Severe idle problems after TB/Plenum/O/R X-pipe install

[ThrowedOff]

I installed these 3 things at the same time on my 1999 GT, and also used some DIY mil eliminators to hook to my rear O2 sensors to make sure I didn't get a check engine light.

Well, after installing all of this, I have severe idle issues. It's very random, sometimes at a stop the car will repeatedly drop to ~200rpm and then rev up to 1500, sometimes it will die completely while doing this. Sometimes it will sputter while driving at 1300rpm. Sometimes I will literally have to floor the pedal to get it to move from a stop, sometimes it is completely fine.

After resetting my computer and driving about 20 miles, my check engine light comes on. I got the codes read at autozone today and this is what came from that:

Code: P1151 -- Please note that the TPS I am using DID come with the plenum I purchased, it is not my old TPS.
Definition:
Accelerator Position Sensor (APS) property malfunction
Probable causes
1.-Open or short circuit condition
2.-Poor electrical connection
3.-Failed APS



Code: P0136
Definition:H02S 12 circuit condition (Heated oxygen sensor bank 1 sensor 2) Can anyone tell me what O2 sensor in particular this is? I know that it is post-cat, but not what side it is on.
Explanation:
The powertrain control module uses the oxygen sensor to calculate the air/fuel ratio in the exhaust.
Probable Causes
1.-Oxygen sensor defective
2.-Fuel system running very rich or lean-check other codes first
3.-Engine misfire condition-repair
4.-Fuel pressure very high or low-fuel pump or pressure regulator


Code: P1131
Definition:
H02S 11 - Indicates Lean- Correcting for over rich condition
Probable Causes
1.-Leaking injector, regulator or excessive fuel pressure
2.-Engine vacuum leak or open EGR valve at idle
3.-Engine mechanical condition
4.-Failed H02S or MAF sensor


Where should I start looking? Could all of these problems be caused by the TPS problem? As I stated, I do have MIL eliminators hooked up, which should work, so I don't know why the O2 sensors would be throwing codes.

 

[the98stang]

If the TPS isn't a Motorcraft part, get rid of it. Did you torque the plenum to spec? Did you use new gaskets? You might have a vac leak or faulty IAC.

 

[ThrowedOff]

If the TPS isn't a Motorcraft part, get rid of it. Did you torque the plenum to spec? Did you use new gaskets? You might have a vac leak or faulty IAC.

I believe the TPS is a motorcraft part, everything should be torqued to spec, and I did use new gaskets... I also checked for vac leaks, etc.... So I'm clueless.

 

[Brute03]

i doubt the tps is an oem part, have you checked the voltage to see if it's adjusted properly?

 

[ThrowedOff]

i doubt the tps is an oem part, have you checked the voltage to see if it's adjusted properly?

I sure haven't, but I have access to a multimeter. How should I go about doing this?

 

[Dragstr05]

I sure haven't, but I have access to a multimeter. How should I go about doing this?

Put the ignition in "on" position. If you probe the tps at closed throttle, it should read right around .98 - 1.0 volt. If you manually open the throttle all the way, your reading should be somewhere around 5.0 volts. The tps is a 5 volt reference, and it should roughly go from 1.0v to 5.0v. If its off, loosen the screws/bolts enough to slightly move the TPS to get it within range.

The B1S2 O2 code you got is for the passenger side. Looking at the motor from the outside of the car, bank 1 is on the left, bank 2 on the right. It would be my best guess that perhaps the MIL you made on that side isnt working right, try making up another.

Start with checking your TPS voltage and make another MIL for your B1S2 O2. If your TPS is off and you correct it, clear the codes and see if the P1131 comes back, they may just be related.

Hope this helps.

 

[ThrowedOff]

Put the ignition in "on" position. If you probe the tps at closed throttle, it should read right around .98 - 1.0 volt. If you manually open the throttle all the way, your reading should be somewhere around 5.0 volts. The tps is a 5 volt reference, and it should roughly go from 1.0v to 5.0v. If its off, loosen the screws/bolts enough to slightly move the TPS to get it within range.

The B1S2 O2 code you got is for the passenger side. Looking at the motor from the outside of the car, bank 1 is on the left, bank 2 on the right. It would be my best guess that perhaps the MIL you made on that side isnt working right, try making up another.

Start with checking your TPS voltage and make another MIL for your B1S2 O2. If your TPS is off and you correct it, clear the codes and see if the P1131 comes back, they may just be related.

Hope this helps.

Thanks for the in-depth reply. I will definitely try this when I get a chance (hopefully tomorrow) and report back with results.

Edit: To the person who asked earlier, I checked and the TPS is indeed an OEM part.

 

[hotdog71]

Why don't you just throw your original TPS back on and see if it makes any differnce, it only take a few mins to change, unless of course it's faulty..

Don't know why they would send you a new one with your TB anyway unless they have some kind of odd ball setup that requires a modified TPS.

One thing to check is the IAC gasket when I fitted mine I notice the gasket has slipped and the hole was half covered.

 

[ThrowedOff]

I just tested the middle wire of my TPS (with key turned to acc) and it gave 1.03v closed, and 4.67v WOT. Does this need to be adjusted to be exactly .99v or is 1.03 close enough?

I asked the guy to send me a TPS with the TB if he could, as I can't get the old one off of the original throttle body (and I don't have a rotary tool, was trying to not buy one if I didn't have to.). This is also the reason that I haven't switched it out with the old one.

