Chev 454 P30 Chassis Engine surging - Audio clip linked!

[klasicecream]

https://youtu.be/ondixOwvVgg


Short Version: Our RV was having engine issues, I recorded the noise to help with diagnosis. You'll hear the surging, and then it seems to "catch" and run nicely for a few seconds, and then begins to surge again. Please see the bottom for questions.


Long Version: Our '93 Winnebago Itasca C-Class Motorhome (Chevy 454 engine with P30 chassis) is experiencing intermittent issues. After a few hours of highway driving it would have issues idling and would die (sometimes we could turn the engine over again, but as soon as we touched the gas it would die again), the engine was also overheating. We had the radiator replaced in December, and at the time the tech said that our transmission looked to be newer and in good condition. The new radiator helped the engine overheating but did not fix the stalling issue, as it has reared its head twice since, both times after having driven for 3 hours on the highway. If we let the engine cool down for a few hours, we are able to continue on - which means that by the time we've gotten it to a tech they can't recreate the problem (and thus have big issues diagnosing).


A few weeks back we had another issue (unsure if related) where, while driving on the highway the engine seemed to start revving really high, as if trapped in a lower gear, and almost intermittently surge. As we tried to accelerate through to about 40-45 mph we'd experience the surging. If we kept the foot on the accelerator, it sounded like the rv would eventually shift, the revs would wind down, the engine would sound normal. The engine would run normally for about 10-15 seconds, and then the surging would start again. We have not experienced this surging issue at lower speeds, it seems fine until about 40 mph. We checked the transmission fluid and the level and colour appeared fine, and after having spoken to a few techs who said, maybe you were just going up a hill or it was really windy, we thought that perhaps the issue was not an issue. We haven't really driven it since then until yesterday.


Yesterday, we stalled on the highway... again. The tech couldn't recreate the issue, and said that it was likely the fuel pump or the ignition (I had told him that we'd had the radiator replaced in December and that we had been told that the transmission looked good). He couldn't diagnose for certain so we had to make a choice and had him replace the fuel pump. He said that if we encountered the issue again then we would know that it was an issue with the ignition. When we drove it away this afternoon the engine sounded so much better and it was idling normally. We got an hour and a half away from the repair shop, stopped to get gas, and when we went to get back on the highway the revving issue that we had encountered once a few weeks ago, happened again.


THE VIDEO: I pulled out the ipad and recorded this short video before we pulled over in case a tech tried to tell us that it was in our heads again. You'll hear the surging, and then it seems to "catch" and run nicely for a few seconds, and then begins to surge again.


SO TECHNICIAN FRIENDS AND STRANGERS: We are currently pulled over on the side of the road. Here are my questions for you:
1. What does the engine issue heard in the vehicle sound like to you?
2. Do you think the stalling issue and this issue are separate issues or related?
3. If we let the engine cool off for a few hours we can likely drive for a few more without the issue showing up again, should we try to make our destination? We are currently 3 1/2 hours away. Or would that risk further damage to our RV? It is two hours back to the repair shop that we just left, I'm not sure if there is a closer place...


We've had this thing looked at 5 times since we purchased it in July of last year, and our issues still haven't been fixed. We are currently 2,800 km away from home so jumping ship isn't really an option unfortunately, but we can't invest a chunk more money into it either. We need to get it home (or at least back to Canada) before we can part ways with it. Any advice or suggestions you have would be greatly appreciated!!
Yours most gratefully,
Tim and Kaitlyn

[PCarillon]

video link doesnt work ........ ok got it too work sure sounds like its a transmission issue to me sounds like its either jumping down a gear or converter is unlocking

[PCarillon]

try this

[ga traveler]

I think the revving issue is probably the cooling fan kicking in. If you have a rpm gauge watch it when the engine is revving up. If the rpm's stay the same it is the cooling fan revving up. If you don't have a rpm gauge You should buy one. They are cheap and easy to install. You don't have a class C, You have a P32 class A chassis.

