free website stats program Running on only the rear cylinder. | Harley Davidson Forums

Running on only the rear cylinder.

A

AdamCA

Member
Hello, I have a 2017 Street glide special that recently started running pretty rough and spitting in burnt fuel out the exhaust. It is only running on the rear cylinder, when it initially started I had codes for the injector in #1 cylinder, p0261 and 262. I checked the plugs to the injectors and they were fine. So far I have replaced the injectors, coil, plugs and wires. Compression test on both cylinders and they are within spec, all 4 plugs are getting spark. I rode the bike the day before it started and had no issues, the morning it started I started the bike to let it warm up, ran for about 5 mins before I left, I pulled out of my driveway and went 20 yards and it started running very rough and the check engine light came on. I’m not sure what else it could be, it’s getting fuel, spark and has compression yet when I start it up it only runs on the rear cylinder.
 
Welcome to the forum from Gulf Coast AL. Hope you can solve the issue, didn't know there were 2 plugs per cylinder i the newer engines.
 
Welcome from Spokane Washington.
Use a test light on the affected cylinder injector lead.
You need to strip the ends of a scrap piece of wire so you can push it into 1 cavity of the connector, clip the test light to that wire, start the engine and prob the test light into the open cavity of the connector and it should blink if it is getting a signal.
But if you're saying that you have raw gas from the tail pipe it sounds like it is being commended to be an extended on time.
MAP sensor may have a false signal, no vacuum equals heavy load, equal longer injector on time.
Check for vacuum leaks to the affected cylinder.
Weak spark from a plug could cause this.
Does this engine have a external fuel pressure regulator?
 
Last edited:
joel said:
Welcome from Spokane Washington.
Use a test light on the affected cylinder injector lead.
You need to strip the ends of a scrap piece of wire so you can push it into 1 cavity of the connector, clip the test light to that wire, start the engine and prob the test light into the open cavity of the connector and it should blink if it is getting a signal.
But if you're saying that you have raw gas from the tail pipe it sounds like it is being commended to be an extended on time.
MAP sensor may have a false signal, no vacuum equals heavy load, equal longer injector on time.
Check for vacuum leaks to the affected cylinder.
Weak spark from a plug could cause this.
Does this engine have a external fuel pressure regulator?
Click to expand...
It does not, it is in the gas tank. I had someone else mention it could be a cam issue and suggested I pull the cover and look in there and see what’s going on and make sure that all looks right. So I’m in the middle of pulling the exhaust so I can pull the cover.
 
Pulled the cam cover and thankfully there was nothing obviously wrong or broken, no metal shavings floating around or anything. The chain and tensioner looked to be in good shape. I’m wondering if it’s something within the ECM that is causing the issue.
 
Thanks for the welcome, I think it is one of two things. Either it has somehow jumped time but I would think that both cylinder would have issues, or that there is an issue with the ECM. I’ve been wanting a Thunder max so I guess now is as good a time as any to order one, I just hope that it fixes the issue.

The original owner put in a SE 447 torque cam and I’m thinking I may upgrade that as well, might as well drain the bank account right before Christmas so I’m the only one with any presents.
 
Not that familiar with the M8 motor but it's not "jumped time" and don't think it is the ECM. JMHO but following Joels suggestions would be the path to take before replacing the ECM and/or cam. Solve the curent issue and get the motor running properly first.;)
 
You must log in or register to reply here.
Back
Top