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Discussion Starter #1
Can someone tell me the signs of a bad TPS sensor. My bike acts up now and then. Its hard to explain, but I will try. Sometimes it revs up at idle, to around 2000 rpm, this may only last a few seconds. Sometimes when you give it gas and go through the gears it will cut out , bad . This also only last a few seconds. It never runs bad when you are just cruisin. It also has started using a lot more gas. 35 mpg, it has gottin 47. Thanks for any help.:confused: :confused:
 

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Hard to say, the symphtoms seem contradictory, the TPS might be consistent with the cutting out under acceleration.
The best way to check the TPS if you have a friend into electronics is to graph the output voltage with a scopemeter. You might be able to catch it with a DVOM if you can get hold of a fast one like a Fluke.

It would not account for a decrease in mileage.

Given all your symphtoms I would suspect a vacuum leak and/or a engine temperature sensor out of spec. (or bad connection for ETS), unless there is more then one fault with the bike, and providing it is otherwise mechanically sound. Something as simple as plug wires could be a contributing factor on a 96 bike.

The idle adjustment procedures have also been revised several times.

If you are not familiar with testing the sensors with a DVOM (or scope) you might be better off letting the dealer scan the bike. Under NO circumstances attempt to replace the TPS yourself unless you are really familiar measuring this sort of stuff. The ETS you could just switch with another bike, no problem.
 

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FWIW
I heard of Engine Temp sensors failing where it tells the computer that it is cold all the time (passes 5vdc) - causes sputtering, fouled plugs. check your plugsand if their foulded clean them, unplug the ET sensor and ride to see if the same symptoms show up. (withthe sensor unpluged cold starts will be a PITA)
 

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Discussion Starter #4
Thanks, hippo and rustler. It sound like I need to look at the ETS. Are you telling me to un plug it and and ride. Will this mess up anything?? Also it appears to be hard to get to, can you unplug it fairley easy? If this is my problem, can I change it myself without having to put it on a machine to re program it. Thanks Again!
 

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Well, if you had a hard failure you would have a code 14, and if you run with it disconnected you will have a code 14. I guess you could do it but it's not the way I would go about it. I'm assuming here that a Marelli code for the older bike would be the same as for a later bike, but you get the drift. I don't have books here to check it out.

Removing it is a piece of cake, like removing a spark plug. All you need is a deep 3/4" socket. There is a table in the FM that tells you exactly what resistance it should have at what temperature. You can check it in hot water with a thermometer and DVOM to make sure the values are not shifted, but it sounds more like a intermittent. The sensor has two wires, one from the ECM with 5V and the other goes to a common sensor ground. Find the ground and undo it and clean it and if it does not help you may want to substitute it temporarily for a known good sensor. Also check the connector pins for corrosion and don't forget the little things like plug wires mentioned before.
 

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If it is like the later Marelli dressers the sensor ground is in the two posts on the frame crossmember under the seat, and it has a common black white wire for the ETS, ISC and TPS, and the interconnect between the EFI harness and the main harness is usually under the right sidecover and has either 8 or 12 pins, I forget. May want to clean that one too.
 

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As always hippo is right in what he is saying - what I was trying to say was - on newer bikes you could disconnect the sensor, clear the fault (14) - disconnect the battery, ride to see if the problem goes away. One guy I know did it this way and the sensor did indeed cause his problem, another did it and no difference was noticed but it did turn out to be another problem. But I was not advocating disconnecting and riding without it forever.
 

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Discussion Starter #8
Well I checked every plug connection I could find, and rode it down the road, Guess what? I still have the problem. Just my luck. One good thing is, it is getting worse. Before it was just every now and then, maybe I just need to give up and take it to the shop. ( I hate for anyone to work on my stuff) One thing I noticed today is I let it idle for a few minutes and it would idle up and down just every so often. (Not consistant) What else can I look at before I take it to a shop. The nearest HD shop is 60 miles away to make matters worse. Thanks for any help or suggestions.
 

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Well, if you checked all the connectors, and removed the ground wires under the seat and cleaned them, and performed a proper idle speed adjustment according to the latest info as outlined in M1105, the only options you have is to either gamble with the ETS or let the dealer scan it.
 

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Discussion Starter #10
If a dealer scans it, can they tell whats wrong? I have never seen my engine light come on. Tell me how to make a proper idle adjustment. Also witch ground wire are you telling me to check? Is it the ones going to the battery??

Thanks Hippo
 

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There is a technical service bulletin, M1105, that perhaps your dealer might make you a copy of.

