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Hey Everyone. Been a while but life got in the way of quite a bit. Going to simply copy and paste this, as it’s a bit of a long post- But every hint might bring us closer to getting this old gal back on the road.
Short story begins now:
Question for the group:
2005 Dakota 4.7 (not the H.O.)
Original symptom: Running rough at idle and off idle for a few minutes usually after a warm restart. (Does so mildly on a cold start) Runs fine once it figures itself out.
Codes set: Usual P0300 random misfire (no kidding?)
Work done: Plugs and coil boots. (OEM Champion plugs installed) Had to replace 3 O2 sensors before this truck went on the road. (2 broken off by last owner, 1 had dead heater) Issue still occurs. Noted we did have some weepy injectors (fuel pressure test showed system wasn’t able to maintain fuel pressure beyond 10 minutes.)
Most recently: Cleaned throttle body. (Did this on car using exact instructions on can) Found coating of black crud. Removed the IAC and gave it a light cleaning with some silicone lube. Also found negative battery terminal was loose. Removed, cleaned, and reattached. What I was able to reach with the intake and the butterfly air valve held open? Super clean now!
Gave it a test drive: Truck promptly fell on its face. Refused to accelerate with a lot of bogging down. Idle wasn’t the greatest. If you punch the gas-It downshifts as usual and takes off like a scalded dog until it upshifts. Computer set a few codes: (do not remember the IDs) One was System rich bank 2 sensor 1. The other was bank 2 sensor 1 circuit high. (This is the only O2 sensor we did not replace with the others)
Yesterday did more work on it: Replaced the weepy injectors. Factory injectors (obtained from the local P&P yard. I hooked them up to the fuel rail and gave it a test to ensure they all had a decent spray pattern and didn’t slowly weep out. All good) New O-Rings as well. No fuel leaks.
Yesterday’s test drive: Idle had mild improvement. Made sure to clear all PCM codes so we have fresh data. Truck did manage to accelerate much better. Idle still is crappy. Fair power but had a noticeable stumble at various sections of the power band. Not as bad as before, but noticeable.
Returned back to our work area and checked for codes. Had a couple of doozies in the pending area: P0175 System too rich bank 2. And one code I was hopeful NEVER to see… P0430 Catalyst system efficiency bank 2. (Hopeful that once we get the “Rich” code fixed, that efficiency code might become less problematic)
I’m off tomorrow (Friday) and will be doing the following: Replacement of the Bank 2 sensor 1 O2 sensor. Thought process is that the circuit ‘high’ code that it tripped, might point to a wonky sensor. Should be interesting, as that sensor is in an unholy place. I can’t see the fuel injectors causing the “Rich” condition, as they have been changed and verified to have a good pattern and not leaking. (Also did a resistance check. Each injector ran about 12.3. 2 were slightly less (11. 8 ), but within tolerance.
Also picked up another IAC motor and a TPS from the local P&P yard. Those will get swapped out as well to see if things get better or worse. Also, I have a borescope camera. So, I’ll be sticking that inspection camera into the O2 hole and seeing what the converter looks like.
Sorry for the short story. Any input or constructive advice is helpful. Really trying to get this Dakota back full force. But that one 02 sensor is going to be a treat…There ends the copy and paste express! I posted this on a Dakota group page over at the “Book of Faces”. But so far no one’s really responded. I’ll be working with this tomorrow on my day off from work.
Thanks!!
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Sidebar note: It’s rather late and I’ll check for additional goodies tomorrow morning (responses) I thank everyone in advance for any assistance they can offer. The ol’ gal is high miles! But in this economy I can’t afford to get another truck or car. Gotta muddle through and get this one figured out.
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Okay, going to need to back pedal and go forward again.
Changed out the last O2 sensor that was on the truck. Found the last owner was true to his nature, and he used what looked like generic eBay parts. The sensor wasn’t branded and looked rather cheap. Installed the Denso sensor and that did in fact cure the bank ‘2’ too rich code from the system.
I ran a full check with a multimeter on the installed (also generic) TPS. It’s okay with no dead spots. Did put in the P&P IAC motor. Didn’t clean it up much. Just did a light coating of silicon on the sealing rings and blew some of the carbon off the valve.
Everything ran fine for about 15 minutes, and then we went back to square 1. Here’s what happens:
Random miss-fires occurring during either idle or just off idle driving. The other day it flagged cylinder #3. So, we picked up a couple of coil ‘packs’ (this uses coil over plug design) Installed and made no difference.
Then noticed something really unusual. I reset all the codes using my HT200 blue tooth reader. (it’s slow for the data stream, but for the price it does pretty decent for data). After tracking accessing the miss fire monitor system. ALL the miss fires are only occurring on bank 1. To some degree of severity all 4 cylinders on bank 1 just ‘out of the blue’ will start miss firing like wildfire! Bank 2 appears to be 100%. Sure, it still reports a pending code for a bad converter. (I ran the scope down. It’s got light carbon build up-but does not appear to be plugged) We tossed a can of the converter treatment into the gas tank. That monitor (yes it actually showed how bad it is) The converter is only about 10% over the threshold to flag the CEL. So, we’re hopeful the chemical cleaning agent can help restore it enough.
So, my quandary. What would cause this issue with the miss fires? Only on bank 1. And only at off idle or at idle. The truck drives 100% the rest of the time. (Once it’s driven for a short while the issue also vanishes)
Any help is appreciated. I’ve been tinkering with cars for going on 35 years. This one has me stumped. was thinking vacuum leak (gets hot and seals) But that would be more ‘whole engine’ effect and not just 1 entire bank of the engine.
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I would do a routine compression test on ALL cylinders for comparison.
All should be greater than 100psi and within 15% of each other.Injector issues maybe. Run a top quality injector cleaner through it.
The black crud build up suggests blowback potentially.
Have you considered the ECM?During our last firing of the “parts cannon” I replaced all 8 injectors. We had a loss of fuel pressure when it was just ‘sitting’ after shutting the engine off. (Some injectors where slightly weepy). The ones I installed came off a newer model Jeep with the same 4.7 (same part number stamped on the injectors) I hooked up the injectors into the rail before installing the rail into the intake and ran a quick and dirty check. No weeping, Decent spray patterns on all. Resistance on the injectors ran from 11.8 to 12.3. I knew we had that for an issue, so that’s been removed from the naughty list.
The light coating of blech might be blowby. This ol’ gal has almost 200,000 on the engine. Runs like a scalded dog just about every other time! Just that entire bank of misfires. The last owner was also fighting with the same issue. Pity he spent all his money on cheap eBay parts. (Found 2 physically broken O2 sensors…1 dead sensor. And the last one he fiddled with was another eBay knock off. Everything was replaced with the Denso brand.
Just find it odd that when all the misfires happen, It’s all 4 cylinders on Bank 1. It’s not tripping any codes for open or shorted wiring for the injectors or coils. Thought maybe a mouse decided to have lunch. God knows we pulled enough mouse nests out of the blower box.
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