Not smooth (not exactly rough) idle on Jeep GC 2000...

Buy one and swap it out until you find the bad one. :biggrin:

or until you don't.

 

Yup a bluetooth adapter along with Torque on your phone would do the trick as far as reading live data. Some are better than others (faster response etc), but I've used this one and it works well enough for how cheap it is. The main thing you want is a ELM327 adapter. I'm sure all the cheaper ones are coming from China (like the one I linked) so some seem to work better than others, but haven't had any issues with the one above for live data etc although the readings are delayed maybe a second or so.

Otherwise you're looking at $100+ for one with better support and faster PID read times etc.

 

Yup that's the same one, that along with the Torque app will let you monitor live data. Just keep in mind there is a very slight delay.

If it's an intermittent cylinder misfire it likely won't throw a code, I've seen it plenty before on various vehicles. That's where you'll see the RPM's drop, then it'll start working again etc. Once you can look at the live data, you'd see one cylinder misfiring when the RPMs drop if that is indeed the problem. Doesn't mean it's necessarily the coil pack (although more times than not it is) so I always verify by swapping that coil pack with one on a different cylinder and make sure the misfire follows it.

If it's not a misfire at all (or multiple cylinder misfires etc) there's still plenty of live data to look at to diagnose the problem without having to randomly throw parts at the vehicle. Well worth the $25 or so if you work on any OBDII vehicle even once a year IMO.

 

I bought this (from this seller) and it works with my Android tablet and Torque application

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160550105283#ht_3843wt_901

Have I steered you wrong in the past? Seriously, for under $15.00 this is a blazing bargain. Go for it. You would be more thrilled than the C3 impact wrench which I hammered you on!

By the way, a drop in the rpm of 50 is going to be tough to pinpoint. I am not sure if your vehicle supports faster update speeds. Also I do not know how fast ELM27 can run. Your current scanner should be able to give you pending codes if there are any. You would require a manufacturer specific scanner to get the proprietary misfire count data. Unfortunately, those type scanners are not affordable to us backyard wrenchers.

With the live data, you should be able to verify the correct operation of your TPS, O2 sensor, MAF sensor etc. But don't get your hopes high to find the slight idle problem with the generic scanner.

- Vikas

 

I am sure Amazon one is a good one. As a matter of fact, that was the one I was going to pick up before stumbling upon the one on ebay.

I have had a similar kind of issue with my 1999 Odyssey. This is going on for years and continued even after changing timing belt, drive belts and spark plugs. At idle you can feel a very slight rhythmic thump every few seconds. The tach does budge. Given that nothing in engine has a rotational period of few seconds, I am thinking this has to be some weird kind of resonance with pulleys, belt or cranks. I have not bothered to take off belts to see if this is indeed the case.

This engine needed a coil and the replacement was bought from Advanced Auto. Could it be a coil? Can it give a weak spark after every 100 firings? For example, if has a on-board circuit with a leaky capacitor, that is a remote possibility. But I am not motivated enough to get new OEM coils and try.

You might end up with similar rationalization!

- Vikas

 

Where have you seen this? I haven't seen an issue like that on any domestic or numerous Asian imports. Using the "OBDII standard" with "proprietary data" would defeat the purpose. Sounds like something the German automakers would do, they love proprietary stuff.

 

Most manufacturer have manufacturer specific PID's which generic scanners do not handle. Misfire counts per cylinder (or say transmission oil temperature) is NOT a generic PID and thus the Torque application will not be able to display it. Some people have reverse engineered some of those PID's for some specific manufacturers but generally it costs lot of money to get the official support from manufacturer. That is one of the reason why Snap-On can (and needs to) charge thousands and thousands just in annual license upgrade to their scanner software.

OBD-II architects certain PIDs to be common for all manufacturers but does not dictate manufacturer specific PIDs. List of generic PIDs supported by a vehicle is interrogated by the scanner by issuing a known command. ECM then spits out a list of supported PIDs which are architect-ed by OBD and thus can be decoded. For the manufacturer specific PID, scanner manufacturer needs to purchase the decoding ring (aka rights to it) and essentially has to hard code them in.

But all is not lost as the later version of the OBD standards have mandated lot more generic PIDs than the early 2000 model years i.e. if you have a late model CAN based car, you can get lot more PID's on your generic scanner than from a 2000 model year car.

Few inquisitive individual with good monitoring equipment have been able to reverse engineer some of the manufacturer specific PID's and some scanner manufacturers (e.g. ScanGauge) allow you to input the raw PID to the car's ECM.

- Vikas

 

Using "unknown" PIDs ╪ proprietary data.

OBDII doesn't define any PIDs, it's SAE standard that identifies the common PIDs

And again, I've used the Torque app with both a more expensive OBDII Bluetooth adapter and the one I posted above for $24 and had no issue pulling misfire live data on various vehicles.

There's also Torquescan, a plugin for the Torque app, that allows you to search the extended (and undefinied within Torque) PIDs if you want to try reverse engineering them.

