OBD 1 scanner?

[frankd]

Does anybody have an OBD 1 scanner that I can borrow? I'm looking for one that will read all of the outputs from the sensors. I've got a 1993 Olds. Silhouette that goes lean when you apply more than 1/3 throttle. I've checked the fuel pressure, the mass air flow sensor and a bunch of different things but everything seems to be good. I rented a $400 scanner from O'Reilys, but it only reads error codes on OBD 1 and it seems to have a problem doing that correctly. I need to watch all of the sensor outputs and see if I can see what's happening.

 

Thanks,

 

Frank D.

[KIC]

If you have a Checkers/Orielly's or an Autozone in your area they have the latest that they loan out. You can take it home or do it in the parking lot. At least their's should have the latest software.

[bkuhr]

heres the one I have

http://www.2toolguys.com/axr6000

 

pm address

[saddlebum]

Just a shot in the dark here, but it almost sounds like a bad O2 (oxygen sensor). these were a common failure on GM products. they are usually screwed into the exhaust pipe just past the exhaust manifold.

[wes0778]

I don't know how on the '93 Olds, but on my '83 Caprice there is a way to make the Check Engine light flash the fault code. You count the flashes and get the table that goes with your car and look up the code, to define the fault. It has been a while since I had to do that on the Caprice, but think it flashed 4 times with a pause then 4 more for a code of 44. Regardless of what it was, it said O2 sensor. Replaced it and no more codes.

[Keemez]

I don't know how on the '93 Olds, but on my '83 Caprice there is a way to make the Check Engine light flash the fault code. You count the flashes and get the table that goes with your car and look up the code, to define the fault. It has been a while since I had to do that on the Caprice, but think it flashed 4 times with a pause then 4 more for a code of 44. Regardless of what it was, it said O2 sensor. Replaced it and no more codes.

 

Yep. Not too hard to do.

 

From paragraph 3 of ( http://www.streetdirectory.com/travel_guide/56868/car_parts/obd1_codes_secrets_for_check_engine_light.html ): For GM domestic vehicles made before 1995, the diagnostic connector is located under the dash panel by the driver side. To get the check engine codes to flash in your dash panel, use a jumper wire or a paper clip and connect terminals A and B of the diagnostic connector. Turn your ignition key on with engine off and the codes should start to blink. All codes should start with code 12 which is one long flash followed by 2 short flashes. This code 12 means the diagnostic system is normal and will repeat itself continuously if there are no trouble codes. Otherwise, code 12 will flash 3 times before flashing the fault codes.

 

Here's a pinout of GM ALDLs:

http://www.webpg.net/sc/toplevel.asp?cat=2

 

[frankd]

KIC,

 

I've already been there....O'Reilys had an Innova 3120LAT that works with OBD 1 & OBD2, except on OBD1 it only reads error codes. Autozone only had a scanner for OBD2 cars. My check engine light is NOT on, and when I do a manual dump of the codes it told me that I had a code 31. In the Chiltons manual for my van it has no code 31. It jumps from code 26 to 34 for a 3.8 engine. The Innova tester said that I my engine coolant temperature was too high, but it didn't turn on the cooling fans!!! I pulled the temp. sensor and it checked good. My O2 sensor bad is code 13, and when I bought the van it had that error code. I replaced the O2 sensor (7 years ago and a lot of miles, it could be bad) and things have been fine.

 

Brian,

 

I searched for the manual for the AXR6000, and couldn't find it. Is the actual manufacturer AutoXray, or do they have an other name? Do you know if it just reads fault codes for OBD1, or will it read and display the output from the sensors?? It would sure help if I could watch what was causing it to go lean.

 

Today, it's snowing here, so I really can't apply the throttle enough to see if it's fixed, but after we put the coolant temp sensor back in and put the throttle body back on, I disconnected the negative battery terminal to reset the fault shown on the Innova. I drove it a bit, and I have no codes showing now.

 

Here's what I have checked so far. This is from an Email to a friend, so it's a bit long.

