Do you have a tune?I have a 2003 GT that keeps throwing P0133 and P0153 codes. This started about 2 years ago. I've replaced all 4 O2 sensors, IAC, EGR, MAF and coolant temp sensor. All replaced parts are Motorcraft parts. But the codes still come back. The car has Longtube headers, off road h-pipe, slp loudmouth catback, bbk fender well intake and a 70mm one piece throttle body. Any ideas as to what I'm missing? The vehicle itself runs great.
No tune. Long tubes have been on the the car for 6 years. This issue started about 2 years agoDo you have a tune?
O2's slow to respond is because of the long tubes. With the long tubes, the o2 sensors are furthur away from the engine than with the stock manifolds. Because of this they take longer to heat up, and longer to register changes the computer make to a/f. This, and your other issues can be fixed with a custom tune.
As stated in my thread. All the O2s, IAC, EGR, ECT and MAF sensors have been replaced within the past year. This issue started about 2 years ago. The headers have nothing to do with it. All the mods were done before I bought the car 7 years agoIn my 2001 when I put longtube headders there were o2 sensors I replaced the stock 02 sensors out for that read faster and worked with the headders and it seems like you have the same deal....I have so many vihocles with different 02 sensors but from what I remember they were either NTK and I forget the second but I do know its not Bosch..
Have you tried replacing the o2 sensors? As sensors get older they dont read like they used to and although it may seem like a crude way to test their function while in operation is with an OBD2 reader with live PID setting can read 02 sensor voltages......
I remove and clean mine in a shotglass full of lemon juice to decarbonize them then rinse them in a vinegar bath for a few mins then finish them off with rubbing alcohol..
This method works really good for sparkplugs too and saves money on harsh chemicals.......
The upstream 02 sensor measures the amount of oxygen in the engine exhaust that is about to enter the catalytic converter.
When this cross-counting voltage activity drops below a minimum level, the PCM will set the P0153 trouble code.
You can trace the reduced cycling rate of an oxygen sensor’s cross-counting voltage activity to problems that affect either the device, engine performance or the exhaust system. The following issues can cause the PCM to set a P0153 code:
Bad or failing 02 sensor
Oxygen sensor circuit problems from rust stopping proper grounding of the 02 sensor or damaged wires or poor connections at the 02 plugs
A rich or lean running engine
A leak in the exhaust system
An issue with the PCM where you many need internal repairs and/ or a PCM reflash...
First things I do is remove all grounds at their grounding points one at a time clean the spots and replace the hardware if needed...
It might sound strange of a longshot but on my 2001 my mystery issues were started because of a bad cell in the battery.
Car started up fine too....LOL
Good Luck
The car has never had a tune or a problem until 2 years ago. All the mods were done on the car before I bought it 7 years agoIt is the tune with all your mods...the PCM cant calibrate correctly with a/f ratios.....with all your mods you will probably pick up 25 peach hp and 40 tq easily with a full dyno tune....and over 60 in peak rpms....I had the Same problem years ago....tune is needed at this point...
Ed
So I read somewhere that if you let the car idle a few minutes before driving it'll help too. So I tested this theory and put over 100 miles on it without the CEL coming on at all. Then this morning after I drove to work I had to leave and go somewhere a short distance away and the light came back on. So it seems if I let the car idle for a few minutes before driving and then drive a long distance, the light will stay offI had intermittent faults with O2 sensors popping up years ago when I first started modding the car to a certain point..... I would unplug the battery and reset the codes and sometimes it would last a month or just a day... when you have item's like headders, CAI, and TB/Plenum, the computer tries to read during its cycle... sometimes they pop up and sometimes they don't... does the MAF go inter the fender well with your CAI or is it in the engine bay.... typically, the CAI needs to be 16 to 18 inches downstream from the TB ...with CAIs these may move the distance by 1-2 inches or another 10-12 inches if moved into the fender well... the space/gap between sensors from the TB to MAF can cause codes including O2 sensors due to A/F mixtures being inconsistent with parts and current tune... I have heard of people running for years without issue and then one day they get Mutiple codes, and they never go away... a tune will fix all your issues ... trust me ... I tried tuning myself long ago (2004-2005) but timing curves and A/F ratios drastically change with the mods you have... there is a threshold where you are more than likely running too rich or too lean and the tables need to be adjusted based on modifications... The stock computers parameters arer out of tolerance with the air flow of the engine... Plus with a dyno tune alone, the car will be so much more fun to drive and have quite a bit more power and tq when A/F and spark/timing tables are aligned and calibrated...
Ed
I think I might just put my stock throttle body back on and see if that helps. I also noticed that my car doesn't high idle at first startup in the morningThat is true...the computer has some curve and fuel trim adjustments based on voltage feedback from spark fuel and sensors....when at full temperature it can regulate itself al low idle and cruise speeds.....that tells me your fuel and timing trims are out of tolerance due to improved airflow from opened up intake and exhaust...these could be off by 10 percent or more...not sure how much percentage the stock computer calibration can adapt too...
I don't think just switching your TB will fix the issue.... Here are a couple of posts for comparison that show just how far off fuel trims and modification effect HP/TQ and drivability...
o here is one of the 1st Dyno Sheets...around 2004ish....this was with full bolt ons for - Catback (H-Pipe), BBK Under Drive Pulleys, Accufab TB with BBK 70mm TB, BBK Intake, 373 gears, Stock Heads and cams, and a Diablo tuner with a can tune.... I also had an A/F Adjuster that attached near the MAF that I could adjust.....I did a couple of tuning sessions on my own based on feel and drivability but could always tell it was running rich...
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So I don't have any drivability issues but I did find that the coupler that connects my intake tube to the throttle body was torn and cracked on the bottom sideBasically, I had similar bolt ons as you with the only real change is a custom dyno tune..
Car went from 237/263 to 263/293.... car picked up over 75hp at 6k rpms.... and over 100 at 6500...if the graphs were extended out... went from running 14.1s to low 13's in the 1/4 and gained several MPH on top end... Most codes for O2s are either a ground issue or tune is off.... The reason I say ground issue is with 02 Extenders and Long Tube Headers you really need to ensure the wires don't melt against the exhaust as this happens alot if you don't secure the wires away from the headders.... plus some people just splice the line to extend and don't solder the wires and just wrap with tape.... just some more thoughts....
So I don't have
So I don't have any drivability issues but I did find that the coupler that connects my intake tube to the throttle body was torn and cracked on the bottom side
So I actually repaired it last night and cleared the code with my scanner and drove it to work this morning and it seemed to run fine. Should I still unplug the battery when I get home?I’m surprised that didn’t throw a p0171 and p0174 by letting unmetered air in!
Good find tho
Disconnect your battery for 30 minutes after fixing that coupler. Let car idle for 5 minutes, then turn a/c on and idle for another 5.
This helps the PCM relearn the idle and establish fuel trims
So I actually repaired it last night and cleared the code with my scanner and drove it to work this morning and it seemed to run fine. Should I still unplug the battery when I get home?
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