24 replies to this topic

[FTodaro]

I need to buy a scanner for 99/01 what is the tool to buy to diagnose electrical issues. I do not need to go crazy, suggestions?

[Tom Hampton]

Scanner?

Do you mean OBD scan tool, or Multi-Meter, or wire probe?

What type of electrical issues are you trying to diagnose?

[FTodaro]

OBD2

[Charles Boehly]

I have a Go-Point module that works with an Iphone. It was great to monitor my 99.

 

http://gopointtech.com/products/

[Michael Novak]

Innova   --- They have worked pretty well I think about $250...

[Tom Hampton]

Innova is what I've used, as well (not on a Miata).  You can borrow one from autozone to see if you like it.  $250 was what I paid for a 31xx model. 

[RWP80000]

I like SPX/OTC tools as they also do most of the high end dealer tools.  The link below is for a 3111 OTC Tool available for $190.  I have a unit very similar that is about five years old and has worked just fine for fault code reading for reasonable dollars.

 

 

Rich Powers

 

http://www.mechanics...ag-P185712.aspx

[tynor]

Yikes.  $150-200 for a OBD2 scan tool?  What do these things do that a $50 scanner from Harbor Freight (or the $19 one I've been using from Amazon) can't do?  Features or longevity?  I'll admit that the $19 single-line display is pretty cheesy, but it reads and clears codes...

 

[Tom Hampton]

I haven't used the cheap ones.  So I can't compare.  However, the Innova unit can read all the mfg specific codes, had embedded DTC lookup and most common solutions.  Also has a PC connection and a PC side SW tool to download the codes and do further lookup via web.

https://www.innova.c...561334130645481

[speedengineer]

I use a ~$10 shipped Bluetooth reader from Amazon, with the free Torque Lite app on my phone. Works great on all the vehicles I own. Reads and displays all the broadcast channels, customizable displays. Reads and clears both current and history codes. Wireless, obviously. Not sure why I would want to pay more?

[Steve Scheifler]

There are federally mandated PIDs that all scanners cover, but as Tom mentioned there are a lot of manufacturer-specific channels not available from the basic readers. For troubleshooting mystery problems like Frank wants to do, if it isn't throwing a code then a basic scanner may not be much help. I have the AutoEnginuity and purchased the Mazda code set. It is far more than a scanner/reset tool. Depending on what the manufacturer built into the ECU it allows you to run various tests and control all manner of things like cutting spark or fuel to one cylinder at a time, opening and closing solenoid-activated devices etc. Unfortunately OBD was just a few years old when the first NBs were built so they offer far less information and control than many later cars.

Something else worth having, particularly when looking for intermittent problems that don't throw a code, is a recording and playback feature. Many hand scanners offer that but some may be more convenient to use than others.

[FTodaro]

Thanks for all the input, I may invest in a more expensive unit since like a dumb nut, i used the kill switch when i parked the car and cleared any codes i did have. It only seams to do this on track so far so it may be hard to diagnose at home.

 

Just so you can see what i am up against, this problem started out as just a miss fire shifting from 3 to 4 on the front straight, in one session  to then doing it on the back straight on 3/4 and 4/5

 

The fuel pump is new this year, I checked and re gaped the crank sensor and put in a new cam sensor before this video was done.

 

 

I have a few things i am going to do, Like swap out the switch on the clutch, crank sensor and check over all the connectors.

 

The wiring harness in this car is out of a 30,000 mile car.

[Tom Sager]

Frank, this is a bit outside of my area of expertise but some years ago I had brief and intermittent hesitation problem in my Neon race car. It threw no codes or check engine lights.   I went to a practice day at Road America equipped with a data collection device provided by my crew who was a tech at a Dodge dealer.  It plugged into the OBDII port and recorded lots of data.  I was instructed while on the track to push a button on the device upon experiencing the hesitation.  The device captured a 1 minute historical picture of bunches of engine data. In one short session I  was able to capture 3-4 instances of this hesitation.  My crew went back to the local dealer, downloaded the data and had it immediately viewed by a technician with Chrysler in Detroit.  The technician in Detroit determined in minutes that the problem was one of 2 parts.  My crew returned to the track with both parts in hand.  We installed them and the problem was solved forever. That was nearly 20 years ago.  I have to believe that a Mazda dealer in this day and age has similar or better tools to diagnose problems such as yours.  It might be worth a phone call to a dealer in the area given the difficulty in diagnosing a problem like yours. 

[RWP80000]

Frank,

You need to think back about what you have done most recently with respect to working on the car.  What parts have been removed or installed.  What electrical connectors were involved?

 

Prior to our recent trip back to Mid-Ohio, I removed the engine and replaced the oil pump and engine bearings.  Everything seemed perfectly fine on start up but after a short period I noticed a long crank times and poor throttle response.  I also noticed an engine miss when it was rev'ed to 4000 rpm or above. It quickly got to the point of not wanting to even start. I was suspicious of the fuel pump or relay but the diagnostic tool only gave me a knock sensor fault and a camshaft discriminator "pending" fault but no fuel pump related faults. What happened next was most interesting. 

 

After studying the wiring diagrams and trying new fuel pump relay the problem remained but I noticed that when the diagnostic tool was connected the car would both start and accelerate under load just fine. If I disconnected to diagnostic tool the problem came right back. I also found that grounding the fuel pump using the diagnostic connector under the hood did nothing to help the problem so it was not in the fuel pump relay ground circuit.  This meant that I had to have a poor power feed.  It turns out the fuel pump relay power comes directly from the engine side injector harness B+ feed.  

