| Author |
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Shooter
| | Posted on Wednesday, March 24, 2010 - 12:01 pm: | 
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My 2000 S3 has developed a real bad misfire / backfire when warmed up and cruising. It is not rpm dependent, but throttle position dependent ( 5-25%).Starts up cold great, runs very strong at WOT, and reasonably well at larger throttle openings
No trouble codes
Zero'd the TPS with ecm spy
new plugs /wires
new 02 sensor
inspect wiring, nothing obvious
AFV was 105
battery voltage about 13 vdc
Front plug dry fouls ( black and sooty insulator, rear plug was ashen on the electrode)
When I watch it on ecm spy everything appears fine , but as soon as I get on the road behind a car, pop pop pop, stall...reset the key and it starts right up.
Intake seals are my next step, I tried the water bottle trick but couldn't get any change in the idle, nor did the seals tend to pull the bubbles in ?
(Message edited by shooter on March 24, 2010) |
Blake
| | Posted on Wednesday, March 24, 2010 - 01:14 pm: |
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Intake manifold seals are good candidate. Fouled injector is another.
(Message edited by Blake on March 24, 2010) |
Blake
| | Posted on Wednesday, March 24, 2010 - 01:28 pm: |
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Swapping front & rear injectors and observing the effect on spark plugs can aid diagnosis. |
Shooter
| | Posted on Wednesday, March 24, 2010 - 02:10 pm: |
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swapping the injectors would identify if an injector is bad? I have fixation on the fact that the bike runs great in every other condition than small throttle opening when fully warmed up.
How difficult is it to identify faulty intake manifold seals?Spraying water on them didn't make any immediate change in idle.I was expecting the idle to drop off immediately |
Blake
| | Posted on Wednesday, March 24, 2010 - 03:41 pm: |
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According to your spark plug inspection, the front is running rich, the rear on the lean side. If when you swap the injectors the front plug indicates lean and the rear rich, then you've identified an issue with one of the injectors, the one that is causing the lean condition would be my guess.
(Message edited by blake on March 24, 2010) |
Blake
| | Posted on Wednesday, March 24, 2010 - 03:46 pm: |
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I've used electrical contact cleaner to diagnose leaking intake manifold seals, and it worked very well. It works best if you have the little extender tube to fit into the nozzle to help more accurately direct the spray. Careful to avoid directing any spray into the intake itself. You should have the engine running at a fast idle, around 2,000 rpm. Engine speed will drop noticeably when/if you direct the spray onto the area of the leaking seal. |
Blake
| | Posted on Wednesday, March 24, 2010 - 03:47 pm: |
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One other possibility is a faulty cylinder head temperature sensor. |
Shooter
| | Posted on Wednesday, March 24, 2010 - 04:32 pm: |
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Thanks for the insights Blake.
The temp sensors ( engine and intake air) appear to be reading correctly, I can watch them respond appropriately in the ecm spy program.
I am going to try using contact cleaner tonite on the intake manifold seals. |
Dck996
| | Posted on Wednesday, March 24, 2010 - 05:10 pm: |
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Your misfire sounds just like my leaky intake seals. I didn't have any luck checking for leaks with various sprays. I went ahead and changed the seals, and both seals had uneven marks around them.
It's all part of the Harley experience. |
Nallac
| | Posted on Thursday, March 25, 2010 - 05:42 am: |
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Had a similar sounding problem with my X1,
found the header pipes where loose ,must of been sucking air in past the O2 sensor.
Once tightened up she ran good. |
Shooter
| | Posted on Thursday, March 25, 2010 - 11:25 am: |
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Thanks all for your responses...I have owned this bike from new, and will never sell it. However it has had it share of trials and tribulations...
