One Cylinder Going Hot on Long Pulls

[jim]

09 M8 Boondocker PG turbo. Runs awesome but I have a hot cylinder (EGT) problem which I posted about before and couldn't resolve.

Egts start climb at 1100 to 1150 WFO. Both cylinders generally run the same temps except for WFO extended climb. By end of climb I am 1250 pto and 1325-1350 mag.

PTO hits 1250 pretty quick (5 seconds) along with mag, but the mag creeps to 1325 and makes me wonder. Runs awesome, but makes me nervous. I have swapped EGTs to verify it is a cylinder temp reading, not EGT error...is the same result from same mag cylinder if I switch EGTs.

Interesting thing is, last year I wanted to get better mileage one day and dropped boost to 5 PSI at 8k elevation (I can run up to around 8PSI and max injectors out to 95% there). When I dropped the boost to 5 PSI, both EGTs hit 1250 and stayed there all day. The more boost after that, the hotter the mag side gets. And the wash seems to back this up, although I admit wash it challenging to read because I'm not WFO very long on a turbo and I think the wash is from most of my daily riding where I'm on and off frequently.

Can anyone tell me why the mag side would creep in temp like that? I have cleaned injectors, checked for leaks, talked with Boondocker and tried stuff...all the standard things a person would check...but the creep is still happening. Again, sled runs great top to bottom and without EGTs I'd never suspect an issue. Thanks in advance.

 

[Hardass]

So what psi were you running before turning it down to 5 was it 8? is that really maxed on the injectors? have you ever had your injectors tested and cleaned.

 

[Hardass]

Pretty simple to swap injectors to see if thats it

 

[kiliki]

I would check the wiring harness over for rubs by the injectors. also I have see them have the wire break at the injector but not show signs in the wire coatings. and DMM is your friend and also check the connections pins at the ecu for hot spots.

 

[Hardass]

If the wire broke wouldnt there be no fuel

 

[jim]

Thanks guys. I have removed, checked and cleaned injectors. Both showed good signs of free flow...and equal flow. I checked by using battery to fire them with carb cleaner under pressure via tube to injector.

I was running about 8...this about maxes the duty cycle at 7 ro 8k ft elevation. Dropped to 5 to use less gas and noticed egts were 1250 and no creeping.

Seems as if I'm running out of fuel on the mag. Is it possible that one injector cant cycle as fast as the other? No trim settings on controller, else I would try that.

Sled runs perfect...so I dont suspect leaks. I had a leaky turbo sled in the past...no symptoms of that.

 

[boondocker97]

I would say that since the problem happens near the injector's capacity that the hot side injector just can't quite deliver the amount of fuel you're looking for. Whether that is from it having a slight blockage, it's electrical function is deteriorating, or it was just manufactured a little differently so it's on the lower end of the acceptable spec. Going deeper, if the injector really is fine then maybe it's not being fed the proper voltage or signal at high demand. I'd switch the injectors from one side to the other and see if the problem follows with it.

 

[jim]

Thanks guys...will try injector swap and see. Odd issue.

 

[xpturbo600]

You can't see the difference in an injector if it is slightly different. That said, it may just be that your hot side cylinder just is more efficient in the system due to porting or exhaust scavenging differences. If so, it may just flow more air, having a higher VE on that side. If your sampling point for correction is down stream, the computer will never correct for the difference between the two. Work through your issues and keep an eye on it for sure.