New 02 sensors, still won't idle

I finally got around to replacing my O2 sensors today. My car kept stalling out after 30 seconds of idling and it would stall when coming to a stop while driving.

New O2 sensors, same problems. The car is still struggling to idle. Now it won't even idle smoothly for 10 seconds before stalling out. I can't figure out what else could be causing this...the vacuum is good with no leaks, new O2 sensors, fresh plugs, wires, etc.

I really need to get this car running soon. Here's the background of everything that I've tried up to this point http://www.novipower.com/forums/show...=&threadid=728

Any more ideas? If I can't figure it out by next weekend, it's going to the shop to get fixed because my patience is drained. :(

Here's something wierd...

I was messing around tonight and took off the vacuum line for the bypass. It was hooked directly to the tree on the firewall and when I removed it, I didn't cap the end on the firewall. I started the car and it idled decent. It was surging but not stalling out. I went around to the vacuum tree and plugged the end with my finger. When I did this, the car almost instantly stalled. When I removed my finger, the idle rose and began to surge again.

When my finger wasn't plugging the vacuum, my gauge showed 16-17. When it was plugged the gauge showed 19-20. Wouldn't the car run BETTER when the vacuum wasn't leaking?

Also, there was alot of water/condensation coming out of the tailpipes when I revved it. Could this cause a problem? The condensation is from the car being stored for the last 7 months.

Whistler,

Sounds like your IAC (idle air control) valve might be sticking, have you tried cleaning it out with some carb/throttlebody cleaner? Sometimes the servo motor inside them just up and dies. (IAC valve is the small barrel-shaped doohickey on the side of the throttle body)

Also make sure your throttle stop screw is set correctly: after the car is warmed up, disconnect the IAC plug (while running & set the stop screw so that it idles without the IAC at @ 600-700 rpm. If the car won't idle with the IAC disconnected, turn the screw in one turn at a time until it will. If you have to turn the stop screw more than a turn or two, you should double check the TPS voltage at idle, make sure it is not set greater than .99 volt.

Whistler,

Are you using an FMU?

What is your base fuel pressure??

I had a prob with my fmu last year and the fuel pressure would stay way high and i would have to unplug hoses under the hood to lean it out to drive it. Just to get it home of course!

Check your base fuel pressure just to be sure.fanglemeister

Also what fanglemeister said is true, make sure that you iac is working corectly that can solve a pile of probs.

I'm not using the FMU and my fuel pressure is set at 38 psi. My timing is at 11*

I'm going to try adjusting the IAC to see if that helps. The car idles kinda low now (650-700 rpm). I will try bumping it up to 900 or so and see if that solves some of the problems.

The IAC and TPS voltage are two things that I haven't checked yet so I'm hoping that the problem is with one of those things. I'll report back tomorrow night. Keep your fingers crossed!

Sorry for the late update but working 13 hour days doesn't leave much time for the Stang.

I was fiddling around tonight when my dad stopped over to see how things were going. He never heard the Novi at idle so I told him I'd fire it up. Before I did, I warned him that the car would probably die in 30-45 seconds like it always had. I started the car and as it idled, we chit-chatted. A few minutes went by and the darn thing was still idling! And it was smooth too! We kept talking and at one point, I got in and revved it up a few times. When the rpm's came back down, the thing idled just like it had been. It was strange. After about 8 minutes, I shut the car off and we went to dinner.

Now the only thing that was different was my fuel pressure gauge. When I installed it, I never put a fuse between the lead wire and the battery, I just had the lead wire directly connected to the solenoid. I had removed the lead wire from the solenoid so it wouldn't be draining my battery day after day. Could my idle problems be related to this? I think they have to be because it's the only thing that I had changed. I never got a chance to mess with the IAC. I just unhooked the FP gauge's wire. I knew what my fuel pressure was because I never changed it from teh last time. FP was 38 psi and timing 11*.

So here it is in a nutshell:

Fuel pressure gauge connected = bad idle. Car dies after 30-45 seconds.
Fuel pressure gauge dis -connected = great idle. Car idled very very smoothly for 8-9 minutes.

I'll be taking it for a test drive on Sunday to see what the driveability is like. What do ya guys think? Think she finally got tired of fighting with me and decided to run correctly? :D

just hook up the wire while its running and see if the idle goes to ****

Quote:

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Originally posted by Mike Gager
just hook up the wire while its running and see if the idle goes to ****

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It was the gauge all along. The idle was fine today with the gauge unhooked. I connected the lead wire for teh gauge and the car almost instantly died. I'm so happy that I've finally figured this car out. I checked everything but I never thought to check the gauges. All that's left is to call up Autometer and find out why I'm having problems with their FP gauge.

On a side note, since the car was running good today I took her out for a drive and OMG this thing feels great. 11* timing and FP at 39 psi. Not a hint of detonation but it was running a tad rich at idle (check engine light would come on and engine would stall every once in a while). I saw 5 psi in third gear. My DR's were spinning through first and half of second!

After hating my car for the last month, I love it again!!

Whistler: what kind of fp guage do u have? Electronic, or mechanical?

Mark

It's an electric gauge. I didn't want the hassle of running an isolator and I didn't want to mount the gauge outside.

I removed my O2 sensors after my test drive to see what they looked like...they are brand new and were covered in carbon already. I guess I was running pretty darn rich at idle!

Whistler,
Why would the fuel pressure gauge effect how the car idles??

Brandon

Quote:

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Originally posted by Cyulost
Whistler,
Why would the fuel pressure gauge effect how the car idles??

Brandon

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That's an excellent question but I don't have an answer. I'm going to get Autometer on the horn this weekend and find out the answer.

Without the gauge hooked up, the car runs like it did when it was n/a, but with the gauge wired, it runs like poo :flush:

Now that's one of the craziest things I've heard in a while... good thing I like those little puzzles.
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-Eric