ok all... my '93 FD has a freshly-rebuilt engine in it right now, w/ only 375 miles on it so far (it has not been put to any real boost or WOT since install) and my car is consistantly acting this same way everytime i drive it... it starts up fine, idles at 1000-1100 rpm's as it warms up. but after a bit of driving (30 minutes maybe?) and being parked warm, when i come back to the car and start it back up it has a really bad idle... very low, around 550-720 rpm's and w/ a vacuum of 330-360. the whole car will feel shakey as the idle dips around, sometimes hitting 500 rpm and feeling like its going to die (it usually doesn't). after a few minutes (3-6), the idle will just all of the sudden level out... the tone of the engine gets higher and the rpm's steadily start rising, ending up at a normal feeling 1050-1150 rpm. it does this consistantly *every* time i drive the car, after being parked warm it will hunt desperately for idle for a few minutes, and no amount of prodding the gas can bring it to a normal level before its ready to. wtf is wrong w/ my car?

i'll list my configuration as best i can below, i know it is far from stock (i thought about putting this posting in the single-turbo forum but decided here was best), if this behavior rings a bell or sounds an alarm to anyone, your input would be greatly appreciated..

'93 FD3S, BB base
Haltech E6K (w/ 3-bar map sensor)
freshly-rebuilt motor w/:
*2mm Hurley seals
*very deep street-port w/ ceramic coating
Garrett T04 'Q' single-turbo w/ custom manifold (stainless)
550cc primary injectors
1300cc secondary injectors
modifed fuel-rail (for secondaries)
HKS Twin-Power ignition
Inline fuel-pump
Custom surge-tank, w/ braided lines upward


...any help w/ this would be great, i'm really worried that there might be something wrong w/ my new motor!

 

Gosh that doesnt sound good.Was it running fine for the first 375 miles? It sounds like maybe the hurleys arn't seating right. Dont let this scare you because it also coud be many other minor things like vacuum hoses crossed or pinched.etc..I am having mine rebuilt with those same seals (2mm hurleys). You need to get the car looked at by the builder of your motor.. Usually the vacuum is a bit lower for the first few hundred miles until the seals set and vacuuum rises...

 

thx for the reply... hmm, my vacuum seems normal, except at these odd periods when the car is started after being parked warm... after going single i don't have the rats nest of vacuum lines any longer, i'm pretty sure its not a line since it goes away after a few minutes... it has acted this way since being rebuilt..

 

Sounds like it could use Decaf.
Is everything torqued right? Did you check the compresion?
It doesn't sound good what ever it is. I would tell the engine builder, and have it looked at asap.

 

Dont freak out here. First things first adjust your idle screw ..Its facing the hood you have to loosen the 8mm nut around the screw first than tighten down the screw till you get 1000rpm or so then
retighten the nut. then check you vac pressure again.

 

When you put everything back together, I'm assuming you ditched the fuel pressure regulator solenoid. This may be a long shot, but what if it's vapor lock?

 

That concerns me a bit because my car has the original engine with about 61k on it and it idles around 700 to 800 RPM and it too sometimes sounds like it is going to stall. Is there something I should be checking? The car runs pretty good aside from the idle speed.

 

thx for the replies people... yes, the engine builder has played w/ the idle screw repeatedly now... it doesn't seem to stick however, maybe helps for a short period of time. is a compression test in order in this case, even when an engine is this new and w/ so few miles? i payed a lot for this motor and don't want it to explode the first time i hit it w/ 14 lbs. of boost (it *should* be able to handle that!)... i don't think i have the normal fuel-pressure regulator solenoid, i have an external fuel pressure regulator (paxton) and no fuel pulsation dampener any longer... any advice appreciated as always!

 

bump on this (sorry!), i am clueless as to what is going on... is the warm-start/low-idle problem indicative of any certain condition, failing engine, low compression? the turbo is bad, leaking seal in it... its just a loaner as mine is being rebuilt, but i was told it was safe to run around lightly w/ for a while, as long as i wasn't hammering on the car..

 

how is the haltech tuned?

 

Send dave at kdrotary (kdrotary@enter.net) an email...make it as detailed as possible. He's always very busy, but he should be able to give you an answer. Trust me, dave knows FDs inside and out.

