Engine/Transmission (1994 - 1998) OK to drive w/AFC cover off?

[barngal6]

I'm trouble shootiing a low boost, low power no smoke issue



I/m looking for a leak, I suspect the AFC diaphragm is the problem or at least part of it



I saw this post--is this safe to try?



'You can test it by taking the AFC off. Cover up the hole to keep oil from flying out of it and go for a test drive. If the AFC was the problem it will go pretty good and smoke like a wildfire:[

 

[hsmith]

Probably so for a short test drive. Never have done it though. No oil pressure there but will splash I would think. Cover the hole somehow.

 

[champspa]

Oh not for me , to much dirt stirred up under that hood for me to take a chance like that. get a vacuum pump and check the diaphragm.

 

[barngal6]

Oh not for me , to much dirt stirred up under that hood for me to take a chance like that. get a vacuum pump and check the diaphragm.

OK, I've got a small vacuum pump kit,

can you point me to directions?



I thought the boost lines were pressure not vacuum,

how do I test the diaphram?

thanks

 

[kenny61]

OK, I've got a small vacuum pump kit,

can you point me to directions?



I thought the boost lines were pressure not vacuum,

how do I test the diaphram?

thanks

just put a little vacum on it and see if the gauge holds. On my 96 the waste gate diaghphram went and it resulted in the truck running like crap all the boost would leak out so the afc would not fuel the motor

 

[champspa]

Ok , Kenny's got the lead, do like he says if it doesn't leak that's not it

 

[barngal6]

just put a little vacum on it and see if the gauge holds. On my 96 the waste gate diaghphram went and it resulted in the truck running like crap all the boost would leak out so the afc would not fuel the motor

I



Put a llittle vacuum where exactly?

I'm installing the boost elbow where it comes out of the AFC housing

But I can't use that because it has a presure release. right?



I was hoping not to take the AFC off one more time. .



Sorry, I can turn a wrench (well, learning) but I know nothing, and woiuldn't do anything myserlf if it wasn't for this forum. So far everything has turned out, sometimes painfully though.

Thanks a lot for your patience

 

[kenny61]

Dont need to take the cover off. If I remember right on my 96 the boost came off of the manifold and then teed to the afc and wastegate. you can either test both afc and wastegate at the same time by disconecting the mainfold or test each one individually by hooking to either side of the tee. waste gate was easy as it was just a slip on hose I cant remember afc

 

[barngal6]

My vacuum pump measures inches HG,
not how its usually measured
It held to 20 inches, then I stopped because I wasn't sure how much vacuum is the right amount...
Should I go to 30 with this gauge?
thanks

 

[kenny61]

As long as its holding its probably ok If it was torn it wouldn't hold

 

[hsmith]

20 inches HG is pretty good vacuum. If it holds that it probably is ok.

 

[barngal6]

So should I disconnect the ferrlule at the manifold, to test the line going back to the AFC?



I'll have to block the boost elbow somehow, which will be a pain. .



It was kinda hard to get on, limited space, but guess I could put the old barb back on and plug it. .



is this the best way to go? I'm trying to test the afc diaphragm

 

[kenny61]

i'm sorry but I just cant remember the exact set up. If you want to test just the afc you can plug the line going to the afc put a bolt or golf tee in the ruber house actually you cant because of the new barb you put on. If you can just disconect the line that goes to the afc and test it from there

 

[barngal6]

Sorry for Whining

Cowgirl'd up



Plugged the the afc to wastegate



Disconnected the boost line from manifold, and vacuum tested that line to AFC

Doesnt hold vacuum and it should have, right?



then I would have a leak in the line between the manifold and the afc,

-OR the afc isn't holding vacuum, which would be the diaphram?



i

 

[kenny61]

YES YOU HAVE A LEAK SOMEWHERE BETWEEN THE VACUM PUMP AND THE AFC DIAPHRAM. YOU DID BY PASS THE BOOST ELBOW CORRECT? dON'T WORRY BOUT THE WHINING ILL BE SITTIN AT THIS COMPUTER TIL 7AM

 

[Bob4x4]

Most 12v's will still have a hard plastic line to feed the afc. They can crack and leak. I have also come across some that have been on and off a few too many times with missing ferrules. A leaking diaphram is less likely

 

[kenny61]

Whats your boost gauge reading?

 

[barngal6]

Yes, I plugged the AFC to wastegate port.



The line I tested was the hard plastic line between aFC and manifold.



I don't see any cracks, in that line, there's 2 little rubber o-rings on each end.

Thats all on those hoses, a rib on each end, with 2 orings in front of it. The ferrules are the little rib at each end, yes?



guess I'll just replace that line completely, won't hurt

 

[barngal6]

Reason I'm thinking diaphragm is because the hole in the middle of the diaphragm looked frayed when I put in the afc spring,

so when I didn't see any improvement I suspect it.



Always been a dog, and not much improvement with my changes so I"m thinking there's a problem.



My boost runs 0 when I'n just going along, thats at start up and any gear.

If I accelerate normally, it might go up to 3



If I jump on it pretty hard, it goes up 8-10 but back to 0 immediately when I stop accelerating



If I'm in 4th or 5th, standing on the pedal and having to watch my RPMs, it will hit 20 for less than a second, then goes down again. And i have to be careful because to get it there I'm gettin close to 3Krpms and wot



Big puff black smoke when I start it after messing with things, didn't use to do that. but barely smokes when I"m test driving, and only once or twice with heavy acceleration, then no visible smoke for rest of drive.



After putting the medium afc spring, a #11 fuel plate and starwheel fully retracted, only change is that I get to 10 boost a little faster, for a second, but I'm trying hard to get there. and I get to 20 slightly easier, but still rare unless I'm trying hard.

This is driving flat, not towing.



I plan to take it to Imler for fine tuning, but I'd like to have results before I go,they're $100 hr. I know they would have the problem diagnosed right off,

but then I'll be paying them parts and labor, which adds up pretty fast.

I'd like to save up for a new clutch, so I can put in a GSK someday.

 

[kenny61]

Go ahead and change the line and then check it again I'm guessing but I dont think it would cost that much. Also check your boots on the intercooler connections. I put my 10 plate in and wound up blowing out one of the original boots within 2 days. I think your boost numbers should be higher with the 11 plate