WELCOME TO RIVER DAVES PLACE

TCM 1200 Hard Backfire

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
Hi all, a question for those of you with TCM 1200 engines. This one is a 2018 quad rotor not the newer single 5.0 whipple. Trying to start the engine and had the throttle cracked open about halfway, and after several seconds it backfires hard (like popped the engine cover up hard). We got the engine started after that but now its way down on power, and doesn't seem to be making the boost it was before that.

So my question is, on a backfire with the whipple's, can a backfire cause damage to something that would keep the engine from making boost properly? I was thinking of burst panels or something but dont see any.

If not, then my second possibility is the batteries were very low when trying to start the engine, and maybe the engine ECU got messed up or lost its program. We did wind up replacing the batteries because the volt gauge wouldn't go above 12 with the engine running initially. Now after the replacements volts is about 12.5 and then goes to 14 with some rpm. I do see the volts drop under 10 though when cranking the engine. Batteries are Odyssey AGM 31-PC2150's. Two on one side of the battery switch and one on the other. Doesn't make a difference whether the switch is on 1 or 2.

Engine starts and idles normally after the backfire (and the battery replacements), but then won't spin much over 2,500 in forward, though you put it in neutral I can rev it past 5K. Engine is making boost in idle, its about 0 on the boost gauge but anything above that doesn't go further than like 5-6 PSI, when it should be higher. Also the exhaust note sounds different at higher rpm than it was prior (not as loud, less deep rumble).

Thoughts?
 

wet hull

Well-Known Member
Joined
Mar 19, 2008
Messages
1,325
Reaction score
1,580
Maybe a vacuum hose popped off? My turbo on truck has done this. Different beast but just a thought.
 

Blackmagic94

Well-Known Member
Joined
Apr 4, 2017
Messages
3,355
Reaction score
4,196
Low battery voltage does all kind of bad things to efi

Injectors can pulse less so less fuel and more lean. If you heard hollow sounding pops and saw the intake flex that is a lean back fire. Rich back fires are fireballs out the tail pipes.

Most likely you blew intake manifold gaskets and the boost is leaking out hence why down on power.
 

Blackmagic94

Well-Known Member
Joined
Apr 4, 2017
Messages
3,355
Reaction score
4,196
Pcm won’t lose it tunes. Either the computer works or doesn’t. If it’s running it’s working.

Fuel pressure test
Compression test
Leak down test
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
Pcm won’t lose it tunes. Either the computer works or doesn’t. If it’s running it’s working.

Fuel pressure test
Compression test
Leak down test
Well I've been told that low battery voltage or a major voltage drop can reset the ECU into a base program. I don't know what ECU the TCM engines use but I've had trouble with them.

Sometimes I've started the boat, warmed the engine up, and try to get on plane and I get this down on power sensation (engine won't rev up or build boost). Throttle back to a stop, turn the engine off, turn it back on again and its back to normal. I've had this happen before without the backfire on starting it so it is something that occasionally seems to happen with TCM EFI engines I've had.

We use 31-PC2150 batteries so I don't know how much better the batteries can be in supplying juice to everything in a start cycle (starter, ECU, fuel pumps and injectors) to keep everything happy.
 

Blackmagic94

Well-Known Member
Joined
Apr 4, 2017
Messages
3,355
Reaction score
4,196
Cranking voltage is not an issue for what I said. Just running voltage.
 

zx14

Well-Known Member
Joined
May 4, 2010
Messages
2,394
Reaction score
2,746
There are 2 valves under the air intake, vacuum operated by a arm on each side. They allow boost to go back in front of the rotors. Make sure they are not blown stuck open, see if you can move the arms manually. If they stuck open your boost is going round and round, and not in the engine.
These are what allows a whipple not to surge.
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
There are 2 valves under the air intake, vacuum operated by a arm on each side. They allow boost to go back in front of the rotors. Make sure they are not blown stuck open, see if you can move the arms manually. If they stuck open your boost is going round and round, and not in the engine.
These are what allows a whipple not to surge.
Great, thanks I'll check on that.
 

