Hello,
Looking for some advise.
As the above states i am having an idle issue...

Not quite the normal idle issue but one that when the truck is starting from cold, it starts and runs fine for about 1 minute then it starts running rough.

Also rough and spluttering on acceleration.

I have checked and changed all spark plug leads.

Maf and the other sensor near the maf.

Everthing is tight with no vacuum leaks around tge throttle body.

Fuel pressure is 60psi before firing and drops to 54 on idle but when the idle gets rough after starting so does the fuel pressure change. It fluctuates between 55psi and 57psi and is irratic.

Hopefully have someone that coukd point me in the right direction.

Thanks in advance.

 

1. Do you have any codes?
2. If your scanner has live data, does the rough idle start when the fuel system transitions to closed loop?
3. What is your ten min fuel pressure leak down?

George

 

No codes

Haven't done a leak down test yet

Do not have a scanner but any recommendations on a cheap end one?

Going to take to EGR off today and look at it

Is it a good idea to unplug 02 sensors?

 

https://blazerforum.com/forum/2nd-ge...lazers-103424/

If you have an Android device then a BAFX Bluetooth dongle and inexpensive software is probably the most cost effective way to get everything you need including O2 sensor graphing.

George

 

Just done 10 min leakdown

Results

57psi
After 10 mins 54psi

Anyway to test the egr?

 

https://easyautodiagnostics.com/gm/4...gr-valve-tests

George

 

Back again....

Swapped EGR valve and no different

Will buy the Bafx obd2 and report back

 

Hello

Had a chance to look at the Blazer yesterday, pluged in the OBD2 dongle and have downloaded the Torque Pro on my phone.

As always, the engine runs fine on start up but quicky changes to a rough idle and i did notice it smelt heavly of exhaust fumes this time.

I have tried to upload screenshots from the app but cant seem to manage.
I will explain some of the finding that i think are relevant (or not).
I did notice quite a few fault codes that have never shown up on my handheld plug in OBD2 and i have no light on in the dash at the moment.

The following codes are green with a tick and are listed as historic
P2506. Ecm/pcm input signal
P2903 no info
P0320 ign/distributor input circuit

This code is red and listed as current fault


​​​​P2907 no info.


Also under emmisions readiness....
Missfire - complete
Fuel system- complete
Components- complete
System type complete
Calalyst incomplete
O2 sensor incomplete
Egr system incomplete

What should the live data on the o2 sensors look like?

​​​​​​A mountain range?




​

 

look at the o2 sensor graphs one at a time with no other parameters on the page. The two precat sensors should vary between approximately 0.15v and 0.85v changing around once per second at idle. The post cat sensor should flat line somewhere between 0.45-0.7v.

George

 

Also I have just searched engine vacuum spec.
Normal is between 14 and 22?
On the pro torque it's saying the blazer is -17?
Could this be my issue.... A vacuum leak?
That would explain a lot