And holy ****, you might be the biggest lurker catch I've seen yet.

 

It is possible that my terminology is not right but what I was talking about was the "PID supported list" which scanner requests from the ECM using PID 0x00 and gets back 32-bit bitmask indicating which PIDs are supported.

Since you are a Torque user may be you might be able to help me. My evaluation copy of the Torque (Android Tablet HTC Evo) does NOT give me separate STFT or LTFT readings but only single FT readings (99 Camry 4-cyl). I have other four scanners and they all give STFT and LTFT; so it is definitely not an issue with the car.

I would love to know which vehicles you were able to get the misfire data. I have not played with any newer than 2000 model year cars.

I am not exactly lurker but just a sporadic contributor

 

The free/lite version is missing quite a few features from the full version, still has some bugs that were fixed in the full (for whatever reason *cough*$$), and the defined PIDs aren't as extensive. Can't say for sure if they'd be in the full version or not, but I know when I went from the lite to the pro version quite a few more PIDs became available. I do know for sure on my car (09 Pontiac - CANbus) it definitely gives STFTs and LTFTs, on the pro version anyway. It'll list them as such when you go to add a display.

For misfire data, I have them set as one of my default panels so I always scroll past it at least. I've pretty well covered the gamut on GMs, quite a few Chrysler cars & trucks, a Ford Taurus and F150, and quite a few Toyota's and Honda's. Thinking about it though it's possible not all were getting a reading, but usually if that's the case it will say 'no data'. It's worked every time I've needed it though.

I actually do have a Blue Point (aka Snap-on) microscan but don't really use it anymore. The Torque app on a touchscreen is a waaaaaay faster interface to deal with. tbh I've made a point of holding on to it in case the I have issues with Torque but haven't so far. Hence why I bought a better bluetooth scanner for Torque (OBDLink) and keep the cheap one I listed above in the car to always have handy and that one still works fine, albeit a bit slower than the OBDLink, after 2+ years.

 

Are you talking about newer CAN-based vehicles though? All my experience is with the slow as molasses ISO protocol :-( How fast is your ELM327 bluetooth module? Can you see the primary O2 switching?

By the way, isn't technology amazing? For under $30 you can get an amazing setup which used to cost thousands and thousands of dollars just few years ago. Even then lot of owners still do not want to buy one. They will even go and post a question asking "I got a check engine light. If I replace O2 sensor, would it go away?". And these are the guys who can RR half of the engine on their own.

 

As I had expected, circa 2000 model year vehicle will NOT have misfire counts. What is the variation of rpm? Are you running free or paid version of Torque?

 

It should. Anything 1995ish or earlier should be obd1 and not have misfire counts, but my 1997 F150 and 1998 Infiniti and 2000 Jetta all showed misfires on my autotap.

 

I hope we are not talking different terminology here. I am suspecting there may be a confusion about per cylinder misfire count PID and misfire detected DTC. The latter are part of OBD-II i.e. P0300, P030x etc.

If autotap can show you misfire PID on all of your three vehicles, I am surprised. Did you have to pay for the manufacturer specific PID support for that software? Do you have a link for your specific autotap scanner?

This is what autotap website shows for

Generic Parameters

A/C System Refrigerant Monitoring Status
Auxiliary Input Status
Catalyst Monitoring Status
Comprehensive Component Monitoring Status
ECT
EGR System Monitoring Status
Engine Load
Engine Load
Engine Speed
EVAP Vent Solenoid Command
Evaporative System Monitoring Status
Fuel Pressure
Fuel System Monitoring Status
Fuel System Status Bank 1
Heated Catalyst Monitoring Status
IAT
Ignition Timing
LTFT B1
LTFT B2
MAF
MAP
Misfire Monitoring Status
O2 Sensor - B1S1
O2 Sensor - B1S1 (mV)
O2 Sensor - B1S2
O2 Sensor - B1S2 (mV)
O2 Sensor - B1S3
O2 Sensor - B1S4
O2 Sensor - B2S1
O2 Sensor - B2S2
O2 Sensor - B2S3
O2 Sensor - B2S4
OBD Requirements
Oxygen Sensor Heater Monitoring Status
Oxygen Sensor Monitoring Status
Secondary Air System Monitoring Status
STFT B1
STFT B2
Throttle Position
Vehicle Speed

 

Should be in the list when you go to add a new gauge to the dash panels. Use the graph and set it for current counts, one for each cylinder. Makes it easy to reference it with a drop in rpms that way.

 

The F150 and Grand Prix had custom data plugins that would give specific counts per cylinder with the autotap. The infiniti only used the PXXXX codes.

 

I'm sold. Just pulled the trigger and bought one. I've had this autotap forever and paid $199.99 for it back in the day. Its been invaluable to me but is now considered ancient (even though its USB). I can use my ipad with this bluetooth one and it should work fine I think. If not, then my phone will work.