Dies at idle

[mkiii222]

Starting this morning my 7MGTE is stumbling then dying at warm idle.

AC on it will idle at ~900 and warm up it will idle at 750-850 or so. It only dies once it fully warms up with the AC off.

I cleaned the ISCV on my lunch hour and it's still showing the same symptoms. ISCV clicks 4 times on shut down as it always has, just a bit cleaner now. I was hopeful that this would be the issue as it was thoroughly gunked up.

I'm thinking I've got either a leak somewhere or an electrical issue.

Any other suggestions on things to check?

In case it matters: Mods:
Comp Cams valve springs, Mishimoto rad, DM downpipe, test pipe, 3" cat back (NUR), Greddy Timing belt, HKS intake, and Greddy EBC @ ~11.5 psi.
Head gasket was done last fall w/ARPs and OEM gasket. Changed upper and lower intake gaskets, exhaust gasket (DM exhaust studs), EGR gaskets.

Last week I did pop a coolant hose that sprayed all over the intake side. It ran rough for a couple days until it dried but has seemed fine since.

 

[digihonk82]

vacuum leak will cause that symptom. check the hose to the bypass valve!

 

[supraguy@aol]

Did this suddenly just begin happening one day?
And do you have any diagnistic codes?
~750-850rpm warm idle is pretty much ideal. Is it a steady idle, or is it stumbling up and down?
As mentioned, check for vac leaks, such as any unplugged vac hoses, and spray carb cleaner strategically
around the engine, looking for idle changes. Also, check your ISCV, TPS, CPS, and AFM connections.
It's a shot in the dark, but they're worth checking.

AND- If you fix it, let us know.

 

[mkiii222]

Did this suddenly just begin happening one day?
And do you have any diagnistic codes?
~750-850rpm warm idle is pretty much ideal. Is it a steady idle, or is it stumbling up and down?

1) Yes. Just started this morning on the way to work.
2) No. No codes are showing.
3) Steady idle during warm up and with the AC on.

ISCV connector looks solid. CPS connector is on the 'to be replaced' list already as it requires the occasional jiggle to start (once a month for a DD). AFM and TPS were among the first to be checked.

I can hear a hiss coming from below the intake manifold. It started lightning not too far away so diagnostics are done for the night. I have yet to replace the vacuum lines under there or the CSI gasket. It's definitely coming from that general area though.

 

[airhead04]

Check your egr vac lines under the intake manifold. They may have come loose, or cracked. Assuming you have egr that is.

 

[supraguy@aol]

Well, at least you are successful in narrowing down your search.

 

[mkiii222]

OK. It's not the CSI. I threw some FIPG on it last night and still doing it this morning.

EGR is on the back of the manifold, the hiss is coming from the middle somewhere. Narrows it down to a vacuum line, VSV, or I blew out the bottom of one of the intake manifold gaskets. If it was a gasket it's the perfect excuse to get one of the heat shield gaskets.

 

[supraguy@aol]

Yeah, I got on of those ppp gaskets for the intake.
Don't know if it does much, but it doesn't leak.
I did have the bottom of my intake gasket blow out once;
symptoms included hissing when accelerating lightly, normal driving behavior,
but horrible idle. Since you haven't mentioned it yet, I presume that you have not
tried spraying carb cleaner around the suspected area. Use the included straw/nozzle to pinpoint
your spraying, and figure this out!

 

[mkiii222]

At this point I think I'm just going to tear the upper intake manifold off to get the room to inspect everything under there. I'll report my findings once it's all back together.

If I'm lucky I'll have time to do this next Monday or Tuesday night.

 

[airhead04]

Hey bud, there are VAC lines UNDER the intake manifold for the EGR......just saying.

 

[mkiii222]

Forgot about that one. And it's right behind the CSI which is where it sounds like it's coming from. I'll have a look when I get it apart. Work and after work activities all week and going out of town Friday to Sunday.

 

[digihonk82]

i took off my runner and upper intake off to replace all the gaskets with felpro upper and lower, then i made my own TB gasket and ISC gasket. Once it was all back together it ran like a new car!. supraguy said it with the carb cleaner spray around those gaskets. . if the idle kicks up you know you have vac leak

 

[mkiii222]

OK, the carb cleaner trick wasn't working at all. So I figured it was something below the manifold.

I finally got around to getting it apart this past weekend and found.... NOTHING. Both gaskets were intact (both have less than 2 years, 20k on them), all bolts were snug, no broken vacuum lines. The ISC valve gasket left a little to be desired so I threw some FIPG on it and snugged it back down. I replaced 90% of the vac lines anyways since I was already there. I also went ahead and replaced the coolant line on the block (I have the ISC and TB coolant ports removed).

