Car was retuned on a dyno the day before and the next day I decide to drive it to work, had some trouble. First thing I noticed halfway to work is when I put it in neutral and coast it does the crazy reving up and down. I tried restarting it, but when I do it jumps all the way to 4-5rpm and stays there for about 30 sec and then goes into the crazy rpm/oil pressure/boost jumps shown in the video below.

Symptoms I noticed:
Seems laggier to boost, don't think I'm getting the full power
Car shaky at standstill a little.

Best way I can describe it is a car running without a MAF

Car has a single turbo setup /w HKS fcon and some electronics, theres under 10k on the rebuild, hope it's nothing serious.

Thanks in advance!

 

a few more things:

the day before it was leaned out on the dyno until there was no backfire, when this problem started I got some backfire and bucking..

Also, then I press in the clutch I get the same rev bouncing as you see in the video.


Bad TPS?

 

could be, or its to lean and not enough fuel, turbos 7s need that extra fuel, sounds like it has the throttle body mod, but they forgot to take out the idle spring thats required in the mod, if the spring is left then it jumps like that

 

he tuned it conservatively lean, he has tuned rx7s before. It ran perfect for almost 2 full days and then half way to work started acting. BTW its an FC with an FD throttle body

 

60 views and nothing seriously ??

swapped tps, nothing btw

 

1-- work out if is initiating the AWS on startup
,, is normal for revs to go to 3K for 17 secs ,, and sink back through 1500 then 850 then 750 rpm over the next 120 seconds when the engine is cold
-- starting with 5th gear selected should usually bypass this sequence

this AWS sequence is to protect the cat when it is cold , speeding it up to temp

if there is not 17 and 120 second periods on the steps,, it is doing the warm start routine
( to counter perculation )
the ECU uses the inlet air temp sender,, and the ECU coolant sensor results on a sliding scale to determine the length of the fast idle period , and if any shift in the basic idle timing is required during this period


ie,, 107 C + ( coolant ) and 100 C inlet air makes for 60 secs of extra fuel injection period ,, 90 secs of raised fuel pressure , 60 secs of bypass air,, and 70 secs of revised leading and trailing idle timing

conversely
65 C + coolant temp,,60 C inlet air temps amount to -
40 secs of increased injection period , 50 secs of higher fuel pressure, 40 secs of added bypass air and stock idle timing

to me it sounds like you are getting the warm start sequence, possibly that low temp end of the scale,, judging by your periods


combined with this,, your TPS calibration is out of whack ,, possibly due to not being calibrated properly once the engine is warm
( this causes the hunting idle )


--------------
to the OP,, you issue is likely the TPS,, or its calibration,, and it also sounds like you are using the FD air temp sender
-- the FD sender follows the delco curve,, and it is NOT suited to the FC ECU
replace that air temp sender with a functional FC unit

and then go to the coolant temp sender ,, check carefully that it is snapped on tight at the connection,, and that the outer plastic top does NOT rotate
if it does,, replace the coolant sender

NB-- the above is true only for markets with the AWS system ,, namely US and oz cars,, and maybe a handful of other nations

 

PS
,, if it is uber lean at idle it may also hunt, you may find you need to tweak the idle mixture with the adjustable resister beside the AFM to hold the steady 750 rpm
-clockwise is richer

 

I get the exact same symptoms when fully warm or cold
I'm pretty confident that it's running rich as im backfiring when im giving it a little gas.

Another thing I should mention, when this issue occurred while coasting say at 80km/h the car would rev up itself a little and let go (bouncing, but slower than at idle) so the car was throttling itself.

going to spray every gasket/host with brake cleaner now.


I don't have maf anymore, map sensor?

 

backfire is LEAN ,, bog is RICH
why dont you have a AFM? realtek? that sort of info is handy in the OP

if the symptoms are both hot and cold,,, then sounds to me you are running the FD air temp sender
( which is off scale )
and also the coolant temp sender has failed
( which substitutes a constant 80 C signal default )

and thus you go through the same warm up routine everytime,, and the engine runs lean before it fully warms up
( due to lack of correct coolant corrections )

 

If all that didn't work, I suggest starting simple. Turn the idle down as low as possible when vaccum is at its greatest and listen for leaks while the car is started (idling). If you hear a hissing open the throttle and see if it goes away. If so find it, fix it.

 

I don't ever remember the car warming up this way even after I started it after it's been sitting for 3 weeks.

I think I have the AFM in the fcon display

Can you tell me where the coolant temp sender is located please? It's an FC with an FD throttly body

 

OK I will try that, I just sprayed brake cleaner on all the gaskets /vacuum hoses I could find, no leaks found by that method.

 

fcon - doh - i missed that bit,, not very common in my part of the world ,, which one do you have?

the coolant sender is the one behind the water pump ,, has a injector type ev1 connector

if you have the FD UIM conversion then may you have the FD air temp sender on the underside ,,, and it should be bushed with a smaller FC unit installed , or one better is to put the FC unit back in the snout
if you have only the FD TB,, then do you should have the FC IAT probe installed in the snout

 

I have the gold version, it was tuned by an HKS dealer in Japan and had a few things adjusted here in Alberta for elevation.

I try to change the sender asap, if it's not the sender what else could it be just in case?

 

ID which air temp sender you have
you may be able to check the AIT and coolant senders via the fcon , or you can multi them and check them against the FSM

other than that i suspect that a sticky throttle,, or a wax cam system on the TB
or even overadjusted double throttle mech
may be pushing the throttle plates out or binding and effecting the TPS calibration

( which is certainly the hunt that is still visible after the warm start sequence drops down )

you should set the tps when the engine is hot,, and you may have to use the set connector couple method
( unsure if it can be calibrated from the fcon via software method )

 

i hear a massive leak now somewhere, can't find it.... any other methods other than spraying brake cleaner on all hoses/gaskets?

