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94 Rx7 has been randomly cutting off engine from time to time (all lights on cluster comes on) while driving around town. Sometimes it cuts off when left idling for a period of time. Not really sure where to start looking .. engine is not stock mild build and running off apexi fc ecu. It use to run #10 plugs both T/L, but have since switched it to #7 and #9. Prior to plug changes its been doing this. Car does seem to drive fine but does feel like a slight lag in response when giving it throttle.
When you say it cuts off driving around, are you cruising along then all of a sudden the engine is turned off, or it stalls coming up to a light/stalls when idling?
When you say it cuts off driving around, are you cruising along then all of a sudden the engine is turned off, or it stalls coming up to a light/stalls when idling?
Dale
Yes engine turns off no signs of engine studdering or surging at idle. Most of the time its during coming to a stop but has also happen when in gear while just cruising. Has not cut off during acceleration.
Still having this issue.. friend mention maybe fuel filter is clogged and needs changing so ill be doing that soon .. at first crank car struggles to idle (surging between 4-900rpm for a few cycles before settling down to around 970rpm), with a/c on rpm drops to around 740.. things i notice that if i blip/release the throttle real quick the delay is real noticeable and eventually engine cutts off.. and if left idling for awhile theres a slight studder then cutts off.. engine temp shows halfway mark on the cluster but radiator fan has yet to kick on..
Thats a possibility.. its done this before when i got it but its been doing it alot more lately.. haven’t met too many rx7 fd owners/recommended tuners in the area.. as mentioned car drives/boost fine till engine cutts off unexpectedly..
Thats a possibility.. its done this before when i got it but its been doing it alot more lately.. haven’t met too many rx7 fd owners/recommended tuners in the area.. as mentioned car drives/boost fine till engine cutts off unexpectedly..
In my experience, tuners aren't the type of people you just meet if you're not in a rotary heavy area...they're the type of people you seek out. I managed to find one in Colorado Springs and a remote tuner based out of Georgia, so you should be able to find one if you look.
Make sure you change that fuel filter (its not as hard as people make it seem, DaleClark has a great write up on how to do it in less than 20 mins) and I'd recommend getting rid of those 7 heat spark plugs (from my understanding, they were only to pass emissions. I'm from NC, I know you don't have to smog your car) and switch to 9s all around...or whatever the tuner you finds recommend. Also while you're at it, check and make sure your air filters are clean (if in doubt, throw them out) and check for any sort of hoses and IC pipes that seem faulty. And dude, trust me, get an aftermarket water temp gauge. Had I had one last year, it could've saved my engine.
Keep us updated on your progress so we can help point you in the right direction if you need help. This forum has helped me TREMENDOUSLY and I want to help pass that forward and keep this thing alive for years to come.
For sure.. ill update progress as i do them.. some threads leave you hanging with original thread starter never updates 😶 if issues were resolved.. thanks
I had a similar issue, but it ended up being a faulty/defective HKS Twin Power ignition(brand new less than a year old), car would basically stall once it was warmed up.
okay so I'm finally getting around doing some maintenance. First off I changed the fuel filter (pain in the *** if you ask me!) and noticed the fuel residue that was coming out of the old one was brownis/dirty which tells me hasn't been changed in awhile since fuel inside the tank appear clear!!! also went ahead and updated the fuel pump to walbro 255lph and replaced the coolant filler neck with the banzai billet version + new apexi cap, Installed banzai 50amp starter relay kit aswell including a new battery since old one was dead.
1. So at first start for the year it took awhile .. had to do a few cranks before it finally started but still idle was very rough and bouncing from 8-300 rpm then cuts off .. it would take a few more tries before it idle stabilizes normal around 9xx rpm.
2. not sure why but I thought that when engines cold or at first start up normally cars would idle 1.5-2k warm up before it would settle to 9xx rpm or are rotaries different? (apexi ecu with commander) sorry for the newbie question..
3. So after letting the car idle for a period of time atleast 10mins. I been watching the temp on the commander and cluster (stayed about half mark) and around 90 Celsius but fans never kicked on.
** 4. still engine cuts off on its own if left it idling for several mins but also noticed the coolant temp on the commander would sometimes show - - - - - - not reading.. And just so happens that the one time when it did work I noticed the coolant temp started dropping from 25 Celsius downward as if it was on a timer all the way down to -6 before engine cuts off. tried to see if I could catch this again but couldn't replicate this..
For the moment this is about how far I've gotten.. will keep at it for a few more days before I just take it to a shop.
The commander shows the temp from the main ECU water temp sender, it's in the back of the water pump housing, 2-wire green connector. The 1-wire fan connector is right above it. It's accessible if you remove the alternator.
This is one of the PRIMARY inputs to the ECU. The ECU has to know coolant temp to richen the mixture up when the engine is cold. If you are getting goofy readings on that sensor, work on that first before troubleshooting further.
Those sensors rarely if ever fail but it's possible. It could be the connector or wiring to it, i would start with that. If the plastic connector is broken and doesn't want to stay on good you can buy a new plastic connector and pop the 2 pins into the new shell. May be worth getting a new sensor while you're in there for the heck of it.
