arutha

iTrader: (2)

Ok. I have an idle problem after the car is WARMED up. It fluctuates between 14-12Hg vacuum and the rpms jump between 700-800. This is without any additional load. Once I back out of the driveway, push in the clutch, the rpms go way low, sometimes stalls, and then fluctuates from 14-10Hg vacuum and I think when the vacuum is around 10Hg is when I see the rpms around 500. Most things I've read mentions lower vacuum=higher rpms though so I am a little confused.

When the car is cold this doesn't happen. Once I start it in the morning the rpms are around 1100 and I get 17Hg. My problem only happens when the car is warm(above 180, maybe even closer to 200F).

As long as the car is moving it seems to run fine. I get full boost. And the MAP sensor is connected if anyone goes down that path. The one time it was off it was much different than this.

Motor is stock with exception of most bolt-ons.

downpipe, hi-flow cat, catback, greddy smic, airbox mod, pettit ECU. Plugs have maybe 500miles on them, wires and fuel filter changed last summer, maybe 2k on them.

I also have not gotten any error codes.

I hope its not blown but the engine does have 90k on it and I've never had a compression check done. Also have not had the injectors cleaned.

arutha

iTrader: (2)

Oh I wanted to add that the the engine is not shaking violently, or at least not when the vacuum is jumping between 12-14. Saw a few posts asking this so figured I'd add it now.

dhahlen

iTrader: (5)

I had the same problems, I could get boost too, your problems are almost identical to mine. Except I could feel the loss of power since I was only running 1 rotor, more or less. Eventually it will get harder and harder to start, and then not turn over at all if you keep running it.

Check this out... when you're driving the car normally, get on it a bit in second gear... then as SOON as you LET OFF THE GAS, check your boost gauge, the Vacuum should drop to 20inhg, or something very very close.

My Idle would bounce from 12-14, and wouldn't sit anywhere. It now sits at 17 at idle after the rebuild.

Best Idea is a compression test, if you're not sure how to do it, I suggest you take it into a shop, unless you're comfortable with the work you do. It will cost you about $40, and you'll have a for sure answer if it's a blown engine. Make sure you take it to a shop that knows what they are doing...

arutha

iTrader: (2)

Well I took it for a drive today and now it seems more erratic. Today the car rarely did it. I had a steady 14Hg at idle. Only a few times did it drop. It seems much more noticable when I back the car up. Its almost like the car is having a tough time recovering from the deceleration. Instead of it stopping at 750 rpm it dips down to 500 and then bounces some, eventually evening out.

Yesterday it did this pretty much non-stop. I even reset the ECU and it still did it. I am guessing if it was a blown engine it would always happen?

And yes I will probably schedule an appointment to test the compression either way unless it being erratic defiently means its not a blown motor.

Thanks

rotary

im having the same exact problem too if u find out what it is someone pm me.

arutha

iTrader: (2)

Ok sorry but bug you guys more but I am just tring to get a strong grasp of my issue.

1) Since this bouncing of vacuum doesn't always happen is it safe to assume it is probably not an internal engine problem?

2) I've been reading some and am curious on a couple things. Since my vacuum will bounce sometimes and the idle does the same is it safe to assume that the bouncing of the vacuum is causing the idle to change or could it be the other way around, the idle fluctuation is changing the vacuum? Reason I am asking this is I've read about people having idle problems and it being switches which might affect the ECU making the ISC do things at the wrong time but I do not know if those issues would cause the vacuum to jump.

Any help would really be great.

Thanks

Mahjik

iTrader: (1)

Do you notice that the car almost stalls when you press on the clutch or does it matter whether or not you are using the cluch?

arutha

iTrader: (2)

It will jump between 12-14Hg with the clutch released and in neutral and if the clutch is pushed in and in a gear. But again yesterday this rarely happened.

The more drastic fluctuations are only if the car is warmed up and upon deceleration with the clutch in. Coming from 2k rpm. If I down shift coming to a light and keep it in gear to around 1-1.5k rpm it doesn't happen.

Mahjik

iTrader: (1)

I would suggest checking your clutch switch (doubtful, but it's a cheap part and easy to get to).

After that:
https://www.rx7club.com/showthread.p...hreadid=242321

tahmid

might be as simple as changing ur plugs........maybe ur running rich and fouled up the plugs..........

clayne

arutha: it's not the engine failing, so relax on that.

First things first, do the standard vacuum line check. Second, recalibrate the idle per factory procedure.
Third, your car is doing the typical idle hunt/bounce that happens when something minor is wrong.

arutha

iTrader: (2)

little update - I wasn't able to work on the car but Friday I noticed why I said it always seems to do it when the car is warmed up. It happens when the fans kick on. Sometime this week I will yank the UIM off and look for any hoses that might be off as well as check the ISC since I will be in that area.

Clayne - Thanks for letting me know about the engine, I had my doubts that it was the engine but I didn't know. I had a sigh of relief after reading your post.

