EGT dilema
 

hey guys so .. after my new rebuild .. ( blew a Atkins apex seal .. just the very end ... but no harm done to the housings and or rotors miraculously ... i don't understand ) i have a bit of an issue , while cruising and breaking in the motor...when i took my foot off the gas on the freeway , my egt gauge gives an alarm ( 900 C ) at twins exit b4 dowpipe ... i was like WTF is this .. i have never seen 900 even boostng 13 PSI ... b4 rebuild

rebuild using rotary aviation O ring kit
RX7 specialties 2,, apex seals and springs
new side seals
all the rest including bearings are 15k km`s old ( atkins )


What can cause EGT`s to shoot up on deceleration ( throttle off ) ... mainly above 4K???? i am really puzzled by this

details :

Stock ECU + HKS fcon V 2.1 pro ( not PFC F-CON ) mapped by FEED ( timing and fuel ) NEW [ used to have pettit unlimited b4 rebuild ]
Upgraded exhaust all 3" cat rez muffler
upgraded intercooler ( quivalent to pettit medium stock mount )
plugs 4 x b9egv ( no resistor ) NEW [ stock 7`s 9`s b4 rebuild ]
2 boost controlers
that`s about it for engne related stuff


b4 rebuild ... car ripped the asphalt from the floor ... ( primary 12 ... secondary 13 psi )
all i changed is what is indicated above

now i get egt hot as hell on decel .... i did not push the car yet to boost past 7 psi ... still want to give the new parts some sealing time
also seem to have some ignition break off boost >5K rpm
what can cause this ????


thx for reading

please clarify: 900 C (1650 F) in the exhaust manifold before the turbos or in the downpipe? car has major emissions equipment including air pump, ACV, and EGR?

900c`s at the downpipe but my probe is not in the down pipe it`s in between the 2 turbo`s ... 1cm b4 the downpipe flange .
car has no more emissions equipment ( no air pump , no double throttle , no nothing )
i have a high flow cat
it did not do this b4 i resembled it
the only chages is the HKS ecu and the plugs ... that`s it


if i accel it`s fine egt`s are good ... but smetimes when i lift off ... they shoot up

but lets say .. hypothetical situation .... what can cause a egt rise on full decel ??? ( timing .... fuel ... tps ... ) ?
THX

How about this (says the person who is no mechanic): Is fuel cut set on your car? Maybe on decel your car is not cutting fuel and it is igniting and shooting flames, hence the dramatic rise in EGT temps.

As a guy who was shooting flames out the back, I set fuel cut upon decel and no more flames. never did look at EGTs when this happened, but I would assume temps would go way up when exhaust gases are ignited.

Just a thought.

that is what i am thinking as well ... my ECU is not detecting idle status of TPS ( which i set to correct voltage ) ... and continues to provide some fuel on decel

and as for fuel cut ... im not able to set any on the car ... it`s stock ecu with a pre programmed HKS ecu piggyback

Gotcha on the HKS piggyback. You could verify this by having someone drive behind you and see if you are shooting flames. Or on decel, listen for a "pop" or "gurgle" coming from the exhaust. If you can hear this, then it's flames. FYI - kept hearing this on my way back from DGRR and didn't really think too much about it until I noticed cars swerving behind me and hitting the brakes to get away from my car. Put two and two together.

IF (and that is a big IF) this is the case, can't you get a fuel management system to take care of this? I think the AFC-NEO incorporates fuel cut into its program so you could compensate for too much fuel at decel. Others probably do also.

i will try running stock ecu alone see what it does .... ... then add the hks
i was just wondering if anyone else has experienced this

and there are not considerable backfires made... some small pop`s
im gonna have a friend drive behind me and check for flames

btw this is the ECU im running .. could the non resistor plugs interfere with this bad boy ?

http://e30gumball.users.btopenworld.com/fcon5.JPG

I'm not convinced there's anything wrong. Running in 5th gear on the highway produces very high EGT's, especially with stock ports and stock turbos. Those are the only conditions under which the factory EGR system operates. The purpose of EGR is to reduce EGT's in order to limit NOx emissions.

https://www.rx7club.com/attachment.p...1&d=1248749328

i actually dont have EGR , i have a JDM fd3s im sorry i forgot to mention that
so here is the update

non resistor plugs seem to interfere with the HKS computer ( b9egv ) and possibly my prosport electric gauges
i swapped them out for stock 9`s all over and no more rising egt , no more unstable idle .. misfires
and max egt`s are now at 750 C at turbo exit ( down pipe flange ) when boosting on the highway 2-3-4 ... ( 12.5 psi )

:( i just wasted money on 12 b9egv .............. but hey .. i just saved a bunch of money on my car insurance :) .... GAIKO !!!! ( j/k)

so it appears for now ... non resistor plugs = no no with HKS ECU ... and /or prosport electric gauges

i appreciate youz all reading and scratching your heads on this one

HKS specifically calls for no non-resistor plugs with the Twin Power. this makes sense

i don't understand why you were running the b9egv. they are the same heat range as stock and they need a special plug socket. There are no advantages to them.

i dont have a twin power .. i have a HKS fcon v piggyback ( JDM equivalent of the pettit unlimited )
now that i rethink about it .. i regret getting these plugs .. and spending time enlarging the housing plug socket to fit my modified socket tool ... to get interfernece ...

bah .... who ever wants .. 12 B9EGV`S ... 8 are brand new ... 4 have 2 hours idle time and 150 km`s .after a rebuild let me know

Congrats on solving the problem. Nice easy fix too:)