shower causing engine to idle rough?

I recently had my hot water shower installed, I now have noticed that when I run the hot portion of the shower it causes my engine to idle really rough. I increase the rpms to 2000 and it cleans up but it will stay that way for the rest of the day. charging systems checks fine. Took it in to the shop they counld not find out what it was doing it said the cpu was fine and no error codes. ran like a champ until they also used the hot shower. what could this be??????

Voltage is the only explanation I can think of.

Did you run all of your accessories at the same time, then check the voltage meter?

yep sure did, plenty of volts, just came from the water today, idle ruogh in nuetral about 1500 rpm's cleans up, in idle noticed gas smell, plus I got hot water out of the cold water side and it never did that before?(this ruined my weekend camping didn't want to break done on the water). taking it back to the shop tomorrow but still trying to get ideas since they are stumped. This happened right after the 100 hr service, heater/shower install.....

side note when we first fired it up it ran great it didn't start it seems until the motor warmed up..



(Message edited by ghostrider 2 on September 18, 2005)

Is it possible one of your sensors is being starved of water and the ecu trys to compensate some how for what it thinks is a malfunctioning motor by increasing the rpms? Peter you around, he may have a better idea of what is going on?

"I now have noticed that when I run the hot portion of the shower it causes my engine to idle really rough."

Lack of voltage and amperage. The pump draws too much power away from the engine electronics. You will need to run a new power supply to the dash or to the pump. Hopefully they used a relay to begin with but doubtful.

I wanst using the shower this past weekend when it started doing it, I only tried the shower to see if it was getting both hot and cold, but no cold out of the cold side (steaming hot). when I sut it off it was hard as hell to get started?

It ran rough but it didnt smooth out til I uppered the rpm to about 1500.

If you have hot water coming out of the cold side it's not connected to the raw water pick up then.

I wonder if they connected both hot and cold to the block ? I don't think that would make it run rough though unless a sensor is picking up the lack of water pressure ?

Have you checked the engine temp when using the shower? The incorrect plumbing might cause the engine to run cold or hot and send the ECM in to a spin.

just got back from the shop, shower hot water was put on the wrong point easy fix, but we ran it for 3 hours and could not get it to repeat the issue. purrrred like a kitten! the only thing we could think of maybe the water pressure sensor since it only happens in idle at the lake, but not a tidle with a fake a lake... ???

Fake a lake is pushing water in under pressure.
when the boat is in the water the water pump has to draw it out. that could be the difference.
to be sure, you could run the hose from the fake a lake to a bucket that you keep full of water, that would be a better simulation of being on the water. hope that makes sense.

NOT THE SHOWER!!! found out today it is the IAC Valve!!! how many of these have you guys seen go bad?

More than I can remember. Super common Ford Problem (They like to surge), although all makes have issues.

Glad you got that figured out. I'm getting my boat back this weekend from having a shower put in. Trying to get ready for the winter season.

Had me worried.

How much does it cost to get a hot shower installed?

I think its worth installing yourself, Ithink its like 2-4 shop hours they charge + shower kit.

Do it yourself........It's really easy.

Hmmm...dealer incorrectly installed Kenny's shower. I bought my last boat used and the dealer that installed the shower never tightened one of the hose clamps. Fortunately boats are not under very much water pressure, unlike an automobile.

Was the IAC faulty or just dirty? Idle bypass passages are often dirty and need cleaned but rarely does the IAC motor fail completely.

Is one shower any better than another? Where can you get them cheap?

you can actually get the shower parts at home depot. they just messed up the cold water connection.

IAC faulty, not dirty. only 115 hours on her... (I asked aboutjust being dirty)

just curious how do you clean it if its dirty? also where is it located on the motor?

Does anybody have a list of parts and a how to DIY list?

I found the parts list somewhere one wakeworld, it cost less than $100. though this is not what I installed on mine but I was going to until well you know "hook-ups"....

http://www.wakeworld.com/MB/Discus/messages/65921/84572.html

this is the link..