 

I have a 93 3.8L Silhouette van with a zillion miles on it (the odometer quit a long time ago). It's been running great, but now it idles smooth and runs OK at light throttle, but past about 1/3 throttle, it goes lean and starts missing bad. The plugs are OK, and there are no open plug wires. I've run a can of injector cleaner through it and changed the fuel filter, no help. I checked the fuel pressure, and it wasn't reducing when the motor was started, but I found the vacuum hose to the presure regulator had split. I replaced it and the fuel pressure is correct (38# @ idle, and goes up to 43# when you blip the throttle), and does NOT reduce when you load the motor. The IAT sensor and the TPS are good. I cleaned the MAF (wasn't very dirty) and tested it. At idle it has 2.4KHZ output, and when you blip the throttle, it goes up to about 7KHZ. O'reiley's had an OBD-1 readout, but when I hooked it up it told me that it couldn't communicate with my vehicle (yes, the key was ON). I'm out of ideas and any help would be appreciated.

 

Since I wrote the above, there is another update...

 

Frank and I found the problem with the O'Reilly scanner (wrong digit in the VIN code input into the scanner) and hooked it up. It said that the temperature sensor was indicating that the coolant was too hot. I didn't think that was correct because the temperature gauge is reading normal (it uses a different sensor) and the computer wasn't turning on the cooling fans, but we took it apart last night (the sensor is in a nasty spot) and pulled the sensor. The socket slipped when we were removing it and the connector cracked. However, it measured good @ room temperature. We installed a new sensor and are putting it back together this morning, but I am expecting it to be the same. I tested the old scanner by heating it in a coffee can, measuring the temperature and resistance of the sensor--it was good. I think that the scanner is reading wrong. I can tell the wires to the computer are OK because when I turn the key on I have 5.0 volts across the leads and with the key off, I measure 300K ohms to ground from the sensor lead. BTW, the throttle body is clean (amazing because I cleaned it 7 years ago when I first bought it--new gasoline must be better like they say).

 

I jumpered the OBD 1 plug and made it flash the error codes in memory. It says that I have an error code 31. Number 31 code is NOT listed in the Chilton maintenance manual for my van. I did an internet search for it, and found it is used in a Buick Turbo 3.8 and it indicates a waste gate problem. I found another chart online that says it is the PRNDL switch. On mine, that works fine, and it wouldn't cause the engine to miss anyway.

 

Frank D.

[frankd]

Keem,

 

Thanks for the data, it looks like the cable and the free shareware may be the way to go with this thing to view the sensor outputs.

 

Frank

[yamtom]

Hi,

Ive read the whole thing here, and wonder how it is that you know its going lean after one third throttle. Not trying to be stinky about it, but just wondering how youre so sure. For me to ask this, you must know, that seemingly every time I get into a mindfxxk situation like you are in, I have learned to question, every little thing that I believe about the situation and it appears to me that this question needs answering.

I am no particlularly skilled gm mechanic, but this summer got two vehicles running that were sitting long periods of time, both were of similar vintage, and both presented mindfxxk situations similar to this.

 

Does this vehicle have an intake heater of any sort? Is your heat connector pipe, that goes from the air cleaner to the exhaust manifold, intact and if there is a valve in the air cleaner, does it open correctly? Your symptom reminds me of a situation with my old granada, and it turns out , that increased air speed, and high humidity was freezing up the carb, at higher speeds in cold weather. The heat pipe, from the manifold to the air cleaner, was loose or something, maybe missing entirely, and this stuff started. It ran fine, in very dry and in warm weather, but if there was any serious humidity, and the temps were fifty or below, it gradually got worse until the engine would only idle. It turned out,,, that ,,, if I just shut the engine off, the engine heat would melt the ice in the carb, and it would be good for another twenty miles. The situation was compounded for me, by the fact that when it first started, I had limped to a gas station, and bought some dry gas and put it in, and the thing took off just fine. It wasnt the dry gas, it was the engine shutdown that did the trick, unfortunately for me, I just kept putting dry gas in every time it got bad and it seemed to correct it, hhahahahhaeheheheheee, this went on for months, but due to the fact that I only drove a few miles at a time for work, it never happened until I was out on the road for long distance. After a while, I began to connect this problem to low temps, and hi humidity, then read up on the issue, and voila, the heat connection was discovered. Oh well, just one more in a long line of hard knocks, haha.