I'll post my fix once I figure it out.

clayne

arutha

iTrader: (2)

Another update and question


I checked the hoses under the UIM. One might have been kinked but none were off. I did find a nut missing from one of the underside TB-UIM bolts....I'll get that fixed. Not sure what that would have caused except maybe a loss of boost?

ISC checks out, at least the ohms. Is there something else to inspect with it?

AWS is way off with the ohms. Dont' think that is causing my problem but guess I should fix it either way.

Neutral switch appears fine, might replace it anyway since its fairly cheap. a-b of the 1-2 switch doesn't read continuity when in 2nd. So guess I will replace that.

I wanted to test some of the connections at the ECU like AC, but I have no idea how anyone can do that. There is no room, especially if I have to keep the ecu plugged in for the tests. Is there any tricks to doing this? The repair manual of course talks about the special "tool" that goes inline from the harness to the ecu to check the readings. Any recommendations on doing this would be great. I am not overly young and that is just a crowded place to work.

clayne

Well you're definitely on the right track. Keep on digging. As far as measuring signals to the ECU, have you thought of a paper clip or safety pin into the relevant ECU pins? Make sure not to ground anything out, of course.

I would do some searches on AWS elimination just to take it out of the picture.

This is one place where the Apex'I PowerFC ECU really helps - the commander shows sensor signals and voltages. If you've got an extra 1000$ saved up, it wouldn't be a bad investment in the first place (it is a better ECU anyways).

arutha

iTrader: (2)

Alright I think I am getting closer to solving my problem. It appears to always happen when the PAC is one. Port Air Control according to the PFC. Now in the repair manual the service notes mention that there would be no ill effects if this part is malfunctioning. So what else happens when the pac is in use? The reason I ask this is all I honestly care about with the whole ACV system is to make sure that air is pumped to the cat since I have one. Is it possible to disconnect the PAC and switching valve solenoid and cap off the vacuum points while still retaining use of the airpump for the cat? Or will this cause the cat to get too much air since it looks like(according to page F115) the switching valve might stop air from being applied to the cat at certain points to force air else where?

As some info whenever the PAC is on I lose about 3 inHG of vacuum which seems really strange unless I am loosing vacuum from one of the solenoids when its on. According to the diagram on F115 I wouldn't think anything other than the solenoids could affect the vacuum. Any tips would be great.

Thanks

arutha

iTrader: (2)

Alright. Fixed part of my problem. The relief 1 solenoid was malfunctioning. This is what was causing my idle to jump.

I still have an idle issue though so I might be posting again shortly.

arutha

iTrader: (2)

Yep could use some more advice. I've fixed my jumping idle but still have a problem.

Before I started working on this I lost 3 inHg, had a jumping idle and it ran rich. Now remaining problem is the car will start to run rich and lose about 2 inHg of vacuum. No smoke or anythign like that. Just a strong smell. My O2 volt output to the PFC will read around .89 when this happens. This is something I would expect at WOT not sitting at idle. I dont' think its the O2 sensor causing it since I can disable it through the commander and this still occurs. Now I can turn the car off, wait a minute, and normally this is gone until I get it back on the road. Some times I can pull to a light and it doesn't do it, other times it will. When this occurs I take a can of carb cleaner and spray it around the vacuum hoses but it never seems act up so I am assuming it isn't a leak except the loss of some vacuum kind of tells me differently.

Now this was happening before also. I've found a few things not working and fixing those has helped my problem some but not entirely. The purge control, which I just disabled by capping the UIM and catch tank, and the relief 1 solenoid which I unplugged both the vacuum line(caped the UIM) and the wiring and left the rest of the ACV related solenoids connected but without a vacuum source. So should I unplug the rest of them so the ECU knows it can't activate them or does that not matter? Doubt its the cause of my remaining problem but I've taken the UIM off about every day this week and am getting closer but its a pain, literally in my back.

clayne

What are your emissions like in PA?

I know you're already NS, so remove everything you don't need and *use blockoff plates*.

That's the right way to do it and you'll save about 20-30 lbs (including the A/P). Not to mention UIM removal takes 10 minutes.

arutha

iTrader: (2)

Actually, I am still sequential. We have a sniffer test here in PA but no visiual thing. Since, my last post on here I have removed the ACV, used block off plates, disabled the EGR, Removed the metal pipes used by the airpump and blocked those off and ran a direct line straight from the airpump to the cat with the check valve in place.

Still have the same problem with it running rich but I have noticed a slight miss so that's my next project. Buying new plugs and will test the coils and wires. Hopefully its just a plug that might have a tiny crack.

I also have a strange turbo issue where the secondary works in 2nd gear but not in 3rd so I am guessing there might be a leak down around the TCA so that's another thing I need to investigate.

I was hoping I'd just have one problem part but so far I've found 2 bad solenoids and I still have issues. So I'll keep digging.

clayne

Yet another reason to go non-sequential