How to: Lean condition procedure

[MoparMatt72]

Not Ready status

The check engine light went off, the truck was not throwing out codes, so I took it back to the smog place and they hooked it up before they tested it again, and there were no codes but the system was in "not ready" status... The guy at the smog place said to just drive it and the car would basically reset itself. I've driven it at least 100 - 150 miles since then and when I took it back, there was only 1 system not ready (Catalytic Converter), and 1 code was back (P0174), but the light still isn't on. I don't understand why the system says not ready. Any suggestions? Smog dude said that the 1 code wouldn't make me fail smog again because the check engine light isn't on, but all systems need to be ready.

 

[craftsman67]

With no loss of performance, I have the bank 1 and bank 2 codes only. When I do the tps test at closed throttle it reads 1.2 volts, and at WOT it reads around 5.9 and has read up to 6.0 volts with no unexpected variations while moving the throttle slowly as instructed. According to the test, this is bad right? Could this throw the bank codes? I've already cleaned the maf sensor and reset, only for the cel to return. Any thoughts?

 

[2000StreetRod]

repeat TPS test

With no loss of performance, I have the bank 1 and bank 2 codes only. When I do the tps test at closed throttle it reads 1.2 volts, and at WOT it reads around 5.9 and has read up to 6.0 volts with no unexpected variations while moving the throttle slowly as instructed. According to the test, this is bad right? Could this throw the bank codes? I've already cleaned the maf sensor and reset, only for the cel to return. Any thoughts?

I suggest that you repeat the TPS test. As I recall the supply voltage from the PCM to the TPS is only 5.0 volts. It would be unusual to read a resistance divided voltage that exceeds the supply voltage. As I recall, if the TPS voltage exceeds around 4.8 volts the PCM reports an out of tolerance TPS voltage.

 

[craftsman67]

I suggest that you repeat the TPS test. As I recall the supply voltage from the PCM to the TPS is only 5.0 volts. It would be unusual to read a resistance divided voltage that exceeds the supply voltage. As I recall, if the TPS voltage exceeds around 4.8 volts the PCM reports an out of tolerance TPS voltage.

I have repeated it several times, with the same results. Is it possible that I may the meter on the wrong setting? I may try another setting on my meter and see what happens, but I think I have it on the right one. I may make a short video to show you, if you will watch it. Thanks for responding!

 

[craftsman67]

Am I doing something wrong to get these readings? Please let me know. Thanks!

http://www.youtube.com/watch?v=XNYWAABuMd8&feature=youtu.be

 

[2000StreetRod]

voltage not resistance

Am I doing something wrong to get these readings? Please let me know. Thanks!

It looks like your meter is set to resistance (K ohms) instead of D C voltage. Go back and carefully read the TPS procedure.

 

[craftsman67]

It looks like your meter is set to resistance (K ohms) instead of D C voltage. Go back and carefully read the TPS procedure.

It is set on DC voltage and not k ohms. 1st reading is at 200v 2nd at 20v settings, but I will go back and read through the procedure again.

 

[2000StreetRod]

measure the reference voltage

It is set on DC voltage and not k ohms. 1st reading is at 200v 2nd at 20v settings, but I will go back and read through the procedure again.

Measure the reference voltage to see if it exceeds 5.0 v. What is your battery voltage? Is your system stock?

 

[craftsman67]

Measure the reference voltage to see if it exceeds 5.0 v. What is your battery voltage? Is your system stock?

Yes, it is stock except a homemade cai using the stock tube, but I'm sure thats nothing related... right? I'm reading 12.58v between the battery terminals. Here's another vid for the reference voltage test.

http://www.youtube.com/watch?v=q7AC0XYSUiw&feature=youtu.be

 

[2000StreetRod]

sensor ref volts = 6.59

It looks like you have the OHV V6 engine in your 1998 Sport. The only wiring diagram I have for that engine and year is in my Haynes Repair Manual which is not very detailed. However, the TPS wiring looks identical to that shown in my 2000 Ford Wiring Diagrams for the OHV V6. The reference voltage should be about 5.0 volts. My Haynes Manual confirms that. The reference voltage (BRN/WHT wire) also goes to the differential pressure feedback EGR (DPFE) sensor. Check to make sure the DPFE sensor electrical connector is making good contact. Then disconnect the DPFE sensor connector and see if the reference voltage changes. Fortunately, the 2nd generation PCM measures the TPS voltage when the ignition switch is placed in Run and assumes that to be the idle voltage. Periodically, it checks for a lower TPS voltage and if it occurs the PCM accepts that as the new idle voltage. I'm surprised that the PCM is not generating an out-of-range error code when the throttle is at WOT and the voltage exceeds 5.0 v.

