Misfire when raining with WH vent kit.

[forest]

Heres the story. 2008 Itasca Sunrise 35A w/W22 chassis.
Kept having problems with the engine starting to backfire and sputtering when it got warm. Had to dealer who checked all wires with no problem found. Installed Workhorse ventilation kit. Everything seemed great, run all day long without a hiccup. Until it rained. Once it would start raining, it would kick and buck and misfire like a bugger. Put duct tape over the air scoops in the grill. Problem solved while raining, but arises again when hot. Can't get Workhorse to respond, and now the coach has actually quit a couple of time after pulling of the highway and sitting at idle.

Any hints???

[JCM]

Move the intakes so that they are protected from the rain or modify the opening like the old tuba mods that were done for the same reason.

[DriVer]

Quote:

Originally Posted by forest Can't get Workhorse to respond, and now the coach has actually quit a couple of time after pulling of the highway and sitting at idle.

I'm not sure what that means. Has the service center plugged in a Tech II to scan for codes. It the engine does not run and consistently stalls when wet this should shoot a code which the center will be able to read.

The event that I have found when raining is that the MAF sensor gets wet and this could issue a service engine soon light (SES) on the instrument panel. I have not experienced a stall condition when the MAF did get wet so I would expect that there a secondary cause that should be ID'ed using a Tech II.

The problem could be located in a modular connector but I can't begin to speculate which one if any.

[TrekPR]

Reacting to both heat and wet but not cool would suggest to me it might be electrical.

[wa8yxm]

Workhorse has "Fix" for water ingestion..

Suggestion: When this happens, get to a dry place and crawl under and pop the air filter, Good bet it's wet. This indictes water ingestion by the "Tuba" air intake.. As I said Workhorse has fix for it.

Now.. The thing is.. Not all motor homes have this issue, only some makes and models, even though others may well be built on the exact same chassis.... To me, this says "House builder caused it" but what the heck do I know.

[CoastieSCPO]

I do not have a Workhorse Vent Kit on my W-20, but I made my own air kit from tubing, vac cleaner fittings and tie straps that I ran from the top of the grill to the # 4, 5, & 7 plugs. It, along with Taylor wires and heat socks solved the (heat) burnt plug problem.

On our trip to Alaska and British Columbia while driving thru lots of rain, the stock air filter got wet more than once, causing the engine to miss, the MAF to get wet and a code to be displayed on the Tech II that my mechanic had. Now I have a Scan gauge II. When I got home, I changed the plugs and ordered a Brazels Ultra Cold Air kit from Oemy. Like DriVer said, have a service center check it out, but since I installed the DIY air vent and the Ultra Cold Air kit, we've been good to go (knock on wood).

Bob

[Full-Timers]

If the rain problem goes away when duct tape is applied over the vent kit intake then the problem is not on the engine air intake (“Tuba” of MAF sensor).

I would say you need a new set of plug wires, simple as that. Heat helps conduct elect and so does moisture. If there is a void in your plug wires the spark might be going somewhere else instead of the plug when it gets hot, the vent kit will only mask this. Also the vent kit might allow moisture to reach the void in the plug wire with the same results.

I can’t believe they installed the vent kit with no problem found. Must be more profit in that then a set of wires.

Get a net set of wires, keep the vent kit installed and problem solved.

[DAN L]

Quote:

Originally Posted by forest Heres the story. 2008 Itasca Sunrise 35A w/W22 chassis. Kept having problems with the engine starting to backfire and sputtering when it got warm. Had to dealer who checked all wires with no problem found. Installed Workhorse ventilation kit. Everything seemed great, run all day long without a hiccup. Until it rained. Once it would start raining, it would kick and buck and misfire like a bugger. Put duct tape over the air scoops in the grill. Problem solved while raining, but arises again when hot. Can't get Workhorse to respond, and now the coach has actually quit a couple of time after pulling of the highway and sitting at idle. Any hints???

i pulled the plug on the maf sensor. this put the computer in default mode. my moho ran ok with the plug pulled. i found that the new k&n panel filter i had just installed had been over oiled. cleaning the maf sensor fixed my problem. the k&n filter has a much better seal than the original paper filter did. imho, with the k&n, the air box will not leak.
i wish i had installed the s&b instead of the k&n because it has much thicker gauze for better filtration.
if your moho runs ok with the plug pulled, imho this rules out ignition problems. you either have a wet air filter or a dirty maf sensor.
i was getting water in the tuba inlet with the old air filter until i installed weather stripping on the top of the engine hood opening.

[hamguy]

[QUOTE=Full-Timers;814168] Heat helps conduct elect and so does moisture. /QUOTE]

How does this work? And to what degree?

[Dmkapolei]

Any relation to my 2000 Bounder Chevy 454 stalling after warm-up? Added Heet to fuel, but problem persist. Any ideas?

[DriVer]

Quote:

Originally Posted by Dmkapolei Any relation to my 2000 Bounder Chevy 454 stalling after warm-up? Added Heet to fuel, but problem persist. Any ideas?

This could be a problem manifesting with the fuel pump. Attach a fuel pressure gauge and see what the pressure reads after it warms up.

Please don't use too many chemicals in your engine's fuel system.

[Dmkapolei]

Thanks I'll investigate, but it seems to be flooding and backfiring on subsequent attempts to restart. After cooling for about 20 minutes, I can start it again and it purrs like a cat for about 5 mins and does the same thing again.

[DriVer]

Quote:

Originally Posted by Dmkapolei After cooling for about 20 minutes, I can start it again and it purrs like a cat for about 5 mins and does the same thing again.

Exactly! It sounds like a classic fuel pump on the way out routine but we won't know until you get a pressure gauge on the fuel rail.