Thanks man. That was a huge help!

no worries......

IAC located on side of throttle body. To clean revove air cleaner and look for bypass port in side throttle body should look like open hole above throttle plate. Idle engine and spray air intake cleaner into this hole slowly for aprox. 1 min. You may have to fast idle engine to keep it running. The IAC is a stepper motor that the computer uses to control idle speed by restricting the passage. During idle nearly all air that the engine burns flows through this passage. Any blow by oil and or moisture can over time restrict/plug this hole.

took the boat out this weekend and that wasn't the fix still having the same issue.

WOW this is becoming a huge headache!!!!!!

I would remove the IAC to clean it. Do a search on any chevy site (there is an IROC one that has a step-by step) to find more info. I had a rough idle problem that was real intermittent awhile ago that was a plug wire shorting out, but there are quite a few computer things that can cause this also..............

The IAC valve was completely replaced, It only does it once it warms up then will not go away until you increase the rpms, etc.

It is very important that the iac passage is clean not just the valve. Is poor idle all the time when engine is warm now or just when shower is used? I have had voltage regulators stick at 12 to 12.5 volts and only affect idle also check battery connections and ground to engine block is clean.

shower wasn't the probnlem it is fixed. only at idle and batery connections are good etc...

Do a search on a car/truck site on this problem. It is common in the auto world I searched alot when I had the problem and learne quite a few different things it could be. If the marine setup has a TPS that was another common culprit EGR valve was probably the most common, however I have no idea if the marine 350's run them. I am taking for granted this is a TBI Chevy 5.7?.............

(Message edited by Tracktor on October 04, 2005)

Did I mention that this ONLY occurs on the lake but will not occur with fake-a-lake...

Since it only occurs at the lake and not with the hose we have to assume that it has warmer water at the lake.... only thing it could be is the ect signal/ sensor causing pcm to over fuel. Lets try to unplug the ect and see what happens. It is located in the intake manifold and has two wires going to it.Damn do I whish boats had o2 sensors!

Marine engines do not use EGR, water does not burn well.

nope not it........

What happened when you un pluged the ECT?

Sounds like time for a wet test with the scanner hooked up. For instance what is the long term fuel trim and the short term? Are they within 14% or less when the problem occurs? Without 02 sensors they use a flat fuel curve not as variable. What does the ECT read when all this is going on? Is there a TSB for a software reflash? Very common, in fact right now GM is repairing 70% of their driveability problems by reflashing the PCM. The dealer needs to step up and fix it or have someone else fix it. This is not YOUR problem, it is a boat that is under warrranty.

So which injection and ignition system does your boat have? Is it a waste spark system? Does it use a cam crank sensors? Hook a lab scope up to them and see if they are reading correctly. If they are not in sync you will have all kinds of problems. Which leads to the question of was any mechanical work done to the motor?

Peter,
Can you have fuel adaptives without an O2 sensor? I thought the only inputs to pcm were IAT ECT RPM and MAP. A basic speed density system.

well today they said they found the problem, when they installed the return hose for the heater in was in the wrong spot on the manifold causing the back pressure issue making it idle rough. not sure how that was not spotted in the first place?? I will be taking out this weekend to test it out. I will let you guys know, and yes my patience is running thin!

Brad, I wrote it then being a dumba$$ didn't properly modify it when I stopped thinking "car". Guess that happens with only a few hours of sleep and I just got home from work. I wrote and meant "Without 02 sensors they use a flat fuel curve not as (should read "a") variable." I probably should learn more about boat computer systems as I am ignorant, but why? I don't work with boat techs.

Are they using an IAT sensor? If it is sequential injection then they need CKP and CMP sensors along with TPS.

Kenny, without seeing it does not make logical sense that the hose being in the wrong spot would cause an issue. It is a through flow heater core and would not return cold water near the ECT. Hmmm...I would have to see it. For you I hope it is fixed.

I agree with you..