Don Johnson

Don Johnson
Joined
Mar 1, 2008
Messages
1,599
Reaction score
1,847
There are 2 valves under the air intake, vacuum operated by a arm on each side. They allow boost to go back in front of the rotors. Make sure they are not blown stuck open, see if you can move the arms manually. If they stuck open your boost is going round and round, and not in the engine.
These are what allows a whipple not to surge.

I would contact TCM but the above is good idea to check That bypass valve if bad would bleed a lot of boost. Easy to check.

Another thing to check, are both throttle bodies opening together? If the sneeze was severe enough it could have damaged the throttle body blade or the linkage that connects the 2 throttle bodies together. There is a flex joint between them. Take off the spark arrestors and check to see that both throttle body blades are working in unison.

Also could have damaged one or both of the TPS's

By the way, never start these engines with the throttle open, they are designed to start with the throttles closed and at idle
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
Thanks Don for that advice. Unfortunately for this boat the exhaust is underwater and cold starting with the throttle in idle is tough on the starter. So cracking the throttle seems to help the engine gulp enough air to push the water out of the exhaust downpipes. I certainly don't leave it cracked open, as soon as it catches I pull it back to idle. But it does concern me that the engine isn't starting in the idle program like it should.

When it's warmed up, it mostly starts with the throttle in idle but not always. We even had the boat in the ocean one time, that was worse for starting, I guess because of the density of saltwater made getting that water out of the downpipes even worse.

Anyway we called TCM and Bob helped get the boat into Savage Marine and then sent out an assortment of parts out for them to swap out. I think it was an ECU and the MSD box and the valves someone mentioned earlier. Anyway, its in good hands at Savage. I just hope they lake test it because it would start and run on the trailer and start and idle around the marina, but it sure as heck didn't have the power to get on plane.
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
I would contact TCM but the above is good idea to check That bypass valve if bad would bleed a lot of boost. Easy to check.

Another thing to check, are both throttle bodies opening together? If the sneeze was severe enough it could have damaged the throttle body blade or the linkage that connects the 2 throttle bodies together. There is a flex joint between them. Take off the spark arrestors and check to see that both throttle body blades are working in unison.

Also could have damaged one or both of the TPS's

By the way, never start these engines with the throttle open, they are designed to start with the throttles closed and at idle

Also, what's a TPS? Throttle Position Sensor?
 

farmo83

Well-Known Member
Joined
Jun 9, 2008
Messages
1,642
Reaction score
1,185
Thanks Don for that advice. Unfortunately for this boat the exhaust is underwater and cold starting with the throttle in idle is tough on the starter. So cracking the throttle seems to help the engine gulp enough air to push the water out of the exhaust downpipes. I certainly don't leave it cracked open, as soon as it catches I pull it back to idle. But it does concern me that the engine isn't starting in the idle program like it should.

When it's warmed up, it mostly starts with the throttle in idle but not always. We even had the boat in the ocean one time, that was worse for starting, I guess because of the density of saltwater made getting that water out of the downpipes even worse.

Anyway we called TCM and Bob helped get the boat into Savage Marine and then sent out an assortment of parts out for them to swap out. I think it was an ECU and the MSD box and the valves someone mentioned earlier. Anyway, its in good hands at Savage. I just hope they lake test it because it would start and run on the trailer and start and idle around the marina, but it sure as heck didn't have the power to get on plane.
Sounds like good service from bob and crew good luck getting rid of your gremlins.
 

FROGMAN524

Well-Known Member
Joined
Mar 16, 2013
Messages
2,643
Reaction score
3,616
Thanks Don for that advice. Unfortunately for this boat the exhaust is underwater and cold starting with the throttle in idle is tough on the starter. So cracking the throttle seems to help the engine gulp enough air to push the water out of the exhaust downpipes. I certainly don't leave it cracked open, as soon as it catches I pull it back to idle. But it does concern me that the engine isn't starting in the idle program like it should.

When it's warmed up, it mostly starts with the throttle in idle but not always. We even had the boat in the ocean one time, that was worse for starting, I guess because of the density of saltwater made getting that water out of the downpipes even worse.

