Sarchavius

Hey guys!
The other day I was on marketplace and found my dream car for a STEAL. RHD 1995 RX-7 Type R Bathurst. Anyways, I got the car and theres a couple issues.

• Car doesn't idle well and will die sometimes if given throttle.
• When the RPM's start to rev out it feels like the motor chokes up and it starts to backfire or bog down.
• Tach sometimes doesn't show RPM gauge accurately and flickers (probably a ground issue)
• Slight power draw causing the battery to die
• Car wont build boost.

So I am trying to figure out the best way to tackle these issues. The previous owner said he replaced all the vacuum lines under the intake manifold and replaced the basket soloniod. New Battery, spark plugs, alternator and ac compressor. I definetly want to go single turbo kit. Thinking about just getting the rotary-works v mount ic and radiator. I want to also get the BorgWarner EFR IWG 8374. I know I need an ecu, I think my local tuner would prefer a link ecu but I need to double check with him. So here's everything I want help with:

• What turbo setup is the best for this car on stock internals?
• What supporting mods do I need I do to make good power reliably? (400ish)
• Can I make this much power without tearing into the motor and rebuilding it or modifying the ports?
• What are common issues or parts that I should replace and maintanace that I should do right away to keep the car healthy?
• In what areas is it best to spend the extra money?

FDAUTO

iTrader: (4)

So step 1 is to stop........

Step 2.... is to address MAINTENANCE. Sounds like you have a lot of it in front of you. You need make sure you have a good running car before you even begin thinking about mods or turbos that no one can get.

Spend your time and money on fixing the engine bay and getting the chassis sorted. There is a WEALTH of knowledge here on the forum. Do some reading and start fixing things before you waste your money on things you dont need or shouldn't be buying.

Its easy to get excited but dont get carried away.

Sarchavius

Thanks for the reply! I totally agree that I need to get the car running properly first. My worry is that I will spend a lot of time and money replacing vacuum lines and issues with the twin turbo setup that I could have just gone single turbo and saved money from the beginning. Any idea what could be causing the engine to choke? Is it worth fixing the twin turbos if I plan on going single turbo soon anyways?

c0rbin9

iTrader: (2)

Is the car actually stock? It sounds like it has exhaust and intake mods in that video clip.

I would make sure the car is running correctly before even thinking about any additional mods. When you add mods to a car with issues, you're just adding complication and making it harder to troubleshoot.

For mods, it's important to keep in mind your goals for the car, and how you'll be using it. The stock twins max out at around ~350 whp with full bolt-ons, which is more than enough for the type of curvy road that I enjoy. Personally I would look at optimizing with the setup you already have, rather than diving in with a single setup. People underestimate the complexity involved completely re-engineering the car for a single setup, not to mention the tuning required. Keeping the stock twins if they are still functioning okay is going to be considerably cheaper and easier, and yes, the sequential twins are still more responsive than even the most advanced modern single. A 350whp sequential twins FD is fast and fun.

Sarchavius

It has a blitz exhaust. I don't believe it has any other performance mods. It does have a new metal intake box. Maybe it has an aftermarket blowoff valve. Stock IC though. I want to get rid of the twin turbos more because it's so difficult to diagnose vacuum leaks and its so much more complicated. I really believe the problem with the car has something to do with the turbo seals leaking. Guy I bought the car from did a smoke test and is pretty sure the turbo seals are the problem.

c0rbin9

iTrader: (2)

My message above got cut off: Personally I would look at optimizing with the setup you already have, rather than diving in with a single setup. People underestimate the complexity involved completely re-engineering the car for a single setup, not to mention the tuning required. Keeping the stock twins if they are still functioning okay is going to be considerably cheaper and easier, and yes, the sequential twins are still more responsive than even the most advanced modern single. You might be surprised at how fast it feels after it's sorted.

I'm not an expert but it's unlikely turbo seals will have anything to do with idle or drivability issues.

Sarchavius

Any ideas what I should look into?

scotty305

iTrader: (2)

My guess is the loss-of-power at high RPM could be a boost problem (which is often a solenoid or vacuum line or actuator related to the twin turbos), or clogged cat converter, or ignition problem. If it were a fuel system problem, the engine would likely have hurt itself already. I would focus on the 'reliability mods' before switching to single turbo. Personally I prefer to make just one change at a time, or a few related changes, so I can know that the new part is working properly. Aftermarket parts sometimes need troubleshooting, and it's easier to troubleshoot a single new part than a dozen new parts. If the car was bone stock and running well, I would go in this order. I might skip steps 4-5 for your car, and come back to the cooling system after you've found and fixed the high-RPM power situation.