 

As I was inspecting the harness for any signs of a power feed wiring problem I noticed that the bolts for the intake manifold harness grounds (by the throttle body) were installed less than finger tight.  After tightening these two bolts the problem was solved.  I have no idea why the system is able to find good B+ voltage with the diagnostic tool installed but I tried a second device plugged into the dash side OBD2 connector and it had the same result.

 

When ever a new problem shows up you need to really take a hard look at what the last things you were doing to the car.  Many times we are the source of our most elusive problems.

[FTodaro]

Frank,

You need to think back about what you have done most recently with respect to working on the car.  What parts have been removed or installed.  What electrical connectors were involved?

 

Prior to our recent trip back to Mid-Ohio, I removed the engine and replaced the oil pump and engine bearings.  Everything seemed perfectly fine on start up but after a short period I noticed a long crank times and poor throttle response.  I also noticed an engine miss when it was rev'ed to 4000 rpm or above. It quickly got to the point of not wanting to even start. I was suspicious of the fuel pump or relay but the diagnostic tool only gave me a knock sensor fault and a camshaft discriminator "pending" fault but no fuel pump related faults. What happened next was most interesting. 

 

After studying the wiring diagrams and trying new fuel pump relay the problem remained but I noticed that when the diagnostic tool was connected the car would both start and accelerate under load just fine. If I disconnected to diagnostic tool the problem came right back. I also found that grounding the fuel pump using the diagnostic connector under the hood did nothing to help the problem so it was not in the fuel pump relay ground circuit.  This meant that I had to have a poor power feed.  It turns out the fuel pump relay power comes directly from the engine side injector harness B+ feed.  

 

As I was inspecting the harness for any signs of a power feed wiring problem I noticed that the bolts for the intake manifold harness grounds (by the throttle body) were installed less than finger tight.  After tightening these two bolts the problem was solved.  I have no idea why the system is able to find good B+ voltage with the diagnostic tool installed but I tried a second device plugged into the dash side OBD2 connector and it had the same result.

 

When ever a new problem shows up you need to really take a hard look at what the last things you were doing to the car.  Many times we are the source of our most elusive problems.

I actually had those grounds loose a few years ago, i wish that was it but checked that early. This was a new build this year, but i swapped over the entire electrical system from the other car as the donor was a flood car.

 

This past weekend was its third weekend out and worked fine till the first race Saturday. The only thing i have done to the car since the build was replace the steering rack and change the oil, I bought a diagnostic scan tool that you plug in and drive the car on track. so i hope to capture it if it persists.

 

I plan on changing a list of things and bring a spare harness with me to the track, hopefully i find it.

[ChrisA]

Check the wires at the MAF connector. I've had both the ground leads break within the sheathing and the power lead connect went bad at the pin causing a fault contact. The video does sound like something electrical is happening at an engine vibration node when you resume acceleration after the shift.

[SaulSpeedwell]

A little late to this party, but I really liked running the ScanGauge in my NB - you can plug it into the OBD-2 "permanently" and monitor water temp, air temp, ignition timing, and battery voltage continuously (and possibly have it viewable on video).  It also displays OBD-2 codes and allows you to clear codes as well.

 

Now you don't need an AutoMeter coolant temp gauge taking up an eyeball vent (or installed somewhere that will give you bogus readings, i.e. heater hose), so put an AutoMeter electronic fuel pressure gauge in.  Now when the car stumbles (or lays down) you have, in one quick glance, an idea of water temp, air temp, battery voltage, IGN timing, and fuel pressure.  That's pretty damn good, and not very expensive.

[FTodaro]

A little late to this party, but I really liked running the ScanGauge in my NB - you can plug it into the OBD-2 "permanently" and monitor water temp, air temp, ignition timing, and battery voltage continuously (and possibly have it viewable on video).  It also displays OBD-2 codes and allows you to clear codes as well.

 

Now you don't need an AutoMeter coolant temp gauge taking up an eyeball vent (or installed somewhere that will give you bogus readings, i.e. heater hose), so put an AutoMeter electronic fuel pressure gauge in.  Now when the car stumbles (or lays down) you have, in one quick glance, an idea of water temp, air temp, battery voltage, IGN timing, and fuel pressure.  That's pretty damn good, and not very expensive.

That is what I ended up buying. it was like 160,00. No good way to find issues without one. In my case the code was coming back Mass Air flow so i swapped mine with Kyle's, it did not fix the problem so i moved on to the harness.

 

On another note, the first time I replace the Mass air flow sensor, i did not realize that the 99 sensor and the 01 sensor while they look the same have different part numbers, so i am not sure they were interchangeable.

 

After throwing all kinds of parts at this problem, the problem turned out to be the harness from the ECU to motor.

 

It was so weird how the problems started, first only the 3 to 4 shift on the front straight, then both the front and back straight, then the 4 to 5 shift on the back straight then mid corners, the only trend was it was getting worse.

[Ron Alan]

Specifically what wire and how did you trace it Frank? Or did you just shotgun the whole piece/harness?

[FTodaro]

Specifically what wire and how did you trace it Frank? Or did you just shotgun the whole piece/harness?

I replaced the entire harness from the ECU to the motor, its a short harness, its just difficult to get under the dash to unplug and replace but otherwise simple. plug and play.