When the coolant temperature is higher than 210 degrees Blazer doesn`t start at all. I need to wait until the temperature drops to at least to 190 deg. What could it be?

 

You need to cut the problem in half by seeing if its spark or fuel when it wont start. Once we have that we can go from there.

Does it crank when this happens?

George

 

Hi! Thanks for the answer.
The starter rotates the crankshaft, but the engine does not start.
There is fuel, but there is no spark

 

OK good, that’s progress. I assume that you looked for spark at the plugs. Next check the output of the coil to see if the distr is getting spark.

Since this is only a problem when hot then the ICM and coil are prime suspects but it can also be wiring/power/grounds or the engine computer. Another possibility is the crank sensor. We’ll find it.


George

 

The main problem is that I can’t create the conditions for repeating the malfunction on purpose, so I started by replacing the crankshaft sensor, and thermostat (I already had them), spark plugs,and spark plug wires(will arrive next week). This will reduce the possible causes.

Best regards,
Evhen.

 

I understand, intermittent electrical problems can be a PITA. The next time it does this check the spark at the coil output, that will help narrow this down. If that’s OK then you work backwards to the ICM output then ICM input. In the meantime there are some things you can do to look for clues:

mist the engine in the dark with water while it’s running and look for arcing

look under the distr cap for carbon traces

look at the outside of the coil for cracks or traces

check the quality of the power and grounds to the ICM and coil

inspect all ignition wiring

check for codes

measure CMP retard


George

 

How to measure CMP retard ? I`m using torque pro with BAFX OBD2 scaner.
About codes: classic collection P0300, P0132, P0131.

 

Torque Pro is good especially for graphing but you will need to add Car Gauge Pro/Car Diagnostic Pro for CMP retard (same BT module). This is an important parameter for our engines especially for misfire detection so you need to get this parameter within spec.

You have an O2 sensor/circuit that is not working on Bank 1, this can be causing many problems. Use Torque Pro and graph all three O2 sensors at idle after closed loop.


George

 

Hi there!

I have new information. From the previous time I changed the thermostat, and the car no longer heated up to 110. But the problem appeared again. I had an OBD scanner with me, and the value that caught my attention was the data from the СTS sensor. It showed more than 100 degrees Celsius, when it was 30 outside. I repeated again just now, 17 on the street, 44 on the gauge.
I also made a graph of O2 sensors, and unfortunately I didn’t find CMP retard in the list of available sensors even in car gauge pro.

There is no avalible CMP retard.


O2 Sensors graph
O2 sensor 1 test(sensor 2 is not responding)

Best regards,
Evhen

 

That ECT disparity was with a dead cold engine from sitting overnight?

There are 3 or 4 O2 sensors on your truck, depending on the year. Can you clarify the year?. All trucks have B1S1 and B2S1, can we identify and graphs those 2? I am not familiar with the labels in your graphs. If L means left bank or bank 1 then we need R or bank 2 (B2S1).

When Im at my scanner later I'll look for CMP retard.

George