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Geordie, Mobile Mechanic & Motor Trader
Category: Car
Satisfied Customers: 456
Experience:  22 years of mechanical experience, and I am the mechanic in my own automotive partnership
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2001 isuzu rodeo: Random catalytic converter..coil packs

Customer Question

2001 isuzu rodeo - Random misfire. I have had a misfire in my engine for a long time. I had to replace my catalytic converter once bucause of it once, but when I unplug my coil packs they all seem to work.
Submitted: 9 years ago.
Category: Car
Expert:  Geordie replied 9 years ago.


Random misfires are usually caused by intake system air leaks, and you say that the vacuum is low, which would point to an intake air leak.

Have a good check of all the intake hosing and vacuum lines. If you spray carb spray or the like around all the seams and joins and the engine revs increase slightly, then you have found a leak.

Let me know how you get on and we'll trake it from there.

Very best regards


Customer: replied 9 years ago.
Sorry I waited for too long to get a reply. While I was waiting I researched the net for answers and found a lot of information. I will be checking into many of these posts that I have read. I tried your suggestion once before with no results but may try it again. It is a nice and easy troubleshooting technique. I thank you for your time and attention to this matter.
   Here is a little something for your troubles. It is the most comprehensive breakdown for troubleshooting these errors that I have found. Keep it under your belt and maybe you can ase it in the future. and if all this fails I will give you another chance.

1) Take off and inspect every vaccume line going to the manifold. This
should not take too much time and is FREE. Usually the smaller diameter
lines are your problem because they split eaisley. I had a split one
going to the FPR.

2) Remove your EGR Valve and inspect and clean. Make sure it is not
stuck open. If your EGR Valve is stuck open then it is putting Exhaust
Gas in the intake during idle which will kill the engine. Again this is super
easy. Maybe some PB Blaster on the two bolts if they are stuck. Before
you put the EGR back on check that you have vacume on the intake port.
There are two holes under the EGR valve. One for exhaust one for intake.
Plug the exaust hole (warning hot), and plug the intake. Start the truck
and make sure the intake has vacume by removing the plug. Should
make a loud sucking noise and motor might die so be quick.

3) PCV valve. If stuck open this will kill your engine at idle and give you
bank 1 and 2 lean. Just replace it with an ISUZU PCV vlave. You can
get these at a HONDA dealer. Just ask for one for a 00' PASSPORT.

4) For the ION sensing ignition use only Denso PK16PR11 spark plugs.

5) Fuel filter. #1 problem when your truck stumbles when you first start
it. After it gets really clogged your truck dies.

6) Fuel Pressure Regulator. Cheep and easy to replace but I think the
fuel filter is more prevalent problem.

7) Remove + battery and unplug MAS sensor. If the MAS is bad then
unpluging it will cause the computer to go to a generic setting. Might have
to start your truck twice to keep it running. The MAS is a sensitive device
that can be ruined if you leave the battery connected. If the MAS sensor
is bad then after starting the truck for the second time the truck should
run fine.

Cool Reset the computer by removing + battery cable for 30 min.

After all this then go to the gaskets. Reason being is that usually only one
side will go bad first. Just does not make sence not at least till 70K.
Usually when these start going bad the symptoms start slowly. For Eg
slightly eradic idle. Bizar highway crusing performance. Full throttle
acceleration is OK because low vacumme.
Expert:  Geordie replied 9 years ago.


Thankyou, theres some good stuff in there. We would have gotten to the EGR valve etc if we had carried on.

The best of luck with the repair, I hope you get there without too much hassle.

Very best regards