It basically outlines the procedure but it's a couple of pages long, so I don't remember the whole thing. In a nutshell you set the cold idle at 0.61 to 0.64 TPSV with the ISC retracted and then set the hot slow idle at 140C (284F) between 950 and 1050 rpm.

The sensor ground goes to the two threaded studs on the frame under the seat, but it is a good idea to also check the battery grounds at the starter bolt and on the frame near the battery box. Might as well look at the regulator terminal on the main breaker. One thing I do when looking for something is to check rest, cranking and running battery voltage. Just in case there is some discrepancy and to rule these things out.

I would say the dealer may find something, as they can scan sensor values. The more frequent the symphtom the better chance for them to catch something out of spec. Even the best wrench needs a little luck with these things.

That is one clean bike, cleaner then my 02, but mine sleeps outside. Almost the same color too.
 

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I'm not too clear on the symptoms but let me tell about my latest - dang thing would run great but every now and again it would cut out or stumble, almost always around the 3k rpm or higher. It also hunted occasionally at idle. kept getting worse and worse, it turned out to be a wire almost broken off the cam position sensor itself. I think, though I have no way of proving it, that the yokel who did my cams (should have bought the tools needed and done it myself!) may have nicked the wire and all the vibration since has broken one strand at a time. If your symptoms sound similiar you may want ot look a the cps and the cps connector for corrosion.
 

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Discussion Starter #13
I found the ground wires, I cleaned them, and rode again. Same thing. What do you think about the possibility of a fuel pump going out or the fuel filter in the tank. It does seem to act up more when I am jacking on the throttle, like when you are changing gears.I am going to check the cps next as per Rustler. Where is this sensor and wire located?
 

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dang it! Sorry about that I saw the Ultra and thought TC88 - obviously with a 96 you have an EVO, damn really sorry - I guess this is why I am not a pro like Hippo. Don't believe there is a CPS on the EVO's but I could be wrong again. I'll just go hang my head over a beer now - ROFL
 

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Discussion Starter #15
I called the Harley Shop today, they tell me it will not do any good to scan the bike if it is not throughing any codes. Now what???
 

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Well, one at the time. eh?

The EFI EVO's have a different Crank sensor then the TC's but it's still pretty much in the same place, on the left case next to the stator plug.


I think you are barking at the wrong tree. The way you describe the problem it sounds like a misfire under power. While it could be anything, odds are it is electrical (as in ignition) or a lean misfire. While the fuel filter should be changed now and then, a filter or pump problem would show the bike loosing power under full load, sort of like dragging an anchor.

To be honest with you, I don't think you have followed thru with checking the basics, intake/vacuum leaks, replacing plugs and wires (they are good at best for two years), etc. The other thing you can do is run a strong injector cleaner thru the bike, as a injector with a bad spray pattern may cause something like this.

I also disagree with your dealer. It is obvious you will not find a code if there is no engine lite, but you can scan sensor values and see if you can find a discrepancy or unusual reading.

I can just tell you one more time, and it is just a guess, but if you have eliminated all the basic things, the odds on suspect is the ETS and to a lesser degree the Cam sensor. When Crank sensors get weak, the bike is usually very hard to start or will not run at times. Odds also are a Crank or Cam sensor, and even a TPS will set a code. The ETS on the other hand can have shifted values and not set a code.

With these things, even if one is there in person, one has to work with hard data, and that means reliable measurements and numbers.



The only other thing you can do, if you have a friend with a garage, is to hook the bike up to a infrared exhaust gas analizer and get CO and HC readings, preferably when the bike is showing the symphtom. Then tell me what the readings are.
 

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There is a e-mail list where a couple good dealer techs hang out. They may be able to further confirm or deny my ideas. E-mail me privately and mention this discussion so I know who you are, and I'll give you the info. The fact that someone works at a dealer does not guarantee a lack of rectal cranial interference.
 

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Discussion Starter #18
I am on the road again!!

I did go ahead and change the plug wires and plugs. I have to say that my performance did improve, but my problem was still there. I loaded up and went to the shop. Guess what?? It was the temp sensor, so $200.00 later I load up and head home. As of now my bike is running better than it has in a long time. Trying to fix this problem myself, I did find some other things that needed fixing, etc. intake leak, plugs, wires, check valves were lose.

For now I am on the road again. Thanks HIPPO, also thanks RUSTLER.

I am sure I will have more later.

THANKS AGAIN
 
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