Anyway we called TCM and Bob helped get the boat into Savage Marine and then sent out an assortment of parts out for them to swap out. I think it was an ECU and the MSD box and the valves someone mentioned earlier. Anyway, its in good hands at Savage. I just hope they lake test it because it would start and run on the trailer and start and idle around the marina, but it sure as heck didn't have the power to get on plane.
What kind of boat is it in?


Sent from my iPhone using Tapatalk
 

Dalton

Well-Known Member
Joined
Apr 15, 2011
Messages
1,555
Reaction score
1,071
That’s a powerful engine, and fuel injected, I don’t think you should have to open the throttle to start it


Sent from my iPhone using Tapatalk
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
IMG_1364.JPG

Based on the position of the exhaust pipes in the attached picture, you can see they are well below the water line, and not traditionally above it as in most boats. So this setup has to pump the air out of the down pipes and out the exhaust to get the water out. Makes it a more difficult start than if the pipes exited above the waterline.

This setup was chosen so the exhaust is not heard while idling, and you only hear it as the boat comes on plane and is on plane.

After running this build, I've come to the conclusion that this was a bad idea. I'm considering having the exhaust exits brought up to be about level with the waterline or just slightly below, rather than this excessively below, to make it easier on the engine for starts and so I can always be in the idle program.
 

hallett21

Well-Known Member
Joined
Nov 9, 2010
Messages
9,879
Reaction score
7,052
I love this boat.


Before all this would it start ok? Or was it just hard on the starter?


Sent from my iPad using Tapatalk
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
The boat has always been a bit of a pain to start cold, though after it warms up it definitely improves and after its warm you can mostly start it in the idle program. but when its cold we've been told to open throttle to get the air into it. I think this time though the batteries were low enough, or weak enough that it led to a combination of factors that nothing was happy when trying to start it cold.

So we replaced the batteries, and Savage replaced one of the bypass valves that Don mentioned, and they ran it and said they felt that was it.

We'll see, we are going to be out there for DS and we'll be down by the Springs Card Stop.
 

Husqy510

Well-Known Member
Joined
Aug 9, 2011
Messages
574
Reaction score
570
You shouldn't have to crack the throttle to start that motor. There are a bunch of performance motors with exhaust that dumps below the water. I'm sure Teague and Salvage will get it sorted out
 

Outdrive1

Outdrive1 Marine Sales https://www.outdrive1.com/
Joined
Dec 19, 2007
Messages
28,895
Reaction score
17,044
View attachment 993010

Based on the position of the exhaust pipes in the attached picture, you can see they are well below the water line, and not traditionally above it as in most boats. So this setup has to pump the air out of the down pipes and out the exhaust to get the water out. Makes it a more difficult start than if the pipes exited above the waterline.

This setup was chosen so the exhaust is not heard while idling, and you only hear it as the boat comes on plane and is on plane.

After running this build, I've come to the conclusion that this was a bad idea. I'm considering having the exhaust exits brought up to be about level with the waterline or just slightly below, rather than this excessively below, to make it easier on the engine for starts and so I can always be in the idle program.
Badass boat.


Sent from my iPhone using Tapatalk
 

SBMech

Fixes Broken Stuff
Joined
Jul 25, 2012
Messages
9,782
Reaction score
15,241
Almost every EFI controlled setup has an idle boost when cold, precisely to act like a choke, pulse width is increased and IAC steps up to make it idle around 1500 for a few seconds, then down to around 1000 for a minute, then slowly should drop to near warmed up speed after a few minutes.

It naturally should overcome any sort of need to crack the throttle open, when you do that you are confusing the ECU.
 

Don Johnson

Don Johnson
Joined
Mar 1, 2008
Messages
1,599
Reaction score
1,847
The boat has always been a bit of a pain to start cold, though after it warms up it definitely improves and after its warm you can mostly start it in the idle program. but when its cold we've been told to open throttle to get the air into it. I think this time though the batteries were low enough, or weak enough that it led to a combination of factors that nothing was happy when trying to start it cold.

So we replaced the batteries, and Savage replaced one of the bypass valves that Don mentioned, and they ran it and said they felt that was it.