Edited January 12, 2012 by yamtom

[bkuhr]

Brian,

 

I searched for the manual for the AXR6000, and couldn't find it. Is the actual manufacturer AutoXray, or do they have an other name? Do you know if it just reads fault codes for OBD1, or will it read and display the output from the sensors?? It would sure help if I could watch what was causing it to go lean.

 

 

 

Frank

yes, autoxray 6000.

can watch sensors real time during operation, can capture current and pending fault codes, displays codes both number and english, resets all codes, also time frame event capture. probably have to play with it a bit to figure it all out, but should show what you are looking for.

 

pretty expensive, but will ship with insurance if you ship back same.

PM address

[frankd]

Tom,

 

This is a port fuel injection engine, so no stove pipe to heat the imcoming air, and nothing to freeze. However, I also dealt with that problem with carbuerated cars, and that was one of the first things I checked when I had one that went lean or backfired. I know this one is going lean by the way it acts--it looses power bad when you open the throttle too much after it's warmed up, but it recovers instantly if you let the pedal up a little. Also, it has backfired a couple of times. Also, when I fixed the fuel pressure regulator vacuum hose, it actually got worse, not better (less fuel pressure).

 

Brian,

 

Thanks, but hang on for a bit. I'll get back to you with a pm so we can exchange info. Of course, I will insure it if I borrow it.

 

Frank

[MikeWa]

First thing you need to check is your fuel filter then fuel pressure. These won't show up on a scanner or with fault codes but they will cause you to lean out and stumble. Next thing is make sure your exhaust is flowing freely. Then go for the scanner and trouble codes.

Mike

 

Oops sorry I missed the part where you measured the fuel pressure. If the car is going lean it should set an o2 sensor lean code. Temp sensor should read about .6 to .9 volts on a warmed up (operating temp) engine with a DVOM connected in parallel with the sensor. Should read about 3.5 volts on a 60 degree engine.

 

I don't have a wiring schematic for yours but some cars use a separate temp sending unit for the cooling fan. Also if it is activated by the PCM then there is a relay in the circuit. Map sensor and air flow meter are major players for fuel mixture. Test your air flow meter by unplugging it. If it is the problem the car will set a code but run good.

Mike

Edited January 13, 2012 by MikeWa
Oops

[frankd]

Mike,

 

The first thing I did was to change the fuel filter. A couple of days ago, I did check the fuel pressure. With the engine off, and the fuel pump cycled a few times, the pressure was 43#, which is correct. When I started it, it did not reduce to 38# like it should have. I found the vacuum hose to the pressure regulator cracked. I fixed that and the pressure went down to 38# at idle. When I blipped the throttle, it went up to 43# like it should. I also brake torqued the engine until it started missing and the gauge never moved off of 43#. It's not running out of fuel pressure. Afterwards, the van ran a little worse (lower fuel pressure made it a little leaner). So now I need to find a scanner for it. I've been online and found some OBD2 to OBD1 adapter cables, and if they work I have an OBD2 scanner that displays the sensor output. I should have an answer from the vendor in a couple of days. IT's not the end of the world, it runs good enough to drive, if you stay under 1/3 throttle.

 

Frank

[yamtom]

Hi Frank,

 

Ok, youve done lots , have you checked the intake versus the exhaust temp, on the cat con? My local mech said that twenty degrees difference is about right, I checked mine on my old truck last summer, and it was eighty degrees difference on mine so the cat con was the first thing off. I used my handy dandy HF laser temp gauge to do that, so who knows. It didnt make any difference, so I guess there is is a wider temp difference than my local so called master mechanic said. So this may or may not be something you want to check, although, it seems counterintuitive at this time, since increased back pressure would tend to make the thing run richer than other wise>>>???? or maybe not. Also, have you tried taking the pipe off the muffler, to see if running that exhaust open, makes any difference. I heard of another mechanical guy, that went so far as to change cam gears and cam chain, to no good effect,, only to find that the muffler had fallen apart, and a piece had blocked exhaust flow. The symptoms, were basically similar to what you are describing here, it should be simple enough to check, so not much time would be wasted if you tried that. I know nothing about the differences between tpi and my old tbi equipment so youve tapped my knowledge base completely now, I will be watching this thread for when you finally find the answer with great interest. Good luck Frank.

