labman

Car: '93 RX-7 Base, 66k miles.


Got a few questions for those that know some about these wonderful cars. I understand that a few of my questions are already answered in other threads, but this is another way to increase post count while introducing myself to the community and incorporating my other questions.


- How far can the stock turbos be turned up with stock fuel system? How far with upgraded fuel system and what needs upgraded?

-What are some cheap(ish) upgrades that are suggested for a stock car?

-Is it dangerous/not suggested to take the car to Jiffy Lube for oil changes?

-This might be shunned, but how can I get the stock BOV to make noise? I have been told there is a line that recycles the air back into the intake to dampen it but haven't found it myself.

-What should I know about these cars that are different from piston vehicles? (Already know to high rev once in awhile, change oil often, high grade gas only, etc ...)

He's On Toroids

iTrader: (2)

I'll address these one at a time:

How long do you want your engine to run? There are many things to consider on this and it is a wide open topic. With the stock fuel system (I am assuming stock ECU too) you should remain at 10. If you want to push it, you can go up to 12 psi but I'd add Auxiliary Injection (AI). any higher then that you are asking for a blown engine. Upgraded fuel systems... well all depends on what injectors you put in. Here is a good Thread for you to understand Fueling needs:https://www.rx7club.com/single-turbo-rx-7s-23/feeding-turbo-rotary-horsepower-airflow-fuel-cooling-899019/

Stock turbos will have significantly shorter lifespans the higher that you turn them up. 12 is accepted as safe, 14 is high wear, highest I've seen quoted on here is 22 but they were non-sequential. To run anything over 12 you need an aftermarket or 'chipped' ECU and fuel mods.

Look at the FAQ or search 'Reliability mods' Do these first. Better yet, here: http://www.fd3s.net/reliability.html This is so important that I linked it up for you. Do these mods before anything else. It will save you money in the long run (thus 'cheap'). It is an old page but I still agree with everything on it (maybe not the turbo timer).


Dangerous... not always, but it can be. Definitely not suggested. If you are going to own this car for any length of time you are going to need to learn how to do basic maintenance. I'm sorry if no one told you before you bought it, but it is true. The only way to get around it is to spend a lot of money. If you cannot turn a wrench and absolutely have to bring it to Jiffy Lube, give them the right oil to put in it and the right oil filter too, they will not have them on site. You are going to be risking damage to other parts of your car though since few people understand what all is going underneath the hood of a FD. Also, you need to change the oil in these cars every 2-3000 miles so the Jiffy bills are going to start to add up. Learn to do it right, and save yourself money and the heartache from when a JL tech knocks off the vacuum tube to your MAP sensor and you think you have a blown engine.


It is shunned you are right. I don't understand the ricer mentality, but I understand that some people only buy these cars to be 'cool' in front of their friends and turn people's heads. Anyway, here is a thread started just last week on this subject. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/bov-install-vent-atmosphere-957640/
I know it is time consuming to search for these things but just remember you are not the only one who has ever come up with these questions so there is likely a thread out there about them already.


There are many things to know, that list is a good start. The most important thing is that they do not tolerate mistakes on the owners part as much as piston engines do. This has unjustly given them the perception of being unreliable. This is not true, it is just that often the owners let the cars down. As I typed earlier, do not make changes until you know all of the consequences. The FD is only as reliable as the owner is knowledgeable.


NOTE: This was all a freebie because you are a noob and don't know what you are doing. To increase post count you can post your questions in the 'flame free zone' called New Member RX-7 Technical.

Also, try to remember that this is a forum and not a help desk. People on here are not getting paid to do this and there time is as valuable as yours. Do them and yourself a favor by searching on the simple questions and only post when you are really stumped or need clarification.

Good luck with your car, try not to kill it by doing modifications before you understand what is going on.

labman

I didn't realize how close to max the fuel system/turbos already where to being maxed out.

Thanks for the Fuel system link, haven't found that one yet. The reliability mod link I had found one myself but wasn't that in-depth, think it was off the FAQ or Introduction threads.

I didn't hop on here to use it as a Technical Manual, that's what the book is for. Just trying to get familiar with the community.

I fully know how to work on cars, I have been rebuilding a '95 Cobra for over a year now all solo (with Chilton's book). I'm just looking at taking advantage of the local Jiffy trying to pull extra business with their 9.99$ oil change once every 6-8 months. Buying the Oil alone costs more than that.

You need to get your idea of "Ricer" re-evaluated, having the BOV make some kind of noise is not Rice at all, it's simply wanting to hear it. If you need help, this is Rice.

What exactly do you mean by "This was all a freebie"? Because of the attempt to stoke a conversation and expand my knowledge of the workings of the Engine/Car before attempting to improve it, or did I miss something that mentions requiring payment for using these Forums? Strongly doubt the latter given: Don't take this wrong, just trying to get information, not start a retarded flame war. Tried this in the Introduction sub-forum, but just got flooded and disappeared down the pages.

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Got a legit technical issue for ya then.

