cornholio

iTrader: (1)

Ok, I originally created this thread when stranded in a parking lot- I'm updating OP now to include all info. And yes I have searched and read a lot.

00 auto, 215k miles. Not my DD, just for weekends when i'm not supposed to use the company vehicle. The last few months (winter) I noticed rough idle when starting in cold temps. I'd say my idle has been high (1200-1500 rpms in P/N) for a while- didn't pay much attention as it had been like that ever since I got it off my dad 10k? miles ago.

So the car shut off while sitting at light a few weeks ago. I was able to start it, get through the intersection, and coast to a spot where I could call a tow. The car would start up and turn off immediately. While waiting on the tow to show up I tried to start and gas it to see if the idle would work itself out-it did not. While giving it gas the SES light came on. My tow shows up, takes me to destination, car now starts up and drives.

The code from SES gives p0505 - first I pulled ECM to check for shorted chip. Everything looks (and smells) normal. Next went (partially) through FSM diagnostic for p0505. Verified there is power to IACV, continuity between IACV and ECM, and proper resistance across IACV pins (all was around 23-24 ohms). In my mind I rule out IACV failure here.

During FSM diagnostic I stumbled on step 4 relating to the power steering air control valve. I did not feel any vacuum (i understand it's pretty weak?) and still didn't feel anything after turning the wheel. I paused here to do more research. From what I have read since then, it doesn't seem like this part would cause the car to shut down- but just keep triggering p0505 code? Can anyone comment to this?

Additionally I did the following:
-Cleaned throttle body
-Cleaned MAFS

Drove it around the block twice and everything seemed to work ok. This past weekend I tried to do idle relearn. Drove about 10 min away to Walmart to pick up some stuff, when I got back in the car it was back to the original problem. Car turns off and dies right away. On the third try it turned on. I decided I would try and drive home. Just pulling through the lot I noticed rpms wanted to just drop (below 500 rpm) to where it would shut off without me giving it gas. I drove it home but would have to make sure to keep the rpms up when I stopped or got off the accelerator. When I got back, I tried the idle relearn anyways. Maybe it worked, maybe it didn't- rpms seemed right, but right after doing the procedure I turned it off and back on. It died right away and wouldn't restart. Disconnected MAFS to see what happened. It turned on.

Is the MAFS likely the issue? UPDATE - NEW MAF DID NOT FIX IT
Can the ps air control valve cause these problems?
Or am I overlooking the IACV still? UPDATE - YES

Maybe I should just replace everything?

***IACV FIXED IT WOOOOOO***

cornholio

iTrader: (1)

I'll add that it had been driving fine earlier this afternoon. I had been having problems this winter with a rough idle on start- had a tb clean on my list of things to do. Battery still has power

cornholio

iTrader: (1)

i tried giving it gas after starting to keep it going, eventually this threw the SES light but seemed to keep running for a bit, i tried to move it and it shut off again after going like 5 ft. while i was waiting on my tow truck i'd try to start it a few times, most of the time start and then stop, one time it started fine and idled normal. i just left it as i had already called the tow and didn't want it to shut down as soon as i moved 5 ft again.

once it was on the tow truck we tried to start it and it started up. once towed to my nearby shop it started up again and we were able to drive into a parking space. i'm going to steal a scanner from work tomorrow and see if i get it figured out without help from the shop.

yes im a noob with working on cars. any input or insight with my limited descriptions is appreciated.

DennisMik

iTrader: (2)

There are so many things...

Can you determine if the check engine light is on? Getting codes read would be helpful.

The MAF could be the problem. Unplug it and the car should start and stay idling.

cornholio

iTrader: (1)

the check engine light was not on when i started having problems. it wasnt until after i tried to gas it to keep it running the SES light came on. when it would start and keep running the only light on is the SES, not the CEL

if i can find a scanner tomorrow i'll get some codes. will also try to remove MAF and see if that solves it. thanks.

dfj240

iTrader: (1)

I second that. Sounds a lot like a MAFS issue. Definitely get codes though. No need to remove the MAFS completely. Just unplug it, and see what it does.

maximasicilian123

Wondering...if a maf sensor is bad and you unplug it will the car run better? Is that how you would diagnose a bad maf?

cornholio

iTrader: (1)

OP here with an update....

Yesterday I went to the shop I got towed to, tried to start it up and it worked.. let it idle a bit, moved it forward and backward some until I got the confidence to drive it a whole block to bring it home. Tried to pick up a scanner from work but it was locked up so that had to wait an extra day. Went ahead and cleaned the throttle body. Afterwards seems to start up fine and the idle is much more consistent than it has been the last few (cold) months. Drove it around the block, no issues.

Today I brought the scanner home. P0505. From what I'm reading that points at IACV replacement (and ECM?).. the code (SES light) didn't throw initially when I stalled, only after I tried to gas it (probably stupidly) to keep the engine on for a restart. Is there a chance my IACV might still be ok or is it done for? Any way to check if it's still good? I guess I should also pull the ECM and look for the fried transistor?

Martinez87

Could a bad fuel pump be a possibility? Could affect idle, starting and wont throw a check engine light directly.

gapboi210

Thats a **** move to have it towed to the shop then go get it.

cornholio

iTrader: (1)

its a block away from my house, they werent even open either day to even know it was there. sorry that doesn't align with your values

dfj240

iTrader: (1)

It will not necessarily run better. Obviously with no MAFS it's not going to run properly, what you're looking for is a difference in how the car acts when it's unplugged. If there's no change, then it is a reasonable deduction that the MAFS could be bad. If there is a change in how it runs, whether better or worse, then the MAFS is at least doing something while it's plugged in.

