1997 Isuzu Hombre

Engine Performance problem
1997 Isuzu Hombre 4 cyl Manual 198000 miles

Today I noticed my truck began to idle roughly. The engine runs roughly only at idle. The engine does not seem rough while I drive. When at idle it feels like the whole truck is rocking.
We are thinking there is a valve problem. Are we correct? If so. Would we need to have them changed? Or adjusted?
August 7, 2009.


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.


Aug 7, 2009.
It came up with 3 problems: Definition
BBABS rough road system fault
Probable cause
BB1.-ABS system fault - check other systems for
BBtrouble codes

BBCylinder misfire detected number 2
BBThe powertrain control module monitors the
BBcrankshaft speed and has detected a misfire
Problem cause
BB.- Ignition system fault-spark plugs, ignition
BBwires, coil
BB.-Vacuum leak
BB.-Injector fault
BB.- High or low fuel pressure

BBFuel trim bank one condition

BBThe Power train control module uses the oxygen
BBsensor to calculate the Air/Fuel ratio of the
BBengine. The computer has recognized a rich or lean
BBcondition on one engine bank only.
Probabe Cause
BB.- If one and two codes set together suspect fuel BBpressure or MAF (mass air flow) sensor
BB.- Oxygen sensor defective
BB.- Ignition misfire repair
BB.- Fuel injector problem

Any insight into all this would be welcomed and greatly appreciated.
Thank You!

Aug 12, 2009.
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.


Aug 13, 2009.
The last tune up was 2 weeks ago. New spark plugs, air filter, fuel filter, & pcv valve. The wires were changes the tune before. Anything else we could have done?

Aug 14, 2009.
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.


Aug 14, 2009.
The guy who did it did not give us actual codes. What I sent you was all he gave me.

I have had 2 people since asking the question tell us it sounds like a vacuum leak. My dad being one of the two. He used to do a lot of mechanical work. He said to check for a vacuum leak and that it could be a bad sensor in the fuel system.

The hubby is going to start with checking for a vacuum leak and go down the list from there if it does not work. I wish I had the codes to give you.

Thank You for your help.

Aug 14, 2009.
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.


Aug 16, 2009.
We went to the only auto part store that hooks up the tester and that is all he gave us.
Does he have to redo it so I can get codes?

Aug 17, 2009.
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.


Aug 17, 2009.
We went by today to get the actual codes.
He gave us these codes

Hubby is having a hard time finding the vacuum hose. He has never had to change one before.
We do not have a covered area and it rains everyday here lately so it is hard to find a chance to work on the truck.
Also he is leaving in the morning for 2 weeks for work so it will be that long before he gets to work on the truck.

If you can tell us exactly what those codes mean so we will know exactly what to fix that would be great!

Thank You.

Aug 21, 2009.
Page 1 of 2