Well, unfortunately things have gotten worse before they get better. I decided to take my car out for a drive on Monday, since it really hadn't gotten run well in a while. I've been dealing with an "Add Collant" light issue, but believe we determined the issue is not mechanical, so I just ignored the buzzing and drove it anyway. Despite the light and the noise, it is/was running just fine. I drove it for at least an hour, stopped, let it sit, then did a few errands, and began to head back to work. No problems, purred like a kitten at each stop sign and traffic light.

I started to play around with it a bit on the highway, and was boosting hard at WOT for a brief period of time (hit ~6800rpms at full boost... ~120mph). It seemed to respond okay, so I didn't think anything of it. Probably kept the RPMs up around 3500-4000 most of the way... Until I hit some traffic, and was forced to come to a complete stop. It was at this point, I noticed that the car was not idling good at all. The first time I thought was a fluke, when the RPMs dropped below 800 and the engine just started choking and clunking, as if it was going to stall. So, I quickly gave it some gas, but, each time I clutched in and let it drop, it was sounding horrible.

I can't say if the "clunking" is litterally a metal-hitting-metal sound, or more just a pre-stalling, low idle sound. I can say, that even at 2000rpms it isn't running perfectly smooth either.

Worried that I'd brakedown in the middle of this fantastic traffic jam, I spent 3 miles keeping the RPMs up over 2000... so it wouldn't die (braking with the e- brake)... and just trying to get the car back home. Even at 2000-3000rpms, it was definitely not running like it usually did.

Observations:

• It still made boost, though I didn't get on it hard, I did start boosting a bit in 4th and 5th gears, just to get up to speed on the highway... no balking, the turbos spooled up fine.
• No black or white smoke out the back
• Coolant level is still just below cap
• Still seeing a strong vacuum reading on the boost gauge, 23-24 when decelerating... returns to 18 or so at idle, even with the clunking.
• Car doesn't stall, but idles VERY rough... clunk clunk clunk. And there is a bit of a fuel smell.
• The A/F gauge reads RICH on throttle (which is generally normal), though it will briefly zip to lean and back if I feather the throttle. Reads full LEAN at idle.

So far, the only thing I have done was to check all visible hoses, to the best I can see, nothing has popped out. I thought maybe it is a bad plug, so my friends and I replaced the plugs tonight. 4 new plugs didn't seem to make a difference, though a few of the plugs were carboned up pretty good.

So, the question is... could this be related to the Coolant gauge issue? maybe... if I have a bad ground, who knows. But, the car does start and run... albeit a bit rough. I'm wondering if maybe my coil went? Really feels like an ignition issue. Battery power is reading 12.5-13.5 on average, but something just isn't right. If it were something as simple as my idle adjustment screw that might have gotten loose, I would think that wouldn't effect how smooth it ran during warmup.

The initial prognosis I received was that it might be out of balance, if a bearing went... or something else to keep it from physically rotating smooth. There are a few other things I was told to check. Like, how does it sound when I try to turn it over after removing the EGI fuse. Also want to see if the vacuum is holding steady during warmup...

I know this is such a car specific issue... but any thoughts, at least, even to diagnose would be great.

Thanks

 

How old are the belts? Check them for breaks. Oh and make sure your engine isn't toast -- get a compression test done on it.

 

Im having a similar issue with my FD. I also had the coolant issue, got it fixed and im still having the idle problem.. I have shitty tune on my PFC so im hoping its that.

 

i remeber reading soemthing about when the map sensor (or some sensor) pops off this happens. does anyone know more about this? its a common problem...i just never read it carefully as the issue never happened to me.

 

(hey matt)

So... I thought maybe a video might be usefull to people, if they want to hear and see how it's behaving. It's a little difficult to get a sense of the "shaking" from the first part of the video - but once the car drops to idle revs, like 800-900... it is pretty clear. The car used to purr like a kitten.

http://www.stephenbarrante.com/idle_trouble.html

Hey efranklin... what turned out to be the coolant issue, cause/fix?

 

Fuel smell is dangerous. You shouldn't smell fuel at all under the hood. DON'T drive the car until you locate the source of the smell. The FPD, Fuel Pulsation Dampener, is a known failure point in the fuel system. It is located under the UIM on the fuel rail. If you have'nt changed this item, do it. No Joke, many a seven has lit on fire because of it failing.

