No code intermittent misfire

TONY2CARPRO

MEMBER
1997 GMC SAFARI
4.3L
6 CYL
2WD
AUTOMATIC
147,000 MILES

Hello, recently experiencing a jerking and sometimes engine sputters and shuts off. 14 months ago, a new Standard Motors coil was installed as well as new HQ Taylor wires and Bosch Platinum plugs. Also a new ACDELCO spider injector assembly and fuel filter. Two years ago, the fuel pump failed and a new Spectra Premium Tank with factory fitted pump was installed. Things going good until I have recently hit several large pot holes causing some slamming? No apparent damage as mechanics can see.
My question after watching your Oct 13, 2018 video is, Can a single coil feeding a distributor give intermittent operation and thus cause intermittent misfire?
Thanks, Tony

PS. I do have a BlueDriver OBD2 scanner. I did have a O2 sensor failing and so last Friday, I had all four replaced. Codes were cleared and have not returned. The above problem is just like as you mentioned in the video.

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,192 POSTS

Hi,

Yes, a coil can be the issue. However, if that was to cause a misfire, it should set a code for a specific cylinder. Since there are no other codes, the one thing in my mind that could be an issue is the crankshaft position sensor. It can fail and cause misfires and stalling and never set a code. Do me a favor. I'm attaching two links. The first defines the sensor I'm talking about and the second describes common symptoms. Take a look and see if what you experience seems to mirror what is described.

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

I do have a couple questions. When it does stall, dies it immediately restart? Also, although all the prior work was done, have you considered checking fuel pressure or has it been checked?

As far as the crankshaft position sensor, I attached a pic of it so you can see location. Make sure nothing is loose on the connector.

Let me know.

Joe

Image (Click to make bigger)