Intermittent Surging Offroad

[Mfb]

Hi All,

I was hitting the tracks this weekend when out of the blue the car started to surge (when stationary and when moving)! The first time it surged the revs dropped and I stopped the car, put it in park and gave it a good rev a few times until it came good. After rev'ing the car a few times there was a heavy smell something best described as burn petrol...

Second time it happened was while driving up a hill, the car lost power and even with a heavier right foot movement was slowly lost until I switch the LGP to get over the hill and then back to petrol without any notice of surging for the rest of the afternoon.

I drive the car 2.5 hours home on petrol and testing the rev range without any other noticeable issues and no issues on LPG.

Being a '94 I did the paperclip test on the diagnostics port and noticed the 'check engine' light blinked twice and then once = 21 - Oxygen Sensor.

Could this symptom be related to the O2 sensor or could it be something else?

Thanks in advance.

 

[Mfb]

bump

 

[1ststatecruiser]

My 94 threw a CEL when the o2 sensor was loose due to rust didn't affect the engine performance . New pipe and new o2 sensors later.

 

[baldilocks]

I have read that O2 sensors lose their accuracy long before they let us know by throwing a code. How old are your sensors?

 

[Mfb]

I'm not sure how old the sensors are as I have only owned the truck for a short time, so I dont really have a baseline... From a fuel consumption point of view, I get about 450-500km per 90-95ltrs unloaded, the truck is running 33" A/T tires, has a 2" lift. I have recently fitted a full steel roof rack and since then I think the fuel economy has gotten worst, but come to think about it I'm not 100% sure if it was getting worst before the rack was fitted...?

 

[inkpot]

Sounds a lot like a failing Throttle Position Sensor. BTDT on a Chevy. Should pop a code. John

 

[Mfb]

Sounds a lot like a failing Throttle Position Sensor. BTDT on a Chevy. Should pop a code. John

This is an old thread, and the problem has resurfaced, or perhaps never gone away!

If it was a failing TPS, would this also be symptomatic on LPG as well? On LPG the car is fine.

I’ve also noticed there is an intermittent hesitation/mis from a standing start take off.

 

[Mfb]

The problem was fixed.

It was due to a vacuum leak with a hose under the manifold. Replaced the hose and it fixed the problem.

 

[BILT4ME]

The problem was fixed.

It was due to a vacuum leak with a hose under the manifold. Replaced the hose and it fixed the problem.

Thank you for continuing to post follow-ups and information.
This will help others in your situation, as most of us on here have little experience with LPG systems and these trucks.