Suzuki Forums banner
61 - 80 of 116 Posts
Discussion starter · #61 ·
OK. I'm going to put the ECU with the bad IAC driver back in and see if I get the same responses.

Thanks. Malcolm
 
Discussion starter · #62 ·
OK. I'm going to put the ECU with the bad IAC driver back in and see if I get the same responses.

Thanks. Malcolm
Neither ECU sees any action on the down stream O2 sensor. Don't know why it doesn't set a code but I'm going to replace it and check the wiring once I get it disconnected. That could be he cause of my low (16 - 17mpg) mileage.

Will report back. Malcolm
 
Neither ECU sees any action on the down stream O2 sensor. Don't know why it doesn't set a code but I'm going to replace it and check the wiring once I get it disconnected. That could be he cause of my low (16 - 17mpg) mileage.

Will report back. Malcolm
Hold it!

Are you referring to the 02 sensor after the cat(downstream)?? When working with a good CAT, the B1S2 should read close to a steady 5vdc..

If you are referring to the UP stream O2 (B1S1and B2S1, close to engine, before CAT), they should be actively switching...

If not, and are flat lined, are they at 0vdc or 7-9vdc?

... Philip
 
Discussion starter · #64 ·
Hold it!

Are you referring to the 02 sensor after the cat(downstream)?? When working with a good CAT, the B1S2 should read close to a steady 5vdc..

If you are referring to the UP stream O2 (B1S1and B2S1, close to engine, before CAT), they should be actively switching...

If not, and are flat lined, are they at 0vdc or 7-9vdc?

... Philip
The only data I see are for B1/S1 and B1/S2.

B1/S1 idles at 0.2v, runs up to 0.5v as I apply throttle and drops back to a steady 0.2v as I hold the elevated rpm. Then 0.2v at idle. (The other ECM gives slightly different results -- somewhat higher voltage on return to idle -- but they were at a different time with different conditions.)

B1/S2 idles at 0.0v and does not change with rpm. (Both ECM's give same results.)

I'm assuming B1/S2 is the downstream sensor (after the cat). The upstream has already been replaced.

Malcolm
 
You will need to verify the harness between the ECU and the O2 sensors..

Is this a 6 cyl or inline 4

If v6 you should see both B1S1+ B2S1, before CAT

.... Philip
 
If this was my vehicle I would connect a lab scope to the O2 harness (a DVOM may not be fast enough), start the engine and activate the sensor (warm them up to operational temp), open a vacuum line and the reading must go down (lean), inject propane and the reading must go up (rich). Perform on both S1 sensors...
If the sensors are confirmed as working, connect to the ECM end of the circuit, you should get the same readings, if not investigate harness for opens/shorts..

Remember you will be working in low voltages .1 to.9vdc generated by O2 sensor..

Point of warming, if you have applied raw battery to the sensor, you may have inadvertently killed it... same goes for some silicone sealers (O2 killers)..

The heater side of the O2 sensor is a timed application of 12vdc, via a relay.. the ground side is triggered..Keep both side separate when testing...

.... Philip
 
Discussion starter · #67 ·
You will need to verify the harness between the ECU and the O2 sensors..

Is this a 6 cyl or inline 4

If v6 you should see both B1S1+ B2S1, before CAT

.... Philip
4-cylinder inline.
 
Discussion starter · #69 ·
Thought about your issue last night, I think you need to start fresh, first remove the O2 and bench test it to ensure it is working

https://www.youtube.com/watch?v=o6iXNBPPhwc

https://www.youtube.com/watch?v=NKsS6AELPuM

... Philip
Sorry to be off so long. Had some medical issues to take care of.

I put a new downstream O2 sensor in and everything is the same. Upstream reads 0 - 5 volts with a short term average of .1. Downstream reads constant .3 volts. Most monitor tests will not complete.

I saw your videos and I think I need to see if the heater voltage is there. Then I'll do your test on the downstream I took out. Malcolm
 
Discussion starter · #70 ·
If you don't have an FSM for the 1.8 then I would suggest checking the 1996 1.6 FSM, available on Acksfaq. The FSM details the conditions required for the tests to be completed.
Do you know where that info is in the FSM? Malcolm
 
Discussion starter · #72 ·
Thanks. Knowing what to look for, I found it in my Sport manual. I did the called-for driving sequence and got a P060 code for the first time. Looking that up for OBDII in general it is a memory check sum error in the ECU. Which could be caused by a lot of things including a poor ground. At the time, I had the ECU unbolted from its bracket. If that's what it relies on for ground, I shouldn't get the code after I bolted it back up.