[rlyons]

Are you sure your convertor is not plugged? I have worked many GM cars that had a partially pugged cat and they acted just that way. Full or hard throttle they bog down, let up and they gradually accelerate. Idle smooth and low speed runs great. Check for exhaust flow and look for a smashed pipe or plugged cat. You can unhook the exhaust at the manifold and run it to check.

[flb_78]

If you have 43psi of fuel pressure, it's not running lean most likely.

 

I too would check the catalytic converter. With that many miles on it, it may very well be plugged.

[yamtom]

Regarding the use of computer technology for troubleshooting, I called my Tuffy Muffler people, they do engine tuning as well as the usual exhaust brakes bla bla. When I asked them, regarding diagnosing my problem with my 92 gmc 4.3 tbi, they flatly said, the puter stuff cant be trusted, bring it in, and for fifty bux, we will go thru the old fashioned steps to diagnose the problem as well as do the puter diagnostics.

 

And just a couple of weeks ago, I had a problem with a check engine soon light on my 2003 chevy 5.3 vee eight. I went to the best professional type auto parts store, and asked if they had a loaner puter diagnostic tool to help with the engine, the guy, almost laughed at me, he said,, and I quote,, No, we dont mess with that, they usually wont work,,right,,you can go to auto zone or something, and borrow one of those,, and then when youre done trusting that to tell you what to change, youll be back and be buying parts from us that the auto zone diagnostics machine failed to find. Unquote. Not trying to be a dixk about it, but the freebie type puter diagnostic stuff is a little shaky by the look and sound of it. I did in fact go to auto zone, and they diagnosed a major fuel leak. I checked my gas cap, and have to check my vapor canister and lines, and look for a vac leak is what the machine suggested or thats what they told me. Indeed the vac lines are all eight yrs old, so its past time to just change them all out. Be sure to let us know what you find Frank.

[frankd]

First off, I don't think the catalytic converter is plugged because when the motor is cold it takes off like a scalded cat (pun not intended, but...) Now, here's where it gets interesting. Barb and I were on the expressway runing about 65MPH this morning, and for the heck of it I floored it. It kicked down to 2nd and ran right up to 5000 RPM and shifted, and then pulled good in 3rd gear-not missing at all. In no time at all, we were past 80MPH. After I did this, it quit missing when you went past 1/3 throttle for a bit. I dug out the Chilton's manual, and saw what terminal on the ECM the lead from the 02 sensor went to. I pulled a couple of panels off the interior and pulled the ECM down where I could get to the wires. I found the O2 sensor wire, and connected my Digital Volt Meter(DVM) to it. The O2 sensor is good, and the system bounces above and below .5 volts like it's supposed to in closed loop operation. When I drove it and pushed it to 1/3 throttle and it started to miss a bit, the output from the O2 sensor still was bouncing aroiund .5 volt. It's not going lean like I thought. The plugs are about 3 years old, and probably have about 60K on them. They're Champion double platinum, so I'm wondering if they may be the cause. Plug wires are pretty inexpensive also, so I'll probably put a new set of a different brand plugs and also some plug wires on it and see where we stand then. I'll probably wait until a warmer spell though. Those back plugs and wires are a b**ch to get to==you get to them from underneath, and it's best to lower the subframe.

 

Frank

[flb_78]

It sounds like it runs fine until it goes into closed loop. In open loop is runs on a preset program until closed loop mode engages and runs off all the sensor readings.

 

I wonder if that vehicle has a knock sensor and the sensor is giving a false reading causing the ECM to retard the timing and the vehicle falls on it's face.

