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FD Stalls at Stops
Hi everyone, I'm really new here, and I just recently purchased an FD. The previous owner of the car said it has an JDM engine swap. While driving the car, I can tell you that the car runs super strong, and it will pull and haul ass like no other. The only problem running-wise with the car is that it has really bad idle when it comes to a stop and will more than often stall. The owner said the car probably has a problem with an apex seal on the rear rotor, and since there is no grinding coming from the engine, which may come from the apex seal coming completely off and tearing up the inside of the engine, I am assuming that the apex seal may simply be stuck. However, since I am fairly new to rotary engines, I am wondering if any other problems may induce the motor to stall. Please reply with any suggestions. Thanks!
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I had the same problem. Does your car have a strong exhaust smell when you first start it? I am willing to bet that your airpump just took a poop if you do! I removed mine and the exact same thing happened to me. I adjusted my idle by using a guide from one of the guys here, just do a search for airpump.
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Start troubleshooting with Section F of the Factory Service Manual. You can download a copy for free from the stickied thread near the top.
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Does anyone else have any other suggestions?
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We can't magically solve your problems for you over the internet. You are going to have to get out the FSM and get your hands dirty. Or take the car to a shop if you aren't willing to do that.
If you suspect the motor is blown, then get a compression test and be done with it. If the motor's ok, it could be lots of things -- clutch switch, bad TPS settings, bad idle speed settings, etc. |
check your idle speed control valve. the idle speed is computer controlled and should not need adjustment unless you have an aftermarket ECU. if the other owner had the engine swap there could be a chance it was left unpluged by mistake.
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I had that problem with two other cars, it was a bad torque converter on both. Just snipped the wire going to the TC and worked fine. Little less mpg, but it was a cheap fix!
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Does anyone know how to "unstick" stuck apex seals without having to remove the engine?
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dude, you dont have a stuck apex seal, i can pretty much say that period.
Stop running round the route and do what the other guys in this thread have recommended, or else stop posting. Theres no point in asking for help if you wont follow the advice given! Let me repeat though, you do NOT have a stuck apex seal. The engine would not "haul ass like no other" if you did. It'd be in pieces by now (grenade style) For your info, ive got the same problem, ive rebuilt several RX7 engines myself and i have the same problem as you on my current car. I agree with everything these guys have said. My air pump took a shit of me, my TPS went bad on another car. Check them all. Your air pump is the leftmost pulley in the engine bay nearest the air filters/box. The centre of the pulley should be spinning at idle, and stop spinning above 3k rpm. If it isnt spinning, check your AC fuse (on the US drivers side fender in a black box, just above battery), air pump relay (under the black cover at the nose of the car, held down by two 10mm bolts)and if both the fuse and the relay are in good shape, pull your multimeter out. Check you have 12v across the two terminals that the air pump plugs into. If you do, replace your air pump, if you dont, check wiring further. If your not willing to do that, tkae it to a shop. If you cant afford to get a shop to work on your car, get rid of it. |
Sounds like a TPS issue.
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but can you un stick his apex seal?
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Well, I took my baby to Gotham Racing today, and it turns out the motor was blown. Two faces on the rear rotor were bad.
Now, I'm having a Mazda reman engine installed in the FD. |
harsh!
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Hmmmm. I had this problem at one time, but all it was for me was my TPS. I set it corrctly and now it runs fine. SOrry to here it was a lot worse for you.
goodluck, -josh |
my tps was the problem bought one from fritz then it was fixed
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Check your wires, plugs, clean the TB, adjust the TPS
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Realy need to ask what TPS stands for and were on the car is it ? A pic on it will help to :)
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Originally Posted by RobTheBankz
Realy need to ask what TPS stands for and were on the car is it ? A pic on it will help to :)
It's on the firewall side of the throttle body, you can see the wiring harness for it just above the oil filter. |
That sucks. I'm sorry to hear about your car.
I'm curious. How much diid you pay for this car? It's sounds like you haven't had it long at all and now the motor is dead. Did you do any mods to it? Or did the you just get taken advantage of? |
TPS stands for throttle positioning sensor. Here is some links that you may be intersted in.
goodluck, -josh Throttle Position Sensor ( TPS ) adjustment, fix idle / hesitation problems: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fixed-my-idle-problems-backfiring-bucking-more-170731/ https://www.rx7club.com/showthread.p...0&highlight=tps |
Originally Posted by jpandes
That sucks. I'm sorry to hear about your car.
I'm curious. How much diid you pay for this car? It's sounds like you haven't had it long at all and now the motor is dead. Did you do any mods to it? Or did the you just get taken advantage of? |
This problem is common to many FDs and does not necessarily indicate a bad apex seal. When I bought my car, it did that but went away after cleaning the TB and adjusting the TPS. You should go get a compression test if you are worried.
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Originally Posted by TheOneChen
...it turns out the motor was blown. Two faces on the rear rotor were bad.
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Originally Posted by New Phase!
