RPG Posted October 1, 2007 Share Posted October 1, 2007 Recent 24k service on a '04 RT. Takes almost forever to start when cold. Starts perfectly when warm. Had the same problem before the service (new NGK Iridium plugs, TB synch, TB cleaning, valve adjust, fuel filter replaced) so I don't think I made it any worse. I thought the problem was a bad Air temp sensor (on the air cleaner) as the contact was a little dirty. I cleaned it a few weeks ago and things improved but now the problem's back. Last night I pulled fuse 5 and reset the Motronic. Same problem this morning. Was wondering if I can either check the air sensor (with a multimeter) or if I might be able to hack into the error code log with a multimieter? thanks, Rick Link to comment
Ken H. Posted October 1, 2007 Share Posted October 1, 2007 When the bike is warm, do you get about a 1000 RPM bump up in RPM when you pull the "choke", fast idle lever to the first click? If not, it needs adjustment. Link to comment
RPG Posted October 1, 2007 Author Share Posted October 1, 2007 Absolutely, the RPM increases perfectly when warm. RPG Link to comment
T__ Posted October 1, 2007 Share Posted October 1, 2007 Recent 24k service on a '04 RT. Takes almost forever to start when cold. Starts perfectly when warm. Had the same problem before the service (new NGK Iridium plugs, TB synch, TB cleaning, valve adjust, fuel filter replaced) so I don't think I made it any worse. I thought the problem was a bad Air temp sensor (on the air cleaner) as the contact was a little dirty. I cleaned it a few weeks ago and things improved but now the problem's back. Last night I pulled fuse 5 and reset the Motronic. Same problem this morning. Was wondering if I can either check the air sensor (with a multimeter) or if I might be able to hack into the error code log with a multimieter? thanks, Rick RPG, you can easily check that air temp sensor with an ohmmeter.. It is just a simple reverse resistance sensor.. I don’t have the numbers handy here (have some at home) but basically it should be somewhere in the 2000 ohm range at 40 °f & somewhere in the 4000-5000 ohm range at 75-80° f range.. Place the sensor in the refrigerator & then quickly pull it out & hook up your ohmmeter.. It should slowly & smoothly track from lower resistance (probably in the 2000 ohm range to about 4000 (give or take) ohms at room temperature.. If you suspect the temp sensor just try pulling the connector off the sensor & substituting a 2000 ohm resistor for starting purposes.. If the temp sensor is OK (probably is as those sensors are about as reliable as a paper clip) make sure you have good fuel pressure on start up,, make sure you aren’t giving it TOO much throttle (too much TPS will foil the starting),, make sure the cold cranking voltage is high enough (low cranking voltage will effect injector spray quantity, effect spark production, & lower fuel pressure).. You might also look at your hall sensor as that in itself can effect starting.. The oil temp sensor can also effect starting as that tells the Motronic that the engine is cold & to use the appropriate cold start open loop fuel & timing mapping.. You don’t have a vacuum in the fuel tank from sitting all night do you? A plugged or miss connected vapor canister could allow a vacuum in the fuel tank (long shot but possible) .. Are you getting a lot of timing chain rattle on start up? If so maybe the tensioner pistons are bleeding down overnight & effecting valve timing on cranking ( while a bleeding down T-chain tensoiner didn’t keep my 1150 from starting it did cause a start/stall on cold start.. How does your bike start the rest of the day? Is your problem ONLY first start in the morning? Then OK the rest of the day? You aren’t using an aftermarket fuel controller are you? If so turn that off & see if the starting improves.. Twisty Link to comment
RPG Posted October 1, 2007 Author Share Posted October 1, 2007 I don’t have the numbers handy here (have some at home) but basically it should be somewhere in the 2000 ohm range at 40 °f & somewhere in the 4000-5000 ohm range at 75-80° f range.. Place the sensor in the refrigerator & then quickly pull it out & hook up your ohmmeter.. It should slowly & smoothly track from lower resistance (probably in the 2000 ohm range to about 4000 (give or take) ohms at room temperature.. If you suspect the temp sensor just try pulling the connector off the sensor & substituting a 2000 ohm resistor for starting purposes.. If the temp sensor is OK (probably is as those sensors are about as reliable as a paper clip) make sure you have good fuel pressure on start up,, make sure you aren’t giving it TOO much throttle (too much TPS will foil the starting),, make sure the cold cranking voltage is high enough (low cranking voltage will effect injector spray quantity, effect spark production, & lower fuel pressure).. You