1997 Isuzu Hombre Rough Idiling

Hello,

Usually with a valve problem you will hear them tapping.

I would first check for Vacuum Leaks.

Also is the engine light on? If so go by your local parts store and have them pull codes. Could narrow down cause of rough idle.

Post codes here.

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Ok, when was your last tune up? If been a while I would do tune up and see what happens. Change the Plugs and Wires.

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Ok, other possibilities are.

Bad or Weak Fuel Pressure Regulator and/or Fuel Pump.

Vacuum Leak

Bad or Leaking Injector(s)

Bad or Weak Spark - Meaning possibility of one of the towers on the coil pack could be bad.

Also do you have the Number Codes? Should look like this P****. The **** represent the Numbers like P0301.

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Ok, you can get the codes by going by your local auto parts store. The will pull them for you, and most do it free.

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Did they charge you for pulling codes? If not call them and ask if they can give you the code itself and not just the defs. If they can, and they should be able to, you'll probably need to have them pull the codes again.

I ask for the number codes because it is usually easier to figure a problem with a simple easy to understand code def.

For example this def -

BBCylinder misfire detected number 2

Could be P0302 - cylinder 2 misfire

Which as you can see is very similar to the def they gave you.

The other defs they gave you could just be a symptom caused by another code. It is easier for me to dianose with the number codes.

Also what has been checked so far with the list I suggested.

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Ok, here are the code defs.

P0172 System too Rich (Bank 1)

P0302 Cylinder 2 Misfire Detected

P1380 EBTCM DTC Detected-Rough Data Unusable.

So, with the #2 cylinder misfiring I would suggest swapping one plug wire for another and if the misfire moves to the cylinder you swapped with then I would say you have a bad wire and would change wires again. You could also check with the parts store if you have the receipt and see if they have a warrantee.

And if that wire is bad that can be causing the code P0172.

I will need to check on the code P1380 because that reffers to the Transmission Control Module and they are usually only used on Automatic trannies.

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Ok, is the truck 4 wheel drive? If so I believe it is referring to the Transfer Case Control Module. Which would indicate that it is possibly bad.

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Well, Honestly I don't like or recommend them. I haven't had any good experiences with them.

And yes it is possible the plugs are the cause. I always recommend using OE (Original Equipment) or an OE Equivalent Design.

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/Ok, there are at least 2 O2 Sensors one in the Exhaust Manifold at the engine then one by the Cat some models also have one behind or after the cat.

As far as changing it and fixing the problem it may or may not, here some info on running rich.

Because the sensor reacts to oxygen in the exhaust and not fuel, any engine problem that allows unburned air to pass through the cylinders will also trick an O2 sensor into reading lean. A misfiring spark plug or a leaky exhaust valve - even a leak in the exhaust manifold gasket - may allow enough air into the exhaust to screw up the sensor readings. It won't damage the sensor, but it will create a rich running condition that hurts emissions and fuel economy.

So, I would also check for vacuum leaks, and if the misfire is still present in the #2 cylinder then need to find cause.

The biggest one that would cause the lack of acceleration is the misfire. If it is still there then need to find cause.

So, if still have misfire need to check Injector and Injector Harness.

Here is more info on the P0302 code - Cylinder #2 Misfire.

A code P0302 may mean that one or more of the following has happened:

Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer
Possible SolutionsIf there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.E. Spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.K.A. Coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Here is more info on the P0172 code - Rich condition Bank 1.

A code P0172 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak.
There could be a fuel pressure or delivery problem
Possible SolutionsPossible solutions include:

Inspect all vacuum and PCV hoses, replace if necessary
Cleanthe MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect fuel lines for cracks, leaks, or pinches
Check the fuel pressure at the fuel rail
Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.
Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)

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Ok, well think I have found the problem. Here is the Isuzu code def.

P1380 ABS Rough Road Data Unusable

And from what I have read and found on this code the most likely cause is your PCM. It describes pretty much all the problems you have describe.

I will email you the info I found.

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