Topic: Exhaust Backfire (Read 9807 times)

103_RK · « **on:** September 22, 2005, 05:49:19 AM »

I have an intermittant backfire through the exhasut. This is a 2003 SERK (103" Road King). Everything seems to be fine when I ride to work in the AM, also if I ride out to lunch all is well. When I leave work in the afternnon after the bike has cooled for approx. 3 hours it tends to backfire through the exhaust. The temp. is usually in the mid 80's to low 90's in the afternnon. I have Electronic Feul Injection and was wondering if one of the injectors was leaking into the intake or what could cause this. I have the SE air filter and Rinehart exhasut with stage one EFI remap. Thanks in advance for any tips.

103_RK

grc · « **Reply #1 on:** September 22, 2005, 07:57:53 AM »

It appears from your description that this could be a temperature related issue - I would first have the temp sensors checked out. H-D has had a lot of issues with intermittent or out of spec sensors. I'm planning to pull both of mine, cylinder head and intake air, and check them at various temps against the specs. I have the opposite problem; bike runs OK at low speeds when hot, runs like chit when cold (below 70 ambient temp).

Ed Ramberger - One_Screamin_Eagle · « **Reply #2 on:** September 22, 2005, 11:41:34 PM »

Quote

I have an intermittant backfire through the exhasut.

103_RK · « **Reply #3 on:** September 23, 2005, 07:18:08 AM »

Thanks, I am planning to get the race tuner. It will have to wait for funds though.

103_RK · « **Reply #4 on:** September 23, 2005, 07:21:01 AM »

If I can find specs for the sensors, I will check them. I don't have money right now to spend a lot of delor time checking things out that are occasional. Most days it does not do anything wrong. When it backfirs, it is only the one time on startup. Afterwards it runs fine.

HDJamsTX · « **Reply #5 on:** September 23, 2005, 11:06:50 PM »

103 RK, not sure of when or where your going to get your RT, but
here is the link to chicago HD and they offer 25% off on all HD items.
http://www.chicagoharley.com

Unbalanced · « **Reply #6 on:** September 23, 2005, 11:18:58 PM »

Only offered me 20 percent off on my new wiring harness for the road king only problem was they sent me another police harness and I needed the standard road king one .... /sigh

103_RK · « **Reply #7 on:** September 24, 2005, 07:22:41 AM »

Thanks for the tip om CHicag Harley. i use them when I'm buying something expensive like this. I usually check ebay first.

103_RK · « **Reply #8 on:** September 28, 2005, 06:06:37 AM »

I wonder if the exhaust backfire can be from an injector? When the the ignition is turned on and the kill switch is set to "run" you always hear the fuel pump on EFI bikes. What stops the fuel from entering the cylinder? Is it the injector or is there a regulator? I thought the injectors only allowed fuel when told by the ECM. If there is a problem with too much fuel entering the cylinder, what would be the most likely cause? THis is only on warm starts. It never happens on cold first starts for the day. If I buy a race tuner, can I play with the warm start settings?

grc · « **Reply #9 on:** September 28, 2005, 10:50:59 AM »

Quote

I wonder if the exhaust backfire can be from an injector?

TB · « **Reply #10 on:** September 28, 2005, 10:53:55 AM »

I would try to follow the KISS method and check out the easy things first.

Did the condition first manifest itself after the change in exhaust? If it did, I would check for an exhaust gasket leak at the head. I would check it anyway as they can loosen over time. Cool air is drawn into the system causing flame throwing and backfiring particularly on deacceleration.

TB

PCC · « **Reply #11 on:** September 28, 2005, 01:37:42 PM »

The Stage I re-map is the culprit...there is some small amount of fuel still injected at 0% throttle opening. With a PC or Race tuner you can dial this out and ...no more backfire. That IS the KISS! [smiley=7.gif]

103_RK · « **Reply #12 on:** October 03, 2005, 06:47:03 AM »

TB, this is a true backfire. Sounds like a gunshot. It didn't start with the exhaust change. It is not a popping on deceleration. I do have that as well but that is something that I paln to fix as soon as my funds allow me to purchase the race tuner.

103_RK · « **Reply #13 on:** October 03, 2005, 06:50:21 AM »

PCC, Thanks and as soon as I can purchase the race tuner, I will. I can start the bike fast by not waiting for the check engine and alarm light to go out. This seems to not allow time for the fuel to get in there and backfire.

103_RK · « **Reply #14 on:** October 03, 2005, 06:54:15 AM »

grc, WHat if I just find a temperature sensor on ebay and replace it? I sometimes see a map sensor or other sensor listed and wonder if I find the corrrect sensor that is the problem if I should just take a chance and still avoid the dealor high labor. I need to try to save $'s as I still need a bck tire before next season and can only spend so much on the bike without cutting too many other things short.

grc · « **Reply #15 on:** October 03, 2005, 07:37:07 AM »

Quote

grc, WHat if I just find a temperature sensor on ebay and replace it?

grc · « **Reply #16 on:** October 03, 2005, 08:09:16 PM »

Engine Temp Sensor

grc · « **Reply #17 on:** October 03, 2005, 08:10:01 PM »

Intake Air Temp Sensor

103_RK · « **Reply #18 on:** October 04, 2005, 05:58:46 AM »

GRC, thanks for the info. Is there any way you could email it to me along with the ecm pinout diagram so that I can try it out? I read through it and it sounds like good things for me to check. It says to check specific ecm pins though and it would be easier if I had the pinout diagram. If this is not too much trouble, my email address is scon@comcast.net. I am hoping that the race tuner will help the overall performance of the bike. But, I don't see how it will help this backfire. I guess it's possible. I see a throttle body for a late model touring bike on ebay. If it stays cheap, I may just buy it for parts. That would give me the injectors and intake sensor anyway. Thanks again

grc · « **Reply #19 on:** October 04, 2005, 09:06:01 AM »

Quote

GRC, thanks for the info.