I checked the heater supply to the new downstream O2 sensor by plugging the old one in then idling the engine. The sensor eventually got hot. I re-checked the TPS and the voltages were in spec. The MAF sensor is new as are both O2 sensors. Yet I still can't get it to "complete" the monitor tests and ready it for smog. I would suspect the used ECU but it gives the same results as the old one except that it has a good IAC driver.

I've been working on this for over 3 months and I have yet to come up with a diagnostic plan that leads to the source of the problem. I could put a brand new ECU in it but that's a lot to risk. Malcolm
 
Memory Checksum error could be caused by a poor ground but what it means is that the self test on the processor has detected an error in the programme or mapping, I would expect that to put it into limp mode. It would seem to indicate a dead ECU. Is it repeatable? if you clear the codes and key on again do you get the same code?
The ECU case is only used as a ground for noise suppression and ESD protection, there are several grounds from the ECUs internal circuitry that should be checked.
 
You need to confirm the fault code, P0601 is memory checksum error.
 
Discussion starter · #75 ·
You need to confirm the fault code, P0601 is memory checksum error.
Sorry, typo. P0601 is correct. Freeze frame 0x03 shows "Fuel system status: Open loop due to insufficient engine temperature." (?) Gage and scanner read OK.

I'm about to clear the code and go through the drive cycle again.
 
Sorry, typo. P0601 is correct. Freeze frame 0x03 shows "Fuel system status: Open loop due to insufficient engine temperature." (?) Gage and scanner read OK.

I'm about to clear the code and go through the drive cycle again.
OK! being what?

Strange if the ECU sees an "OK" reading from the ECT, but reports other wise..

Keep in mind the dash gauge has nothing to do with the ECT or, what the ECU is getting info from..
Have you check engine temp with an IR thermometer?

...Philip

BTW: hope you are feeling better
 
After thought:

I have know a lazy thermostat, and air bubbles in thermo housing to trigger that code...

.... Philip
 
Discussion starter · #78 ·
OK! being what?

Strange if the ECU sees an "OK" reading from the ECT, but reports other wise..

Keep in mind the dash gauge has nothing to do with the ECT or, what the ECU is getting info from..
Have you check engine temp with an IR thermometer?

...Philip

BTW: hope you are feeling better
The 1.8 FSM lists driving cycles that are designed to repeat a specific fault code if the fault is real. They're also good for speeding up the learning process and have the ECU report "completed" on a specific item. I drove one specified for the TPS which is warm up, 5 minutes at speeds equivalent to 2000 - 3000 rpm, then 1 minute with steady throttle at 50 - 60mph, decelerate with engine braking, stop, turn off, turn back on and repeat the cycle. The first time I did that, I got the P0601 and the fuel system error.

I cleared the codes and ran through it again and did not get the P0601 or the fuel system error to repeat and the EGR test turned to "completed". I still have monitor tests incomplete which are keeping it from being ready for smog test. I'm not sure if it's reasonable for the downstream O2 to always read 0.3v unless that means the cat is super good. About 2 years ago, I checked the coolant temperature with a thermometer and the stat housing with an I.R. pyrometer. I did notice today that the ECU was reporting a temperature of 217 degrees but that was a few minutes after the engine was shut off. It wouldn't hurt to replace the sensor and the stat. Jerry once told me that most aftermarket stats for the 1.8 are wrong and somewhere I have the details of what to look for.

Do you have any idea where the ECU grounds are located. I can see them on the circuit diagram but not where they're physically located.

Thanks for the well wishes. I'm glad the docs can do a better job of keeping this 80-year-old body upright than I seem to be able to do on the Suzuki! Malcolm
 
If all is working per spec, the downstream O2 (after CAT), should be hovering around .05vdc. It may vary dependent on the condition of the CAT and the condition of the gasses moving past the upstream O2.

The key is, it should not switch or follow the B1S1

... Philip
 
Discussion starter · #80 ·
If all is working per spec, the downstream O2 (after CAT), should be hovering around .05vdc. It may vary dependent on the condition of the CAT and the condition of the gasses moving past the upstream O2.

The key is, it should not switch or follow the B1S1

... Philip
The downstream never fluctuates from 0.3 v - straight flat line. The '97 1.8L FSM in the diagnostic section says that the recorded data should be .35v or lower so that's good. For the upstream, it says the minimum should be 2.55v or higher. I've never seen it above 0.5 volts. Another diagnostic section says it should be above 0.5v. I need to do some more reading. Upstream was replaced when I got the car a few months shy of 2 years ago. It does fluctuate when the RPM is changed.

If you would have any interest, I could send you copies of that section. Malcolm
 
61 - 80 of 116 Posts