1. Replace the spark plugs and spark plug wires. Change the oil. Add some premix to the fuel in case the oil metering pump isn't working properly.
2. Install a functional coolant temperature gauge, the stock gauge is known to be center-weighted and won't move until the engine is already silly hot (over 230 degF, from what I remember).
3. Replace the original thermoswitch with the FC part which triggers the radiator fans at lower temperature: https://www.rx7club.com/3rd-gen-arch...tch-fd-447606/ . Use your new coolant temp gauge to confirm the engine runs cooler.
4. Buy a Lisle no-spill funnel, or similar. Flush the coolant, multiple times. I've used Thermocure to chemically remove rust, it worked well.
5. Replace all coolant hoses with new factory ones, unless you know they are under 5 years old. Do this after the coolant flush, so you're not running old coolant through new hoses.
6. Add a boost gauge.
7. Add a wideband O2 gauge.
8. Replace the fuel filter.
9. Replace the original precat with a downpipe, and visually inspect the condition of the cat converter when you have access to it.


If that doesn't fix the high-RPM problem, it should at least help rule out a few things. The boost gauge can help identify if you have a boost control (or sequential control) problem. The only part that couldn't be reused with a single turbo setup is the downpipe, but you can probably sell it.

suzukisteve

iTrader: (4)

Just listening to the video it sounds like one of your solenoids is not working properly causing the actuator that opens the door for the secondary turbo to stall. I could be wrong on this. I would recommend pulling the UIM testing the solenoids and looking for any other issues, worn heater hose, oil leaks, etc. As far as idle issues there is a wealth of knowledge on the forum about setting a good idle. You IAC valve may be gummed up and in need of a cleaning.

Do everything Scotty305 mentioned in post #8. Do not drop everything to go single unless you have $12k burning a hole in your pocket. There is nothing more fun than a reliable FD.

Sarchavius

so I spent the whole day trying to diagnose the car. Still no luck. I will look into the UIM. Not even sure what that stands for. As well as the IAC valve. I wonder if I should just pull the turbos out and convert to the non-sequential setup and buy a new ECU. Might save me some headache since I want to go single turbo at some point in the future. Also, I am not opposed to dropping 12k on the car. I plan to fully restore it. I will take another video showing the car choke under load ASAP. Thank you guys for the help!

c0rbin9

iTrader: (2)

The sequential setup is complicated, but it's worth getting working right. The old-school mechanical turbo control is part of the retro 90s charm of the car.

Have you considered bringing the car to a rotary specialist? They could diagnose and fix any issues, and then you'd have a much better baseline to work from.

Converting to non-sequential is not a trivial task either, and it's just going to be a waste of time unless you're planning on keeping it that way.

scotty305

iTrader: (2)

I wouldn't bother making a video without a boost gauge. Get a cheap mechanical one similar to these:
https://shop.advanceautoparts.com/p/...213/10717231-P
https://www.autozone.com/gauges-and-...uge/131381_0_0
You don't need to install it permanently, just run the vacuum line run through the partially-open passenger window temporarily and use blue painter's tape to stick it on the steering column so you can make a video showing RPM and boost at the same time. There is usually a capped-off port on the Upper Intake Manifold (UIM) that you can un-cap and use for the boost gauge vacuum line.

UIM stands for Upper Intake Manifold. IACV is Idle Air Control Valve. Spend a few minutes reading through the FAQ page each day, there is a lot of good info but it's too much to take in all at once. Search that thread each time you come across an acronym of word you don't recognize yet.
https://www.rx7club.com/3rd-generati...l-links-68640/


If you want to get things working, sharing your tests (and especially the results) would be more useful to the rest of us than saying how many hours you spent checking things. If you can act like eyes and ears, the more experienced people on this forum can usually help double-check your conclusions and also suggest what to check next. Otherwise you're stuck needing to learn and check every little thing yourself until you happen to find and fix the problem.

Sarchavius

that’s a good idea. I’ll see if I can get one tomorrow and rig something up. I unplugged the vaccum line for the brake booster and it make the car run better at idle. I think I’m running too rich right? And when driving the car will rev up to around 3-4k rpm then choke out and start backfiring. I definitely think it’s an issue with boost.