 

thanks to you friends... i'll try to write up something detailed to send over to Dave tonight... as for my Haltech, it is running a fairly generic program right now for my single T04 and my injector configuration, as my tuner cannot really tune it properly until my engine is 'broken-in' from what i was told... made sense, since he tunes w/ a wide-band from the passenger seat, and a lot of WOT is needed for tuning... we have checked the fuel pressure and the air/fuel mix, both are normal... just for that period after a warm-park does the car act wacky... intermittant problems, i *hate* them..

 

UPDATE:

ok, the situation seems to have deteriorated... took the FD out today for a 20 mile drive, it started up fine, idled at 1080-1140 rpm as i waited for her to warm up a little, drove fine to my destination, and sat parked for 30 minutes... as i return to take off again, i start her up, expecting to have to sit a few minutes while i wait for the idle to return to normal... well, this time, it never does.

i wait 25 minutes, and the idle stays at a mushy 610-680 rpm, never 'catching' like i've become custom to after a little while... so, i bite the bullet and go to drive home in low-idle mode... big mistake. of course, rush hour has set in by now so i am in stop-n-go traffic the entire way home, while my blasted FD periodically dies in traffic and has to be restarted (starts getting harder and harder to start as this goes on)... i get near home, and in my ire i decide to stop at a gas station for cigarettes (need them by now), another mistake on my part. get back in the car, start it up, it now idles around 320-490 rpm, and will die if you take your foot off the gas. i limp home, still in rush-hour traffic, but now having to *dance* on the pedals, keeping my foot on both the brake and the gas so she doesn't die. i get her home, and as i let up on the gas rolling into the driveway she of course dies utterly at that point.

i sit and fume, think about setting it on fire, and then come up here and rant on the rx-7 forum... is my engine dying w/ only 390 miles on her? trying to get w/ the engine builder but i don't want to be in the dark here... any advice from you guys that actually understand how these motor's work?? i just know to slip my wallet into the vent on the hood..

 

My 2 cents. First back off the "idle speed screw" on top near the throttle, its not the idle speed screw. With you engine warm short the "TEN" pin with the ground pin in the diagnostic connector - I use a paper clip. Turn off all electrical stuff like fans AC etc. Next under the intake angle pipe near the bottom right nut that holds it on - you will see a recessed big screw. This is the idle air bleed screw or "true idle speed screw" adjust it for about 750RPM depending how hairy your port job is, you want it around 850RPM. Make sure the top screw near throttle has no effect turn it back and forth. then turn in in until it just starts to increase speed - stop there. Pull the jumper from "TEN" to ground. Your idle should stabilize turn on fans lights etc. the speed should increase as the load increases. This procedure is in the manual page F-16 to F17 and it works. If after this you still have problems then I wish you good luck as it may be hard to find this kind of problem.

 

hi luneytune, thanks for the detailed reply! mmm, does the procedure you describe still apply if you've scrapped the factory ECU altogether? i am running a Haltech E6k and don't have a normal ECU at all any longer..

 

Yes, it should. The Haltech does control the injectors for idle as the factory ECU does so if the Throttle position sensor (TPS) is calibrated correctly the correct fuel will be injected but the amount of air availble is controlled by the 2 screws, the primary underneath and the secondary near the throttle. The only difference is you won't need to do the paperclip thing I believe, since this is not used by the Haltech but the PowerFC would need adjusting this way but in the case of the PowerFC you can also control your idle speed via fuel injector - still have to calibrate air though. Try the lower screw adjust only at this time, if you have an Air/ Fuel ratio guage it may show some change but you should notice a change in idle speed or just the roughness as you go from one way to the other. If your port is extreme a lumpy idle may be the norm but you should be able to compensate with your Air bleed and maybe your haltech. Good luck.

 

thanks very much luneytoon, you've just set my weekend for me! have a good one, i'll let you know my result...

as a side note, i took the car out just now for a quick jaunt; started right up w/ a strong idle, and idled at 1140-1230 rpm's the entire time, w/ vacuum ranging from 420-465 mm/Hg... the weather got a lot cooler here tonight, whereas earlier today it was unseasonably hot w/ humidity up in the 1000's... perhaps changes in climate could effect or exacerbate the condition? i am clueless, but will try your suggestion first thing tomrrow, thx!

 

Yes my friend dont be a rikki had similar problems and that described aboved cured this.no where to go but up from here.