 

massive vacuum leak found, there was a hole under the throttle body manifold thing there was nothing in it, i put in a screw in there(circled in red a few times on the pic) and now the bounce does not occur at idle BUT WHEN I PRESS THE GAS PEDAL!!!. Question: how tight is the screw suppose to be ? All the way ? Because I have another problem now (see video below)





New problem:
Idles fine now, but when I give it a little gas it bounces idle and it won't rev past 3 RPM? (see video below, you have to click on the pic to see the video), please tell me if the screw has to be in all the way in the pic above and if the TPS has to be set a certain way( I changed the TPS, but there was no tension on the spring inside the TPS when I installed it)

 

sigh,, the spot you have bunged is where the air temp sender should be on the FD UIM

i keep telling you the 3K on start issue is related to a bad AWS signal,,likely a faulty air temp sender and maybe the coolant one too
-guess what?-

you also have the oil injector spider purge air open ended
,, and so this is unmetered air
it should come from a purge air port from the TB ( not true engine vacuum )


do the checks i have pointed out above,, i dont type them out cause i feel like it,, i type them out cause i see them as the issue

and i STILL do

air leak is only PART of the problem

check especially the coolant sender for the ECU,, resistances for temp should be in the FSM
( pretty sure the coolant is delco curve )

 

Just an FYI, I'm a newb,

some more info: the spider you are talking about was like this when the car was running fine, I will look for a place where it may have fallen off.

I will have to get a new air temp sender, I don't understand how it just came off though.

Also noticed one of my injectors were leaking a little bit.

 

sorry mate

i will spell it out a little better for you

because the fcon i know ( of old ) AFAIK were interceptor style piggyback
i expect the sundry stock ECU functions for other devices like the AWS ( if fitted ) to still be functional

my advices relate to how i would expect a stcock ( sic ) ecu will work with its Accelerated Warmup System,,, with a couple of twists to cover bases for jap and US or oz variations in the warm up
and to cover that you have an FD UIM,, likely missing some of the AWS critical components
- the ABSv ( air bypass solenoid valve )- responsible for the difference between 1500 and 3000 rpm start on the US/oz version compared to only 1500 of the jap ( which has no ABSv )

- the ASv ( air supply valve )- responsible for air bleed to the secondary mezzanine plenum for the low fast idle step ( and for power steer fast idle )

---------
with the above in mind,, your 3000+ rpm start is behaving like a US/oz warm start everytime
- looks like the fcon has a cold start delete ,, or your AWS flag sensors are bad -- air temp and coolant temp

and also the idle bouncing is usually-
-a TPS cal that is bad,, -( sometimes a wax cam that has its water diconnected and the cam is still interfering )
-or a lean running condition= tune + air leak
-or ( on a MAF car ) unmetered air leak

----------------


so,, there is what i was spelling out from the start

now,, seeing that you DON'T have an air temp sender
( at least one that is not plugged into the manifold )
is probs a good reason for the start routine ,, though the faulty sensor limp default is 68 F ( 20 c )
[ am suspecting the limp flag may also default to a warm start routine everytime ]

it ( the air leak ) is also a good reason why you have a 3000 lift,, working as if you actually still had a ABSv
and a good reason ( as shown above ) for a lean idle bounce

- so is the potentially disconnected wax cam affecting the idle adjust and pushing out the tps cal


other issues you have,, that oil injector purge air spider is open ended ,, that may be a little filter that is added to it
but really it should run to the TB purge port vacuum
also,, if injector leak ( fuel ) don't mess about,, needs fixing right away
,, and double checked with leakdown periods under pressure after assembly
-safety first-


NB
maybe the Fcon is calibrated for the FD air temp sender,, replace it first and try it

if it proves not,, you will have to bung and fit the FC one somewhere

 

Honestly I have always used rubber to seal up a vac. leak. They should sell plugs at your local parts house. If they don't sell them or they do not fit then rig something up that doesn't look out of place. But IMO it doesn't matter as long as the car runs right.

Also bumpstart could be pushing you in the right direction, although I am too lazy to read all of what he has put he sounds really confident and a lot better than me at this stuff.

 

I probably should have mentioned earlier, this is an FC RX7 with an FC harness with an FD throttly body and a manifold.. is this the air temp sensor? (greddy elbow pic)

Is this an air temp sendor



I don't have any black connectors that can reach all the way up to the manifold

I don't understand how the sensor can fall out and not stay attached to the connector ? Was there something in place of the sensor ???

 

If this is the ATS connector, there is no way it was connected to the sensor as it doesn't reach and it's from a FC (FC harness)



What the hell was in that ATS spot ????

 

Also update, when i have the screw plugged in (the leak closed) the original ATS spot start it cold and rev it a little, it dies when I give it gas, I tried 2 TPSs

 

the first pic shows an added in AIT probe,, it is not a FC one either ,, and so i highly doubt it gives the correct curve ,, like i said before there is the possibility it is calibrated in the Fcon


if the engine stall now you have the air leak closed off,, then it was tuned with the leak,, and is possibly now to rich to run ( while cold )

it may only be a momentary period where it is too rich as the car warms and you should try and keep it running with the throttle and see if it idles by itself with in a few minutes

else,, the car was setup with a FC UIM ,, and is expecting to see the AWS solenoids bypassing air when cold starting
( which are no longer there )