CNG Pete

I was given this vehicle to work on because it ran like crap.

Initially I found damaged and broken wires. They were repaired.

Suspecting poor connections on the CNG conversion (done by another shop) I opened up the harness and made sure it was all soldered correctly.

I also secured the main harness away from the #1 coil that it was laying on top of.

Final work was new plugs and wires.

Van ran great, and the driver was impressed how well it was running.

Add a week, and its running crappy again. Driver complained of backfires too. My test drive confirmed it didnt run as well as when I gave it back, and further the driving deteriorated where it barely ran but I got it back to the parking spot.

Is there anything common to fail on these with a heat soak?

Next is getting codes. They will give a clue, but last time it was multiple codes that really didnt make sense.

After this, next job is fixing the ABS properly.

-Pete

mp2140

That sounds interesting. I've never had a CNG system on a vehicle. It irritates me when mechanics don't do their job right. I've repaired a lot of wires because mechanics are either too lazy or too ignorant to cover up and secure wires. You'll have to let us know what you find out.

Rednucleus

Is it a system that you can switch back and forth between gasoline? Run equally bad on both fuels?

CNG Pete

BUMP! Back to the top.

Havent had time to look at this until today.

Didnt take long to find the problem, but will take MORE time to find the source.

Even bank lost its spark. I had previously repaired damaged wiring on that side and thought the repair was done. I guess not. Wiggling the wires restored the spark. Now to find out just where the bad connections are. It appears that ALL coils drop out when it has the problem. Time to dig up the wiring diagram.

-P

CNG Pete

Found it! Pink wire on the connector to the coil pack.

Already repaired two other wires, so I think its time for a pigtail.

-P