might also look at your hall sensor as that in itself can effect starting.. The oil temp sensor can also effect starting as that tells the Motronic that the engine is cold & to use the appropriate cold start open loop fuel & timing mapping.. You don’t have a vacuum in the fuel tank from sitting all night do you? A plugged or miss connected vapor canister could allow a vacuum in the fuel tank (long shot but possible) .. I don’t have the numbers handy here (have some at home) but basically it should be somewhere in the 2000 ohm range at 40 °f & somewhere in the 4000-5000 ohm range at 75-80° f range.. Place the sensor in the refrigerator & then quickly pull it out & hook up your ohmmeter.. It should slowly & smoothly track from lower resistance (probably in the 2000 ohm range to about 4000 (give or take) ohms at room temperature.. Are you getting a lot of timing chain rattle on start up? No, not really, the motor is pretty quiet after starting. If so maybe the tensioner pistons are bleeding down overnight & effecting valve timing on cranking ( while a bleeding down T-chain tensoiner didn’t keep my 1150 from starting it did cause a start/stall on cold start.. How does your bike start the rest of the day? I ride to work nearly everyday. So when I go out to lunch it starts better than in the morning but generally, the longer it sits, the harder it starts. Is your problem ONLY first start in the morning? Then OK the rest of the day? You aren’t using an aftermarket fuel controller are you? If so turn that off & see if the starting improves.. Link to comment
Ken H. Posted October 1, 2007 Share Posted October 1, 2007 Does it crank for a long time before catching/firing, or crank, start, and stubble, stall, or not stay running Link to comment
T__ Posted October 1, 2007 Share Posted October 1, 2007 RPG, DON’T use any of those resistance numbers I gave you.. They sounded correct when written but that is a reverse resistance device so they can’t be correct.. The resistance MUST get higher as the temperature gets lower so I either have the numbers reversed or I have them confused with another test I recently ran.. Look back here later tonight as I have some REAL test numbers written down at home & will publish them here later.. Twisty Link to comment
T__ Posted October 1, 2007 Share Posted October 1, 2007 RPG, yea, I had the numbers backwards.. These numbers below were measured on (2) fully functional AIT sensors.. The ohm readings are right on the money but the temperature could be off a couple of degrees one way or the other as I used an analog temperature gauge that had small numbers on it so was difficult to tell between the major marks.. 41°= 4650 ohms 45°= 4270 ohms 75°= 2400 ohms 80° = 2190 ohms Maybe try a 4000-5000 ohm resistor in place of the AIT sensor to see if it starts better.. Also keep in mind if the temp sensor becomes disconnected or resistance in the wiring or terminals allow the Motronic to view it as out of range it will automatically default to somewhere in the mid 70°f range.. A 75° temp fueling map is not rich enough at 50°f to give a good cold start.. Twisty Link to comment
RPG Posted October 2, 2007 Author Share Posted October 2, 2007 RPG, yea, I had the numbers backwards.. These numbers below were measured on (2) fully functional AIT sensors.. The ohm readings are right on the money but the temperature could be off a couple of degrees one way or the other as I used an analog temperature gauge that had small numbers on it so was difficult to tell between the major marks.. 41°= 4650 ohms 45°= 4270 ohms 75°= 2400 ohms 80° = 2190 ohms Maybe try a 4000-5000 ohm resistor in place of the AIT sensor to see if it starts better.. Also keep in mind if the temp sensor becomes disconnected or resistance in the wiring or terminals allow the Motronic to view it as out of range it will automatically default to somewhere in the mid 70°f range.. A 75° temp fueling map is not rich enough at 50°f to give a good cold start.. Twisty Twisty, the numbers I show are the following: 40F 5.22k 45 4.3k 50 3.85k 55 3.35k 75 2.16k 85 1.7k 95 1.4k The numbers appear close to the values you posted but more importantly resistance falls as temp increases. Now to look at other things. The battery is now 3+ years old but cranks fine. I will check the cold cranking voltage this evening. Oil temp sensor. Do you happen to know where it's located? Appreciate your help, Rick Link to comment
T__ Posted October 2, 2007 Share Posted October 2, 2007 Oil temp sensor. Do you happen to know where it's located? Appreciate your help, Top of engine near the oil thermostst.. Twisty Rick Link to comment
RPG Posted October 2, 2007 Author Share Posted October 2, 2007 thanks much Twisty and others. I will check it out this evening and let you know what I find. Rick Link to comment
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