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Ask Don 'Mo Lurch' Your Own Que...
Don 'Mo Lurch'
Don 'Mo Lurch', Aftermarket & Factory Electronics
Category: Chrysler
Satisfied Customers: 510
Experience:  Cert. Chrysler Warnty, Heavy Line Mech, Mobile Electronics. Sales, Installation & Repair for 30 years
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2002 RAM 1500 4.7L V8: Throwing P0172 & P0175 Codes - Runs

Customer Question

Hi,
JA: Hi. What is your issue regarding?
Customer: 2002 RAM 1500 4.7L V8: Throwing P0172 & P0175 Codes - Runs strong - very slight rough Idle - Swapped out Coils, Plugs, Fuel Injectors, MAF - still can't get codes to go away - like I mentions very slight roughness at idle - Help ?
JA: Is the rough idle intermittent or consistent?
Customer: consistent
JA: Are you fixing your Ram 1500 yourself? What have you tried so far?
Customer: I replaced plugs, coil packs, fuel injectors, maf sensor, vacuum test is at 19 - have not checked the fuel pump pressure yet
JA: Anything else you want the mechanic to know before I connect you?
Customer: 178,000 miles - engine is very strong
Submitted: 1 month ago.
Category: Chrysler
Expert:  david craig replied 1 month ago.

Hi Im David, P0172 DODGE - Fuel System 1/1 Lean Fuel System Rich
Possible causes - Faulty front heated oxygen sensor - Ignition misfiring - Faulty fuel injectors - Exhaust gas leaks - Incorrect fuel pressure - Faulty Mass Air Flow (MAF) sensor

P0172 Dodge Description With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios. In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).
P0175 DODGE - Fuel System 2/1 Rich
Possible causes - Faulty front heated oxygen sensor - Ignition misfiring - Faulty fuel injectors - Exhaust gas leaks - Incorrect fuel pressure - Faulty Mass Air Flow (MAF) sensor

P0175 Dodge Description With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios. In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).

I would definitely check the fuel pressure

Customer: replied 1 month ago.
is it possible that I could have 2 O2 sensors go bad at the same time ? or should I rule those out ?
Expert:  david craig replied 1 month ago.

do you have a scan tool that can read live data?

Customer: replied 1 month ago.
No, I don't have one
Expert:  david craig replied 1 month ago.

also try and clean out the throttle body and idle air control valve

Expert:  david craig replied 1 month ago.

i dont think the o2 sensors are the problem. they are just going haywire trying to figure out whats going on.

Customer: replied 1 month ago.
OK .. will do
Customer: replied 1 month ago.
do you recommend getting the PCM re-flashed ?
Expert:  david craig replied 1 month ago.

have you checked the pulse to the injectors at idle?

Customer: replied 1 month ago.
no, have not checked pulse
Expert:  david craig replied 1 month ago.

do you have a noid light?

Customer: replied 1 month ago.
No, sorry - I only have basic mechanical tools
Expert:  david craig replied 1 month ago.

if theres a harbor freight nearby they sell a set of noid light real cheap. other than that, you will need to use a long screw driver and put the flat end against each injector and put your ear on the plastic end and listen to each injector for clicking.

Customer: replied 1 month ago.
OK - do have a H/F down the street - will try - Thnx
Expert:  david craig replied 1 month ago.

you get the noid lights?

Customer: replied 1 month ago.
Hi - not yet - have to wait until Saturday. I'm puzzled as to why the truck runs smooth as silk and strong on the freeway but has the slight mis at idle ?
Expert:  david craig replied 1 month ago.

well with the codes you are throwing, it may be a slightly clogged injector or 2. run a can of injector cleaner through the tank and drive it the rest of the week.

Customer: replied 1 month ago.
OK - I've read SeaFoam works good - is that OK or is there a specific cleaner that works better ?
Expert:  david craig replied 1 month ago.

sea foam is ok, but lucas fuel treatment is better.

Customer: replied 1 month ago.
great - Thnx - will try
Expert:  david craig replied 1 month ago.

no problem

Expert:  david craig replied 1 month ago.

any luck?

Customer: replied 1 month ago.
Hi .. I put in the fuel inj cleaner and seems a little better - will do the fuel pressure test and noid test this weekend
Expert:  david craig replied 1 month ago.

ok. great.

Expert:  david craig replied 1 month ago.

any good news?

Customer: replied 1 month ago.
Fuel pressure tested normal - 49 psi - noid lights get here Monday - I ordered from Amazon - cheaper than harbor freight .. Still puzzled man. Humms on the highway - just a slight rough idle ?
Expert:  david craig replied 1 month ago.

we'll figure it out.

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