k... not sure whether this is the right place for this or not and if it isnt feel free to move me around

i have an 87 z28 tpi 305... great car... no problems except the SES light gives me a code 34 (which is the MAF sensor, i believe)... i need a new one... anyway

i got up to around 100 on the interstate yesterday and the car was shaking pretty bad... was up to about 3000rpms... it didn't seem like it wanted to go any faster and i didn't wanna blow the engine (i know, im stupid ;D)

anyway... it was shaking and vibrating pretty violently... engine's got about 170k miles on it... is this normal, or is it a sign of a tired engine, or what?

i'm stupid when it comes to cars... so bare with me

- justin

 

It probably wasn't the engine shaking. It was probably from the suspension or from bad tires. Both will cause this. You could need new tires, an alignment, or some new bushings in your front and rear suspension.

Or it could even be a unbalanced driveshaft....or bad U-joints.

 

yah i agree with 88camaro. check tires for bubbles. Then check your u-joints by jacking the car up (use stands or ramps!), climbing underneath and try wiggling the driveshaft left or right. if it feels loose, replace your u-joints, or maybe buy an aluminum ds off ebay. its an easy job though...gl

 

When you have the MAF unhooked the computer goes into safe mode and does a few things to keep the engine running.
It stops all timing advance and runs on a set 14 degrees with no advance. Also no fuel injector change to incress fuel, this is why engine will not pull good over 3000 RPM.

It shakes because of this and the HIGH speed and engine timing retarding.

 

I'd have to disagree with this statement, when you unplug the MAF, a defaullt airflow setting is given to the ECM...timing, etc, is based on this input (IIRC, 255gm/sec), and you'll still have advance and inj PW according to O2 feedback.

If the MAF were to die while the engine is running, then the last known MAF value is stored for correction, unitl you restart the engine.

In most cases, unplugging the MAF and running yeilds a rich condition, due to the high default value of airflow that the ECM is being told to correct for.

Regardless, fixed timing and PW wouldn't cause the engine to shake, at the most, a fixed PW *could* cause a lean surge.

Also, before replacing the MAF, test or replace the relays.