I don't understand how does it possible that a blown motor that can "run super strong" just "stall at stop? (Don't get me wrong, I am not mocking you, just trying to learn here)
Also maybe because the user was not aware of putting the gear stick into neutral on a traffic light / stop position. Thus the stalling. Otherwise it's "hauling ass" https://www.rx7club.com/images/smilies/fawk.gifBest thread I've read today.https://www.rx7club.com/images/smilies/fawk.gif |
The seller did indicate to me that the car had a bad rear rotor, but when I drove it, it still seemed to create a lot of power. I ended up buying the FD for $8500. The car is in excellent condition, except for the engine, of course. I did get a compression test at Gotham Racing, and that is how they concluded that the rear rotor of the engine was bad. Also, since the previous owner never upgraded the ECU, I came to the conclusion that that was the problem, and the stock ECU could not keep up with the engine after all of the aftermarket modifications, thus causing it to blow. The modifications on the car include an A'PEXi N1 exhaust, A'PEXi twin intake, Koyo radiator, ACT clutch, downpipe, GReddy turbo timer, as well as many others, not all of which contribute to the destruction of the engine. Right now, however, I am still very confused as to how the car could still run with such power on one properly working rotor.
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...and kuning, yes I DO no how to drive manual! I've been doing that all my life, so keep smartass comments to yourself!
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you guys can be such assholes sometimes. I cant wait till your motor blows and someone rips into you for it.
are you fucking 17? |
Depending on how badly the apex seals are you can have a strong running engine at high rpm's, but it would run like crap at idle. At idle the engine is not spinning fast enough for a good seal, you will get a lumpy idle. You can probably keep the engine idling by adjusting the idle speed up a bit until you get the rebuild. At high rpm the rotating forces is spinning the apex seals outwards so that you are getting a much better seal against the rotor housing. The high rpm will compensate for a bad apex seal spring or a cracked seal (all the pieces are in place and have not been ejected out of the motor yet) You can drive the car for a while but just take it easy, when the seal(s) goes it can also take out or at least chip your turbine blades in the turbo. I know because it happen to me about 7 or 8 years ago. I drove the car with a blown motor for about 3 or 4 months, I was just to lazy to put the mazda rebuild I had bought and, so I just ran with the tb adjusted to compensate and maintain idle. The car gave me about 6-8 miles to the gallon and shot flames everytime I left off the throttle or shifted when boosting. The car ran strong as hell at high rpm but ran crappy at idle. When I finally put the rebuilt in the car didn't run right. The car would idle at 3K rpm. I didn't want to break in the rebuilt at such a high idle. It took me a day to figure out when when wrong and it ended up being that I have forgotten that I've adjusted the tb to compensate for the bad apex a couple of months back.
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fd3rew, thank you for that awesome explanation. That pretty much answered all of my questions as to the condition of my car. I am very grateful!
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Also, before, I asked about "unsticking" apex seals without removing the engine because I had read somewhere that you could poor a special liquid into the engine and hand crank the motor to get rid of carbon buildup that might keep the apex seals from working properly. I asked Alex at Gotham Racing about this and he said that such a procedure exists, but the success rate was very minimal, and that I would most likely be better off with a new Mazda reman engine.
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I'm not sure if there is any special liquid you can use but at worst case senerio you can try automatic tranny fluid. ATF contain detergent which can help clean/soften or possible break away some of the carbon or sludge buildup. Some mechanics would use it in crankcases in piston motors for sticking valves and lifters or to clean up things up under the valve cover before major work, but for the rotarys you will need it in the combustion chamber. You'll need fill the combustion chambers with ATF (add fluid, rotate motor by hand, add some more, and continue until there is a good amount of fluid in the motor) let the motor sit for over night. There are many different ways of getting the ATF in (remove upper plugs, remove upper intake manifold, or thru the tb, all of which will work, it all depends on what you think is easier for you to do) After the ATF soak, pull the EGI fuse or disconnect the fuel pump and crank the motor over to blow out all the ATF and depending on how much patients you have you may want to repeat it so you can be sure that ATF have reached behind all the apex seal groves in the rotor give the springs a good soaking too. If you still have emission devices on (pre cats and cats) you may want to unbolt them and block them off before you start so that you don't flood them with oil, but if it is straight thru exhaust, it will probably coat everything with oil and eventuallu blow out of the exhaust. Either way, it will be messy. Have a another set of plugs ready to swap out because they will get soaked with oil. The ATF method is similiar to the method used to unflood the early generation RX7 but instead of using the ATF to provide better compression for starting, the ATF will be used to remove buildup. Either way it will be a smoke show when you start it back up. I also have to agree that the success rate will probably very minimal but if you are trying to avoid having to replace a motor and have some time on your hands, it doesn't hurt. If your problem is with the apex seal springs, chances are the springs are already shot. The motor might have ran hot at some point and the apex springs already loss some of its tension, or if the apex are cracked, it will not seal perfectly and will probably only dig into the rotor housing over time.
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You can de-carbonise your engine by adding a line to where the boost gauge normally sits and submerging the line in water while the engine is running. Youll need to open the throttle a bit to stop the car stalling here and keep the car in vac (no boost!) just let it idle at around 2krpm while sucking in the water and youll do good. Itll blow a crap load of smoke and it might help you out though. Connect the line to both nipples on the UIM there as you need to do both (one front rotor one rear)
I doubt itll work though... |
Again, thank you very much for the information, guys!
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