do you have an aftermarket stereo?

 

yep, had it since day 4 of owning the car. it's been more than a year already.

 

check your amps to see if they are wired to turn off when the car is off, sometimes installers get lazy and use the same wire for acc and remote

 

subscribing for reference. My car started harsh starting (I have to push the gas in a little or it'll stall on startup and die) after I added an aftermarket stereo. I had the battery disconnected for a long time, wondering if that hosed my ECU? I'll try cleaning the TB and doing an ECU reset. Oh sadness.

 

My car still has the problem. It happened today. Turn the key the first time and the car fails to start. Start the second time and it makes a weak attempt to start.

 

To introduce another theory to this thread: Check the oil.

This seems to happen to my wife's sedan, and invariably it is because the oil is low. These engines gobble up a quart per 1K miles it seems.

Good luck!

 

I checkd before and it wasn't consuming oil

 

It starts now, but drops down to around 400 rpms, idles rough, and then pops back up to "normal."

Per the Motordyne Engineering instructions, do I have to reset the ECU after doing the idle air volume learn deal?

BTW, in looking through my old subscriptions I found this thread. Holy old factor! And it's doing the same thing. I think it went away tho after a while.

I'm going to do the following (anyway) and will report on what I find:
clean TB
clean MAF (with this junk)
run fuel injector cleaner
reset ECU (might not do this)

good night!

 

i reset the ecu and dumped a can of bg44k into the tank. didn't work.

 

definitely try the "Idle Air Volume Learning" reset at:
http://www.motordyneengineering.com/manual.asp

It's on the last page. It's different than the ECU reset, and it was what had the greatest effect for me. Seemed like it didn't work correctly at first, and it was VERY finiky regarding the timing and junk. Here's what I did to get it to work:

1. Warm up engine
2. Turn off, wait 10s
3. Turn ignition to on (don't START until later) wait 3s
4. Depress/release pedal 5x within 5 seconds
5. Wait 7s
6. Depress pedal and hold. The SES light will start flashing, and then go to steady on. At this point, release the pedal.
7. START engine now (I had to blip the gas to get it to stay on).
8. Let engine idle for a few minutes. Mine was running rough, right at 500 RPMs. Even after a few revs, it would still settle out at 500 RPMs and run rough.
9. Shut engine off. Wait 10s before trying to restart.

I'm not sure if I'm supposed to re-run the total ECU reset after this or not. . .I ran both a bunch of times, and the above was the last thing I did to get the engine to at least start. It did start, bounced down to around 400 RPMs and then recovered without stalling. I hope the ECU gets smart again soon. That's annoying!

best luck!

-andrew

 

did that too. I even disconnected the negative terminal of the battery and left it overnight.

 

Let me ask you a couple of questions first. Does this happen only when you let the car sit for a while, say overnight? In other words, it doesnt happen if you turn off the car and start up again within minutes, correct?


I have the same exact problem with my FX35. After extensive research, it seems like the problem reside with the injectors. According to my research, if the injectors are not working properly, when you shut off the car, gasoline is leaking from the injectors into the engine. That causes the fuel line to lose pressure. During the second start of the car, the fuel pump would have generated just enough pressure to start the car again but you get a rough idle for a split second.

You dont have any symptoms when the engine is running because the fuel pump is constantly generating fuel pressure. But when you turn off the car, and let it sit for a long time, the injectors slowly lose all the pressure.

When you start your car again within minutes of shutoff, the injectors slowly leak but would still have enough pressure inside. However, if you wait say overnight, then all the fuel would've dripped inside the engine.

So it might be in your best interest to check out your injectors. Hope this helps.

 

Hmm today I drove a mile and stopped to have lunch. Started the car after lunch and the same thing happened. So i'd say it doesn't have to sit overnight for the problem to happen.

My idle is pretty stable, only +- 50 rpm fluctuations.

 

Here's what I found from my research:

If the car is cold, when it is first started the engine idles higher (~800 RPMs) to warm up the car faster. Thus a cold start will generally get the engine turned over and running. When the engine is warm, the idle drops to 600 RPMs. However, from a warm start, when the idle air volume isn't correct in the ECU, the engine will not rev up on the initial start to a high enough RPM (around 1000 instead of 1200ish) and on the initial drop, it'll get down to 400 PRMs or so and usually stall.

I find it odd that this happened to me right after doing a stereo install with the battery disconnected for ~24 hours. However, this is indicative of an ECU memory issue. Battery disconnected = ECU memory wiped. I guess some things need to be re-learned?

I doubt--in my case--that it was/is the injectors since it only showed up after the battery was disconnected overnight. Never happened before. Using the "idle air volume" learning procedure above got the engine to a point that it starts warm, but gets close to stalling, but doesn't. I think if I remember back in 2004 when this happened it eventually re-learned where it should be after a few days or so. I'll still do the TB cleanup and MAF cleanup (since that couldn't hurt at 108k miles) but I'll keep everyone posted as to whatever else happens.

-andrew

 

make sure ur two positive and negative wire that connects to the battery is well tightened to the battery, and see if the connection is clean. sometimes that causes cars to not start at once and sometime it makes the car to stop while driveing...