HELP…
98 MS 131K 2WD Auto. Just had the following done at the dealership.
New Timing belt, New cam sensor, new crank sensor, crank angle sensing blade, new water pump, new plugs, new cables, trans flush, fuel injection flush.-

I thought that the transmission was shifting weirdly, but it ends up that the motor is cutting out while I am driving. I'm just not sure what is causing it.


The motor problems started when the crank angle sensing blade became disengaged from the crank pulley. This created poor engine performance and a lot of headache finding the problem. After all the engine repairs were completed, I thought the truck was having inconsistent transmission shifting problems, hence the flush.

Driving it I was able to diagnose the problem but I have no idea what is causing it.

While you are driving, during acceleration and slowing down, the truck feels like it has major hesitation or the motor is almost cutting out. The problem is that it only does it while the truck is moving and at lower RPM's
I tested this today by putting it in drive and accelerating up to 30 MPH. I then put the truck into neutral and got the RPM's to about 1750 (still "coasting" along) at this RPM the motor starts cutting out but then kicks back in. You can HEAR it cutting out and can see it on the TACH. As it cuts out you can see the TACH move up and down between 1200 and 1750 RPM. If you give it gas and get the RPM above 2000-2100 it runs fine. Again it only does this while the truck is moving. While doing the test above I kept the RPM's in the affected range and started applying the brake to bring the truck to a stop. When I finally got it to a complete stop the problem immediately went away. It idled fine in the previously affected range (1500-1750 RPM).. So at a stop or in park it is fine. When the vehicle is moving and the RPM's hit that range it cuts on and off. This is causing a huge impact the MPG and the drivability
The check engine light never comes on.

Sorry for the long post but I figured more description would help.

The problem started out inconsistent. About 80-85 % of the driving time. Every once in awhile it would run fine, but that's pretty much gone away. It just drives like crap now and jerks a lot while driving it..

Is there any electrical part that could be affecting this? Why does it only do it while the car is actually moving?

Have also read about IAC’s.. I checked with the dealer and the IAC is $370.00. Is there a way to test it, before I start chasing parts. I’ve read through other posts and have found a test for the 3000 (30 ohms)ISC but I’m not sure if the ohms should be the same on mine. I did do an ohm test between 2-1, 2-3 and 5-4, 5-6.. All read out to be .043 cold and .046 hot. Does .043 equate to 43 ohms?

 

have the dealer had the battery disconnected? i dont know what a 98 MS 131K 2WD Auto is but the throttle body may need setting up. the idle stepper motor may be to high this will cause it to cut out. ive done timing belts and had batterys off then on start up they wont idle or cut out when changing gear.

 

Hey, I have a 99 eclipse with a similar hesitating problem. It started out kind of choking occasionally until I reached 1500-1750 rpms and now it hesitates all the way to 2500 rpms. It's not 100 percent of the time but most of the time it just doesn't have much power until i'm over 2500 rpms. After replacing my spark plugs and wires and an 02 sensor i believe the problem is the fuel injectors. I haven't had them diagnosed but I know this can be done to see how effecient each injector is. My check engine light has been thrown a couple of times from the choking and it was my 1st, 2nd, and one time my 4th cylinder misfiring and one time it was the front 02 sensor. After replacing the plugs and wires the problem went away but came back. The next time the light came on it was the 02 sensor, but this wasn't the same problem. The last time the light came on it was cylinders misfiring and some really good fuel injector cleaner fixed the problem for a while. Occasionally I just have to put the cleaner in with my gas fill up until i can get the injectors replaced or something.

 

I am guessing 1998 Montero Sport 2WD automatic transmission.