Really need 2nd opinions on some engine concerns, Please.
 

Ok here are a couple things im trying to gather some info and advice on..

One day recently, I was crusing 40 mph and in 4th gear, then I step on the gas to feel turbo and it stutters back and forth, like it would pull then stop, then pull then stop, and do it really fast like it was struggling bad... yet after about 5 minutes more of driving it seems like that problem went away, however once in awhile it will show signs of that same problem but not everytime and not as bad as the first time I experienced it.

Since then I noticed these 2 characteristics that were different while driving.

#1) When I take off in 1st, there is plenty of power, then if I shift to 2nd fast and get on the gas quickly, it feels like the turbo does not spool (very low power), I have to let off the gas completely then step on it again to feel the turbo kick in..

Also...

#2) Normally, freeway cruising 5th gear @ 70 mph when I step on the gas I can feel the turbo grab and pull, But NOW, it doesnt have the same kick...

Side note** there is a kinda hissing sound comming from the engine when I am idleing, and if I happen to be driving next to a wall or freeway barrier and get on it, I notice that hissing sound louder and kinda sounds like it has a slight tick in it when Im accelerating.

Idle is a little rough but seems to hold steady. Any help would be appreciated or advice, Im racking my brains and the Search button to see if I can come up with anything.

Have you checked your engine pay to see if any hoses or couplers have come loose? You also need to get yourself a boost gauge as a lot of the boost problems an FD has can be diagnosed by seeing what the boost pattern is.

Sounds like you have a boost/vacuum leak, and/or your turbo is dying. Oh, and the first issue of hesitations sounds like a TPS.

I have checked the engine bay, not totally sure where specifically to look but I did check and didnt see anything unplugged or loose.

what is the TPS? and how can i locate / isolate a possible vacuum leak?

So these are pretty much my only logical possibilities?

TPS is throttle position sensor, mounted on the throttle body, a common ailment of driveability issues for all 2nd gen rx7s. You can adjust them and you can replace them with used ones, new ones are unreasonably expensive so no one goes that route. There is not a bulletproof method of testing them, the best bet in my experience is to pick up a few used spares and spend a day swapping them all out to see which one the car agrees with best. Often you get it right the first swap, but it is nice to have spares around for the inevitable "next time".

There are many vacuum hoses on these engines, most of which you cannot see with the intake manifold installed. Even if none of them are broken or popped all the way off, they harden over time due to heat and fail to seal, and all these small leaks that would not be an issue can become a larger collective leak. Since these cars are airflow meter based, any air leak between the meter (under air filter) and the intake ports on the engine block can affect the fuel injection amount, causing all sorts of running problems.

The best thing to do is tear it down to the block and replace all gaskets and hoses along the way, along with a possible fuel system overhaul.

For those not wanting to go that route, you can try feeling and listening around for hisses and sucking sounds while the engine is running. You can carefully spray starter fluid onto various hoses and areas of the engine (NOT THE EXHAUST!!) while running also. IF the engine revs wildly or dies suddenly you have found a significant leak in that area. Spray only a little at a time, just a 1/2 second shot here, wait 5 seconds, another shot there.

There are hundreds of minute possibilities, these are the most likely in my experience.

Lol! :lol:

Hey man, you never know...I'm sure people used to LOL at the "caution, hot" on mcdonald's coffee cups, too, until that one woman/darwin award winner got ahold of one, and look who got blamed for it.

Supposedly that coffee was over 200f. I used to laugh at that story, but 200f is nasty.

Anyway, as for your boost problem, start by replacing the check valves, particularly the one on the vacuum tank circuit.

Dave

Holy shit. After looking at this again today, I realize I gave some bad advise. For whatever reason I replied to this as if it were in the 2nd generation section, so some of what I said is completely wrong for this car. I have no idea how I got into the 3rd gen section as I did not reply to any other 3rd gen threads last night. :pat:

Your most likely culprits for the weak boost issue are check valves, vacuum hoses/leaks, and solenoids that are broken/unplugged/bad.

Also the TPS' do not really go bad often on these cars. You could still have one causing your surging issue, or yours could be out of adjustment, but it's kinda doubtful.

If the problem persists or becomes more evident, you might want to check your engine grounds (1 on the back of the intake manifold, one on the top of the rear rotorhousing under the intake, one on the lower front corner of the block under the p/s and a/c) and clean/tighten them.