Running the A/C it will start to heat up (more than normal) causing me to shut it off. Weird part is that it ONLY does this at highway speeds. In traffic with A/C on it runs at normal temp, as soon as I exceed 60-65 the temp starts climbing. Nothing is covering the intake in the front clip, coolant hoses don't get crushed at running temperature, etc.

Not sure what else to look for or check, normally the overheating issue is switched (runs fine at highway, overheat in traffic).

He's On Toroids

iTrader: (2)

Yeah, 2x550 primaries and 2x850 secondaries (Stock) only gives you 2800 CC/min. If you are running at 85% duty and a 10:1 A/F ratio you can see that there isn't much headroom. But, that is what is considered 'safe' without AI. If you add AI or want to risk the engine a little more, by all means have at it.

I'm sorry I did not mean to insult you or your abilities. But, due to the questions you asked, I assumed the worst. It is difficult to tell where people are coming from. Don't take it personally. I am just trying to save you from the flames you will get if you were to make a post like this in the 3rd gen forum.

I personally subscribe to the definition of 'ricer' being any modification to a vehicle that is detrimental to it's performance for the purpose of looking or sounding 'cooler.' So yes, this applies. I am sorry if you disagree. I do agree that the car in the pic you linked is extremely riced out.

Buying oil costs more then a $9.99 oil change at jiffy lube for a reason. They use crap. It is the lifeblood of your car and you do not want to cheap out on it. I pay the money and get the good stuff. You can do what you wish with your car. all I'm saying is websites like this don't get started for no reason: http://www.jiffylubeproblems.com/

By freebie I just meant that I answered these questions when most anyone would have ignored you or flamed you for them. I was just trying to help you out instead of just clicking away like the other 60+ viewers of this thread. Poor terminology on my part I guess.


"Running the A/C will start to heat up" what does this mean? Start to heat up the engine coolant? how can you tell? do you have an aftermarket gauge or PFC? what temp is the coolant going up to?

labman

Sadly on the heating issue, it's the stock gauge. I haven't had the time since I bought to car to replace the stock one with an aftermarket. Got a cheapo-depo boost gauge in atleast to cover myself on that end.

The stock temp gauge has NEVER moved until the other day when I turned the A/C on while driving down the highway. I normally runs ~1/2 way up the gauge, started moving near ~3/4 and I had to turn it off. As soon as it was off, the temp tanked quickly and returned to normal parameters.

Wow, never knew that Jiffy was that bad, guess it's worth the 10$ extra to do it yourself.

He's On Toroids

iTrader: (2)

I cannot impress upon you enough about how you should not turn on the AC again until you get an accurate temperature gauge. Here is why, the stock one is heavily center weighted. I do not remember the specifics, but I don't think it even moves from the middle until the water temperature is over 230F. This is bad, very bad temperature category. If our cars still had the original pressure caps on the ast this would be less of an issue, but there was a factory recall that changed the cap and lowered the coolant pressure. This also lowers the boiling point of the coolant and makes overheating happen at a lower temperature. Therefore, it makes the bad gauge even worse. In fact, if you had any leaks at all in your coolant system you would likely already have a blown coolant seal. Great job at catching it at 3/4 though. Most people miss it until it is too late.

I'd make this your first priority so that you know better when to chill out the motor.

As for the A/C problem, it is interesting that it worked better sitting in traffic then on the highway. Has this happened multiple times or just this once and you didn't want to try it again? Either way I'd get the gauge to see if you could really get a better idea about what is happening to your temperatures in each case.

Once you get the temp gauge, one thing you need to figure out is if the A/C not running well was speed dependent or RPM dependent. If it is speed dependent only I'd look to things like your air ducting (under tray) not being sealed very well and causing a lot of blow by. Or obstructions (which said you already checked). If it is due to running at a higher RPM it could be a number of things, too much resistance in the coolant path (pinched or clogged line), exhaust blow by (busted coolant seal), or any number of other things that don't come to mind immediately.

How do you typically shift the car? or is it an auto? If you typically keep the car at low revs around town (or drive an auto) and the only time you have sustained higher revs is when you are on the highway, I'd look to it being RPM dependent rather then speed.

Also, did I mention to get a temp gauge?

labman

It's a slush-o-matic, only thing I didn't like about the car (although it does make traffic driving nice).

I tested it multiple times in traffic, having it run during the WHOLE duration of I-95 South at 5pm on a Friday (You ought to know how bad that is) without the temp ever moving. Once the highway opened up the temp started to climb again, causing me to shut the A/C off.

I remember reading how deadly heat is, and how bad the gauge is, for the RX series so I have kept a close eye on the gauge for ANY change just in case. Noticed it the first time I ran the A/C on highway.

It's not a RPM thing because at highway speeds it will run ~2.5-3k which will be about the same as traffic/casual driving, must be a speed issue. I'll have to check the undertray, i've read about them falling apart or being removed as people see them useless.