Before starting the car check the following.

Check the map sensor first.

Check the couplers on the ic piping, particularily the one on top of the turbos. The boost could have blown it loose and the metal sound could be a IC pipe hitting the hood or strut bar.

AFTER you find the location of the fuel smell and fix it:

Check plug wires for spark. If the wire are old, change them out.

Once you've done those checks it's time for a compression check. Seriously, once you get that over with you'll know where you stand with the motors health.

The coolant light/beep could be on because the sensor on the front of the filler neck is not plugged into the harness.

Well I just saw the video, and my suggestion is get it towed to a rotary specialist and have a compression test done. Get your biggest fear out of the way.

 

yeah mine sometimes drops before 800. and it sounds bad, but I blame the 4" exhaust for that

 

where is the map sensor located? steve u can browse around rob robinette site to find its location as well.

 

Nice video. That should help some of our real experts.


The fact that your vacuum is within spec would seem to indicate the engine is probably fine.

Since the coolant warning came on first, I'd start there. Obviously you've checked the coolant levels. Champagne test? What does the exhaust smell like?

Next, I'd Look at your coolant sensor and the wiring to the Commander. Also check the grounds. A bad ECU in the Commander might cause all these problems, including the idle and AFM issue but I'm no expert on the Commander. If you can take it out of the loop some way it might be worth it, but check with someone of the Commander side of the forum before you go to that trouble.

Proving the Commander isn't malfunctioning, I'd bet the coolant warning has nothing to do with your idle issue, however. That bouncing AFM is troubling and seems to be directly related to the idle issue. Fuel injection system integrity should be your first check step after the above.

The next simplest approach as mentioned above would be to start with the intake/fuel mixture, system looking all the way through to the LIM. The steady vacuum is an interesting tip. I would think it would bounce if there were a gasket leak between the LIM and the UIM? But that's what the exhaust sounds like and the bouncing AFM would seem to confirm that. Spray some starting liquid around the gaskets. What happens? The possibility of a loose coupler near the intercooler sounds like an easy check, but would that cause the AFM to bounce that much? I doubt it.

 

Map sensor, labeled boost sensor, is on the top of the firewall between the intake elbow and brake booster.

 

Hey guys... thanks for all the input. Few comments...

The fuel smell is more out of the exhaust, and not under the hood at all. I know what THAT smells like, having had a potentionaly serious situation with my pulsation damper. It's not that, it's more like, the exhaust just doesn't smell as "clean" as it did before. Like there is a lot of fuel not being burned off...

My friend said he has some cleaner for his MAF sensor (he used on his BMW M3... you spray it on and it "cleans" it. Is this something I should do with the Boost sensor?

I'm almost 100% sure the coolant issue isn't related... but I could be completely wrong. That is still a problem, but the idle issue has become my first priority.

I did just change out my filters and reconnected the intake hoses. But even if those were not on all the way, that wouldn't affect the idle, right?

Would a bad injector cause this issue? Coil? I have new plugs in it now. Haven't done a compression test, but that would be useful just to make sure the engine is ok.

 

definetly sounds like ur MAP sensor came loose. the boost pressure probably blew the hose off the nipple. mine did last week and my car sounded like it was bridge ported, crazy gas smell and black smoke as well. i thought i blew my engine, but i plugged it back in and it runs fine.

 

I can't offer any help on your issues but the MAF sensor cleaner isn't applicable to the RX7 since we don't have a MAF.

 

i am telling you...i think its the map sensor....did u inspect it?

would he still get boost if the map sensor cvame off though?

 

gracer, that's what I figured.

Yea... matt, I'm just not sure that my boost gauge would be reading normally, or I'd be making boost if that sensor were no longer connected or working. But, I also don't understand everything that my Map sensor controls, so I will definitely look at it again.

I did look over the sensor once... I tugged on the hoses a bit.. and they still seem pretty secure... but I'll look again.

I personally think it has something to do with the ignition. Either something is fouled up with the timing in the PFC... or, something mechanical like a coil, or plug wires... or there isn't a good ground somewhere. If you look at the video you'll see the air fuel is bouncing all over at idle. So, something about the way the car is running at lower RPMs is amplified or more pronounced, than when you rev it up pretty high.

