engine sputtering bad need help

[POS Racing]

Cleaned the throttle body lately?

Mine was loaded with ick cleaned it up and now it idles real nice!

YMMV see dealer for details.

[Jiggerachi]

It's been a long time since I seafoamed it, and it shows. It was pretty nasty in there. That's top of the list saturday, with oil change.

Anything special to cleaning the throttle body? Other than hosing it down with Deep Creep and wiping the butterfly?

Edit: sorry, I meant cleaning the intake. I am planning to wipe down the inside of the throttle body while im doing the deep creep thing.

[sammm]

Umm...Titus set it for me a couple years ago. IIRC we set it to 12. Is there a possibility of it slipping out of time...over time by itself?

Only if the CAS is loose or the belt has some bad teefus. I ask because you said it was clattering badly. It could be detonating because the timing is way off. BTDT.

[Jiggerachi]

Only if the CAS is loose or the belt has some bad teefus. I ask because you said it was clattering badly. It could be detonating because the timing is way off. BTDT.

But could that correct itself?? At 160K the timing belt is definitely due. (2nd belt BTW)

At it's worst it sounded like my friends 351 ford when he accidently had his distributer instaled 180 degrees off.

[sammm]

At 160K the timing belt is definitely due. (2nd belt BTW)

Could the timing belt be on the way out and jumping or missing teeth? That will mess with idle, timing and make the car run like

[Jiggerachi]

Could the timing belt be on the way out and jumping or missing teeth? That will mess with idle, timing and make the car run like

Im worried you might be right. No more long trips, untill I can get it changed. For now though, i'll do the basics and we'll see what happens.

[black roadster]

Didn't you tell me you recently replaced the CAS O-Ring? Did you mark it's position first so you could set it back to the correct advance?

I'd check the timing.

[Jiggerachi]

I changed it about 2 years ago, and yes I marked it and set it back. It's leaking again though, and blew the heater hose tuesday. I replaced the hose wednesday night, before this started. I didn't mess with the CAS at all, but the seal needs to be changed.

[Jiggerachi]

Didn't think it was worth a new thread.

This weekend I changed the oil, and did the ful seafoam intake treatment. Have a bottle of techron will put it in with the new tank of gas tonight or tomorrow. Idle is smoother, but something stranged popped up this morning on the way to work. Every stoplight the engine would rev at idle. Would this point to a sensor or the AFM?? Could this be related to my original problem?

I managed to catch it in the act with the camera...enjoy.




Pay special attention to this 3rd one. This is what makes me think it's the AFM. Watch the engine revving when im parking, then watch the idle, it jumps up to 2k all by itself, then straightens out. This is not in relation to the AC cycling.

Also of Note, my idle has done things like this off and on since i've owned the car, but now it's much worse.

[johnwag]

My '94 would do that crazy idle dip thing. I cleaned out my EGR for inspection and the idle issue never came back. It's easy and worth a try.

[jerrykr]

I know you guys checked the vacuum hoses, but this sure sounds like a vacuum intake leak (stumbling at idle, reving, and run smooth at higher RPM).

I had my battery changed on my PT, and after that the idle went crazy. Turned out I found that the guy broke the plastic PCV valve that is in the general area of the battery, causing a vacuum leak and it was really hard to spot the break, as the hose did not fall off.

In the old days of non computer cars, vacuum leak would be low RPM stumble, smooth out at higher RPM.

These days the computer constantly trys to correct things, and symptoms go nuts.

Remove each hose, one at a time, at the intake, plug with your finger/thumb on the intake, not the hose. If everything suddenly smoothes out, you found it. Of course, put each one back as you go, so that you are checking one hose at a time.

I'm probably wrong!

[sammm]

Doesn't the Miata have an idle control valve? I've never had to mess with one.

[Darron65]

I know you guys checked the vacuum hoses, but this sure sounds like a vacuum intake leak (stumbling at idle, reving, and run smooth at higher RPM).

I had my battery changed on my PT, and after that the idle went crazy. Turned out I found that the guy broke the plastic PCV valve that is in the general area of the battery, causing a vacuum leak and it was really hard to spot the break, as the hose did not fall off.

In the old days of non computer cars, vacuum leak would be low RPM stumble, smooth out at higher RPM.

These days the computer constantly trys to correct things, and symptoms go nuts.

Remove each hose, one at a time, at the intake, plug with your finger/thumb on the intake, not the hose. If everything suddenly smoothes out, you found it. Of course, put each one back as you go, so that you are checking one hose at a time.

I'm probably wrong!

That's good advice; sometimes we forget that old time solutions exist too. Your story reminded me of a pesky vacuum leak years ago when VW routed the throttle cable over the fat vacuum hose to the brake booster. It took several years but eventually the cable housing wore a nearly perfect groove in the plastic check valve. I guess I was never on the brakes long enough to notice but I was going nuts trying to figure out the idle fluctuation. To VW's credit, the replacement hose was shaped different to avoid a repeat.

[channelmaniac]

Yes, check the IAC valve on the intake.

RJ

[SirHustlerEsq]

yes, clean the pcv out by dousing it in carb-cleaner.

[Jiggerachi]

Much thanks for the advice guys. I have been on the couch, sick as a dog all week, and impulsively bought another motorcycle yesterday. I hope to tinker with the car tonight after work.

I know where the PCV valve is, but is there any tricks to cleaning the IAC and EGR valves? Or just pull them out and douse them with seafoam?? I searched all this on Miata.net, but couldn't find any pics or anything.

The IAC is on the underside of the throttle body right? Dies it just come right off or is there a bunch of stuff in the way?

The EGR valve is on the header right?

Seafoam is just as good as carb cleaner, they're both high petroleum products right? or should I just get some proper carb cleaner?

I'll open it up and try to figure it out tonight.

[sammm]

Seafoam is just as good as carb cleaner, they're both high petroleum products right? or should I just get some proper carb cleaner?

DO NOT use carb cleaner on the Miata intake (or any other bits). You need throttle body cleaner. Carb cleaner will eat the finish off of it.

[Jiggerachi]

^noted. Hopefully I can get to Vatozone before they close.

[Jiggerachi]

Well, looks like I fixed the wierd idle problem... seems it was a dumb mistake all along.

When I had my original stalling/sputtering problem, I bumped up the idle hoping to limp it back to life. I then read the proper procedure for setting the idle on Mnet, jumping the TEN/GND and going into diagnostic mode before adjusting the idle. I noticed that I did not do this. I had cleaned out the PCV and spraid out the TB as well as I could, I was planning on pullign the TB and completely cleaning out the TB and IAC. I thought i'd set the throttle the 'correct' way to around 850rpm before tearing everything apart. Idle has been silky smooth ever since. Glad I tried this before pulling the TB. I guess the computer was bouncing the revs around trying to figure out what happened to the idle.

Another lesson learned...

I am still going to replace the PCV valve when I can get around to it, and I have a spare TB on the way (found it on da dumpsta on Mnet) incase anything ever goes wrong down the line. Cars running fine, and never really did anything to fix it, or pinpointed the original problem...for now i'll throw some rat traps where I park and around my bike in the garage, be more careful next time im washing the engine, and call it case closed.

Thanks for all the help and advise guys, im sure some mechanic would have emptied my wallet by now if it wasn't for yall's help.