[LVRVLUVR]

Originally Posted by klasicecream

https://youtu.be/ondixOwvVgg


Short Version: Our RV was having engine issues, I recorded the noise to help with diagnosis. You'll hear the surging, and then it seems to "catch" and run nicely for a few seconds, and then begins to surge again. Please see the bottom for questions.


Long Version: Our '93 Winnebago Itasca C-Class Motorhome (Chevy 454 engine with P30 chassis) is experiencing intermittent issues. After a few hours of highway driving it would have issues idling and would die (sometimes we could turn the engine over again, but as soon as we touched the gas it would die again), the engine was also overheating. We had the radiator replaced in December, and at the time the tech said that our transmission looked to be newer and in good condition. The new radiator helped the engine overheating but did not fix the stalling issue, as it has reared its head twice since, both times after having driven for 3 hours on the highway. If we let the engine cool down for a few hours, we are able to continue on - which means that by the time we've gotten it to a tech they can't recreate the problem (and thus have big issues diagnosing).


A few weeks back we had another issue (unsure if related) where, while driving on the highway the engine seemed to start revving really high, as if trapped in a lower gear, and almost intermittently surge. As we tried to accelerate through to about 40-45 mph we'd experience the surging. If we kept the foot on the accelerator, it sounded like the rv would eventually shift, the revs would wind down, the engine would sound normal. The engine would run normally for about 10-15 seconds, and then the surging would start again. We have not experienced this surging issue at lower speeds, it seems fine until about 40 mph. We checked the transmission fluid and the level and colour appeared fine, and after having spoken to a few techs who said, maybe you were just going up a hill or it was really windy, we thought that perhaps the issue was not an issue. We haven't really driven it since then until yesterday.


Yesterday, we stalled on the highway... again. The tech couldn't recreate the issue, and said that it was likely the fuel pump or the ignition (I had told him that we'd had the radiator replaced in December and that we had been told that the transmission looked good). He couldn't diagnose for certain so we had to make a choice and had him replace the fuel pump. He said that if we encountered the issue again then we would know that it was an issue with the ignition. When we drove it away this afternoon the engine sounded so much better and it was idling normally. We got an hour and a half away from the repair shop, stopped to get gas, and when we went to get back on the highway the revving issue that we had encountered once a few weeks ago, happened again.


THE VIDEO: I pulled out the ipad and recorded this short video before we pulled over in case a tech tried to tell us that it was in our heads again. You'll hear the surging, and then it seems to "catch" and run nicely for a few seconds, and then begins to surge again.


SO TECHNICIAN FRIENDS AND STRANGERS: We are currently pulled over on the side of the road. Here are my questions for you:
1. What does the engine issue heard in the vehicle sound like to you?
2. Do you think the stalling issue and this issue are separate issues or related?
3. If we let the engine cool off for a few hours we can likely drive for a few more without the issue showing up again, should we try to make our destination? We are currently 3 1/2 hours away. Or would that risk further damage to our RV? It is two hours back to the repair shop that we just left, I'm not sure if there is a closer place...


We've had this thing looked at 5 times since we purchased it in July of last year, and our issues still haven't been fixed. We are currently 2,800 km away from home so jumping ship isn't really an option unfortunately, but we can't invest a chunk more money into it either. We need to get it home (or at least back to Canada) before we can part ways with it. Any advice or suggestions you have would be greatly appreciated!!
Yours most gratefully,
Tim and Kaitlyn

there are three things needed to make the motor run... FUEL-SPARK-COMPRESSION...

so the first thing needed is to know which one ..maybe all are failing..

what year and is it throttle body..?

[LVRVLUVR]

first thing to do is get the dog house off and the air cleaner...

sounds like fuel to me... also you need a fuel pressure gauge


and also .. this is a note to all that read this...

put lucas fuel treat ment in the tank it will clean and keep clean the fuel system in motor and generator...

also big block chevys love marvel mistery oil

big block cheveys love to stick valves which might be the case here when you lean on the motor. valves are hanging open

I'd run about 5 big gulp cups of water through the carb. followed by a pint of marvel...