CREEPENJEEPEN

iTrader: (7)

I agree with everyone else about taking it slow and focusing on reliability first. It seems you're eager to ditch the sequential setup for a single because you see the sequential setup not worth your time or money. However, switching to a single setup isn’t exactly a walk in the park either; you're basically picking your poison. The quickest and most economical way to get your car running would be to fix the existing sequential setup and then switch to single.

Now:

What turbo setup is the best for this car on stock internals?
The stock internals can reliably handle 10-15 PSI. Any setup that is specifically designed for the FD will do, whether it's from Greddy or another reputable brand.

What supporting mods do I need to make good power reliably? (400ish)
Your main enemy will be overheating. Focus on maintenance over mods, especially with the cooling system—install all new hoses. A pinhole leak can be the difference between overheating or not, as these cars are quite sensitive to air in the system. The coolant air separation tank was added to these cars for a reason. Make sure your undertray is installed to direct air correctly, and consider adding a second oil cooler if you don't already have one.

Can I make this much power without tearing into the motor and rebuilding it or modifying the ports?
Yes, the stock ports can generate substantial power, especially at low revs. Modifying the ports taps into more mid-to-high-end power. For a street car, I'd stick with stock or street ports, as they're fun at city speeds. For track use, like time attacks, a bridge port could offer advantages on straights or when you’re pushing the limits like running from the police on the highway—hypothetically speaking, of course.

What are common issues or parts that I should replace and maintenance that I should do right away to keep the car healthy?
Top priority: coolant hoses. Keep up with oil and coolant changes, and ensure your OMP is functioning (or use Premix). Given your idle issues, look into servicing the ISC or IAC valve, sometimes they need cleaning or replacing. Don’t overlook the dashpot and tweaking the idle screw adjustment. There’s a lot to consider, so keep digging into your research.

In what areas is it best to spend the extra money?
Invest in anything that enhances reliability. Heat management is critical. I forgot to mention water injection or AI—both are excellent for beating the heat and help in reducing carbon buildup by steam cleaning your engine internals.

There’s much more to discuss, but these are some off the dome thoughts. Good luck, and remember not to rush. Focus on reliability before you think about the need for speed.

Sarchavius

Was working on the car today and noticed that the air pump was burning hot to the touch! So I started digging into the wiring and it’s super ghetto. Someone just shoved some wires into the harness. Wondering if I should just delete the air pump right now or if I should try to figure out how it’s wired wrong. What do you guys think? I’ll send a picture as well. Also I ordered a boost gauge to test the boost pressure.

suzukisteve

iTrader: (4)

Eh that is a tough call. If the rest of the engine is wired that way, I would suggest replacing the wiring harness. I just saw one listed for sale in the marketplace. These cars are old and get hot, the wiring requires replacement and patching. Get yourself a good set of depinning tools, some crimping tools, a heat gun, shrink tubing, and scotch super 88 tape. I buy the non insulated crimp connectors and tools from wirefy.com. Haltech has a good video on crimping vs soldering and as a result I will never solder again. A lot of these connectors can still be bought new from places like Ballenger Motorsports and/or you can buy an old harness and use it to patch your current harness.

I would eventually delete the airpump, but get the car sorted first before doing that. The stock ECU will tell you if the car is not running right unlike an aftermarket ECU. The stock unit will put the car in limp mode, not let it start, or will give you diagnostic codes via the check engine light. Something like a powerFC is not going to tell you anything is wrong with the car. It will force the car to run regardless if the air fuel ratios and timing are off or if the car is over heating. This is not something you want from a car that sounds like it is not working right.

scotty305

iTrader: (2)

Come to think of it, the factory connector for my car's air pump failed about 10 years ago. I replaced it with a 2-pin Deutsch connector, but I like the idea of finding the original connector from Ballenger Motorsports if they have it. If you are familiar with how to use a multimeter to find wire connectivity, the power for the air pump should be coming from the factory Air Pump Relay which is located in that funky little relay box hidden under the airbox near the front bumper. Page Z-28 and Z-29 of the factory wiring diagram, you can find a link in the FAQ thread.

I think the air pump should always be running at idle, but the factory ECU does turn it off at high RPM. If someone hot-wired yours to always run, that's something I would fix.

iceman4357

iTrader: (2)

You will get a lot of different answer here. These is a ton of great knowledge here though.

I agree that I would do all maintenance stuff first to start. Including the fuel filter. Less boost up top could be a multitude of things. You could wire the twins to do a non sequential setup and with bolt ons can get to 350rwp easily.

I would also check voltage to fuel pump or just buy the SakeBomb direct wire kit to make sure fuel pump is getting full voltage