Hi all! Picked up an 87 TurboII with 84k miles on it. All stock, except that it came with some generic BOV installed, and has some extra ground wires run. When at full, or very close to full throttle, around about 5000 RPMs and up it can get intermittent stuttering. It doesn't seem like it's the common hesitation problem, it goes through 3800 no problem. It also goes perfectly all the way through the entire RPM range with no problems at all with maybe 50-70% throttle. No CELs, nothing else really seems to be evident that's going on.

Any thoughts or places to start looking to solve this? Thanks!

 

Could be a manifold gasket that went bad and is making it run a little lean under boost. My LIM gasket went bad and it would stutter at anything over 4psi. Try spraying some cleaner or starter fluid around the manifold gaskets while the car is running to see if it changes the idle at all.

 

For starters, I would recommend replacing the spark plugs, spark plug wires and fuel filter.

 

I agree with the above. Having a good base to start with is very important when diagnosing running issues. I would also replace the air filter and clean the throttle body and maf as well. You could have issues with the secondary injectors not functioning properly. Either a poor connection at the injector, brittle wiring, or a failing injector. I would clean the grounds just to be on the safe side. Remember, the ground is obtained through the bolt so be sure to not only clean the ground's ring or blade terminal, but ensure the bolt is not rusty and that the threads are in good shape on the body. Just some things to consider.

 

Ordered new plugs and wires today, already have a fuel filter to go in and replaced the air filter. I'll get on cleaning the throttle body and MAF and grounds. As a side note, when checking the plugs (They've definitely got some carbon baked on), I found the gem attached. Kind of hard to make out, but it's a bolt jammed in a hose that might leak oil? Any ideas on what's supposed to be happening with this?

 

The hose is a vent tube. Do you have a stock emissions setup? Teh spark plug wires look to be the original wires. I would go on rock auto and order a new set of NGK wires in addition to what you're doing.

 

Sorry I didn't specify, but yup, NGK wires are what I ordered! Should be here tomorrow, thanks Amazon. I do believe I have stock emissions, there don't appear to be any block off plates installed or anything removed that stands out to me.

 

Installed all the new parts, and while it seems to do it less, it will still happen. Could my TPS having problems give this sort of issue? Did the test here: FC3S Pro v2.0:&nbsp TPS adjustment for 1986-1988 RX-7 Turbo II models and instead of going from 1k to 5k ohms, it actually goes DOWN when I open the throttle, to around 422.

 

Have you checked your fuel pump? Also, there's a fine screen (https://www.sparkplugs.com/product.aspx?zpid=13547) on your fuel pickup tube. You might want to check/replace that too.

 

Checked my fuel pump for fuel pressure you mean? I did replace the fuel strainer on the pump already.

 

Well, you've done the basic checks and your problem still persists. Apparently, the problem is something more subtle. I would next do what mazdaverx713b suggested. Check your electrical connections and wiring under the hood. I once had a similar problem on my 90 GXL and it turned out be corroded electrical connections at some vacuum solenoids under the hood.

 

If you tps is not reading correctly that is a problem and I would address that 1st.