thebeeguy

First of all I have a 1992 LS400. So today I was on my way to work getting on the freeway and I had to accellerate rather hard up the on ramp. Soon after that, my check engine light came on and my car started to stutter/hesitate soon after the light came on.

I pulled the code and it was a code 71 (EGR). So i went through the steps on how to clean the Vacuum Modulator, and I also removed the actual EGR valve and cleaned it out the best that I could, and then reinstalled it.

I also checked to see if the actual EGR worked (Attached a vacuum hose straight from the throttle body to the EGR valve and the engine started to run really rough, ive read that means the regulator is indeed working).

Pulled the 20amp EFI fuse to clear the check engine light.

The hesitation is STILL there. The check engine light for the EGR came back on about 10 miles later.

The car feels as if its misfiring in one of the cylinders. You can hear and feel the engine running a little rough at idle, and at all RPMs, when you try to accellerate the car stutters throughout the whole RPM range. Not BAD to the point where it feels like the car is going to die, but it is noticeable and the power loss is definately noticable.

If one of the cylinders was misfiring, would that set off a check engine light?

Would this hesitation be related to the EGR? Or was it a coincidence that the EGR light came on at around the same time the car started hesitating? What are some of the symptoms of something going wrong with the EGR? Would the engine run rough like this because of the EGR system?

I just bought the car recently and it purr'd like a kitten until today when I stepped on it hard. The condition of the sparkplugs/wires/cap/rotor are unknown as of right now, I am planning to replace them soon anyways. I was thinking this MIGHT be the problem but it is just too much of a coincidence that one of the cylinders would stop firing and at the same time the EGR check engine light comes on.

Sorry, I know, the post is long, but I wanted to explain every single part of what is wrong and what I did.