Idle droop from hell???

[aMaff]

I'm having a little issue on my NA and I'm not sure if it's idle droop or not. Basically when it's cold the car barely idles. It goes down below the 2nd mark on the tach (<250 RPM) and shakes like hell and won't stop unless I give it some throttle. Once it warmed up a little, it was only mildly better, and when it wasn't 2 RPM above stalling, it was idling really rough. It's only a 10 min drive to work, so I'm unsure if it stops when she warms up. I'll probably take the long way home this afternoon to test that out. I've recently changed the plugs and plug-wires, and put a K&N panel filter in. It felt like it may have stopped right as I pulled in to work, but I'm not 100% sure (I played with it a bit but couldn't get it to drop to much below 750 RPM).

Thanks in advance guys n gals,

Andrew

 

[MiaTurbo]

since the car isn't in front of me, I can't diagnois it. But what have you checked so far? First thing, and easiest and free things to do is put the car in Diagnoisis mode and check idle and timing. Also check for vacume leaks.

 

[aMaff]

Alright, a lot's happened since I posted this. Been going back and forth on the 'other' miata forum, and talking w/ my local guru (Kevin). I fixed the 'normal' miata idle droop. As you know, in order to do that you have to put the engine in Diag. mode. So, after setting the IAC properly, I checked for codes. It was flashing the following code:
1 long
pause
7 short
pause
1 long
pause
9 short

According to the diagnostics fault codes article on 'that' forum (thanks Kevin) there's a code 17, but no 19. 17's a bad O2 sensor (output not changing). However, there is a code 9 that would explain the cold start issues: Water thermistor. That one looks like a treat to replace... I'm going to KISS and do the O2 first and sacrifice a chicken (kidding.....) in hopes that will fix it. If not, that should knock out one of the codes and clear up what the 2nd code is. Should.

Wish me luck.

 

[k-lea]

I remember this happening to my 01 check the "other forum" for "Idle Dip." If I remember correctly it had to do with the manifold getting uber dirtay. It was something of that nature..

 

[aMaff]

I know. I've got a thread over there. I fixed the idle dip / droop tonight. I'm still having cold idle issues (these are not related to the IAC to my knowledge). However, this morning it just felt like all hell was breaking loose in the car (wouldn't idle for s*** cold, the idle droop was only aggravated by that, etc etc), hence this (and 'that') thread.

 

[k-lea]

Ahh, goodluck. :/

Both my Miata's sucked at cold start. End of story.

 

[kcbhiw]

I remember this happening to my 01 check the "other forum" for "Idle Dip." If I remember correctly it had to do with the manifold getting uber dirtay. It was something of that nature..

It's possible. The IAC could be sticking, though, that might throw a code. The bypass valve (the proper name escapes me) could be faulty too. Good call.

 

[aMaff]

It's always been a little rough, but this morning it was almost undriveable. Anyway, I'll get it figured out eventually. Thanks for the help guys n gal

 

[k-lea]

updat0rz.

 

[MiaTurbo]

silly Mazduhs.

 

[aMaff]

I'm going to pick up an O2 sensor in abt 10 minutes on my way home from work. And a lighter to heat the shrink wrap Stupid not smoking...

 

[k-lea]

I <3 shrink wrap.

 

[aMaff]

d'oh! Kroger only had a 2 pack (no, not 2pac). Also picked up an O2 sensor socket. It cost as much as the sensor!!! WTF!?

Seriously, it was a couple cents cheaper than the actual sensor....

 

[aMaff]

Well, returning the O2 socket tomorrow. Couldn't even get it around the sensor without the ratchet on it lol. Made a quick run to Advance like 20 min before the closed and picked up a 7/8" combination wrench. Did the swap (my first wire splice! My parents will be so proud! .... (cricket). Cranked her, and imediately noticed a difference. Idle was a lot better, and it didn't imediately try to diesel out on me. Put it in Diag mode and was still getting codes (turns out they were 1, 9, and 17). Confered with Kevin as to what could be throwing the codes, and after going over a few things he suggested resetting the ECU before we start digging through other more complex things. Reset it, and no more code. Fingers, toes and testicles (eek) crossed in hopes that it stays that way

 

[DeadGeneration]

Try running the car on full open throttle for a bit - either put it on stands and race the engine, or actually race around somewhere safe/track for 15 mins... just a thought

 

[aMaff]

ok.....why?

 

[k-lea]

...that's odd.

 

[DeadGeneration]

open throttle might clear out the carbon deposits...does miata have EGR? thats what happens with the protege5 anyway

 

[DeadGeneration]

also try a fuel injection cleaner - the kind you add to a tank of gasoline, it will clear out that whole point up to the engine, than running the engine open throttle will clear out everything after the engine with the exhaust

works on the p5 and makes sense the whole system just needs to be smoothed out by those two meathods

 

[aMaff]

Mine doesn't. I think egr came on 95+ models.