That doesn't mean that the MAFS is perfect, but if you don't have a scan tool or a multimeter to properly test and monitor the MAFS to know for sure then that is a quick way to sort of rule it out on the fly.

DennisMik

iTrader: (2)

You can check the resistance of the IACV's stepper motor windings to see if they have shorted out.

See page 506 in section EC of the service manual. Link below.

Service manual section EC

Several pages before this (504), the manual says to check the power steering air control valve.

gapboi210

You didn't mention that. I thought you were one of the customers that brings their car in, we spend time diagnosing it, then they want to take it and leave

cornholio

iTrader: (1)

thanks, i came across that section of the service manual also after my last post and decided to tackle it (partially) this past weekend. went through it in a weird order, first thing i did was pull the ecm and look for the dreaded blown chip- everything looked and smelled good. next did troubleshooting around the iacv- iacv was getting power, continuity from ecm/iacv checked out, resistance measured about 23 ohms across the 4 iacv pin combos so no sign of a short. starting to feel better about cost of repairs

then i jumped back to the test relating to the power steering air control valve- not feeling the vacuum so stopped to do some more research and resume testing at another time-

my question this time is where to buy the ps air control valve... google is failing me at the moment. dealership? anybody gotten one from somewhere else?

thanks

cornholio

iTrader: (1)

also want to add i cleaned MAFS this weekend. between cleaning that and the throttle body i already feel big difference. only drove it around the block twice since doing that but feels like a different car

i disconnected the battery at one point so SES light went away and has not returned yet, but i haven't really driven it either

CMax03

iTrader: (3)

Drive at least 50 miles to know you got it!

cornholio

iTrader: (1)

This weekend i tried to drive it further to warm it up for idle relearn. Drove about 10 min away to Walmart to pick up some stuff, when I got back in the car it was back to the original problem. Car turns off and dies right away. On the third try it turned on. I decided I would try and drive home. Just pulling through the lot I noticed rpms wanted to just drop (below 500 rpm) to where it would shut off without me giving it gas. I drove it home but would have to make sure to keep the rpms up when I stopped or got off the accelerator. When I got back, I tried the idle relearn anyways. Maybe it worked, maybe it didn't- rpms seemed right, but right after doing the procedure I turned it off and back on. It died right away and wouldn't restart. Disconnected MAFS to see what happened. It turned on.

Is my problem with MAFS?
Can ps air control valve cause this? When reading it did not seem like this was a symptom of failed ps air control valve.
Or am I still overlooking IACV?

Also want to note I updated OP with all information. Thanks for any and all help you guys can give.

cornholio

iTrader: (1)

i went through all the previous owners (dads) service records last night- he hadn't previously replaced any of these. i've decided to just throw money at all 3 hoping to catch the right problem and consider all the other preventative maintenance.

cornholio

iTrader: (1)

threw a new MAF sensor in today, did not fix the issue.
will tackle the IACV in a few weeks when i have time.

cornholio

iTrader: (1)

so i put in a new IACV about a week and a half ago. the car started again, erratic idle at startup seems to have gone away, 70ish miles on it now and no problems yet.

i think my problem is solved

dfj240

iTrader: (1)

Very nice. Good to hear and congrats on the fix.

D.Stillwell

Glad to hear it's fixed! Congrats on that.

Seems like you threw a bunch of parts at it and spent a bunch of money/time when the problem was exactly what the engine code threw initially (IACV). That should tell people not to throw parts at it, get the codes scanned and that is probably your issue right there.

cornholio

iTrader: (1)

the only time it threw a code was when i did something i shouldn't have been doing so there was no way of knowing it was 100% related. the code wouldn't replicate any other time

and then what do you recommend to do when you scan a code? follow FSM diagnostic? what if the results tell you the IACV is good?

replacing the MAF for $80 i don't think was a waste at all. its an old car and i'll consider that preventative maintenance and time saved later on.

i'll agree with you, the power steering valve was a waste of money but i had somewhat suspected that when i ordered it.

tl;dr - i aint even mad

2248

I just got this code today... Did you replace the ECM at the same time as the IACV? How difficult and how long did it take to replace the IACV and where did you get the part from? Thanks!!!!

cornholio

iTrader: (1)

my ecm was ok, i did at least pull it out to check. should be pretty easy to do- i've read you can just stick your head near it and smell for burning to see if it was affected. i pulled mine to make sure

http://www.courtesyparts.com/23781u-...-p-193630.html

^that is the part i ordered. it looks like they are out of stock now. it took me maybe 2 hours to change it and i had to run to lowes in the middle to get a grabit when i stripped one of the screw heads on the iacv. i recently cleaned my throttle body so i at least knew what i was getting into and going after, other than that i'm pretty amateur at this stuff.

nestorlugo

iTrader: (11)

Recommend going forward with EC.41 first .

If that dont do then EC.112

cornholio

iTrader: (1)

112 or 122?

nestorlugo

iTrader: (11)

ec.112.

Sent from my iPad using and abusin Maxima.Org

cornholio

iTrader: (1)

good to know! thanks!

both of those seem difficult to do correctly when the engine won't stay on long enough to warm up though..

maxiiiboy

Congratulations on having this fixed; it must have been quite a bit of pain. Re. your IACV replacement - did you buy the OEM part or an aftermarket part?

cornholio

iTrader: (1)

OEM, after tons of reading on here it sounded like that's not a part to gamble on