive it on the street!!!

The problem is that when you are driving, say doing 35 mph, and you let completely off the gas, from time to time, the engine will die. I have been told this is symtomatic of a vacuum leak. I have learned to live with it, by goosing the gas after letting off. But the drones at the emmissions testing center will not or cannot do this, and therefore the car is unable to complete emmissions testing.

I am not a mechanic, but I have vowed to do all work on this car myself, I've overhauled the brakes, new suspension, installed airbags, plugs, wires and all filters, set the timing, etc. but this problem existed before any of this work was done, so I am not to blame.

Can someone give me tips on finding the source of my vaccum leek, step-by-step guidance would be greatly appreciated!!! Despite being in my 30's, I'm still learning, and this is my first project car. (prior to this I owned newer Firebirds, Formula's but never a Turbo or anything I could work on.

Thanks in advance for your help

 

[progress1vebmx]

What part of Saint Louis do you live in?

To find the vacuum leak, use the diagram of all the vacuum lines and spray wd40 or some sort of water on the vacuum hoses, it'll bubble up and suck it in.

I know some people with this problem and it was the MAF. Might wanna turn the car on, tap on the MAF and if the car functions differently, you have a bad MAF. Sometimes that test does not work though....

 

[grandwazoo]

I'm in South City, near Tower Grove Park.

Thanks for the tip on the MAF. I'll give that a check in the morning, that and the soapy water test.

 

[progress1vebmx]

Cool.

There is a club for our cars in STL. Meet every few Sundays at GM automotive... Check the midwest section for details. I have yet to go, I work on Sundays

 

[MistaScott]

Buy a MityVac for about $25 and test all the lines. That is the only sure way to find a leak. It's a great tool, available at Sears and Autozone.

 

[grandwazoo]

Well, found no leaks.
But I think I will attempt to try the emissions test again tomorrow.

I tested/tightened/secured all vacuum hoses, then I bumped up the idle a bit, this seems to stop it from dying when I let off the gas quickly.

The odd thing, is with my close inspection of the engine compartment, I found a few electrical hook up clips that are completely disconnected, and an open vacuum hose inlet that has no hose going to it.

I know the road back for this car will be a long one, the previous owner played a little fast and loose with the modifications. Not saying he was wrong, but there are several things I wish were either not done or at least documented somewhere.

Oh well wish me luck on my emissions test.

 

[V6POWER]

When you say you 'set the timing', are you referring to adjusting the cam position sensor?