Now for the bad news.

I put it all back together and now she won't crank. This was Sunday afternoon and I plan to look at it again tonight. It's getting a code 12 as well. I've had CPS issues in the past where it won't fire and I'd have to wiggle the wires but it had always cranked so I'll be looking at the starter area tonight. I will also be looking into replacing the CPS plug and soldering new leads to the CPS as per the TSRM the 'constantly stalls at idle' checklist includes the CPS (as well as the fuel pump but I can hear it kicking on).

All in all it's very frustrating and highlighting my need to acquire a cheap beater Civic/Corolla... for a daily.

 

[90mkiiisupra400hp]

One thing alot of people overlook are injector seals, my car wouldn't idle warm either and I could hear a hissing sound around the same area you are explaining so I tried the starting fluid trick with no luck. I then took off my intake manifold since I thought that gasket may have blown out, but it looked brand new. So upon looking around I found this

[/URL] Uploaded with ImageShack.us[/IMG]

[/URL] Uploaded with ImageShack.us[/IMG]

I am not saying that this is your problem but you can visually check them and check them by trying to spin the injector they are supposed to spin freely. The only thing that throws me off is how it showed up out of nowhere but I suppose if the seals were old they could have cracked and broke but I don't know it's just something to check.

As for the car not cranking check the black and blue wire to the starter sometime when you pull off the manifold if you tug on the wiring harness it could have unplugged it.If it is plugged in try to wiggle, it might not be in all the way. Good luck

 

[mkiii222]

I forgot to mention. I did do the injector seals less than 6 months ago. But yes, they were a BITCH to find and all 6 looked something like your second pic there.

I'm hoping for an easy fix like the starter wire just being slightly out but that area had coolant spilled so I sprayed it with water and wanted to let it dry before going further. I know the CPS needs work but at least it will crank for now and I can give my dad his Lexus back (92 LS 400 w/58k ). All this at a time when I JUST bought all new Moog inner/outer tie rods and still have a heater core waiting to go in AND still need to get a new set of camber bolts/washers. It's like this thing KNOWS when I have extra cash in my pocket and does its best to get it. lol

 

[90mkiiisupra400hp]

I would almost bet it's just the starter wire, I just put mine all back together the other day and it wouldn't crank and all I did was wiggle/push on the black/blue wire for the starter.

As for the injector seals did you use anything to lube them up when you installed them, I had a buddy put mine in and he didn't use anything and that's how they ended up 3 months later but I got it all back together and it runs perfect now. Let me know if you get it going again.

 

[mkiii222]

Actually I didn't use anything on the injector seals. I'll have to look into that. At least they aren't too bad to get in/out. Took maybe 30 minutes last time. If it is them what would you recommend to 'lube them up'?

I can't go much longer without BOOST. LOL.

 

[mkiii222]

Fun times abound.

Starting issue was definitely the little wire on the starter. Got under there and it was unplugged. Plugged it back in and she starts just fine now.

Still having the 'stumbles and dies at idle' problem and now has developed an alternator issue. Only getting ~12.5 volts at the battery and the post on the alternator (idle OR revved at ~2k) and the battery light on the dash is on. I removed it and reinstalled it when I pulled the intake manifold and all wiring is intact and looks/tests fine. I'm guessing tapping it on the pavement when I set it down put it out of its misery since it's an OEM alternator. DM 120 amp here I come.

While under the car I did find and fix the FP up VSV. The red wire had broken off from the clip. Pulled the clip apart and fixed it hoping it would be the issue but no.

At this point I'm thinking the idle issue is either going to clear itself up with a new alternator or when I fix the CPS. We shall see I guess.

 

[Nick M]

vacuum leak will cause that symptom. check the hose to the bypass valve!

Only a really big leak. Including ported vacuum.

 

[90mkiiisupra400hp]

Actually I didn't use anything on the injector seals. I'll have to look into that. At least they aren't too bad to get in/out. Took maybe 30 minutes last time. If it is them what would you recommend to 'lube them up'?

I can't go much longer without BOOST. LOL.

You can use pretty much any petroleum based product, I just used Vaseline, you don't need much just enough to make the seals slippery. And make sure you DON'T nick them cause that will cause a leak.

P.S. If you do have a bad seal go to Napa, the part number is ATM IK2401 and it's only $1.99 per injector. Good Luck