hey babyhuey6810,

thanks for the input, i have a reader, but not a scanner... that's a good suggestion since it will cost $100 for the dealership to hook it up. as far as the injector or wire issue, i would agree with you if it did happen intermittently... but it does not... it is always happening at speed in overdrive... if i clear the codes and take it for a freeway run everytime i start it back up it throws the same code....

 

In regards to OBD, I don't know why I put III there. Mistake there. (was supposed to read DRB III) In regards to IAC: if the gasket is leaking (there is a gasket there) it will suck air through and go unmonitored thus leaning out the A/F mix as well as creating a vac leak at the intake level. If it's stuck or, if it loses home position, the motor steps will be off and as a result, the gap will not be correct thus remaining open allowing air to pass through thus leaning out the A/F ratio.

Those handheld pocket scanners are only good for reading codes and that's about it. An OBD tool (correction DRB tool) or DART is far better and can also be used to reprogram the PCM as well as running tests on specific systems.

All those tools that read data, even laptop software is no where near what can be done with DART or DRB III. Freeze frame is good but, even better is unlimited data logging. You drive it as you would, under load, and then play the data back at your shop. But, you can only read what is available for OBD II for that year, and it's very limited in scope. Especially for his year. Some software companies can't even access some parameters with their software never mind those cheap, hand held pocket scanners such as Auto X-ray, Actron etc. Especially in that price range, it's not going to be able to provide enough information for finding out what's wrong. Pulling codes for misfires doesn't tell you what's causing the misfire only that you have a misfire.

The thing here is to find the root cause and, the way to do that is to list out all the possibilities that cause the same fault code such as a faulty injector, to a bad wire harness, to bad coil pack, etc etc. It's too early to say it's a simple repair as you don't know what the root cause is.

In cases of misfires, it can turn out to be an intermittent coil driver circuit at the PCM or, in some cases, it's a cracked valve seat to a simple, fouled plug to, a bad wire. But, in order to find it, you have to start somewhere to rule things out one at a time.

 

Please allow me to respond.An IAC usually has a seal on the end.If the gasket that seals it is leaking it would only be a vac leak while open.Thats not going to cause a 1400 rpm misfire.It would run like shyt at idle and usually set an IAC code if it gets stuck.The system also has the abilty to richen itself with fuel trim,so the lean condition probably would get masked by the ecm.But no 1400 rpm misfire on one cylinder.As far as pocket scanners go,some are quite advanced.Nowhere near any dealer level software,but I wouldnt expect that for 200 bucks.A good carpenter can build a house with a crappy hammer,but a crappy carpenter cant build a house with a home depot.Misfire codes are almost always injector or coil pack related,especially when they are easily repeatable (1400 rpm or cylinder 3).The hard work has already been done.No need to start pulling heads or removing engines to make a simple repair.As far as the dealer scanning the ecm,they arent going to do anymore than pull codes for $100.That covers one hour.Anymore than that is going to start gettin ugly.I agree that you have to start somewhere,but I usually start cheap.I would pull that plug and replace it before anything.I had an s10 that bucked in O/D after a tuneup.Felt like trans was coming out.Turns out guy cracked a plug when overtightening it.Simple stuff.I didnt start troubleshooting that by removing the crank.Plug,injector,wiring back to ecm.Good luck.

 

Sorry for not reading your post first circus.Being as when its in overdrive the secondary ignition sysytem is working its hardest that makes coil and plug suspect.The injector coil could be breaking down or sticky also .Ignition coil is what I would look at hardest,but you said you swapped them and the problem stayed with cyl 3.A noid light in the harness would maybe help you if you ran the truck on stands,but the engine wont be under the same load as driving.That way you could see if the harness was losing connectivity from the fuel injector.I would recheck that spark plug close before doing anything.Sounds like its maybe no good.Dont completly rule out the wirng harness that feeds the coil.Wiring shorts and opens can cause precisley the type of probs you are having.Good luck.

 

babyhuey6810,

yes, i already did the small stuff... it first threw the code on old plugs in the same conditions. i swapped coils and replaced plugs... #3 plug dry and sooty carbon build up. same conditions, same code thrown. i pulled plugs and did a compression and leak down... everything a-ok. checked plugs again upon re-installation... #3 plug had slight tanning. checked wire harness for shorts/scorches.. nada. checked fuel pressure... a-ok. and all the electrical suggestions chris had... and still the same conditions...

oh and i think and assumed that chris meant DRB III, which is the $7k scan tool the dealerships use... yes i know and am sure that chris knows we are obd2.

and i agree with you, i hate just throwing parts at a problem and that is what most modern engines expect... so, i would and i do try to rule out all issues prior to part pulling/purchase. i guess i'm an oldskool shadetree that would prefer to read/work with mechanical devices then a computer... *gasp* i guess i'm getting cranky and old as well.... hahaha

so you are correct that it can be an injector... and it very well might be with the dry sooty build up... however thru searching this very problem "shift into OD then low rpm shake/shutter" so many variations come up... trans, head, computer. that i'm trying to narrow it down.... i've heard that the dealership might have a device called "co-pilot" which hooks up and i drive around trying to reproduce my problem instead of just leaving it there for the mechanic to say "i can't get it to do what your saying it does" and i'm not paying for that.

it just kinda sucks and is funny at the same time that i can't find the prob.

thanks for the input, and have a happy new year!!!

 

oh and the DRBIII can flash and reprogram the computer with updates... i bought this dodge at auction and don't know the history or even if the re-calls have been done.... even with all the scratching my head problems i'm still way below what it's worth and it gives me a winter project as well!!!

 

I didn't say the IAC was the root cause for his failure and, in one post, we narrowed it down to cyl No 3 only. I was merely listing out all the possible modes of failure prior to narrowing it down to No 3. I also never stated anything about removing heads but, to at least test those areas out in which, he already had done so early on. I believe we had also discussed checking the coil-on-plug.

Now, as for fuel trims, it's limited and, if there's a gross leak, it's never going to recover. I had this happen on my Dodge and, it ran lean and misfired and popped through the pipe along with a slight loping idle condition. I also did not get any CEL or P0 code for it by the way.

I had mentioned to run a full diagnostic scan. It's normally 200.00 and, that's where they check all the systems in operational. This involves running a scope. The dwell section of the firing line just ahead of the spark will tell you what is going on in the primary side of the system. The spark line in the firing section after the spark occurs will tell you what is happening in the cylinder and coil.

This is the type of scan I was referring to vs. pulling codes.

 

What your referring to when you mention the term "co-pilot" is what I had mentioned regarding data logging. What that is, is a software tool that records hours of driving. The data is recorded digitally in the log tool, and / or software package via laptop connected to the PCM and is later analyzed at the shop. This is the best way to analyze what is going on under real-world use environments vs being run on a dyno which is what they will do sometimes at the dealers to simulate a load condition.

 

Yes, that is what I meant. It was late. Thank you for that.

 

Hey chris it was a bad injector. Actually all the injectors are gunked up. Guess that what happens when the previous owner keeps the original air cleaner in for 28k miles. Thanks again for all the help.