khoney

Still trying to find my violent hesitation problem. I have a test connector with LEDS going from the ECU check connector to inside my car. Shows no codes when I turn the key to start, and shows no codes under normal conditions. When I get the hesitation problem, one light comes on for what seems a variable amount of time. Problem is, the hesitation is intermittent, so the condition may obly last for a fraction of a second. Soo, my question is does the ECU issue a complete code even if the problem goes away while the code is being displayed? If so, I think i'm getting an O2 sensor code (would that cause violent hesitation? I wouldn't think so).

HAILERS

Try running a meter to the input signal from the oxygen sensor to the ecu to see whats up with the oxygen sensor.While driving around.

Six Rotors

iTrader: (17)

If you have an 86-88 then the ecu will only issue a code for as long as a condition exists.If the condition is shorter than the time to register you will not get the complete code.Also how can you determine if it is the O2 sensor?You would need to see 5 short flashes on the digit light with some fraction of a second between each flash.
What happens when you disconnect your O2 sensor?If it was some weird output from the sensor your problem would disappear.

Keith

The 86-88 ECU is not an overly sophisticated one, but I believe it would complete a code at least once even if the condition disappeared. Can't verify it though, the failures I have observed on my 87 TII have been there long enough for at least one code readout. The reason I am assuming this is that I have never seen a code readout stop in the middle, and my car's ECU thinks the O2 sensor is bad every time I start the car warm, until the sensor warms up again! I will test tomorrow by connecting up my TPS right in the middle of it flashing out the TPS failure code.

Oh yeah, the code readout for an O2 sensor failure is a single 2-second flash on DCC1 (short flashes are 1/2 second). Then there is a 2-second pause, and the cycle starts over (Looks like a light blinking on and off with a 4-second period). I would be suspicious of the sensor and/or the ECU (grounding perhaps?).

Irv, Keith's dad

Six Rotors

iTrader: (17)

My mistake on the 2sec flash(DCC1 counts in ones and fives).I did a check today with the Mazda code reader.Using the pressure sensor---basically if the code reader was in the pre-readout phase it does not record the code when the sensor is reconnected,if it is in the middle of reading the code it completed it and then immediately resets.In all cases when the sensor was disconnected the audible alarm was present and immediately stopped when the sensor was reconnected.

HAILERS

I don't think the o2 sensor will cause a violent hesitation. I've got that home made lite rig on my steering column and I've seen the 02 code come on during a long trip to Corpus. No violent hesitation at all. It has happen at 3000 in fifth, 70mph approx and no violent hesitation. I have a meter on the idiot lite pouch in the center of the dash and can read the output. I've seen the meter go from generaly around 40mv to zip and the lite come the led's from the home made rig. No violence. I see where BigWoogie corrected his hesitation by cleaning the mesh filter on the end of the fuel pump. I believe his was violent also.

Six Rotors

iTrader: (17)

Completed the same test using the 2 light method and the results are---if the sensor is disconnected and the code begins flashing it will complete the code,if the sensor is reconnected during the dead time between code flashing no fault is flashed.
My conclusion would be that if you see a single momentary flash on DCC1,0.5 sec long then it is a momentary fault on the crank angle sensor and would surely result in a violent hesitation if your right foot is buried.
I would try cleaning the terminals at the CAS,coat with dielectric grease and see if the problem disappears,if not try a known good CAS.

khoney

I tried cleaning the intake filter and a new fuel filter (no luck). I did also see that the code could possibly be the crank angle sensor. Could this result in 'sputtering' hesitation while cruising to the violent hesitation while under a harder throttle? I intend to check out this possibility next. Of course, Rex has been behaving lately, possibly due to cooler weather, so I need to wait for a hot spell to due anything conclusive.

HAILERS

Runs better in cooler weather? Have you checked out the air intake temp sensors? The one on the mass air flow meter and the one on the dynamic chamber? Probably have.

khoney

I finally threw a real ECU code the other day while driving. The water thermo sensor code did three consecutive repeats (not concurrent with hesitation, but it happened after the hesitation started to appear). How does the ECU make use of this sensor? Is it used in determining fuel delivery? Could it be the source of my violent hesitation? I haven't had a chance to pull it out and test it yet.

TRUDSL

I have a similar problem with the violent hesitations on my 87 non-turbo. I replaced both the ignitors, plugs, and coils. Same thing. Unplugged O2 sensor, got a bigger ground (2 gauge), checked all connections, and the problem still exists.

This is what is the car is doing. When I first start it, I can barely see the hesitations unless I bring it up to about 5500-6000 rpm. As the car warms up, the hesitations come at lower rpms. When the car has reached normal operating temperature, the only way it will increase rpm without hesitation is if I barely (BARELY) push the gas.

I have had to drive the car home going about 30mph on 5th gear with my foot barely on the gas.

Is this similar to the problem you are experiencing? If you find the fix please let me know because its driving me nuts.

Thanks

khoney

Nope, doesn't sound the same. You can see what I've been through by searching on VIOLENT HESITATION, or all of my posts. I don't always have the problem. Have you checked your TPS yet with the engine hot? Make sure your fast idle cam has come all the way off the roller before adjusting it. I will definitely keep everyone informed. This weekend is for replacing brake and clutch cylinders, and maybe checking the water thermo sensor. I've spent more on this car than its worth in the last 3 months. I'm either very stubborn or I have an unhealthy love for my 7

HAILERS

KHONEY.....I saw where you asked how something worked, so try this http://www.howstuffworks.com/fuel-injection.htm if you read the whole thing, I think you will find where it addresses the water temp senso to some degree. Also look at the description of the pressure sensor. It seems to relate somewhat to your problem. Just a thought.