No Idle. Rough Running Post Head Gasket change! HELP

barberben

Registered User
Ok guys let's see if y'all can help me keep from losing my mind. I have a 90 Anni. edition that is a very nice car, and in very good condition. Thanks to you guys here on the forum it looks even nicer than when I bought it. New wheels and tires purchased here, as well as Eibach's purchased from here as well. Painted my calipers, new drilled/slotted rotors all around. I Love the looks of this thing. Here is my problem.....
Soon after I bought the car I realized that it had a blown head gasket, so I put of the repair until I had accumulated all the necessary parts. I bought most everything used, and from sellers on this forum. Engine parts I bought include; 42 lb injectors, 73mm maf with red tube (works with the injectors per the manufactures website), late model blower, Kooks headers, and I bought a spare set of heads to have machined so that we wouldn't have to wait on the ones from my car. Everything "supposedly" went back together correctly, with the exception of the headers not having the egr bung. I towed the SC to a muffler shop and had cats connected to the headers and hooked up my factory exhaust (for now). Now for the symptoms.
After my mechanic finished putting the car back together he called me and said that the car wouldn't run worth crap, but blamed it on the absence of back pressure. After taking it to have the exhaust hooked up, the symptoms persist. The car will start almost immediately, but will not idle AT ALL. You can keep it running by feathering the throttle, but even that isn't smooth at all. I did drive it this evening for about 15 minutes, just to see if the computer could even out any of the issues, and strangely never got a CEL. It runs the best at about 1/2 throttle, and falls on its face at full throttle. When it is running, it doesn't seem to have any power at all. It ran very rough, sputtering and slightly backfiring. The only visible issues are; It has developed a substantial oil leak, and the boost gauge doesn't move at all. I have no idea where to start, because I neither tore it down, or put it back together, so I'm hoping one of you can point us in the right direction. Somebody had similar issues and fixed their problem by doing something with an intercooler tube or something. I really do believe I have some kind of leak somewhere.

Any help will be greatly appreciated. I have to get this car running before my mechanic lights a match to it. Lol!!

Thanks
Barberben
 
those injectors are huge compared to stock , you need a tuned computer or use stock injectors, when my boost guage wouldnt boost my harmonic balancer was bad it would start and idle but any uphill it would not go or boost
 
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My boost gauge was fine until the head gasket work. The injectors could be the culprit, but coupled with that maf I'm not sure. I was told by numerous people on this forum that I'd be ok with this setup. Since they are used, we are going to check them, and I do plan to eventually have a tune done as well. I'm just trying to get it running first.
 
After my mechanic finished putting the car back together he called me and said that the car wouldn't run worth crap, but blamed it on the absence of back pressure.

If that comment came from the mechanic responsible for putting the motor and it's accessories back together, then you now know what your problem is. The mechanic missed something when putting it together.

Off the bat I would check for an issue with massive vacuum leaks leading to no idle and no power. Start with looking at the i/c tubes to make sure they are sealed. Then the plenum that bolts to the intake manifold. Then check that all the vac lines are connected. i.e. if no EGR, what plugged into the port where EGR hooked up?

The oil leak bothers me as it sounds like you're gonna have to dig into it a bit. The top suspect for that would be the oil pressure sender mounted just to the mid drivers side of the block behind the timing cover. After that then valve cover gaskets.
 
Yeah they definitely missed something. The more I read, the more I believe there is a vacuum leak somewhere. My problem is that since I did neither the dissasembly nor the reassembly, I don't have a clue where to start looking. I spoke with him this morning and he said that there was a difference in my Blowers where some particular vacuum hoses plugged in. He said my original "early style" blower had a "double nipple" someplace where the "late model" had only a single he said something about it hitting the throttle body. I have no clue what he's talking about, but hopefully it will ring a bell with some of you guys. From what I read before doing the job, it is supposed to be a plug-and-play swap as long as I have the plenum, which I do. So there could be a problem there. evidently they left a hose unplugged that goes to the boost gauge. it seems like that would be obviously stupid, but I'm not a mechanic. SC's are the only forced induction engines I've ever dealt with, and what I have done did not involve anything with the blower, so Yeah. I'm ignorant. If somebody could give me a list of what hoses/lines to check, as well as their general location under the hood, I would greatly appreciate it.

Thanks
Ben
 
the boost gauge goes on a small nipple on the rear of the intake---near the master cylinder just behind a sensor (ACT sensor to be exact) and make sure he installed the vacuum line on the SC bypass, there are just so many its almost impossible to describe without pictures. hope this link works and helps---if it doesn't work go register at Autozone and look in the repair guides for vacuum diagrams.
http://www.autozone.com/autozone/re...epairGuideContent.jsp?pageId=0900c1528006b88c

Dan
 
If the mechanic had those issues then he should have dealt with them in a way that he could describe to you (and should have described to you when he came upon those issues).

Keep in mind, this is a guy that told you lack of proper idle and generally not running right was due to lack of exhaust back pressure.
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Here is a picture that may help you investigate. In it you can see the lines on the plenum for the blower. the one bending down is for PCV. One of the other two goes to a vacuum manifold under the wiper cowl. The other I believe is for EGR and can be plugged if you don't have egr.

On the other plenum, there will be a line for the bypass valve and a line for the fuel pressure regulator, and a line for the gauge.

scassembly1.jpg
 
Sounds like the mechanic didn't reseal everything properly. Pretty much every connection for the components shown in the above picture have to be sealed with RTV or some other substance. Every connection between the the throttle body and the intake manifold is a potential vacuum/boost leak.

With motor trying to idle, start spraying connections with carb cleaner (the flamable type) and you will quickly find the leaks. Most common place to leak is at the IC tube connections.

Savid
 
im thinking maybe more on fuel pressure regulator i recently had trouble with it

and it was like running out of gas or else injectors or tune . i never worked real hard sealing my innercooler tubes mostly just use rtv and let it sit all nite and i prob have leaks but the car runs great

ralph
 
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Ok guys. Great news and unfortunately, not so great news. The answer to my riddle was, in fact, the intercooler tube. I held the throttle at a point where I could get a consistant rpm and started shooting everything with starter fluid. When we sprayed the upper end of the intercooler tube, my rpm jumped about 300. I had my guy shoot a steady stream on it and started gunning the accelerator. The fluid literally began spraying back at him. It was WAY loose on the top side. I tightened up the top nut, and started the car and it ran smoothly. Yay. Later today I decided I should torque down the bottom nut as well. Since the engine and SC are fully assembled, the only thing I could get on the nut was a gear wrench. I started very slowly tightening the nut, but I later discovered that the threads were messed up on the nut end of the stud, which caused the stud to turn and yep; I snapped it off in the manifold adapter. We're going to be chasing an oil leak tomorrow, so I'll be able to get an extractor in there, but can I just use a bolt to replace it? Or do I need to find one of those studs? If so, where can I find one? Does anyone have a part number? Will a local stealership have them? My local Advance Auto did not.
 
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