INTERMITTENT ENGINE STALL ISSUE, MULTIPLE FIXES MADE, STILL NO SOLUTION, HELP PLEASE!!

Hey Guys!

I have been driving my camperised 2006 Chevrolet Express 2500 (4.8L V8) on a panamerican adventure from Canada to Bolivia (currently). It's been great with zero issues, until the last month....

I have been through 5 mechanics out here, numerous 'fixes' but still the same issue, really hope you guys can be the hero's I need right now to complete my journey!!

The problem: In certain conditions the engine idles roughly and when I am below ~30kmph (or stationary) with zero throttle can stall (which is scary loosingpower steering at 30kmph on a Bolivian roundabout). When it stalls it will almost always stall again if started with no gas, instead I must start, rev then drop into drive to continue. I have also recently been experiencing lurching while cruising.

Conditions (please note any number of these may be false leads, they are just apparent observations as over the month i have limped the van the length of peru and into bolivia searching for a good mechanic)

- It seems to get worse after long downhill stints especially when using engine braking (I descended twice from ~4000m to sea level, both rendered the van almost unusable)

- The problem seems to reduce when the van is left to stand/cool down for a while

- The problem is almost completely cleared after long uphill stints and tends to remain cleared for some time after

- There is no apparent link to altitude (stalls at sea level and at 5000m)

- The engine is always warm when i have the issue but not always super hot (I have had it leaving a carpark after the van was off for 30 mins)

- The lurching is only a fairly recent addition to the problem

Fixes so far:

- All spark plugs replaced
- Air intake system cleaned out
- fuel tank cleaned
- fuel fiter cleaned
- fuel pump pressure checked (it drops a bit when hot but the mechanic believed it was ok)
- catalytic converters removed (sorry environment... south American solution)
- checked multiple times on scanner, no obvious issues

Please let me know any questions or ideas you may have.... starting to get a little desperate here

Many thanks in advance,

Tom

 

The only thing that comes to mind is injectors. I would try pulling them out one at a time and see if they're working.

 

Had a good look at them on the scanner today and they all seemed to be working fine. Will suggest pulling them out one by one to the mechanic when he gets here tomorrow. Thanks! Any more ideas are very welcome 👍

 

For intermittent stalling that seems to get worse when its warm, I would think the first clue is that the component causing the issue is affected by heat. I would want to see fuel pressure during the failure condition, fuel pressure can test fine but under stress can yield different results. Second, only because I come across this alot with GM's is the cam and crank signals. These are hall effect sensors, and their readings can be biased by excessive air gap to the reluctor wheel, metal shaving, etc etc. Check those on the scan tool and get back to me. Theres lots more options but let's get some data.

 

are you getting any codes on the scanner......you should be given you removed the cats.....the down stream o2 should be throwing a code....possibly a vacuum leak or fuel pressure issue would be my guess.......you could also have a leaky injector flooding the motor at idle.......post up if any codes show up.....