Ok, so here is EVERYTHING thats been done to the car...

--3k on large street port rebuild
--FD rotor housings
--S5 fuel rails
--Star SPEC stage 3, 4 puck clutch
--Accel 8.8 race wires
--permacool 16" Efan
--Hurley racing seals
--NO emissions
--NO power steering
--NO a/c
--Solid 3" turbo back exhaust/ buddy intake
--720cc secondaries
--resistor pack from 87 FC
--Auto meter A/F and boost gauges
--Racing Beat FCD
--removed twinscroll
--HUGE ported wastegate
--12 psi on HT18

OK, so that is everything thats done to the car. It has only 4 vac lines...all of which are good. I sealed the TB in every place possible, none of the vac lines are leaking. Ive sprayed carb cleaner everywhere, I have even changed out TPS's. Timing has been retarded where it should be and STILL the POS revs over and over...from 1500-1800!!!! up and down and up and down...its ******* driving me NUTS!!!

What is going on!! I am seriously ready to 86 this entire car!!!! Ive been messing with this POS for a year now and it has NEVER run right....EVER!!! If I thought I could get what I wanted out of it, Id sell it and buy a 510, but that wont happen, so I press on.

Dont get me wrong, its very fast, it just never idles right, it either jumps or dies...Please someone tell me they have been through this and it something really simple im over looking...HELP!!!!

 

It will stay alive and just fluxuate between 1500 and 1800?

What vacuum lines/solenoids do you have left?

 

have u tried probing with a vacuum line to your ear? works wonders, Check for leaks on the fuel injectors(bad grommets) and on your intake manifold, mainly lower to upper intake manifolds. What about your MAFs, all connections tight and plugged in completely? And isn't a large streetport like a wild cam on a piston engine, = unstable idle.

 

Arex, I have the vac spider, brake booster, and FPR...so i gues I only have 3 then. Some times it dies, sometimes it jumps...usually it jumps.


1Rev, fuel injector grommets have been replaced...used to have a leak there, but thats fixed now. Large streetport does give an unstable idle but not like this...i cant even adjust this down...it stays there


can oil injectors cause vac leaks? maybe thats where my problem is now.

 

When you removed them, did you put new crush washers in?

 

Did you take the BAC off? I didn't because it can help set an idle.

Mess with the BAC, and the Idle adjust screw on top of the TB.

If you don't have a vacuum leak, then you just need more idle control. If you took off the BAC... put it back on. It's not worth the hassle to take it off.

 

You **can** make one run with no controls, and run well. Mine had a ported mdded TB, 4 vacuum hoses, no TPS, no BAC, and it would still hold an 800 steady idle even with the a/c, p/s and brakes all being worked.

Try the thing with no tps. Some cars will tolerate running without it, some will not. IF you can run without it do so. You will have to readjust your idle to do so. You are adjusting the idle via the hard idle stop set screw on the back of the throttle body right? 8mm locknut with small flathead setscrew inside? That's the ticket.

 

Check your nuetral switch, and clutch switch. Both if which will cause a high idle, and wou will NOT be able to adjust it down without the car stalling all the time. I spent MONTHS fighting that on my GTU, and it was as easy as unplugging both switches to make it idle normally.

 

How will ecu know when the "wot" position is reached? Will it matter is the ecu does not know?

 

The ecu uses the airflow measured by the afm to calculate fuel and mine ran flawlessly without a TPS telling it was at WOT or not. In fact, I stil retained my closed loop feature as well without it.

 

Where might one find these switches, ill try and unplug them, but i wanna make sure thats what im unplugging!

 

Hmmm... I'll try that...

 

The clutch switch is right in front of the clutch pedal (or is it behind). Is a pull\push switch that touches the clutch pedal, look at the pedal and you'll see it.

Sorry, don't know where the neutral switch is at

 

The plugs Mazdaspeed is talking about go from the tranny to the engine, only like 3 of them I think, lemme see in the hayes manual for which is which

 

its on the transmission

 

okay well the hayes manual sucks, its one of those connectors

 

Download the FSM from www.fc3s.org

 

Won't unplugging the TPS make your ECU panic and default to 50% max oil injection or something like that? I thought that was in there as a safety measure in case somethign stopping working so you wouldnt burn up your engine.....?

 

on the 88, the fuel injection isn't electronic, so as far as I know, it's just that mechanical linkage directly to the pump, and has nothing to do with the ECU. On the S5, though, the TPS may affect the oil delivery. Not positive of that though.

 

Yeah I need to clarify that. ON s4's, if the car will tolerate it and run ok, it's safe to run with no TPS. OIl metering is handled via a physical rod linked to the throttle.

ON s5's though, the TPS is a requirement. IT runs the oil injection, the anti-flood startup feature, plus it will set off a check engine light the minute you unplug it.

 

You forgot to mention S5's run like **** without the TPS connected.


The nuetral switch is one of the plugs on the tranny, Look at the FSM to be sure though. I dont remember which is which.

 

if it has a mass air meter check the senser i have seen
dirty sensers do it to other cars

 

You are running on the stock ECU? If so, you might be running rich at idle and causing it to go nuts. Just a thought. 720s are pretty big, but so is your turbo, so i dunno. Im pretty new to the turbo scene so dont take my word for it.

 

The secondaries arent open at idle.

 

and the turbo wouldn't affect them anyways. Would a rich condition cause the idle to fluctuate though? Cause I was running real rich before and the idle was fluctuating, but I thought they were seperate issues.