Combination of driveability issues. Doesn't make sense..

[HISSIN50]

Now what happens if you get it hot, shut it off, disconnect the IAC and then restart it? This will remove the IAC from the equation (and if your idle is set properly, it will idle hot without the IAC anyhow)......

On clearing the KAM, you can also hit your battery-disconnect and then turn on the headlights. This will discharge the capacitors in the EEC (to accomplish the same thing that Brian talked about). It might save a little time........

 

[281pony]

Now what happens if you get it hot, shut it off, disconnect the IAC and then restart it? This will remove the IAC from the equation (and if your idle is set properly, it will idle hot without the IAC anyhow)......

On clearing the KAM, you can also hit your battery-disconnect and then turn on the headlights. This will discharge the capacitors in the EEC (to accomplish the same thing that Brian talked about). It might save a little time........

thanks jt. this is what i just did;

disconnected battery terminals, touched them together for 30 min.

set baseline idle of 900 rpm. set tps (new) to .99 at idle. 5.01 at WOT.

started it, let it get warm. shut it off, disconnected IAC, it still surges on hot starts, still surges lightly when i rev it in neutral.

i also cleaned my maf element, which is a new pmas maf anyways with 500 miles on it. filter is clean. plugs/wires are new. timing is set.

if i cannot fix this nasty bucking crap, which my old fox did NOT do with a 274hr cam (i only have a tfs stage 1). then this surging idle stuff is needing attention atleast.

 

[281pony]

ok, i drove the car now, ran codes again. 33, 41, 91 for codes.

idle, for now, is returning to slightly elevated over baseline when i rev it in neutral.

when i push in the clutch moving, it still hovers at 1200. however, when i am nearly stopped, it no longer raises up to 1400-1500. it just sits at 1200, then settles to roughly 1000. my baseline was 900.

it never seems to settle completely back to my 900 rpm baseline.

still surges badly on hot starts. still has the bucking issue, seems to be less common in 3rd gear and higher now. 1st and 2nd are still nasty.

im too sick (103 fever now, haha) to climb under the car to change or test o2's. do you guys think thats my next/only other resolution? jt, you were suggesting one other thing to me, i forget what it was though.

i believe i have ruled out my tps, iac, maf now? the car did idle better with no tps though, even with this new one installed.

 

[Gearbanger 101]

Have you checked yet for a good old fashioned vacuum leak? Small bottle of propane with a hose on the end to direct the gas around each of the vacuum hoses/connections might shed a little light on the subject. Don't forget the ones underneath the upper manifold.

Hoses will dry rot and/or lose pliability over time. Could be the source of some of your idling issues?

At the very least, you'll be able to rule it out of the equasion if it isn't.

Code 33 has to do with your EGR fuction....which since is no longer part of the equasion, probably isn't going to be an issue.

The other two (41 & 91) are lean codes, which could very well back up a vacuum leak theory. Particularily in the manifold/throttle body/IAC area.

 

[HISSIN50]

It sounds like you've covered things decently. At this point, if it's not a cam or MAF issue, I like going in Brian's direction. We hunt for leaks and think we've checked it all but then they are still there. In other words, they can be a real pain to find, but it's kinda got that feel to it. A stockish cam with sit at 18-20" at idle. Someone that PM'd me recently was at about 15" (I'm not sure if it was you), and depending upon the cam characteristics, that's a bit low.

 

[liljoe07]

Lots of places most dont think to look either. Charcoal Cansiter, vacuum tank in the passenger fender well, cruise control stuff if you got it, A/C and heater controls.

Heres a 02 test if you need it.

I believe the only thing its missing is testing the 02 signal wires from the 02s to the ECM 60 pin. Pay no attention to the Signal Return test, its not used on 3 wire setups.

 

[Foxlover]

I'm having the same symptoms with the bucking when slowing down and then the idle sitting kind of high when you come to a stop and then it drops. So I cleaned out the IAC and it made things worse. So i just replaced it and it went back to the same thing. So I was told to completely block off the IAC and leave it unplugged. It seemed better but didn't fix it. So I was told to check the TPS. If you check it with a volt gauge, you should turn the key like you're turning it on but don't turn it on and then stick the tips of the volt gauge through the insulation on the green and the black wires, (I believe those are the 2 colors). It should read between .8 to 1. Mine was right on the 1 spot. So for me that left the EGR and vacuum leaks. I haven't check/cleaned my EGR yet so I couldn't tell you if that would fix it. Plus you don't have one anyway. So for you that would leave vacuum leaks. Plus when I swapped my 3.8 for the 5.0 I couldn't find one of my O2 sensors. So it's never been hooked up. I thought not having it hooked up might be one of my problems. So I don't know if unhooking yours will fix it or make it worse. But if you figure it out let me know. Maybe it will fix mine too. Good luck

 

[281pony]

well for right now, my car is a paper weight. its supposed to be 4 degrees tonight. cold as hell! i have broncitus too, so any aspirations of working on the car are minimal. im gonna check for vac leaks now, and unplug my o2 sensors.

the car is a blast to drive aside from this stuff. once i fix this, its onto a dyno tune. so it should be just that much better.

 

[281pony]

update of sorts.. i got my christmas bonus the other day, so i just sprung for some new o2's. installed them, still has surging idle, but its not as bad. the surging is less severe, and does not cause the voltmeter to bounce around as often/at all.

so i guess after all of this, i am after vacuum leaks? it still has the bucking in gear. i did notice one thing after replacing the o2's. it seems to drive smoother, and the bucking comes on at a certain throttle position it seems.

outside of first gear, i can completely let off the throttle. it will just gradually slow down/drop rpm's with no bucking. the second i give it a tiny bit of throttle to maintain speed, the bucking came back.

there is a NEW tps on there, adjusted to .99 @ idle, with a smooth transition to WOT @ 5.01 volts.

i've been over it for vac leaks, whats the best/most guaranteed way to find it with simple things? or am i better off paying for a smoke test to be done at a shop?

 

[MH-47gMECHANIC]

or you could convert to a carb and give me your fuel injection parts. i have nothing to offer you but everything to gain from you... its just a thought though.