2000 rodeo at witts end

i have a 2k rodeo with a new motor. I cracked the block at 51k and had a new motor put in. I have issuse with the new motor and isuzu has no clue how to fix it. I am tired of taking it back. I took it in because it had a rough idle and was getting crap mpg 12! from the normal 18. They replaced the IMG and it was good for one tank. first tank 17+ the second was 14 and the third was 12. After the I took it in and they had forgot to hook a vac line to the fuel regulator. Same thing got it back and 17--15--12 mpg. Mind you I only drive freeway to work and back. So the driving conditions have not changed.
now they don't have a clue what it is. oh and it gives no codes.:banghead:
I almost forgot. sometimes when going from drive to park it drops rpm or dies. Or it goes up to 1k for a second. In the mornings the idle is not a fixed high idle it can pulse a bit.

Are you the original owner?

It still sounds like an issue with the IMG.

Your mpg could be due to a bad O2 sensor(S). I would have another shop (non-isuzu) replace the 2 O2 sensors that are infront of the Cats. There are 4 total (2 infront of the cats and 2 behind).

have you ever cleaned out the intake throttle body before? the butterfly maybe sticking.

It also sounds to me like it could be another IMG problem. Even though it was just replaced the bolts could have been tightened too much and cracked the new gasket.

Try spraying some carb cleaner around the gasket to see if the RPMS drop or jump a bit.

I have the same problem right now when going from drive to park and I have a small leak in the IMG.

i have cleaned the egr ,mas air meter and throttle body. I did the carb cleaner around the intake and no change. I just found if I disconnect the batt and reset the comp. It runs better and gets better mpg's but only for a tank or 270 miles or so. I like to think of my self as more than the average wrench head. I have built 3 chevy trucks and four vw bugs from the frame up. Not to for get I can keep a 35 year old harley on the road. But this is one I am stumped on. how in depth is the img . Do you do the upper and lower.Its a 3.2 v6. And sorry to say I am not the first owner, it had 50k when I got it.

Who Installed The New Engine And Was It Already Timed
Any Dtc's Were The Heads Repalced, Vacuum Readings Would Help Sounds L;ike Timing Is Off ,maybe Check Compression On Both Banks To See If One Side Is Much Higher Than The Other
Let Us Know

hey 2eye... nice to see you back.

....,maybe Check Compression On Both Banks To See If One Side Is Much Higher Than The Other ....

are you looking to see if the head gasket(s) are good, or would the timing issue show up that way, too..?

thanks,
//bc

i have cleaned the egr ,mas air meter and throttle body. I did the carb cleaner around the intake and no change. I just found if I disconnect the batt and reset the comp. It runs better and gets better mpg's but only for a tank or 270 miles or so. I like to think of my self as more than the average wrench head. I have built 3 chevy trucks and four vw bugs from the frame up. Not to for get I can keep a 35 year old harley on the road. But this is one I am stumped on. how in depth is the img . Do you do the upper and lower.Its a 3.2 v6. And sorry to say I am not the first owner, it had 50k when I got it.


It does have upper and lower gaskets. The upper is a one piece and is not normally the problem. The lowers are 2 gaskets and thats where they usually break. Two times I think they've lowered the torque values for the intake manifold in an effort to stop the lower gaskets from cracking.

I am always watching you
if compression is much higher on one bank theree is a good chance timing is off best check for this one is vacuum guage $10 at harbor freights
I am almost willing to be the timing is off it really sounds like it is