[bignick]

My G1 w/260k has had Code 12 (EGR with cracked diaphragm) since 60k(1992) and now Code 4 (Crank Angle Sensor) for about a year. I finally replaced the EGR valve a few months ago. But, since there is also a Code 4, the computer is in the backup mode (I think!) and as a result, there is no signal (no vacuum to operate the EGR valve). My questions (or concerns):
1. What are the negative consequences of driving the car with Codes 4 & 12? There is no noticable difference in performance.
2. Am I right in assuming that the CPU is running in the backup mode?
3. Is there an easy fix for the Crank Angle Sensor? Replacing it involves removal of timing belt + camshaft pulley = lots of $$.
I'll appreciate any input. Thanks.

 

[tubby]

you will be in open loop when the check eng light is on, it wont make as much power and will get worse gas mileage.
there is no easy fix, but its not that bad to replace it, I do them under an hour ,no problem. Its an expensive repair because the flat rate is high.you dont have to remove the entire t belt, just the front cover+cam pulley to get to the sensor. The problem is if you do it wrong you can drop bolts into the covers or get the cam timing off.( if you do it make sure the motor is on TDC and keep track of all the bolts)

 

[bignick]

Thanks Tubby for your encouraging response. Since the TB is in tension, won't this make r&r of the cam pulley difficult?

 

[Nick T]

bignick,

The tension is from the TB tensioner, it's a pulley on a spring lower in the block ( have to pull the lower cover to access ) but if memory serves, it places tension on the rear cam and not the front cam which is the one you will be removing. As tubby said, just make sure you don't lose any of the bolts and get the TB back on w/o screwing your cam timing. I put the belt on the cam sprocket, then line the sprocket up with the cam and install the bolts. Not too hard just work slow and make sure everything lines up properly.

 

[tubby]

there is only a slight amount of tension on the T belt(if it has some miles on it it will be slightly loose)the spring is used to set tension when replacing the belt ,once there is tension you tighten the bolt on the T belt tensioner and the spring doesnt do anything (you could take it off and it would still work).So when you remove the belt the spring wont move the tensioner.You cant do this on the new60 degree V-6's(CL,TL,MDX) because the T belt is under constant tension(if you removed the belt the tensioner would pull the belt tight)