More engine trouble! Grrr...

[Chris_North]

So while I was stopped at a light today I noticed my truck was idling a little rough. Continued to drive it and didn't immediately notice any significant reduction in power, but as I drove it around a bit I realized I have lost a cylinder someplace. No codes yet; I have been getting cyl. 6 misfire but only after troubleshooting (pulling wires to check for spark and such), not when driving.

All new plugs (changed right after symptoms started), wires are only about 2 years/16,000 miles old, compression readings go from 120 to 130 which is consistent with what I measured a few months ago. Spark is strong on all cylinders and no apparent arcing from any bad wires. Only troubleshot for a few hours so I have nothing else to go on. My new job requires me to do a lot of driving (about 100 miles a day), so in the past week the truck has seen more miles than normal but they're all highway, and fairly easy. I would really like to get this fixed tomorrow so I'll be ready to go on Monday. Only other thing that springs to mind is changing the injectors, but that's an investment I'd rather not simply gamble. The cam position sensor is due to be changed, but is not giving any of the common soon-to-fail signs. Typically something like this happens before I get to change it and blows my budget for it...

Any advice? Truck is 98 Ranger 3.0.

 

[Earl43P]

Disconnect the vacuum line from the EGR valve. Plug the open line.
Drive it, CEL may take a while to come on.
See if that has any effect.

Too much EGR flow at light throttle and ANY at idle can feel like a misfire.

 

[Chris_North]

Will do. I definitely have a massive loss of power no matter the throttle though. Even floored the truck downshifts and begs for mercy, and anything other than downhill and maintaining speed on flat roads is a struggle.

 

[tmcalavy]

How's your MPG? If it's okay and fuel pressure checks out, seafoam the intake, check for vacuum leaks, check sensor input...engine temp, MAF, IAC, etc. Then check the ignition control module...don't know where that is on your 98, on my 94 with 3.0 it's up by the drivers headlight. I had a recurrent miss that drove me nuts for months...come and go, come and go...not weather related, new plugs, wires, dist. cap and rotor. Checked and replaced the ICM and now it's happy driving again. Codes should lead you in the right direction, if there are any.

 

[Chris_North]

This diagnostic system sucks. Nearly 40 miles of driving and no codes. The other day I accidentally knocked off an EVAP line and it took 60 miles for the MIL to come on.

MPG is eh. Roughly 18 MPG average with primarily highway driving at 70 MPH average speed. Best I ever got was 19, but this problem just popped up yesterday, I don't know if anything has changed since then. Seems to be about normal, possibly a slight improvement. I don't believe I have an ICM, I think it's tied with the ECU and this problem does not seem to be intermittent thus far.

Cleaned IAC, MAF, IAT and pulled the EGR line. No difference. Seemed a little worse off with the EGR out of the loop. When I first started the truck, let it warm up and pulled out of my driveway it seemed fine. Only about 15 seconds later and the rough running sluggishness became apparent again.

I don't pay as much attention as I should to these things when everything is normal, but I don't noticed any more condensation in the exhaust than normal, nor does the cat seem hotter than usual, nor does the exhaust have any off smell to it (as in that sulfur-y smell I'm used to getting with a miss). It definitely feels like a miss when driving and idling, but it doesn't seem to have unburnt fuel, combined with the apparent lack of any change in fuel efficiency (possibly a slight improvement) is leading me to think that it is a fuel delivery issue. I don't have and am unwilling to spend money on a FP gauge, but I think I have some stuff to rig one up quick. Then I guess I'll put an ohmmeter across the injectors I can get to.

 

[Chris_North]

Okay guys pretty sure I got it. Thanks for your help. Only took $200 and a few hours out of my weekend...

MIL came on with bank 2 too lean code and cyl. 6 misfire. Bought all the injectors Advance Auto had (1) and proceeded to disassemble and install. Sure enough #6 injector read open. Unfortunately in the process the inside plastic piece of one snapped, which required another trip out. Fortunately National had 2, albeit at twice the price as Advance, so I did that side and hopefully no other problems with that. I figured passenger side I can check easy enough. Reassembled everything, started up and got my power back and a much smoother idle.

Could have been a lot worse I guess. By the way, my homemade fuel pressure gauge was not a good idea. I got a reading of 65 PSI for about 2 seconds, then the line split and sprayed gas all over the hot engine. Exciting though.