Drivability Issue

[Henrythefirst]

1988 K2500 5.7L. Older but very low mileage. Driving for 150K with camper on. Long uphill pull mixed with freeway speeds. Drivability perfect and all gauges reads as they should. Take exit ramp and reduce speed. All good. Turn into parking area and notice loss of brake vacuum boost. Engine starts to run very rough. Will not idle. Turn off and restart. Rough idle and no idle continues. Very much like water in the distributor cap. Check all external components. The brake booster diaphram is not leaking but the engine runs slightly better with the vacuum hose off the booster and left unplugged.

 

The good news is that in BC our roadside assistance company will tow you home. So, on to a flat deck with truck camper and all, and return home. Now it is diagnosis time. What is your call?

Thanks in advance.

 

 

Since reposting this one from the Drive Train section I have pulled stored codes and have 33 and 45. As 33 is a faulty MAP sensor circuit and 45 is over rich, which I assume can be caused by a faulty MAP sensor.

 

 

So my question now is, can a faulty or non operating MAP sensor cause the symptom listed above?

[Henrythefirst]

This issue was diagnosed some time ago but I thought that I would post the result for the benefit of others and also to ask a couple of questions about the result.

The original problem was caused by a EGR Valve stuck wide open. Removing the vlave and capping the port has resulted in a much better running engine. More torque hauling a camper up a steep grade. No increase of coolant temp. Smoother idle. However, as nothing is perfect, the engine now stes Code 32 (EGR) and 44 (lean exhaust). Also, there is some preignition at max rpm with high load.

Is there anything that I can do to allow this engine to run wihtout the EGR and not experience these issues or should I bite the bullet and preplace the valve?

Thanks for your opinion.

David

[blacksierra01]

if theres pre ignition, try using higher octane gas

[GMstrong]

You can clean the egr valve you should be able to push the valve in by hand if not then its clogged and dirty.Without the egr you will lose highway mpg the only way you can run it with the egr valve is if you get a custom chip and tell him to do without the egr valve.you wont gain anything with out the egr.did you ever replace the dis cap?i would do a whole tune up including the following plugs,msd wires,msd coil,etc i prefer that you get a aftermarket coil youll noticed a difference i did.