can someone please help? i have 99 dodge ram 1500 with a 5.9. i have had an idling issue for a little while but recently i had a check engine light pop on with a random misfire/misfire cylinder 3. So, i changed the spark plugs and wires. it still ran a little rough so i changed out the cap and rotor. It still runs like crap. I did a compression test and this is what i got cylinder 1- 140psi cylinder 2-140psi cylinder 3-130psi cylinder 4-155psi cylinder 5-150psi cylinder 6-150psi cylinder 7-120psi cylinder 8100psi. i checked for spark in the wires and i have spark what am i missing here?
Asked by johnnyg619 Feb 27, 2018 at 06:57 PM about the 1999 Dodge RAM 1500
Question type: Maintenance & Repair
9 Answers
8 Is on the low side. did you also check for a vacuum leak?
johnnyg619 answered 6 years ago
I have not checked for a vacuum leak yet. i know i have one but not sure where. vacuum has been leaking for a while now (many years). with cylinder 8 being low on compression it doesn't make sense as to why cylinder three is misfiring. i have also checked to make sure i have fuel pressure and the pressure is there. would block or body grounds cause this issue?
#3 is missing? did you do any fuel injector testing yet?
johnnyg619 answered 6 years ago
negative. that is what im wondering is the problem the injectors are original from 1999. what would be the best way to test the injectors?
jetjurnigan answered 6 years ago
check to see if the cat is clogged/pull the front O2 sensor n start 'er up...does she idle better?...the #8 cylinder takes the brunt of a clogging/clogged cat, which could explain the low compression on #8. If the cat's clogged, then the next thing you gotta ask, is the floor of the intake manifold a swimming pool of oil? Take a gander down the throttle body, if it's dark brown or black...wet...blown plenum gasket. Idle problems can be caused by sooooo many things. Do you have access to a scanner with live data capability to monitor fuel trims?
johnnyg619 answered 6 years ago
no ticking just a misfire. my vacuum problem has been happening for quit sometime now.... sense about 2007 or so and sense then i have had a engine rebuild. my problem is somewhere in the vacuum lines or possibly behind the dash when i had to replace my heater core. i may have accidentally left a vacuum line partially disconnected.
johnnyg619 answered 6 years ago
ok so ive done a fuel injection service to clear out any carbon build up. when i took the truck on a drive to clear out deposits my check engine light came back on with not only a cylinder 3 misfire but also a cylinder 3 misfire, cylinder injector circuit malfunction and the same thing for cylinder 5. i checked the harness side with noid light to see if the injector harness was firing in 3 and in 5 and found that 3 was ok but cylinder 5 was dim but firing rapidly. Then i did a leak down test on cylinder 3 and found that the cylinder is good, i did the same on cylinder 5 and 5 was good. I checked the cat to see if it was clear and not clogged and looked down into the bottom of the plenum. plenum was dry but looked brown.