BLittle500 Posted May 18, 2009 Share Posted May 18, 2009 Hey guys, Cust brings his truck in for missing/running rough, and smoking. This has been a problem truck. On the road test, it started out fine then it seemed to drop an injector. Smoking badly (thick black smoke), and knocking hard. Running through the test the truck was beginning to hydro-lock when I would go to start it. Went through the tests, #5 injector failed electrical injector test. It had a real weak click the first time, then nothing the last two times. Replaced the injector, and took it out on a road test. Seemed fine for a bit, then back to the same stuff. Brought it back into the shop, shut it off and got the IDS. No codes sitting in this thing, went to do a KOER but the engine wouldnt crank. Waited a bit and got it to fire off, no codes again. Did a relative compression test and it showed #4 was down 13% and #5 was down 6%, all the rest were okay. Running a power balance, #7 was real high, and the rest were right in line. I dont really know if those last two tests will show you guys anything, just ran them to see if something stood out. Any ideas guys? Maybe this thing needs an IDM, but usually when an injector fails and I replace it, if the IDM is bad it'll throw codes for all 8 injectors on the next road test. Thanks again for your help guys, Brandon Quote Link to comment Share on other sites More sharing options...
Aaron Posted May 18, 2009 Share Posted May 18, 2009 I'd do a manual compression test on those holes just to verify. What's the base fuel pressure? Quote Link to comment Share on other sites More sharing options...
exmod110 Posted May 18, 2009 Share Posted May 18, 2009 Check fuel pressure while driving- running rough, I had one that would do the same but with white smoke... turned out to be injector came loose blew out the o rings and dump fuel into one cyl and get combustion gasses into the rail and run real rough only at times, took 3 hard road tests to duplicate. Fuel press was all over the place as was icp when the concern was present. re do the relative compression or manual compression and see if it bent a rod with the hydrolock.. Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted May 18, 2009 Author Share Posted May 18, 2009 Got pulled off to work on a gas truck, sucks. I'll tell my advisor about it, but I'm going to 6.4 school the next 3 days and I'm off till tuesday so I probably wont get back on this thing untill then. Hopefully I'll have time to get a fuel pressure test in on this thing. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 18, 2009 Share Posted May 18, 2009 Where are you attending the training? Quote Link to comment Share on other sites More sharing options...
Mekanik Posted May 18, 2009 Share Posted May 18, 2009 Have you re-done the power balance test? I'm thinking you just have another bad injector. If it is belching as much smoke as you say it is then it probably has a leaking tip. I would think that would give you a inaccurate relative compression test result. It may be trying to fire the cylinder during the test. Definately do the fuel system test. I do that every time I replace an injector. Quote Link to comment Share on other sites More sharing options...
BLittle500 Posted May 18, 2009 Author Share Posted May 18, 2009 Keith, I'm heading to Exton PA for my training. Quote Link to comment Share on other sites More sharing options...
DamageINC Posted May 21, 2009 Share Posted May 21, 2009 I was gonna say, this almost sounds like you've got a leaking injector or something. I'd fear that there's some more serious base engine damage at this point, a manual compression test is absolutely in order at this point. The last leaking injector I had completely melted the #3 piston and there was only a 7% loss in relative compression. (Manual compression showed only 100psi VS the 400+ the other cylinders had). Dave Quote Link to comment Share on other sites More sharing options...
blown99 Posted May 23, 2009 Share Posted May 23, 2009 Can you duplicate the complaint while at the shop not driving? You could run the engine up to the point where it starts to show the heavy black smoke and then shoot the exhaust manifolds with a ray tek. The hottest manifold port will be the injector that is overfueling causing the black smoke. Quote Link to comment Share on other sites More sharing options...
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