I recently had the top end off , put on 1250 cylinders and new (stock) heads... so that leans even more to the intake seals as my hands were on them... The exhaust was torque'd to speck, but I tweaked it a little more since the back fires started... ( my old M2 had a case of the backfires when a exhaust stud nut came off, but that was on the throttle over run)
Tonite / tomorrow morning I will be replacing the seals and will report back |
Shooter
| | Posted on Monday, March 29, 2010 - 04:58 pm: |
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I replaced the seals, but still have the same issue. My seals were of the 2 piece variety ... the service manual describes a later seal. Does anyone have a part number? |
Kalali
| | Posted on Tuesday, March 30, 2010 - 03:25 pm: |
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I have also been wondering about those "elusive" one piece molded flange/seal parts...Do they really exist??!! |
Shooter
| | Posted on Tuesday, March 30, 2010 - 05:52 pm: |
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I could not find the molded one piece seals so I went ahead and ordered James gasket blue ones... |
Kalali
| | Posted on Wednesday, March 31, 2010 - 04:30 pm: |
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You should be OK...Those seals are friction fit inside the flange and along the neck of the intake. |
Shooter
| | Posted on Monday, April 05, 2010 - 03:51 pm: |
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new seals are in, no joy.Still stalling, Backfiring, missing at cruise,no codes. This is getting old. |
Kalali
| | Posted on Friday, April 09, 2010 - 02:30 pm: |
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I know you did mention you got a new O2 sensor but your symptoms seem to point to either a bad O2 sensor or bad connection to the sensor. COuld be a bad air intake temp sensor/connection but less likely. |
Shooter
| | Posted on Saturday, April 10, 2010 - 09:06 am: |
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Kalali, that was my first thought too.
I have watched the o2 sensor go into open loop and start providing a voltage within the parameters ( on ecm spy), and the AFV hasn't been above 105 since I started checking it.
This weekend I am going to pull the fuel injectors, replace the o-rings and try and observe the spray pattern for anomalies.
i only get time to work on the bike on weekends, so its a slow process around here.
update: I started following the service manual flow charts again and came up with the ignition coil out of spec. by 25% on primary and secondary resistance. I have one on order and it will be here on Monday... My experience with coils is that they either work or they don't, but perhaps this is relating to the problem.
(Message edited by SHOOTER on April 10, 2010) |
Shooter
| | Posted on Sunday, April 25, 2010 - 01:03 pm: |
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update:
Still misfiring, stalling at cruising speeds (i.e. closed loop:lightly loaded, small throttle openings)
I have replaced the following:
*intake seals for the 3rd time ( oem ,thin film of syl-glyde, made sure the manifold was in position before tightening, tightened up nice and even)
*new injector orings ( all 4, used oem with syl-glyde)
*checked static timing using ecm spy, it was dead on.
*replaced coil and spark plug wires
*o2 sensor with a Bosch version
The last test ride revealed the following:
plugs came out both the same, evident of very lean running ( greyish / white insulator and electrode)
AFV was 90 : That is the lowest I have ever seen it
I wish I could figure out how to download/ print screen my ecm spy readings , but nothing I try seems to work? The trouble code section is very confusing, the enginr light came on once on the ride, I checked historical codes and there are a bunch. Would be nice if they were time stamped, as I created some of the codes when i had the bike aprt and trying to figure out which one actually came in on the ride would be helpful.
thanks in advance for any insight |
Kalali
| | Posted on Sunday, April 25, 2010 - 03:51 pm: |
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You may might to clear the old codes and look for new ones. Is your IAT sensor clean and connected properly? What about the head temp sensor? There is really not a whole lot of other things to check...Of course other than wiring/chaffing issues. |
Buellisticx1
| | Posted on Sunday, April 25, 2010 - 05:42 pm: |
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Have you checked the fuel lines?....
A fuel pressure test wouldn't hurt either. it will give you some hints and It might be helpful.
Sometimes somethings simples are often the most difficult to find out.
Good luck and let us know the solution.
Regards. |
Shooter
| | Posted on Sunday, April 25, 2010 - 06:39 pm: |
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Fuel Press. was at 48 psi per my cheap gauge.
I dug out some spare injectors I had laying around ( from an e-bay throttle body) and plugged them in. I then lost the rear injector sgnal, the wire broke off inside the connector. I was familiar with that issue from many years ago on a friends X-1. I am fairly certain that this was a new issue from monkeying with the wiring as I had run the injector test function many times before with the original injectors.