Get that 100% before you go further. If the PFC suddenly things it's below zero outside it's going to be POURING fuel into the engine, that's going to stall any engine.
hopefully the links work.. the last video is of engine idle finally stabilizes even waiting after a few minutes and putting it thru first and 2nd gear (while on jacks) let it roll a few mph then let it idle in neutral. I decided to give it little revs and towards the end of the video you can see the water temp readings on the commander suddenly appear and drop right before engine shutoff/stall..
Dale you were right!!! the water temp plug came loose, seemed like the plug itself locking tab maybe broken at some point.. pushed it back in and commander shows temp reading now.. while getting to the sensors I noticed these 3 plugs were not plugged up, the grey and blue plugs seem to fit together but not sure if this was intentional by previous owner and the one 3rd (grey/yellow plug?) sits behind the alternator can't spot where or what it suppose to plug to..
that grey with yellow is probably the purge control solenoid, pcv does not have an electrical connection. i would check to see what other electrical connections are missing and get that fixed, in particular i would check your grounds and the idle air solenoid on the back of the upper plenum.
unless i am going crazy it looks like the pcv is broken and missing, the pcv should be a vacuum connection with check valve between your oil fill neck and the large barb on the front of the intake plenum near the throttle body. also check for other vacuum leaks because i hear a massive one in your videos. if you find a bunch of vacuum leaks i recommend replacing all that old rubber crap with new high temp silicone hose, careful removing the hoses from the plastic fittings, they are brittle and a heat gun is your friend here.
if you are not running the air pump you also need to turn off o2 feedback in the PFC so check that setting.
once the water thermo sensor was plugged up it started up pretty quickly and engine hasn't stalled as of yet, but won't know for sure till I put it on the ground and drive it hopefully this Wkend.. The hissing sound you hear in 2nd video is actually coming from the BOV, even when I put my finger to block the hole it doesn't appear to have any effect with idle. Will definitely be changing out the vacuum hoses later since they felt hard. As far as the pcv connection on the filler neck its always been like that even prior to the previous owner for the past 8-9 yrs or so before i took ownership .
why is your BOV open? the pressure differential should not be high enough to open the valve. so I am assuming that the large nipple on the upper plenum there has a cap on it then? if so at least run that pvc nipple on the fill neck to a catch can, you can get them dirt cheap on amazon and they work fine. so the car idles ok all the way through the warmup cycle now? does the idle return nicely when you snap the throttle? does the a/c idle the car up now?
not sure on the BOV just noticed this a few months ago just never had time to look into it since I was chasing other things. Yes theres a rubber cap on the pvc filer neck As far as the upper plenum fitting I don't recall there was one there prior.. theres still a few what I assume are small vacuum fittings around the throttle body area that doesn't appear to be capped so also will be capping these tomorrow .. when the engine is warmed up it starts fine and idles fine, turn on the a/c idle seems to be stable. Still noticed when blipping the throttle there seems to be slight lag in response if done quickly. Will know tomorrow for sure when I start it up while engine is cold see what it does.
Baught some vacuum fitting caps and started capping fittings that supposedly weren't used.
Cold start is much better fires up, idle still low around 5-6xx rpm, which threw me off since it was around 9xx prior to capping vacuum fittings. I removed 2 caps from the circled fittings in the pic which looks coming off the UIM before the throttle body? Suddenly the rpm started to stabilize around 9xx rpm .. Assuming these use to hook to some kinda EGR system that was removed, What/where should these fittings hooked too if thats the case (capping them off drops the rpm to around 5xx)
Getting what appears to be light grayish/blue smoke from the exhaust, heavy at first but lightens up as I drive it.
So far driven it around the block everything seems to operate like it did when I first got it and engine has not stalled as of yet. So the culprit to the engine stalls may have been cause/related to bad water thermo temp plug which worked it way loose and PFC unable to compensate for temp reading. Fans are also working kicking on at 88 Celsius. Also since I changed out the rear UCA and LCA I'm no longer getting the clunking noise.
Thanks for everyone pointing me in the right direction, especially Dale "cheers!"
not sure what those go to i would have to look at the vacuum diagram, my car is single turbo so the vacuum is very simple. those need to get plugged off and any other ones that are open. there should be 4 ports in that area you circled, 1 big one that used to go to the pcv system with a check valve, one that goes to the purge control solenoid, then two that i don't know off the top of my head. the purge control solenoid used to be mounted to the plenum support bracket that looks to be missing on your car.
the temp correction should be working properly now but you should be able to idle higher with the vacuum system sealed up, those open vacuum ports are masking a problem with your idle control system. did you check the idle control solenoid plug on the backside of the upper plenum? those things get brittle and break and like your ect sensor may have fallen off.
looks like you have a bit of a mess on your hands but with a little work should be able to sort it out.
ill ck and see about the idle control solenoid tomorrow. I was able to find diagrams of the vacuum lines ... so from what I can see going by the colors but the blue goes under the Double throttle control but doesn't really show what it hooks up too maybe a vent? pcv, charcoal canister and vacuum chamber https://line.17qq.com/articles/fmgshkpny.html
06-13-20, 09:52 AM
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... so from what I can see going by the colors but the blue goes under the Double throttle control but doesn't really show what it hooks up too maybe a vent? pcv, charcoal canister and vacuum chamber