Also, could the O2 sensor have anything to do with the way the car idles?

 

My 93 had been sitting in a field for two years outside a local shop. My engine was running really rough at 40K, and a dealer told me I needed a new engine. I thought bullsh**!, but nobody could fix it. Half a dozen looked, nobody could help!

I'm in Kentucky, and all the recommended "experts" were at least 5 hours away. Nobody knew what to do with it. I was thinking of selling, then got a new gf (former truck driver, who knew? heh heh) who said she could find someone to fix it. Sure enough, 50 miles away in Evansville IN, a little indy repair shop called Elliot's diagnosed the problem with a 5 minute test drive.

My cat was cooked. Installed a new SS performance exhaust system from SR Motorsports.

My little black '93 is reborn! I almost cried.

 

That new gf of yours is worth her wait in gold! Make sure you thank her ... repeatedly

 

sounds kinky. how do i get in on it

 

Spent the day at a local shop yesterday, and we ran through a bunch of tests. Didn't find the specific problem, but I think we ruled out a bunch of things.

We started by testing the coil packs and wires. We hooked up a wire between each plug and the sparkplug wire. Each one lit up the light in the middle of the wire. So, we are pretty sure neither the coil or the wires are bad.

Next, we wanted to see if it might be the injectors. Rather than taking the UIM off, we hooked up a wideband A/F gauge and took it for a drive. What we found was that the car was right where it should be in certain spots. At idle it was reading about 14 or so... and at throttle it dropped down to high 10s low 11s. It's running REALLY rich.

So, then we pushed the car a little to see how the boost was behaving. And closely monitored the A/F to make sure I wasn't gonna potentially blow the engine. I put the throttle to the floor and took off. My car is set to run about 15lbs of boost. I spooled up and spike at 14 and then it dropped down to 10, and regardless of how much I pushed down, it would no longer spool past 10. I find this interesting....

Also, closer examination of my boost gauge is showing at idle, it's wavering a little between 15 and 19 (lbs?) of vacuum. It always drops to 25 on deceleration... and then returns to those numbers. Over all the car spools up pretty quickly and smoothly (no balking, or real studdering), but then drops off prematurely.

So, after all this, we're thinking maybe it's a vacuum leak somewhere. We checked most of the visible hoses, intake, intercooler... and at least, they seem to be on pretty securely. As well as the small visible vacuum lines to the two bov's and manual boost controller.

Keep in mind, it's not jsut the boost that is effected. I've had boost problems before, that never effected the idle. So, whatever is lose, or leaking, has to be more integral to the way the car keeps the mixture, or runs at lower RPMs.

 

It just....sounds....like it is not firing evenly at all. It really sounds and acts like a 4 banger that is running on 3 cylinders. The vacuum being as good as it is gives hope that there aren't any seals bad.
I would stake money on SOME sort of ignition problem.

 

This is all very interesting. A bout a month ago My car was leaking water and i had burst a hose that needed replacing. But ever since my coolant beeping has came on even although it says its in between hot and cold and seems to be fixed. So i thought it was maybe an electrical fault with the beeper on the gauge. However maybe a few weeks later I noticed when i started the car up it was not idling correctly but i thought nothing of it. But then one night when i was out, I came to traffic lights and noticed i almost stalled the car as at low revs the engine was almost cutting out. And its not running correctly as its not ticking over correctly. Seems like its not running on all cylinders. I have a feeling it is an electrical fault and am driving to England from Scotland in about an hour to a specialist as no one here can fix it. I Will let u know how i get on. But from what i have read here, the coolant issue, warning beepers and the idling could be related in some weird way, as thats sounds like my exact situation.

 

Hey Dave... good luck! And let us know what you find!!

 

Just travelled all way to England only be told that an apex seal must have broke and i need a re-build! How fecking great

 

!!!!!!!! Dude... that sucks! Did they do a compression test? Do you know what else they tested to come to that conclusion?

If there is anyway to post a video of your car, warming up... idle... etc. I'd be happy to host it, and can give you a place to FTP it. Let me know.

 

Hey Dave... any progress on your car? Or have you decided it's officially "broke". I'm going to be taking my car to a specialist a few hours away, in a week or so. Hopefully I won't be leaving it there!