Pulled out a connector from an e-bay wiring harness and spliced it in, good test.
took another test ride, it misfired once accelerating,but I was able to run along in closed loop for about 10 miles with no back fires or stalls.The AFV was back to 100.
so I think I am looking at either bad injectors, or an intermittent failure on the rear injector.
I was trying to get a peak at the spray pattern while the test function ran in ecm spy but never did see any gas coming out the injector.
I will be riding the Buell tomorrow on my regular commute and will give an update.
UPDATE:
The Bike ran very well when cool, but felt very 'soft" once up to full operating temp. Its almost like I can predict where on the commute it is going to act up  Return idle also started acting up, like between 1 traffic light. It's like a switch is thrown.The missing was still evident, but it was much softer with no stalling or huge backfires.
So, after 3 tries, do I still have an intake leak? I tried to replicate the issue yesterday winding up the idle and spraying the intake seals to no effect.
Another piece of data is that the cylinders are the 1250 ones Nallin sells now. I wonder if they expand greater than the stock ones and the manifold pulls away?
}
(Message edited by shooter on April 26, 2010) |
Shooter
| | Posted on Tuesday, April 27, 2010 - 11:00 am: |
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for those keeping score at home, here is the latest update:
Since swapping in the other used fuel injectors the bike is running 90% better, but still have a hard miss/ backfire under heavy load/ rapid throttle opening ( passing a car, accelerating hard from a stop up a grade)
Idle is not hanging up at all, so I believe the air leaks are gone. Once the bike cools down I will be checking plugs |
Kalali
| | Posted on Tuesday, April 27, 2010 - 11:22 am: |
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This may be a long shot but just as an experiment try running the bike with the "Open Loop Learn Enable" box unchecked (disabled) and see if that makes a difference. I can't explain why this happens but sometimes the bike tends to "react" when the ECM switches from Open Loop to Closed Loop (and visa versa). Easy to do by ECMSPY. |
Shooter
| | Posted on Tuesday, April 27, 2010 - 02:49 pm: |
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I have wondered about the open / closed loop transition myself because that is where I seem to have the issues...maybe the code was written by Microsoft  |
Buellisticx1
| | Posted on Tuesday, April 27, 2010 - 03:37 pm: |
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Take a look in Acceleration Enrichment values (other maps ECMSPY) "Full Accel Revs and Correction" maybe it's wrong.
Regards. |
Buellisticx1
| | Posted on Tuesday, April 27, 2010 - 06:16 pm: |
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Why do you not try to loading a entire Race eeprom? if you want I can email you one Race x1 for a stock engine or one with my particular setup (1250 kit, stage 1 porting heads from NRHS, D&D full exhaust system and C.F. Ham Can air cleaner)..... |
Shooter
| | Posted on Tuesday, April 27, 2010 - 08:01 pm: |
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I am running a "for race use only" ecm... I actually have 2 and have swapped them at various times in the process. I truly appreciate the offers of a map , but I can't understand why the factory fuel maps would cause such havoc...
The bike has 40k miles. The motor has brand new stock T-Storm heads, with new 1250 cylinders and pistons, Buell race air filter, stock exhaust header with a Vance and Hines muffler. Pretty typical I would think.
Swapping the injectors has made the biggest change, I really thought I had it until it wouldn't accelerate cleanly.  |
Kalali
| | Posted on Wednesday, April 28, 2010 - 11:07 am: |
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You may want to take Buellisticx1 up on his offer since his set up seems close to yours. I'm willing to bet his fuel map is a lot richer across the board, both front and rear, as compared to "stock" Race ECM maps. On the other hand, if you're maintaining an AFV=100 the chances are your fuel/air is OK, at least in the back cylinder. As for changing Acceleration Enrichment (revs and correction) values, that usually helps with (slow) throttle response, both off idle and mid-range but depending on your EEPROM code you may need to make the changes directly in the EEPROM as opposed to the table itself.
You could try swapping the injectors front to back and see what happens there... |
Shooter
| | Posted on Wednesday, April 28, 2010 - 01:04 pm: |
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I think I may have to try doing some data- logging, but since my wife and I share a laptop ( I have a desktop as well) not sure the best way / cheapest way to do that.
I remember when all you had to learn was how to shim a needle in a cv carb  |
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