Problems...

[dustang50]

After a winter of storage, I finally brought the car out today. This winter I made the following mods/service:

* K&N FIPK
* IAC Restrictor Plate
* Ported/Polished Plenum/TB
* Replaced PCV Valve
* Replaced plugs

I attempted to install a midpipe, but had problems with a bolt so I put it back together (although the nuts aren't tightened too much since I'll be having it done by a shop this weekend).

I ran some seafoam through the plenum, oil, and fuel today.

So here's the problem: It's idling funny now - hangs at 2k, then drops to normal until more fuel is released to the engine, then it hangs at 2k for a while again. I am now getting 4 codes thrown by the PCM. They are:

* P-1000 (I figure I just have to drive it a bunch since the battery was disconnected)
* P-1131 & 1151 (I'm assuming I may have a leak in the midpipe near the manifold since the botched install yesterday).
* P-1506 (possible IAC Valve problem or vacuum hose leak, although I can't find any leaks)

What could be throwing the 1506? It seems like these are all related, like the engine isn't getting enough fuel.

Does anyone have any ideas?

 

[Kilgore Trout]

A lot of people report idle problems after replacing the TB. I suggest you put the stock TB and plenum back on remove the restrictor plate reset the PCM and allow the car to relearn its fuel trims according to the procedure outlined in the owner's manual.

 

[USMstang]

In addition to what Trout said, I had to tinker with my IAC restrictor a couple of times until I got rid of the idle problems. I think I would remove the restrictor until you get everything cool with the new Plenum/TB. Good luck.

 

[Pearl02]

did you use a volt meter to set your TPS. The TPS tells the pcm how far the throttle plate is open. If it's not set right, it can also effect your idle. At idle the voltage should read from .93 to 1.0. Since you removed your plenum and tb make sure there are now vacuum leaks. Pearl02.

 

[dustang50]

Would re-flashing the PCM with a handheld tuner help the fuel trim issue?

 

[Mike97gt]

you have two codes for the 02 sensors not switching. how loose is your midpipe. do you have exhaust leaks? if so this could be your problem with the 2 o2 sensor codes.

and for the 1506 remove the iac plate and then check your tps voltage at idle and WOT. this can be done with the engine off and key on.

 

[dustang50]

you have two codes for the 02 sensors not switching. how loose is your midpipe. do you have exhaust leaks? if so this could be your problem with the 2 o2 sensor codes.

and for the 1506 remove the iac plate and then check your tps voltage at idle and WOT. this can be done with the engine off and key on.

Come to think of it, the new TB has a TPS on it already. Maybe that one's bad... If the voltage doesn't jive, I'll put the old TPS on & see how that one is.

 

[sgarlic]

Start small.. first check o2 sensors for tightness, leaks. Torque down the midpipe nuts. Clear codes, check codes.

Next, remove IAC plate, clear codes, check codes.. I bet that plate has the wrong size hole in it.

 

[Mike97gt]

another thing that could be the problem is the plate itself. if the car is way lean the sensors will not switch. do you have anyway to read live data. like a sct2 or pred.

 

[dustang50]

I just replaced the TPS & removed the IAC restrictor. It's idling much more smoothly now. I'm gonna take it out for a spin & make sure it idles better while driving...

 

[jstreet0204]

Another suggestion, the thermostat you have is way too cold for the area you are in. The changover to the base fuel table will not happen until 180* and unless you are having problems with detonation, you won't gain anything with the cooler tstat.

Definetely tighten up the midpipe. Exhaust leaks will cause the o2's to see lean, and remove the restrictor plate like others have suggested.

 

[dustang50]

Well, took the car out last night & didn't want to come back... Felt much better, idle was good, response was great. I'll toy around with the IAC restrictor later, if it's even necessary.

 

[USMstang]

In reference to the IAC restrictor, I started with the minimum reccomended size (from the original thread) and moved up a couple times until she ran right. It ended up being the size of a standard round file (whatever that is for the small one that's just a touch bigger than a pencil). I know that is a crude measurement but that is where she purred best. Sounds really cool between shifts now! At least you can redo that mod over and over in a matter of minutes and it doesn't cost anything.
BTW, I obviously used a piece of thin sheet metal for my fabrication.

 

[dustang50]

Another suggestion, the thermostat you have is way too cold for the area you are in. The changover to the base fuel table will not happen until 180* and unless you are having problems with detonation, you won't gain anything with the cooler tstat.

Definetely tighten up the midpipe. Exhaust leaks will cause the o2's to see lean, and remove the restrictor plate like others have suggested.

I don't drive my car in the winter & was told that the 160* thermostat wouldn't be an issue...

 

[jstreet0204]

I don't drive my car in the winter & was told that the 160* thermostat wouldn't be an issue...

Not sure who told you that, but it isn't true. Even if the fans are adjusted in the tune for the thermostat, most tunes do not take into acount other variables that adjust certain change overs that rely on ect (engine coolant temp) for example close loop delay, and base fuel table change over. Unless your car has been tuned changing those things your car will not run as it should. You will be running off of the richer startup fuel table. Like I said unless you are having a problem, there isn't any benefit to running the cooler thermostat.

 

[mity2]

U said you changed PCV valve right? I had P-1506, hangin RPM, stay at 1500 ~2000RPM thing for a while and nothing fixed after I rechecked TPS, check to see if elbow is leaking. And eventuary, it turned out passenger side PCV valve(under intake rubber tube) was not seated tight. re install PCV valve, probrem fixed