 

[craftsman67]

It looks like you have the OHV V6 engine in your 1998 Sport. The only wiring diagram I have for that engine and year is in my Haynes Repair Manual which is not very detailed. However, the TPS wiring looks identical to that shown in my 2000 Ford Wiring Diagrams for the OHV V6. The reference voltage should be about 5.0 volts. My Haynes Manual confirms that. The reference voltage (BRN/WHT wire) also goes to the differential pressure feedback EGR (DPFE) sensor. Check to make sure the DPFE sensor electrical connector is making good contact. Then disconnect the DPFE sensor connector and see if the reference voltage changes. Fortunately, the 2nd generation PCM measures the TPS voltage when the ignition switch is placed in Run and assumes that to be the idle voltage. Periodically, it checks for a lower TPS voltage and if it occurs the PCM accepts that as the new idle voltage. I'm surprised that the PCM is not generating an out-of-range error code when the throttle is at WOT and the voltage exceeds 5.0 v.

You are correct about the OHV. Sorry I didn't make that more clear to start with. I will try this when I get home from work this afternoon and see what happens. I have just received my FSM volumes 1 & 2 for my 98 the other day from ebay, but that seller didn't have the wiring and vacuum book. However I did find it from another seller, and it should be here later on in the week. Thanks for your time and help! I'll let you know what happens.

 

[craftsman67]

Lean codes solved!

I gave this a rest for a while, but since it was inspection time I wanted to get rid of the CEL. After about 3 cans of brake cleaner I finally found my vacuum leak. It was the EGR Valve. There was NO gasket! $1.99 later and I'm good to go. If you are chasing these P0171 & P0174, be sure to check for this!

 

[ExloringXLT]

Man this thread was tremendously helpful. I sure hope it hasn't died!

Here's the scoop - DTC in title. Just replaced plugs, air filter, and PCV valve, checked all vacuum lines, and found no problems (that I could see). Tested MAF and TPS, all fine. Still getting P0171 System too Lean (Bank 1)

Here is my major concern: I was wheeling about 6 months ago, slid and landed on a big ole nasty rock. That's when I learned the 1999 SOHV has no skid plates - lovely. Any ways, immediately heard loud exhaust coming from right side of motor. Checked for damage, and noticed the cover plate to the cat (the one parallel to the motor) was slightly damaged - had a ding in it. I'm from CA, so I have one parallel and one perpendicular cat.

Would the P0171 System too Lean (Bank 1) code have anything to do with the cat? It is the only error code I get after repeated scans. I would think I would get another code if the cat needs replaced. Not real sure????? I'm guessing cracked manifold, but I only got that idea from reading the forums here. I have no mods or changes to the truck - It is stock.

Any help would be greatly appreciated. Again, excellent thread on Lean codes. Thanks!

 

[ExloringXLT]

Man this thread was tremendously helpful. I sure hope it hasn't died!

Here's the scoop - DTC in title. Just replaced plugs, air filter, and PCV valve, checked all vacuum lines, and found no problems (that I could see). Tested MAF and TPS, all fine. Still getting P0171 System too Lean (Bank 1)

Here is my major concern: I was wheeling about 6 months ago, slid and landed on a big ole nasty rock. That's when I learned the 1999 SOHV has no skid plates - lovely. Any ways, immediately heard loud exhaust coming from right side of motor. Checked for damage, and noticed the cover plate to the cat (the one parallel to the motor) was slightly damaged - had a ding in it. I'm from CA, so I have one parallel and one perpendicular cat.

Would the P0171 System too Lean (Bank 1) code have anything to do with the cat? It is the only error code I get after repeated scans. I would think I would get another code if the cat needs replaced. Not real sure????? I'm guessing cracked manifold, but I only got that idea from reading the forums here. I have no mods or changes to the truck - It is stock.

Any help would be greatly appreciated. Again, excellent thread on Lean codes. Thanks!

Thank you all very little...No wonder your Google page rank is so low.

 

[imp]

@2000StreetRod
Excellent and understandable help you give here! Now a quick question: Later models using Drive By Wire "prove out" the TPS as well as the Accelerator Position Sensor each and every time the key is turned to "ON". Would it then be that checking the TPS when diagnosing lean conditions is unnecessary? imp

 

[2000StreetRod]

I know very little about the electronic throttle control models. I purposely purchased a 2003 to avoid the issue. As I recall the IAC valve is eliminated because the PCM has control of the throttle plate to maintain the desired idle speed. If by "proving out" you mean that the throttle plate is cycled from closed to WOT to closed while monitoring the TPS then I assume that the TPS would be reliable.