 

[twogts4us]

Put the old TPS back on. Get a good screwdriver and bear down on it to keep from stripping the head. (The screws have a lil locktite on em)
Don't bother messing with the TPS voltage - I think this is a waste of time. I simply adjusted by ear, then checked the tach to get it to idle at about 800. (This is actually what Accufab told me to do - this is how they do it)
Buy MILs...real MILs...or a chip or tuner.
Is the midpipe leaking anywhere? Especially around those O2 sensors? Do you have a hose plugged into the wrong place on the engine/manifold?

 

[Mike97gt]

Do not mess with your TPS, it is normal on OBD2 fords to have a closed throttle voltage of 1.03 volts. The PCM automatically takes the lowest reading every time the engine is started and learns that as closed throttle. As long as your not above 1.27 volts you are ok.

If you look in the important threads sticky at the top of this forum I have a topic in there that explains the TPS operation on our cars. This explanation is right out of the ford PC/ED service manuals that we use at the dealer for EEC diagnostic


I think your problem is a vacuum leak or a intake leak after the maf check your vac lines and throttle body connections..

You may want to try and spray some carb cleaner at the base of the plenum and see if your gasket is sealing properly there.

If none of this works try the adjustment in the post above mine, maybe if the hole in the TB blade is different on your throttle body this might mess with the PCM's ability to adjust idle.

 

[ThrowedOff]

I just got around to swapping the TPS out with the stock one and spraying carb cleaner around all hoses/gaskets/etc to check for leaks... neither one gave me any luck.

I have no clue what the hell is going on...

 

[hotmustang331]

Do not mess with your TPS, it is normal on OBD2 fords to have a closed throttle voltage of 1.03 volts. The PCM automatically takes the lowest reading every time the engine is started and learns that as closed throttle. As long as your not above 1.27 volts you are ok.

If you look in the important threads sticky at the top of this forum I have a topic in there that explains the TPS operation on our cars. This explanation is right out of the ford PC/ED service manuals that we use at the dealer for EEC diagnostic


I think your problem is a vacuum leak or a intake leak after the maf check your vac lines and throttle body connections..

You may want to try and spray some carb cleaner at the base of the plenum and see if your gasket is sealing properly there.

If none of this works try the adjustment in the post above mine, maybe if the hole in the TB blade is different on your throttle body this might mess with the PCM's ability to adjust idle.

What is the "hole" in the TB blade that you speak of? My BBK TB has no such hole and I have missing problems @ very light throttle input between 1000-1700RPMs....and the same RPM at slightly heavier throttle loads has 0 miss. Wonder if thats whats causing it .


So yea TS see if your TB blade has a hole in it...if not, maybe thats your issue.

 

[Texstang9682]

I had the same issues when I did my Intake plenum. I turned out to be a vacuum line that I had accidently cracked during installation and a faulty TPS sensor. As for your Xpipe, I the rear O2's were a nightmare to get fixed and keep me from getting my car inspected for a year and a half. I tried the home made mils at first, then bought a splice in style from ebay, after tht didnt work I broke down and bought some from BBK even those didnt work. I got it fixed once I bought a XCAL2 tuner and had them disable the rear 02's. Picked up some good power too. I dont want to discorage you on the MIL's some work and some dont, I just thaught I'd share my experiance with them.

 

[Stang|ess]

I just tested the middle wire of my TPS (with key turned to acc) and it gave 1.03v closed, and 4.67v WOT. Does this need to be adjusted to be exactly .99v or is 1.03 close enough?

I asked the guy to send me a TPS with the TB if he could, as I can't get the old one off of the original throttle body (and I don't have a rotary tool, was trying to not buy one if I didn't have to.). This is also the reason that I haven't switched it out with the old one.

How'd you test your TPS? Did you probe the middle wire with 1, then ground the other lead? I still need to test mine.

 

[ThrowedOff]

How'd you test your TPS? Did you probe the middle wire with 1, then ground the other lead? I still need to test mine.

That's exactly how I did it... I used a safety pin as a probe for the middle wire, worked great.

 

[ThrowedOff]

If none of this works try the adjustment in the post above mine, maybe if the hole in the TB blade is different on your throttle body this might mess with the PCM's ability to adjust idle.

What is the "hole" in the TB blade that you speak of? My BBK TB has no such hole and I have missing problems @ very light throttle input between 1000-1700RPMs....and the same RPM at slightly heavier throttle loads has 0 miss. Wonder if thats whats causing it .


So yea TS see if your TB blade has a hole in it...if not, maybe thats your issue.

Nope, my MAC TB does not have a hole in the blade. My OEM one did.

I may try putting the stock TB on later and see if it gives me any problems.

 

[Kilgore Trout]

People always have issues with aftermarket TBs.

 

[hotmustang331]

Im freegin going to throw my stocker on there for a while and see if that helps. If i can find it .

 

[ThrowedOff]

I re-wired one mil (the passenger side, or bank1, one), I cleaned my IAC, I replaced all the shoddy looking vacuum hoses (even though I couldn't find any through and through cracks...)

I drove the car for 65 miles, didn't have a single problem, but my check engine light came on after 25. I'm thinking that the CEL is related to my mils though (so I'll probably get an xcal2 to solve that). After I cleaned the IAC and re-wired the mil, the car seemed to have more pickup.

However, this isn't to say that the problem won't come back (it's done fine for 30+ mi in the past, then started messing up again).

Oh, I also promised myself that if I could get the car working right without spending much money, I'd buy a SCT Xcal2... So I'm crossing my fingers