103_RK · « **Reply #20 on:** October 04, 2005, 10:54:03 AM »

Haven't checked the leak idea yet. I will check it Friday when I am off. I ride it most days and don't feel like messing around with it after work. If I don't get done I can't ride the next day. Thanks again for all of your help, I will try removing the sensor.

103_RK · « **Reply #21 on:** October 17, 2005, 06:23:29 AM »

I looked to see if there was any fuel leaking in tha intake when the ignition was turn on multiple times, I could not see any. Also (GRC) I tried to follow the diagrams to check sensors for resistance. the diagrams are for a newer than 03 bike. Mine only has half of the connector pins. I need to purchase the electrical diagnostic manual and check the pins for my bike. Thanks for the help. I will buy the race tune in the next week or so and try again after the new map is installed.

Unbalanced · « **Reply #22 on:** October 17, 2005, 08:40:38 AM »

103RK,

The reason the new racetuner has the decel and accel pump features added is that Harley already knows there is an issue with changing the pipes. If you had had Vance Hines it would just be the pipes sucking up the air which is why harley insisted that they put a valve in the SE 2 into 1 pipe. Since its the Rhineharts its most likely just a decel pop and the latest software 4.50 fixes that with a simple temp range adjustment it should go away. I would not get way ahead of yourself until after you install / tune the racetuner.

just my 2 cents on it.

Ed Ramberger - One_Screamin_Eagle · « **Reply #23 on:** October 17, 2005, 07:50:08 PM »

Holy cow - all the wasted time and silly ideas thrown out there. It doesn't need a sensor, it doesn't have an injector leak. Tune it correctly with SERT, use decel enleanment to add or take away fuel as different combinations like different things and play with timing on decel if necessary. Also realize that some pipes will always have some decel pop.

grc · « **Reply #24 on:** October 18, 2005, 09:47:37 AM »

Quote

Holy cow - all the wasted time and silly ideas thrown out there.

103_RK · « **Reply #25 on:** October 19, 2005, 05:42:48 AM »

I think i will wait for the race tuner anyway. Maybe this will help. This problem is a backfire on warm starts. I cannot see anyextra fuel in the intake. I am getting ready to order the race tuner, was only waiting for the money. I will let you know if the race tuner helps. It's getting cold now so my riding will slow way down. I don't like to ride as much when it is in the 40's in the morning. Thanks for the tips

Unbalanced · « **Reply #26 on:** October 20, 2005, 09:59:01 PM »

Another cause could be your TPS positioning. (TPS)= throttle positioning sensor.
it could be bad / could be butterfly is closing to close and other things just another suggestion.

If your butterfly closes to tightly should be around .0025 and .003 room underneath it snug to the feeler gauge.

I would still look at the startup fuel / temp comparision and or charge robbing.

If the TPS is set correctly and within tolerances (geesh I hate that) to varied in harley's case, but none the less I would expect you will resolve this with the race tuner.

Another possibility: I may have missed it, also are you sure your mufflers arent sucking air up into a dry port and causing the backfire as well ??

What type of exhaust setup do you have ? sorry if I missed it.

103_RK · « **Reply #27 on:** October 21, 2005, 09:55:40 PM »

I have Rinehart true duals with 2.5" baffles.

Unbalanced · « **Reply #28 on:** October 22, 2005, 02:50:13 PM »

RK,

The rhineharts dont suck air up into them so I doubt its the pipe causing the issue. I would recommend though looking for the 2 1/4 baffles if your bike is stock or near stock unless you just cant live without the sound you get from the 2 1/2 baffles. The bike will run better with 2 1/4 did with my 103 and my 124.

When are you getting the race tuner / powercommander ?

Have you checked the bike for an intake leak? You can do this by spraying break clean around the intake manifold with the bike running if the bike begins to die or does die that would be a fast thing you could rule out.

Ed Ramberger - One_Screamin_Eagle · « **Reply #29 on:** October 22, 2005, 03:25:09 PM »

Quote

This was never described by 103RK as a "decel pop" - it is a major backfire when starting the engine.

103_RK · « **Reply #30 on:** November 19, 2005, 08:49:20 AM »

To update this posting, I finally bought the race tuner and I also downloaded a map fro hd-maps. This seems to have corrected the problem. I rode several hundred miles without a backfire when starting the bike.

Unbalanced · « **Reply #31 on:** November 20, 2005, 02:00:19 PM »

103,

Glad to hear you got it fixed and that it was a simple fix except that it hurt the wallet.

-harry

Author Topic: Exhaust Backfire (Read 9807 times)