We'll see, we are going to be out there for DS and we'll be down by the Springs Card Stop.
Just an FYI, on my TCM 1250's at cold start the motors crank a lot before the ECU fires them, I am not sure why this is, maybe an oil pressure safety deal, the ECU verifying it found the #1 cylinder, ECU not triggering the injectors right away. I really dont know why and I never asked TCM why. Once they have started they start instantly. This is appears to be normal on the TCM motors. I will say a few other 1200 owners have commented the same thing, cold start need to crank on the motors until they start, then once started they fire immediately.

Bob was in my boat a lot fine tuning and he cold started them a lot, if it was not normal he would have addressed it.

Maybe this is not a exhaust location thing and just normal TCM cold start sequence.
 

DaveH

Well-Known Member
Joined
Sep 9, 2008
Messages
1,713
Reaction score
1,252
efi hard starting engines have a couple of issues.......first...most blown engines put the injectors ABOVE the supercharger. this is a TERRIBLE (but convenient) location although it does offer some level of cooling to the supercharger. when the engine is cold, the fuel doesn't want to atomize and get through the blower........this is why many engines have moved the injectors to true port injection. if your engine starts and idles fine once warm.....that's the price you pay for the poor injector location. there is no getting around it.

another reason for hard starting is a sign of a worn-out engine.

some here have mentioned the idle valve adding air to start the engine and that's true. however for large displacement engines (500+) one idle valve barley supports enough airflow to manage idle. it wont support enough air to start the engine.

the best setup is staged injection where you have one injector in each intake port and secondary injectors above for supercharger cooling. most wont spend the $$ for quality electronics that do this.
 

Husqy510

Well-Known Member
Joined
Aug 9, 2011
Messages
574
Reaction score
570
I'm almost certain this motor would be port injection
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
Thanks for the info @SBMech and @Don Johnson that's good to keep in mind.

As for the boat this weekend, huge shoutout to Bob Teague who got it into Savage and a huge shoutout to Savage for taking it and getting it repaired. It ran great. I think one of the idle surge valves was replaced. I didn't get a chance to talk to Bob at the Thursday street party and thank him in person.

We had fun watching the boats run down to the Springs card stop and hanging down at the card stop watching everyone come in for their cards. Awesome weekend weather too.

Now we just have to fine tune the prop aerator, what a pain in the ass. I'm about to take it off and toss it in the lake.
 

Maw

Dont re Member
Joined
Jun 9, 2008
Messages
1,169
Reaction score
598
Perhaps along a similar vein, on Saturday while sitting at Three Dunes I popped the hatch and found this. This is the third time it's happened over it's 10 year life. A Whippled 540 Dart BBC. I've never heard a backfire from this engine.

I was going to send the pic to @cyclone for inclusion in the "Zip-Tie Moment" portion of the shows. Sloppy work, I know.

Aside from a backfire, any thoughts as to the cause of the failed bypass canister?

Whipple.jpg
 
  • Like
Reactions: DWC

SBMech

Fixes Broken Stuff
Joined
Jul 25, 2012
Messages
9,782
Reaction score
15,241
I was going to send the pic to @cyclone for inclusion in the "Zip-Tie Moment" portion of the shows. Sloppy work, I know.
What ever gets you home! Pretty inventive to be honest! I try to carry around a pack of ties just for reasons like this, you can never be too prepared! Zip ties are amazingly adaptive when you need to be creative! As far as the valve, no experience there, but being plastic, makes me think they probably become fragile eventually.
 

JeremyJoyce

Well-Known Member
Joined
May 7, 2017
Messages
103
Reaction score
170
Well I've been told that low battery voltage or a major voltage drop can reset the ECU into a base program. I don't know what ECU the TCM engines use but I've had trouble with them.

Sometimes I've started the boat, warmed the engine up, and try to get on plane and I get this down on power sensation (engine won't rev up or build boost). Throttle back to a stop, turn the engine off, turn it back on again and its back to normal. I've had this happen before without the backfire on starting it so it is something that occasionally seems to happen with TCM EFI engines I've had.