 

You could just start unplugging sensors one at a time until the problem goes away.

 

Unplug the coolant temp sensor, drive it, if the problem is still there, plug it back up and move to another sensor. Once the faulty sensor is unplugged, the ECM will use a preset reading to compensate.

[frankd]

FLB,

 

You may have come up with something. When it misses, it's not 1 or 2 cylinders, it sounds and feels like all 6 get weak. I think it has a knock sensor and I will unplug it. You don't want to unplug the cooant sensor on this wreck. The sensor is underneath the throttle body in the side of the intake manifold. You have to pull the throttle body to get to it. It's good though (actually it's new--we broke the connector on the old one pulling it out when the socket cocked. I tested the old on in a pot of hot water, and it was electrically fine).

 

Thanks,

 

Frank

[bkuhr]

It sounds like it runs fine until it goes into closed loop. In open loop is runs on a preset program until closed loop mode engages and runs off all the sensor readings.

 

I wonder if that vehicle has a knock sensor and the sensor is giving a false reading causing the ECM to retard the timing and the vehicle falls on it's face.

 

You could just start unplugging sensors one at a time until the problem goes away.

 

Unplug the coolant temp sensor, drive it, if the problem is still there, plug it back up and move to another sensor. Once the faulty sensor is unplugged, the ECM will use a preset reading to compensate.

 

 

Likely wont work in this fashon, as when you unplug a sensor, the ecm senses that circuit out of range and switches into open loop mode, disrequarding all the sensors-kind of defeats the purpose, although it should set an ecm code for the circuit sensor pulled from, if you chance accross a sensor that did not set a new ecm code, that may be a defective sensor. Would still suggest an actual scan tool-maybe pay dealer $50-60 just for scan and printout? Offer still open to send my autoxray.

[frankd]

I've only put about 30 miles on it, but my beater van seems to be fixed!!!

 

Brian had a great idea about the knock sensor retarding the spark, so I marked the front engine pulley with a chalk mark, connected my timing light, put the van in gear, and brought the engine up until it started to miss. The timing wasn't retarding, so this wasn't it. I had a discount coupon from Advance Auto, so I figured I'd install new plugs and wires just in case. Now, the old Champion double platinum plugs were only about 2 1/2 years old, and the wires had tested good when I changed the plugs last time. The last time I changed them I did so because it had been missing if I loaded it in 4th gear at too low RPM, but if I brought the engine speed up a bit by pulling it down to 3rd, it was fine. The new champion plugs didn't help a bit (2 1/2 years ago). My son and I decided that now we needed to try a different brand of plugs. The reason we didn't pull the plugs sooner is that the back 3 are absolutely no fun. It's a good thing my son has long arms.

 

Yesterday, we installed new Autolite double platinums plus new plug wires. I took it for a short ride, and it seemed good. Last night I drove it about 30 miles, and it was fine. The old plug wires were still good (6K ohm to 11k ohm ) and no burnt spots on the insulation. The old plugs looked great. One was slightly darker than the other 5, and one had some deposits on the ground electrode, but not bad. I'd guess it was the plugs, but there is no way to tell for certain.

 

I'm sure glad this is over with. My son and I have way too much time invested in a 1993 minivan with so many miles on it. Everybody, thanks for your ideas!!

 

Frank

[frankd]

As Paul Harvey used to say, here is the rest of the story. About a week ago, I'd used the van all morning for a bunch of running around. My wife saw some signs for an estate sale, and when I turned around and gave it some gas, it started missing real bad again. I checked a bunch of things again (throttle position sensor, fuel pressure, MAF sensor) but nothing bad was found. I started to check the spark from the 3 double coils, and when I put the neon bulb tester on the center coil, it ran worse. I started to check the coil output by grounding one terminal and with another grounded jumper I checked how far each would jump. The outer 2 coils would jump over an inch, but the center coil would only jump about 1/8". I replaced the center coil and it's running great again. I guess the new spark plugs fired at a slightly lower voltage than the old set, so it ran good until the coil got worse.

 

Frank D.

[Flyinfool]

Sounds like you may have it this time.