Vacuum

sb5551 · #1 12-12-2005, 05:15 PM

What would cause my 87 supra turbo to have low idle in neutral or when the clutch is in but be perfect when cruising. It also has extremely low vacuum when it is cold ( 8 in). This happens to the point where the car stalls out.

sb5551 · #2 12-14-2005, 11:36 AM

C'mon people someone has to know

Yellow 13 · #3 12-14-2005, 09:43 PM

You should go through and replace all your vaccuum hoses to start. Youll need about 12-14 ft of hose. And also make sure that your car has correct timing and that all the intake hoses are on good. Maybe some new intake gaskets.

sb5551 · #4 12-15-2005, 02:49 PM

I was wondering about the intake gaskets i have not checked them. Would a defective bov cause low vacuum at idle, neutral, and ecspecially at cold start up.

Yellow 13 · #5 12-15-2005, 06:07 PM

I havent had much time to play with my 7MGTE yet, But if im right the BOV cycles back into the intake hose. That may be causing you some problems if its not working right. Maybe the air is being held up or not released properly. But with almost any leaks in your intake there will be a problem of some sort. your computers not getting a reading for the extra/lost air and isnt adjusting the rest of the car for that. Also the main intake gaskets are made of a really cheap paper material that cracks the first time you take it apart. so if its ever been taken down to the manifold you may want to check those.

projectsupramk3 · #6 12-17-2005, 08:51 PM

8 HGin?? What does it read when the engine is heated up and idling normally? Stock boost gauge? How does the power feel on the car? Sounds to me like either a very poor motor (healthy 7M should be roughly 20-22HGin) or a large boost leak (but then it should run poor all of the time). Pop the spark plugs out and do a compression test and maybe even a leakdown test on the engine, only takes a few minutes and that will eliminate alot of the guessing. The stock BOV is simply to check, remove it and see if you can blow through it. If you can, it's garbage.

sb5551 · #7 12-19-2005, 03:27 PM

The car has some issues when accelerating it doesn't seem to have as much power as it used to. I had to replace the fuel pressure regulator with an aftermarket one, but now i can't get the correct air/ fuel mixure because of the vacuum leak. When the car is warmed up it usually has about 14 hg which is still low. The car just had the head rebuilt including the head gasket tourqued correctly. How would i check if the blow off valve is not working (holding vacuum).

sb5551 · #8 12-19-2005, 03:30 PM

I have never really been able to get the engine to idle normally. See my previous posts.

Hybrid1990crx · #9 12-21-2005, 12:44 PM

Well I don't know the car just died today while i was driving it. I got it towed to the dealer, so ill post what the problem was. I was driving it and it started to lose power severly and it wouldn't hold the idle after you rev it; however, it would if you just start it up plus a lot of white smoke was coming out. I hope it is just a boost leak.

Yellow 13 · #10 12-21-2005, 10:37 PM

Sounds like a HG.

sb5551 · #11 12-22-2005, 02:33 PM

They told me that it is the crankshaft pulley is loose because the guy before me had the car installed an under drive pulley that was not harmonically balanced. The said best case 1000 to worst case 4300 dollars to fix it and that will get it running so that they can figure out the problem of why it is not returning back to idle its just dieing out. I think this is bull because it has been running like this for a while (I do know that it is not good for the engine but i don't have a choice at this moment). I told them to check the compression and dash pot and other various but they want to do charge me more diagnosis time.

sb5551 · #12 01-04-2006, 05:02 PM

Does anyone have any ideas on what problems this might cause or is the dealership just trying to pull one on me?

projectsupramk3 · #13 01-04-2006, 07:56 PM

It's a dealership, there whole purpose is to make as much money as possable and that is what there trying to get from you. $4300 for an engine rebuild is rediculious, no question. No way a crank pulley could cause BHG period. What you need to do is pay the shop bill and get your car out of there ASAP before the bill gets higher. Buy or rent an engine lift and some basic tools and swap the engine out over the weekend. If you are at the point where you are going to install a new engine you should look into used JDM engines. JDM 7M-GTE's can be had for $700 or less with transmissions, a good warranty, and usually very low miles.

POST REPLY TO THIS THREAD