Hey all,

I've got a 97 blazer that under normal driving runs great but on occasion while accelerating to get onto the highway or
accelerating to pass someone the vehicle will start losing power and the SES light will flash.. then as quickly as it happens it goes back to normal power

it will happen also if I'm just cruising at say 70 and start to accelerate ever so slightly.. but this doesn;t happen all the time ,that is what is puzzling me.

if anyone has an idea what it might be or has had this problem and figured out the solution I'd be very appreciative..


Thanks,

Jeff

 

Ok first that DTC means random multiple misfire wich could be due to a combination of problems.I would check/replace your fuel filter,however you may have a dying fuel pump or bad fuel pressure regulator,Get or borrow a fuel pressure guage and monitor your fuel pressure.If you find it to be low replace the fuel filter if it hasn't been changed in awhile,thenthe FPR.When was the last time a tune up was done???I had a galant that the fuel pump was dying in that would do the same thing,step on the gas the pump couldn't deliver as the fuel pressure dropped and the engine would almost die.

 

If you do not have a misfire condition at higher RPMs, then I would suspect that it isn't a fuel supply problem.

I have seen throttle position sensors cause conditions like this due to wear (always being driven at a certain throttle angle with slight variation). You can test your TPS sensor by back probing the signal wire to the PCM (the dark blue wire) with the key in the 'RUN' position. You should have around 0.5V with the throttle closed and around 4.5V with the throttle fully open. It should be a smooth transition between the closed and open voltages. Any drop out indicates a failed TPS sensor.

If that doesn't give you the results you were looking for, then I would have a read through the thread linked to below. It is a great source for information concerning the possible causes of a P0300 code. Only problem is, the OP didn't follow up at the end...

The dreaded PO300 CAUTION LONG POST