.

need a lot more in fo to be of help...

you might get lusky with a sudjustion though

[LVRVLUVR]

one other thing.. the fuel system works off the distributor,,,,

a bad modulator would do the same thing...

also... the p30 chassis 454 is one of the best riding motorhomes ever

[LVRVLUVR]

and another thing...

this happens quite a bit... and the people just pass it on to some one else..

not that hard a fix....

we get them in our shop all the time....

the major problem is cheep plug wires...

[twinboat]

You better clarify how to pour 5 big gulps into the carb. Someone might hydro-lock their engine. ( This is done at high idle, very small amounts at a time, to remove carbon from the combustion chamber )

I would look at getting the gas filter changed, if you haven't. Next would be to, somehow, check fuel pressure, while it's acting up.

Once it's fixed, if you want to add some Marvel oil, it won't hurt.

[klasicecream]

Originally Posted by ga traveler

I think the revving issue is probably the cooling fan kicking in. If you have a rpm gauge watch it when the engine is revving up. If the rpm's stay the same it is the cooling fan revving up. If you don't have a rpm gauge You should buy one. They are cheap and easy to install. You don't have a class C, You have a P32 class A chassis.

We initially thought it might be the fan but when you try to accelerate further there is a loss of power. The sound is also very similar to the acceleration sound from a stop, just at a higher pitch. It kind of sounds like it's being stuck in a lower gear or can't shift into the next gear properly but I'm not a mechanic so I don't know... We are worried it might be a transmission issue as we are not in a financial position to put several thousand dollars into the vehicle...

[LVRVLUVR]

Originally Posted by twinboat

You better clarify how to pour 5 big gulps into the carb. Someone might hydro-lock their engine. ( This is done at high idle, very small amounts at a time, to remove carbon from the combustion chamber )

I would look at getting the gas filter changed, if you haven't. Next would be to, somehow, check fuel pressure, while it's acting up.

Once it's fixed, if you want to add some Marvel oil, it won't hurt.

some people need to not open the hood,,....plug wires are the usual copret...

[klasicecream]

Originally Posted by LVRVLUVR

there are three things needed to make the motor run... FUEL-SPARK-COMPRESSION...

so the first thing needed is to know which one ..maybe all are failing..

what year and is it throttle body..?

It's a 1993 Winnebago Itasca Sunrise 23C (Chev 454 engine). I have seen '93 Chev 454 throttle body rebuild kits online so I'm guessing that it is.

Doubt it's a fuel issue. We were having issues with it stalling after driving for a few hours when coming to a stop and idling so the last mechanic replaced the fuel filter and fuel pump which seems to have fixed that issue. He also thought a faulty spark could have been contributing to that problem but we didn't have the ignition module/coil/plug replaced. Do you think that's the next step?

[LVRVLUVR]

Originally Posted by klasicecream

We initially thought it might be the fan but when you try to accelerate further there is a loss of power. The sound is also very similar to the acceleration sound from a stop, just at a higher pitch. It kind of sounds like it's being stuck in a lower gear or can't shift into the next gear properly but I'm not a mechanic so I don't know... We are worried it might be a transmission issue as we are not in a financial position to put several thousand dollars into the vehicle...

takes vacuum to up shift ...timing,..stuck valves... plug wires...

[LVRVLUVR]

Originally Posted by klasicecream

It's a 1993 Winnebago Itasca Sunrise 23C (Chev 454 engine). I have seen '93 Chev 454 throttle body rebuild kits online so I'm guessing that it is.

Doubt it's a fuel issue. We were having issues with it stalling after driving for a few hours when coming to a stop and idling so the last mechanic replaced the fuel filter and fuel pump which seems to have fixed that issue. He also thought a faulty spark could have been contributing to that problem but we didn't have the ignition module/coil/plug replaced. Do you think that's the next step?

look at the plug wires.....see if the ends are burnt... start it in the dark and look for plug wire glo..

these motor are very sensitive to wires and you need to put good ones on...