Posted on November 14, 2011 - by Richard

1997 Chevrolet Blazer Emissions Problems

Symptoms of 1997 Chevrolet Blazer Emissions Problems:

This 1997 Chevrolet Blazer Emissions is so bad my ATS customer refused to drive it because of the cost of the gas. According to him, he had a random misfire P0300 code when he scanned the engine code. This SUV would run rough when the vehicle is driven after 10 minutes. He tested the engine compression, did an injector balance test using the scanner to verify the fuel injector wave patterns.

He went to the parts store close to him and they recommended a complete tune up that included cap and rotors, spark plug wires, crank and coolant sensor replacement. And all of these parts did not work and the engine code came back again!

He was very frustrated and when ATS asked him some numbers about his tests, he sent the following info:

1.) Engine compression readings were all 145-150 psi
2.) Fuel gage pressure for injectors was 55 psi and scanner injector wave patterns were the same.
3.) LTFT and STFT were normal between +- 10 except when it acting up which goes to +41 which is high causing rich condition.
4.) The 02 reading were erratic and it was stuck rich especially when the engine is warmed up. Opening a vacuum line would lean the mixture which shows the oxygen sensor mixture is responding ok.
5.) When tested for spark with engine stopped, he can see steady blue color sparks. To eliminate this ignition issue in case the problem is intermittent, he changed the ignition coil, module including the distributor assembly.

Still this SUV was gouging gas like crazy. (Ouch!)

Diagnostics on 1997 Chevrolet Blazer Emissions Problems:

I am almost convinced this ATS member has done serious expensive repair on this engine and I just wished he was already an ATS member before he started working on this SUV. His membership followed after his frustrations and his wife’s refusal to spend any more money on this vehicle.

There is a common fix for this problem which is very easy to miss. The problem here is the front timing cover where the crank sensor is located. A lot of times, the original timing cover is made of plastic. The crank sensor is mounted there.

When the engine has a lot of miles and due to heat exposure, this cover tends to warp. This alters the crank sensor gap inside to the sensor ring. So even if you replace the crank sensor, the same problem will occur. GM’s solution for this is to shim the crank sensor. They always stock these shims if you asked for it.

Final fix for 1997 Chevrolet Blazer Emissions Problems:

As soon as the ATS customer learned about this, he removed the newly installed crank sensor and added shims as recommended by GM parts. It runs good after that.

More Tips for 1997 Chevrolet Blazer Emissions Problems:

1.) The timing cover for this 97 Blazer can be bought made of steel in aftermarket sources. It is expensive though and shimming the crank sensor is a cheaper alternative.

2.) Common fixes sometimes are the shortcuts to fixing most of the engine high mileage problems. It is caused by flawed engineering designs which only becomes apparent when the engine is used a lot and subject to wear and tear.

3.) ATS stores this common fixes database for easy reference and give it to ATS members when they need it.

Thanks,

Richard