Surging RPM

[neophyte]

Hey all,

I’ve recently noticed that my 2012 Challenger 180 surges at a specific throttle position. It usually happens in the 5000RPM range. When it happens, the RPM will surge about 400rpm higher before achieving it’s nominal rpm and the cycle will repeat until throttle is either increased/decreased out of this zone.

Any comments, suggestions? I asked my mechanic and he said it could be the plugs. I don’t know how it could be since it runs well 4800 rpm and below and 6000 rpm and above. Regardless, I will replace the plugs before I hit the water next time out.

I have the supercharged engine, hoping it’s not related (I have 88 hrs on the engine)

Thx

 

[pvamax]

Plugs do strange things to engine smoothness when they are on their way out. You won't know it by looking at them either. I'd say that's a good place to start.

 

[UPTHECREEK]

I've found over the years that the 4tecs like fresh plugs. You can find them at any auto parts store and they're fairly cheap. It may just fix your surging problem...….

 

[10forty2]

I'd also suggest replacing the plugs with the proper gap set. AND.....add Sea Foam to the gas tank at 1oz/gallon of gas. You might have a slightly clogged injector or two. Some folks might call it snake oil, but I swear by it.

 

[neophyte]

Update... I changed the plugs today. No noticeable improvement

I’ll shift towards the injectors next.

Is there anything else that I should consider?

 

[C9R0J0]

Mine does the same thing. Some days worse than others and some days not at all. There are lots of threads with people looking for a solution to "surging RPM". Nobody ever seems to find a concrete solution. So if you find one, please report back.

 

[dsm]

It might be nothing to do with the engine. I think cavitation from an air leak somewhere in the pump could do this, just based on things I have read. Changing load on the engine will cause the RPMS to change with the throttle setting the same. I am checking out and fixing some pump leaks on my own boat as we speak that I think may be causing this. I'll probably report back in a separate thread in the near future.

 

[C9R0J0]

It might be nothing to do with the engine. I think cavitation from an air leak somewhere in the pump could do this, just based on things I have read. Changing load on the engine will cause the RPMS to change with the throttle setting the same. I am checking out and fixing some pump leaks on my own boat as we speak that I think may be causing this. I'll probably report back in a separate thread in the near future.

This is likely correct, certainly the 50-100RPM fluctuations.

 

[noviceskier]

Smells like cavitation, might be time for a refresh on your jetpump

 

[beergut]

lol- I was just about to post a question regarding the same exact thing before I saw your thread... my 4-tec 155 does something similar in mid-range, except I don't think it's surging. It feels like one of the 3 cylinders misses for a few seconds and the boat lags, then it fires and picks up- feels like a "surge" but it's just the engine coming back up to normal. it almost feels like a rev-limiter that's cutting in & out. I've replaced the plugs, all 3 coils, jet pump, impeller, wear ring and all driveline seals. I don't know where to go from here! seems to occur when I'm cruising low to mid range- (tach doesn't work) I don't feel it when cruising at 75% or above to wot. it's a real pita trying to tow someone in a tube because I have to keep it fast or I'll eventually lose plane if I slow down to a medium cruising speed while towing.

 

[beergut]

well- I just purchased a TPS, we'll see if that helps. if that doesn't fix it, I'll start replacing injectors. the surge would make sense if the TPS was going out- I'm assuming it's the original TPS from 2005, so I wouldn't be surprised if the TPS is bad. if the TPS or new injectors don't fix it- must be the ECM? it's definitely not cavitation- it turns "on & off" way too sharply- it's definitely in the engine.

 

[Guyy]

My 180 had been doing the same thing, and running rough at idle. I ran a tank or two of gas with Sea Foam thru it and it’s running fine now.

 

[Macker29]

My 180 had been doing the same thing, and running rough at idle. I ran a tank or two of gas with Sea Foam thru it and it’s running fine now.

Seafoam and Berryman's B12 do great things to engines that are running rough. Its not always the fix, but more often than not, it will improve the engine's performance. Mechanic told me you can put multiple cans in a tank of gas, so don't be afraid to put it in thick.

 

[IDoSeaDoo]

Both my 2003 GTX 185 and 2004 Speedster 200 with twin 155's does this. Is SeaFoam really the answer? Just needs injectors cleaned?? Hard to believe something so simple can be the culprit of SO MANY 4tecs. @beergut did that TPS do anything?

 

[beergut]

Both my 2003 GTX 185 and 2004 Speedster 200 with twin 155's does this. Is SeaFoam really the answer? Just needs injectors cleaned?? Hard to believe something so simple can be the culprit of SO MANY 4tecs. @beergut did that TPS do anything?

No, seafoam really isn't that kind of fix for this issue. It'll take a lot more than one can of seafoam to clean an injector or carburetor out. The Surge issue I have won't be corrected by putting a can of seafoam in. It's like a switch being turned off and back on again. Maybe a bad injector or a coil grounding out or a faulty mpem or tps sensor. I'm working a 70-hour week so probably won't have time to put that sensor in until Saturday or Sunday.

 

[10forty2]

Both my 2003 GTX 185 and 2004 Speedster 200 with twin 155's does this. Is SeaFoam really the answer? Just needs injectors cleaned?? Hard to believe something so simple can be the culprit of SO MANY 4tecs. @beergut did that TPS do anything?

Not saying it's a "Cure-All" but I've personally used it to cure many a stumblin' engine. I run Seafoam in every internal combustion engine I own....right down to my 1-cylinder lawnmower.

 

[neophyte]

Just wanted to give this thread a bump. I took my boat into an authorized dealer, they say the jet pump, wear ring and impeller are in good shape, changed the plugs and had the SC rebuilt as it was approaching 100hrs.

I have yet to test it, hopefully this weekend.

I will report back!

 

[Jpons]

I just recently bought a 2011 Challenger 180 And I am having serious surging issues. I am surging at low and high rpms, but can find a few ”sweet” spots where it runs smooth. I am not able to get past 6k rpms most of the time. Two days ago I decided to add two cans of seafoam and after 15 minutes the engine started running perfectly.

I filled up the taken with 91 octane non-ethanol fuel (about 1/2 tank). Yesterday took it out again and the surging is back. Again I can find a sweet spot at around 5k and can’t get past 6.5k in RPMs. I did put in new fresh plugs last week.

Any suggestions from anyone? I am getting frustrated with this new to me boat.

 

[C9R0J0]

I just recently bought a 2011 Challenger 180 And I am having serious surging issues. I am surging at low and high rpms, but can find a few ”sweet” spots where it runs smooth. I am not able to get past 6k rpms most of the time. Two days ago I decided to add two cans of seafoam and after 15 minutes the engine started running perfectly.

I filled up the taken with 91 octane non-ethanol fuel (about 1/2 tank). Yesterday took it out again and the surging is back. Again I can find a sweet spot at around 5k and can’t get past 6.5k in RPMs. I did put in new fresh plugs last week.

Any suggestions from anyone? I am getting frustrated with this new to me boat.

Supercharger issue perhaps. Any record of when in was last rebuild?

 

[Jpons]

I should have mentioned this in my post.

The SC was rebuilt by the PO not even a year ago. I have the docs. I also installed a new intercooler since the old one was leaking a bit.

 

[Jpons]

I wanted to make sure and followed up and reported how I fixed my surging rpms. Seems that it was the coils, I replaced the coils with a new set off of Amazon and the boat is running like a champ.

Hope that helps someone else.