Hunting and unable to rev the engine hard past 4,500rpm 1992 FD3s twin turbo touring effini as seen on CAR SOS

[bazjim]

Hi all

very new on here so please be gentle,
this post is for my dad Conor Barry. His "Roxey" FD3s effini Twin HKS turbo is the one shown on Car SOS last year with Tim and Fuzz on channel 4

we are having some major issues since the car was put away for the winter.

when we start the car and leave it to warm up the car is hunting really badly. we know that it should do it a bit on a cold start but its really bad.
we are now unable to rev the engine hard (never tried from cold) only once warmed up to we don't break the baby.

if you slowly increase the revs you can get to the red line, but if you try and stand on the accelerator hard it just cuts, splutters and back fires.

you can't drive it at all it just won't pull, we can only just about move it at 5mph to move on the drive.

so far we have changed the fuel filter only.
when you unplug the boost sensor it idles great but still the same issue with revving.

ive linked the twitter videos I did below hopefully they work.

https://twitter.com/x/status/1102141901405339648

https://twitter.com/x/status/1102141813387874305

https://twitter.com/x/status/1102141505454702592

 

[Jit]

Need some more info about the car. Is it on a standard ECU? If so, could be in limp mode. The inability to rev sounds a bit like a blocked exhaust/collapsed cat

 

[bazjim]

I think it is on a standard ECU, the cat is clear and free, it will rev under light throttle to the red line it just dies if you try to rev hard, as per the vids

 

[Paulm]

Could be injector related, either blocked or no signal to secondary injector(s). But a whole bunch of issues, plugs, coils, leads, wiring, etc etc, could cause this. Would need a bit more info to try and narrow down problem

 

[bazjim]

Yer Andrew at jimmys said it could be injector related.
If the vaccume hose on the back of the boost sensor was connected to the wrong pipe on the rats nest could this cause it?
We did a little bit of investigation yesterday and found one of the vaccume pipes disconnected from the side of the throttle body.
I’m sure there was another pipe with no hose connected also.
We will do a bit of digging and look.
Has anyone else had this issue?

 

[jdmr_neil]

Spark plugs, ht leads. Is it stinking of fuel more than usual. Hunting idle could be a vacuum leak from anyone of the vac pipes

 

[jdmr_neil]

Wrong hose on the map sensor could certainly be your problem. Tbh this sounds like a culmination of issues

 

[bazjim]

The HT leads are being replaced next week. We ran out of time this week.
Will look and make sure the vac pipes are all connected when we take the induction off the top at the same time.

 

[Efini-dan]

Have you run the flash codes yet? Like jit said it could be in limp mode. Thats what it runs like if it is, I've had this before.

Theres an easy how to guide to do it without the mazda test gear on a forum somewhere.

 

[bazjim]

Sorry don’t know how to run the flash code
Will have a search if nowbody has the how to guide.

 

[bazjim]

Afternoon All
so just to update, this is a stock setup on sequential twin turbo's possible HKS but cant see under the air box to confirm.

Today we did a bit more investigation work, The vehicle was stuck in Limp mode (Thanks to Andrew at Jimmy's for the info) and we disconnected the negative from the battery and stood on the break pedal for 2 min's to reset the ECU.
This worked a treat and the vehicle rev'd and drove really well, Both Turbo's kicked in at the correct stage and it pulled nicely.
the hunting is still there and it idles at about 1500rpm-1800rpm, (personally I think this is a little too high)

when we disconnect the Boost valve it drops to 900Rpm but its still hunting. we have a new boost valve on order to try.

we have Luke from Murdock's Rotary Specialist coming on Tuesday to do some more investigative work
Luke seems really knowledgeable and really happy to help.

we are fitting a straight through HKS de cat pipe from manifold and a silent HKS back box.
New HT Leads
pressure test and spark plug clean/ check
New fuel filter already fitted.
Coolant flush and change
Oil and filter change
and a few other bits.

the vehicle was brought into the UK through Andrew at Jimmy's Norfolk. fully engine rebuild and was perfect when handed over in 2002.
due to the distance the vehicle was then serviced by Hurleys of Coventry since and we have never really been happy with the service.
They changed the Clutch on the last service and inspecting it today they clearly didn't do a very good job as the bell housing isn't tightened correctly to the engine, 3 bolts loose.
On the Car SOS show Hurleys doing a pressure test, when the vehicle went to Car SOS it didn't Hunt or have any idle issues, its come back really lumpy and with the issues, we also found one of the HT leads not connected correctly and on valve pipe from the rats nest disconnected. the engine earth at the top of the engine near the lift mount and the fire wall was also not correctly tightened, we have sorted this.
has anyone else had issues with Hurleys?

looking into at the Y pipe we have found this pipe crushed and brittle this will be replaced ASAP but what does it do?
sorry for being so Green about things and abbreviations. all I want is to get the car working correctly and reliable for my dad to enjoy, this is the main reason it was put forward for the CAR SOS show.

below are the pics

 

[shaunwil]

Its one of the vac feeds to either the recirc / blowoff valve for the turbos.

 

[bazjim]

Hi all

Some interesting news

I've found a great gent from the MX 5 world who has created a diagnostics reading tool for a Mk1 and Mk2 MX5.

these early MX5's have the same diagnostic plug as my Mazda RX7 1993.

I gave him the codes off this site and bingo we have new way of reading the fault codes.
as you can see I can also force the fans on and get the fuel system to fire without running.


please NOTE this is a working prototype.

the new more up to date version will have a colour screen and allow more tricks like Volt checks and other items.

https://twitter.com/x/status/1116369819975155712

https://twitter.com/x/status/1116369918021255168

https://twitter.com/x/status/1116369443255463936

https://twitter.com/x/status/1116369148630712321

https://twitter.com/x/status/1116369129555005448

https://twitter.com/x/status/1116369106121392129

the next thing is to fix the two issues I have.
can anyone tell me where the fuel thermosensor is?
we are getting all the vacuum pipe replaced Monday.

 

[jack.am]

Cool diagnostics tool.

Fuel thermosensor is in the fuel rail under the UIM, green backed connector. Have you checked if the idle screws are all set properly? Is the TPS in range?

 

[MKZ7212]

fuel thermostat sits in the secondary fuel rail green plug
how much are the diagnostics tool?

 

[bazjim]

not sure on the final price yet, its in the final stages of development 2-3 weeks away.
I think it will be around £50-£60 it will have a usb connection (to allow for firmware updates), blue tooth and a new phone app to allow you to sit in the vehicle and rad the codes.

the TPS is the next job to check, we did have a go yesterday but our volt meter was playing up.
the idle screw to the front of engine is correct, not sure if the one under the TPS has been set correctly.

 

[bazjim]

just a quick question. is the water sensor the same as the fuel sensor?
I've called mazda and they said the have the water one but can't find the fuel version?

 

[MKZ7212]

just a quick question. is the water sensor the same as the fuel sensor?
I've called mazda and they said the have the water one but can't find the fuel version?

Will have a look at the part numbers tomorrow for you

 

[jack.am]

just a quick question. is the water sensor the same as the fuel sensor?
I've called mazda and they said the have the water one but can't find the fuel version?

Yes, exactly the same. Also interchangable with the Supra temp sensor.

 

[bazjim]

Brill thanks jack. I will get one ordered tomorrow.
I will do a new post when the new diagnostic tool is available with price and features.