I watched the drive video again, and considered what you said about the idle gradually increasing as the car sits running in park. I was paying close attention to the Block Learn value. I noticed it had worked its way down to 105 by the time you shut the engine down. It was about normal while you were driving, but went low at idle at the end of the drive. This points to over-fueling at idle. Eric mentioned a ruptured FPR diaphram. The low BLM value would be a symptom of a ruptured FPR. One or more leaking injectors could also cause this.

I also looked at you coolant temp PID at start up and throughout the drive. I noticed that coolant temp dropped some after start up. This is normal. It then began to rise gradually as the engine ran but never got over 155 degrees. I assume the engine had been run previously and allowed to cool some. Would you estimate that the ECT value was accurate? You said it was cold where you are so this reported temp may be right. Coolant temp sensors can suffer what we call "in range failure". This is a case where the sensor continues to function and no DTC is set because the value remains within the senor's normal operating range. However, the sensor's reported temperature may be considerably different than actual engine temp. Thus the term "in range failure". Typical symtoms of this type of failure would be temperature related rich or lean condition. Somewhat like what your datastream shows. The ECT sensor is just an electro mechanical device, and though they tend to be reliable, they are subject to failure. If you think that coolant temp should have been higher than 155 when you shut the engine down, consider that the ECT sensor or circuit may be faulty. A stuck open thermostat can cause symptoms something like this too.

I also noticed glitches in the datastream and and the "Fault Detected" PID flashed from no to yes sporadically. This may just be a fault in your ALDL connection but it could also point to poor connections somewhere in the ECM circuitry. Remember what I said about the ECM grounds and the ECM/FP fuse by the battery. You may also want to check all the fuses in the fuse panel for good connection.

 

Hi ASE, sorry for the slow response. Yes, I had driven the car and created a separate video that was somewhat longer but I felt that would have been a bit overwhelming for email as a zip file or the like. I could upload that video too if you'd like since that one was filmed on a cold start? At one time I actually had bought a replacement FPR but never had it installed because the shop I was taking it to insisted there was nothing wrong with it but I had my doubts. Where is the ECT sensor located btw?

 

any updates on this? my problem is back. I haven't really driven to much since the gasket changes but the other day I went on a drive and the problem came back, car died when I was turning/braking.

took it home popped the hood let it warm up to temp started pushing on the break on and off the car would stumble and want to die, started disconnecting sensors and hit the brake on and off again kept happening until I disconnected the IAC. I don't know how old it is on my car but it doesn't look very new. is there a way to test the IAC?, I don't want to spend the $65 if I don't have to. the car usually idles steady until I hit the brakes.

 

Honestly man, I'm just going to check everything ASE has said and take out the EGR and IAC valve as well as the TBI and just thoroughly clean out all three with brak lean. It's a cheap fix and rules out carbon build up, try that first. I hope it works out for you, this issue is a pain.

Also, I'm going to post the longer video I made of my car on a cold start and see if that might help.

 

There is a special tool from Thexton for testing the IAC. It's hard to test any other way since it's a stepper motor. A stepper motor operates by cycling two coils on and off. Each coil moves the valve stem a little and holds it in place until the other coil is activated. This on off switching of coils is hard to duplicate without the special tool. The alternative for testing the IAC is to test the control signals. They should be solid 12 volt on/off signals. Like a square wave, with no glitches or drop offs. You really need a scope to properly test this because no other test device will show you actual signal integrity. A test light may flash and a DVOM may change from 0 to 12 volts but that doesn't mean the IAC drivers in the ECM are actually okay. I've been fooled this way before.

Regardless of what you read, do not connect the IAC and turn on the key with the IAC not installed. The pintle can shoot out of the valve and the valve will be ruined.

It's important to remember that poor idle quality is a more common cause of stalling than actual idle speed control. The ECM will always try to maintain correct idle speed for the operating condition of the engine. When the engine can't sustain the loads placed on it at the ECM commanded idle speed, it will stall. The IAC can only movce so fast. It's intended to work with an engine that can sustain most of the load placed on it with minimal idle correction.

If your engine stumbles with the brake depressed, I would suspect a leaking brake booster. Listen for air leakage behind the dash(where the brake push rod passes through) with the brake pedal depressed.

 

Hi ASE, I'm going to attempt to pull my IAC, EGR and TBI out to clean them with brak lean to see if that helps along with checking the FPR. How would you advise I go about removing these carefully without damaging anything?

 

Update: I finally got outside to check some things on the car, the fuel pump seems to be working okay. I cleaned out the IAC, it didn't seem to be too bad. I pulled the vacuum hose off the FPR port with the car running and smelled the hose, no smell of gas. I let it run with the hose off for a good ten minutes and no gas came out of the port so I would assume the diaphragm is okay. When I pulled the plenum off and looked inside the throttle body there was a puddle of gas in the bottom. Also there appeared to be gas on top of the fuel rail. I had two new injectors replaced by the shop and four ones from southbay, could it be a faulty injector?

Once I cleaned out the IAC with brak lean and put everything back together the idle seemed to pan out. I also noticed that my EGR valve is digital so I left it alone. Any thoughts on this?

 

a faulty injector is not going to cause gas to be on top of a fuel rail. It would leak from the bottom.

 

What do you think could possibly be causing it?