idle problems and a few other things

[mchustle]

Ok so on my 95 gst there is a 6-bolt block with a 7-bolt head. Ive had the car around a month or 2 now, and when i got it had a really bad oil leak and it would not idle at all really. so i pulled the motor to go ahead and rebuild to fix all the oi leaks, rear main, cam seals, etc. In the process i found the 6 bolt stuff witch i was happy about. so i went ahead and checked the things with the swap that needed to be done like the injector and plug switch and they were, i was hoping that was the idle. any way fast forward to now motor just got put back in ent ahead and threw a 6 puck clutch and new pressure plate in because mine was toast. replaced the blown t25 with a egay 16g , very temporary got a good deal on it to hold me over for a month or 2. ok it still has the idle issue of where it will not idle at all but if i unplug the maf sensor it will idle very rough but it wont die. also i was trying to rev it up to build some boost but my boost gauge was not reading any boost when it was idleing there was next to no vacum showing and when i reved it up it read vacum instead of boost and wouldnt blow off. im thinking the turbo may be shot even though it is brand new, gotta love china. sorry for the horrible grammer im in a hurry been working on the car all day just to be let down again. any help anyone could give me would be great lt me know if you need any more info and ill do my best to give you an answer.
And also i put my buddies throttle body, maf sensor, and a couple other sensors off his 97 gsx and still didnt have any luck also tried a different coil pack. the boost gauge in it now is different than the one that was in it before so ill switch them back out and see if that makes a difference. sorry again for the long post thats next to impossible to read.

 

[TrevorS]

Just a heads up -- you're not going to develop any boost if the engine isn't having to work (significant exhaust gases flowing), and just pressing on the throttle in neutral isn't work -- takes very little to spin up the engine with no load. On the other hand, if your foot is off the throttle and the engine is idling, then you should definitely be seeing healthy vacuum in the intake plenum. If you're not, then there's a leak. A real vacuum gauge should tell you what's going on there.

http://imperialclub.com/Repair/Fuel/VacuumGauge/index.htm

 

[mchustle]

Just a heads up -- you're not going to develop any boost if the engine isn't having to work (significant exhaust gases flowing), and just pressing on the throttle in neutral isn't work -- takes very little to spin up the engine with no load. On the other hand, if your foot is off the throttle and the engine is idling, then you should definitely be seeing healthy vacuum in the intake plenum. If you're not, then there's a leak. A real vacuum gauge should tell you what's going on there.

Intake Manifold Vacuum Tests

ok thanks for the input like i said im going to switch the gauges out tomorrow just to make sure the gauge isnt broken. Also with it not idling i cant take my foot off the gas i was just tapping on it to keep it between 800 and 1000k and there was next to no vacum showing. the gauge in it now is a aem 30-30 or 25-25 cant remember right off hand and it was barely below the 0.

 

[TrevorS]

If it's unable to maintain any kind of idle, then I would first suspect a vacuum leak. Though it could need a BISS adjustment, or there could be a base timing issue, or even a problem with the idle sensor switch and/or throttle position sensor. My follow up question would be did you or anyone make any change of any sort between when the car operated normally and the way it is now?

 

[mchustle]

If it's unable to maintain any kind of idle, then I would first suspect a vacuum leak. Though it could need a BISS adjustment, or there could be a base timing issue, or even a problem with the idle sensor switch and/or throttle position sensor. My follow up question would be did you or anyone make any change of any sort between when the car operated normally and the way it is now?

well to your follow up question i got a good deal on this car mainly because of the idle issue so i dont know if they messed with something before it had this problem or not. I tried my buddy's TPS off his talon and it didnt help, altough his talon is torn apart so i have no way of knowing his is any good. im leaning more towards the idle sensor and/or vacum leak. i think i found a post awhile back ill have to dig up on testing the idle sensor with a multimeter so ill start with that. then i guess ill try and make sure the base timing is right by the cas and check for the peskey vacum leak with I think is most likely. thanks again for your help ill report back tomorrow and let you know how it goes. its killing me with it sitting on jack stands instead of me driving it . but it has taught me a lot about it so far and im sure it has got a bunch more lessons yet to give me.

 

[galantlvr34]

You cant really use a 7 bolt head on 6 bolt block there are a couple of differences between the two.The head studs are slightly different sizes too so if air is getting in that way it will cause idle issues.

 

[mchustle]

You cant really use a 7 bolt head on 6 bolt block there are a couple of differences between the two.The head studs are slightly different sizes too so if air is getting in that way it will cause idle issues.

No you can use this combo the only difference is the head studs for the 6bolt are bigger and you have to drill out the 7 bolt head to accept them. Thanks for the input though even if it was incorrect.

 

[fwd1gturbo]

Check the IACV and ISC on the throttle body. If these parts are bad the car will not idle because the computer is not getting accurate readings for how much air is in the engine opposed to how much air is flowing thru the MAF

 

[mchustle]

Ok thanks everyone for the replys it turned out to be an easy fix because of a stupid mistake. Whoever ordered my intake gasket ordered it for a 6 bolt and my buddy didn't pay attention when ^he bolted my intake on. Needless to say the bigger 6 bolt gasket leaks on a 7 bolt intake. But that's why it's always good to check for vacuum leaks.