I have tested the overheating several times after the first incident, but it never moved beyond idle temps more than a fraction. I would cut the A/C the second it moved, turned it on for troubleshooting reason only.

I already have the gauge on order, just waiting for it to show up. Got a boost and A/F gauges incoming too.

He's On Toroids

iTrader: (2)

No worries About the slushbox, I got one too. (DC traffic FTW)

I wonder if it could have something to do with the transmission. The ATF runs through the radiator (along with a separate cooler), perhaps your transmission is adding too much heat to the system? I don't think it is likely, but could be another thing to look into. Does your TC lock up in 3rd and 4th like it is supposed to? Have you seen the hold light blink at any time?

If you are missing an undertray I'd definitely point at that as being your issue.

A stupid question possibly, but have you double checked to make sure the coolant is topped up and the correct coolant/water ratio?

It could still be RPM, I notice the car gets much warmer when I am running on the highway for extended periods of time. If your temp starts climbing right as you get up to speed though, it must be something else.

rnz520

iTrader: (10)

labman where in spotsy are you? I work in spotsy

labman

TC lock up? Only time the HOLD light comes on, is when I hit the button

I'm keeping an eagle eye on the Coolant/Trans fluid/Oil levels until I learn how quickly, if at all, it consumes them. So far the only one I have had to add ANYTHING to is Oil but that is due to design. No idea on the Coolant ratio, but I know personally I add 50/50 Prestone when needed.

The car is fine on highway as long as I don't use A/C, I just made a trip to Raleigh NC to pickup a '93 Supra and it ran the same temp the entire way (~3 hour trip).



Thornburg, off of 606 towards Lake Anna. Turn off right before Indian Acres.

He's On Toroids

iTrader: (2)

From a google search, Wikipedia says:

Impelling losses within the torque converter reduce efficiency and generate waste heat. In modern automotive applications, this problem is commonly avoided by use of a lock-up clutch that physically links the impeller and turbine, effectively changing the converter into a purely mechanical coupling. The result is no slippage, and virtually no power loss.

The FD TC should lockup during certain conditions which are outlined in the K section of the FSM. If your TC is not locking, I could see it producing extra heat due to slippage and that would only really affect things in the higher RPM. In fact, the FSM actually says that the Lockup points are lowered when the water temp exceeds 239F. This shows that they use more lockup in order to reduce running temperature during an over-temp situation.

What is peculiar is that if you look at page K-18, you can see that when A/C is turned on that there is a different shifting pattern for the transmission. It contains less lockup then A/C off condition. This inherently would produce more heat precisely what I would think you wouldn't want to do. There must be some other reason for this like potentially bogging the motor or something.

The reason I asked about the Hold light blinking is because it is like a check engine light for the transmission. If you ever see it blinking check your PCMT for codes. Though I warn you, it only can sense when a very limited number of things go wrong, mostly only if the sensors go bad. I've replaced my transmission due to excessive slipping before and the PCMT never said squat.

labman

Transmission has no slips, shifts smoother than new cars. Not sure how to check for TC slippage, but i'll see what I can dig up.

I looked under the car and noticed that the undertray is still there, but in the middle-front of it is sagging down, looks like it's missing a stud that holds it up. Going to zip tie it up and see if that's the heating issue. Going to the local junkyard soon for a parts run (Need starter & map pocket lid) i'll see about getting the undertray and connectors.

He's On Toroids

iTrader: (2)

I've got a spare starter if you don't find one at the Junkyard. I'd prefer to keep it, but I can sell it to you if you really need it. Why are you getting one? Do you have the click click start issue?

labman

I think that's what it is. I was told that it's mostly a Chevy thing, but it's a "dead spot" on the starter. It gets carbon buildup and has a spot where it won't turn.

Some days first turn the car starts, others takes 5 minutes of turning key hearing it click until it turns. Once it turns though, starts instantly.

And it's not a repetitive click, just ONE click when I turn the key.

He's On Toroids

iTrader: (2)

It is a common problem for these cars, the "click, click, start" is a reference for each turn of the key it clicks. Not that it keeps clicking with the key turned. You can find many threads on this subject but here is a writeup I did recently for someone else:


https://www.rx7club.com/showthread.php?t=957536

He's On Toroids

iTrader: (2)

He was manual, so for you the clutch switch doesn't exist. Instead they have what they call an "Inhibitor Switch" that will cut the circuit if the transmission is not in P or N. Check that instead

The reason that I didn't mention the starter in the writeup is because he had already applied battery voltage across the terminals to check it's function.

Some people just get fed up with it and install a starter booster. You can either order one from Pettit. http://shop.pettitracing.com/pettit_.../i-408883.aspx or you can build one for much cheaper yourself with instructions you can find somewhere on this site.

labman

Reading that write up I think I know the issue ... I also have a short in the steering column that causes the intermediate wipers not to work (randomly). Guess I know what i'm doing this weekend!

Good thing i'm getting a steering column pod mount anyways, might as well install it while i'm tearing it apart.