We use 31-PC2150 batteries so I don't know how much better the batteries can be in supplying juice to everything in a start cycle (starter, ECU, fuel pumps and injectors) to keep everything happy.
I fought that for a season and it kept happening more frequently. Had it happen 2 out of 5 starts the weekend before my service. Asked for my cap/ rotor/ wires replaced with my service and the cap had massive growth on the contacts inside and the plugs were very black. 🤦‍♂️ Runs like a champ now though.
 

Maw

Dont re Member
Joined
Jun 9, 2008
Messages
1,169
Reaction score
598
Age and plastic parts?
This one was perhaps three or four years old, but the boat is stored in our air conditioned (78F) Havasu garage so it shouldn't be an aging problem. The plastic halves of the canister are OK, it always separates along the silicon seal between the two halves with the diaphram in good shape. I might try "gluing" it back together with silicon this weekend.
 

DarkHorseRacing

Well-Known Member
Joined
Jun 14, 2014
Messages
718
Reaction score
960
I fought that for a season and it kept happening more frequently. Had it happen 2 out of 5 starts the weekend before my service. Asked for my cap/ rotor/ wires replaced with my service and the cap had massive growth on the contacts inside and the plugs were very black. 🤦‍♂️ Runs like a champ now though.
Ok, good to know, I'll add that to the service list for the end of season stuff.
 

cyclone

Well-Known Member
Joined
Oct 4, 2007
Messages
326
Reaction score
1,049
Perhaps along a similar vein, on Saturday while sitting at Three Dunes I popped the hatch and found this. This is the third time it's happened over it's 10 year life. A Whippled 540 Dart BBC. I've never heard a backfire from this engine.

I was going to send the pic to @cyclone for inclusion in the "Zip-Tie Moment" portion of the shows. Sloppy work, I know.

Aside from a backfire, any thoughts as to the cause of the failed bypass canister?

View attachment 997080
solid repair job right there. i'd roll with it for at least 6 months. lol
 

Teague_JR

Well-Known Member
Joined
Jun 7, 2018
Messages
106
Reaction score
239
Perhaps along a similar vein, on Saturday while sitting at Three Dunes I popped the hatch and found this. This is the third time it's happened over it's 10 year life. A Whippled 540 Dart BBC. I've never heard a backfire from this engine.

I was going to send the pic to @cyclone for inclusion in the "Zip-Tie Moment" portion of the shows. Sloppy work, I know.

Aside from a backfire, any thoughts as to the cause of the failed bypass canister?

View attachment 997080
relocate the vacuum signal line to this diaphragm to the throttle body between the throttle blade and the supercharger. There are many ports to do so as you can see in this pic. When that line is down on the intake, it slams it closed harder under boost but is much more sensitive to backfire pulse blowing them in half. It doesnt have to be a radical backfire even just a little sneeze when cold starting, etc.

JT
 

Maw

Dont re Member
Joined
Jun 9, 2008
Messages
1,169
Reaction score
598
Thanks! When I get back out to Havasu in a week or two I'll poke around. I don't know the arrangement well enough to picture what you're describing from aging memory.
 

Instigator

Just Livin up to My Name
Joined
Dec 19, 2007
Messages
4,388
Reaction score
3,953
Moisture in the bilge will cause condensation in the distributor cap which will cause corrosion on each cylinders contacts. It is amazing how much power will be lost due to that corrosion.
Just maintenance though but overlooked by most.
 

Bpracing1127

Well-Known Member
Joined
May 31, 2012
Messages
5,622
Reaction score
6,278
My dad had a problem where the gear set inside the whipple broke. The pulley is spinning but rotors are not. Would not climb rpm under load. In neutral ran fine. Maybe check that.
The exhaust in the water is not the problem. You shouldnt have to crack the throttle at all
 

HydroSkreamin

Stress Eliminator
Joined
Jan 12, 2014
Messages
1,701
Reaction score
3,920
Nice boat and engine package you have there.

If this package still starts somewhat hard after this last service, I’d consider putting a 1” to 1-1/4” exhaust idle relief in to get an above water break that will help start, idle, and be a vacuum break when you shut it off. There’s a possibility of sucking water back up the exhaust due to vacuum.
 
Top