lOOkatme

iTrader: (19)

Introduction:
First, I am new to the FD. Bought a FD and drove it home over the weekend. When checking out the car....everything looks great.....drove it 1,080 miles back home.....but on the way home I had to stop going up the mountains both in CA (death valley) and during peak temps that day of like 111F or something....and also up the gigantic mountains in CO. (had to stop twice and let the engine cool down on both mountains).


I am going to change the fluids out completely in the car....everything.....and I will change the thermostat to ensure its good to go.....and other misc stuff.


background on situation:

going up the mountains....temps rose....regardless of gear selection (even at 3rd gear).....off boost going slow (2,500 rpm) (stopped up mtn when temps were 110ishC).

I also noticed that temps increased even in hotter states going above 70mph....but nothing out of the norm (85-97C). remember I am new here...still learning...thats what I think is norm.


Idle is good when engine is cold......and it seems like the idle was higher when idling and cruising down the mountains (high elevations (7,000-9,000 ft). it idled under 1,000rpm at sea level and when engine was cooler....high elevation was more like 1,100/1,200 rpms but car was hot and ran hotter.


I noticed the clutch pedal and brake pedal were hot on my feet (no shoes)....only when the heater was turned on......could something be leaking? but were normal with heater turned off. (will check hoses at another time)

I also hit the boost when the car was hot (87C water temp but car was run all day)....and it seemed like the boost would get stuck at like 5,000 RPM's.......like the turbo wanted to spool but couldn't.


Engine temp/boost

My theory is its either old coolant or a sticky thermostat (changing both soon) and/or a clogged cat convetor.


Background On the car
I have a Apexi PF commander, tuned, with down pipe, cat bat, hi flow cat, intake, efni Y pipe, larger koyo radiator, FMIC and boost controller with an 8PSI and 13PSI tuned options. (stock turbo's run as a single)

Car sounds good.....don't see any smoke out the tail pipe........smooth acceleration through out engine rev range.


1st Questions:

Would a clogged cat converter have these symptoms?


2nd Question:

If I installed a mid-pipe on the car....Would I need to re-tune it? Its already tuned, it goes off air fuel mixture right? and I have a boost controller...so I would think it would spool faster but be limited. Question is......is a boost controller and stock wastegate capable of diverting enough boost away from the engine? Would I need to re-tune? It would be nice to get rid of the cat and rule it out entirely...get more heat out the engine.

Thanks!

rx7rcer09

to answer the first question yes a clogged cat could cause over heating issues along with bog down and poor running conditions. if its a cheap aftermarket unit it could be failing as many units cant cope with the temps the rotary engine produces. also if you live in a high altitude area i would re-tune to adjust to the thinner air and lack of good charge temps.

on the second question YES a re tune is a must when converting to a fully open exhaust, other wise you will overboost due to the new more free flowing exhaust. with these cars and engines its better safe than sorry pay the 2-400$ for a tune rather than the 2-4K for a rebuild.

lOOkatme

iTrader: (19)

Why would you re-tune....that doesn't make sense to me. I am not doubting you....just trying to understand.

I understand that tuning goes off air fuel mixture.......and I have a boost controller....set at 8PSI and 13PSI.

Now....whats regulated by the boost controller is pressure.....we have less air in CO....so the Turbo will work harder to get the same pressure....so higher operating temps may perhaps be the results due to the turbo working harder......but if your tuned at 13PSI.....and you get 13PSI...and the boost controller is limiting boost......why would you need to re-tune? 13PSI is 13PSI regardless of elevation correct?

rx7rcer09

you are correct 13psi is 13psi but depending on where the car came from lets say the mid west for example the AFR's the car will undertake will be different due to the air density. in a low altitude setting the air is thicker thus causing the car to run Ideal for those conditions when getting the thinner air the car will run rich and will dump fuel under load because there is not enough air for the turbos to suck and push into the intake. since you have a power FC you can have a map set for low altitude for example what is on there now and get a second map for your driving area.

in short you need to get a map to handle the new levels of fuel and air that your RX-7 will undertake, the power FC is NOT a self learning ECU that can adjust for changes in ambient air and fuel to the map. on stock twins too much fuel will cause premature failure of your turbo system due to heat.

lOOkatme

iTrader: (19)

Perhaps I just don't understand how tuning works.

You have an air/fuel ratio (AFR)......and you tune that ratio at sea level. The tuner specifies a list or an equation or a spreadsheet....or some sort of values that it says....if this input is X...you need to give the engine Y amount of fuel.

Now....obviously at sea level.....the engine has varying levels of inputs......at 0 PSI and up you will have a whole slew of air/fuel ratio's....all the way to 13PSI (let's say thats our max).

I go to colorado.....and where I am at it is 16% less air molecules than sea level.......but essentially....the only value effected is at 0PSI right? at no boost I am getting less air.....but now that boost comes on....I do have a map...because the tuner tuned at AFR's from 0-13PSI at sea level.....and pressure is pressure.....and I would have the same AFR's from boost on.....the only thing effected is off boost. Do they even tune that low anyway?

essentially.....higher altitude just ***** the AFR maps to the left....but thats only for off boost applications?

Maybe I am way off on this one.

CloudPump

iTrader: (2)

Pressure is not pressure.

13 psi of very very hot air has less oxygen than 13 psi of extremely cold air. While this may not be exactly what we're talking about in this thread, it's a good reminder that boost is different with different types of air.

-Geoff

ZipRex

iTrader: (2)

Google gauge and absolute pressure. The difference is that 15 psi gauge (what your turbo pressure meter shows) is only gauge pressure. Thus, if you are at 5000 feet and you see 15 psi you are at 15 psi above the normal 5000 feet air pressure (gauge). Air pressure at sea level is 14.7 psia (absolute). Air pressure at 5k feet is 12.2. You'd need to get an extra 2.5 psi gauge at 5k feet to match the air content at sea level.

arghx

iTrader: (3)

When you remove the cat, you improve the pumping efficiency of the engine. This could lead to a lean condition and it will certainly lead to more boost if everything else is working right. This style of computer does not directly measure engine intake airflow. Read up on speed density engine control.

lOOkatme

iTrader: (19)

The apexi FC + commander doesn't?

I called up the company that tuned my vehicle out in CA. The guy said the car does not need any tuning as long as the mods are the same on the car......and that the pressure difference is accounted for by the MAP sensor. He also said I can run either a mid pipe or hi flow cat....it doesn't matter....as he tuned the car with a test pipe........he said....if I run a mid pipe....watch for boost creep. The car was tuned at 8PSI and 13PSI.

I am going with a hi flow bonez cat.........if people were wondering.

lOOkatme

iTrader: (19)

Thanks for the reply.....I did check the internet and read up on it....exactly what you described.

Its in the last paragraph of whats described below for others.


http://en.wikipedia.org/wiki/Map_sensor

rx7rcer09

false, you will need a re-tune do to the new location of the car, and with changing from a cat to straight piping as stated above you will lean out and have premature engine failure. as also stated the Power FC is not a self logging/learning ECU it will need a new map put on once the exhaust components are changed and the way the car breathes is also changed.

lOOkatme

iTrader: (19)

I replaced the clogged high flow cat...with a high flow cat. essentially its all the same mods.


I don't know all this talk about retuning.....elevation changes here in CO alone are drastic.....we have changes from 5,000ft above sea level to 11,000 ft above sea level....just going through the mountains. I am reluctant to re-tune....because the car runs well with the current tune......and there isn't anyone here that tunes well.