AFRs at idle and 2500rpm, no problems?
09-18-2011, 09:54 AM
#31
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Your voltage at Idle is a bit higher that I expected.
Higher readings from MAF and the AFRs change with electrical load are classical symptoms of a ground issue.
Of course, there is always the possibility that you have damaged components. Which is always a possibility when purchasing used parts. However, since the previous owners (not sure how many) did not experience the same issues, I would think components damage is a remote possibility. But the only way to know for sure is for me to test them.
If you eliminate all possible causes, including grounds. One option is to send me the parts so I can examine them myself.
Higher readings from MAF and the AFRs change with electrical load are classical symptoms of a ground issue.
Of course, there is always the possibility that you have damaged components. Which is always a possibility when purchasing used parts. However, since the previous owners (not sure how many) did not experience the same issues, I would think components damage is a remote possibility. But the only way to know for sure is for me to test them.
If you eliminate all possible causes, including grounds. One option is to send me the parts so I can examine them myself.
09-18-2011, 02:04 PM
#32
Rennlist Member
I just noticed that you have your factory narrow band O2 sensor signal going to the user input on the zeitronix? Is that correct? Has that been hooked up from the beginning or did you do that to help find the issue. I assume the zeitronix user input is high impedance, but the O2 signal is so low and sensitive, I don't know if the zeitronix might have an affect on the signal....
09-18-2011, 02:49 PM
#33
Racer
Thread Starter
I just noticed that you have your factory narrow band O2 sensor signal going to the user input on the zeitronix? Is that correct? Has that been hooked up from the beginning or did you do that to help find the issue. I assume the zeitronix user input is high impedance, but the O2 signal is so low and sensitive, I don't know if the zeitronix might have an affect on the signal....
The NB sensor is now disconnected (in the engine bay) and the Zeitronix simulated NB output is connected to the DME and the Zeitronix User 1 input. I figured that the driver on the simulated output is strong enough not to have any problems with the cabling.
/Dea
09-25-2011, 02:33 PM
#34
Racer
Thread Starter
Not that much to do in the garage anymore, everything except the AFR values works perfect....
Measured the resistance between the MAF connector and the DME connector.
They all measured OK, 0.3-0.5 Ohm (including a long testcable on the DVM).
They are connected like this:
MAF ------- AFM conn -------------------- DME pin
White --------- Green/Red ---------- 7 (Air flow sensor 2, potentiometer)
Yellow --------- Green --------------- 22 (Air flow sensor 1, NTC 1)
Black ---------- Yellow/Red ---------- 6 (Air flow sensor 4, NTC 1, Ground)
Pink ----------- Yellow/Red ---------- 6 (Air flow sensor 4, NTC 1, Ground)
Green --------- Yellow/Red ---------- 6 (Air flow sensor 4, NTC 1, Ground)
Red ------------- None --------------- None connected to switched power
The Blue/Green cable in the AFM connector is left open
DME pin 6 seems to be grounding for the MAF/AFM and it grounds thru the DME.
Can't think of that many more things to measure right now.
One idea could be to measure ground voltage on the MAF and DME while the engine is running to see that it stays zero.
Should probably check the +12 to the MAF as well just to make sure.
Can the MAF be checked?
I'm guessing that there should be zero voltage output on the white wire when the engine isn't running?
What resistance value should the Yellow wire to Ground have?
I still can't figure out why it's in closed-loop when the engine is still cold? somehow this feels important
Will try to get a new DME to see if it behaves the same.
John: anything else I should check or measure in the MAF, chip board, DME etc. before thinking of sending it to you? (and a big thanks for letting me send it to you although it was bought used
)
/Dea
Measured the resistance between the MAF connector and the DME connector.
They all measured OK, 0.3-0.5 Ohm (including a long testcable on the DVM).
They are connected like this:
MAF ------- AFM conn -------------------- DME pin
White --------- Green/Red ---------- 7 (Air flow sensor 2, potentiometer)
Yellow --------- Green --------------- 22 (Air flow sensor 1, NTC 1)
Black ---------- Yellow/Red ---------- 6 (Air flow sensor 4, NTC 1, Ground)
Pink ----------- Yellow/Red ---------- 6 (Air flow sensor 4, NTC 1, Ground)
Green --------- Yellow/Red ---------- 6 (Air flow sensor 4, NTC 1, Ground)
Red ------------- None --------------- None connected to switched power
The Blue/Green cable in the AFM connector is left open
DME pin 6 seems to be grounding for the MAF/AFM and it grounds thru the DME.
Can't think of that many more things to measure right now.
One idea could be to measure ground voltage on the MAF and DME while the engine is running to see that it stays zero.
Should probably check the +12 to the MAF as well just to make sure.
Can the MAF be checked?
I'm guessing that there should be zero voltage output on the white wire when the engine isn't running?
What resistance value should the Yellow wire to Ground have?
I still can't figure out why it's in closed-loop when the engine is still cold? somehow this feels important
Will try to get a new DME to see if it behaves the same.
John: anything else I should check or measure in the MAF, chip board, DME etc. before thinking of sending it to you? (and a big thanks for letting me send it to you although it was bought used
)/Dea
03-19-2012, 03:06 PM
#35
Racer
Thread Starter
Never got to test it on the road last year since I missed the yearly vehicle inspection but yesterday I drove it to the shop to change the turbo (which is legal although it hasn't passed inspection).
To my surprise the 2500 rpm problem only seems to exists at no load (at stand still), at cruise the AFR was stable at 14.7.
Looking at the 30 min ZT-2 log I could only find one or two occasions where it for a couple of second during cruise was moving into the rich area.
Did some accelerations tests with wastegate base pressure (7.25psi) and it stabilized at AFR 13.4 which seems normal, will put up some log pictures later.
Only issue was some light stumbling when going to full throttle at low rpms but this seems to be a common issue?
My conclusion is that everything actually works just wish I could find a reasonable explanation to why the AFR is OK at idle but not at no load@2500rpm?
The plan to pass inspection is to lean out the no load cells with the piggyback, should work.
/Dea
To my surprise the 2500 rpm problem only seems to exists at no load (at stand still), at cruise the AFR was stable at 14.7.
Looking at the 30 min ZT-2 log I could only find one or two occasions where it for a couple of second during cruise was moving into the rich area.
Did some accelerations tests with wastegate base pressure (7.25psi) and it stabilized at AFR 13.4 which seems normal, will put up some log pictures later.
Only issue was some light stumbling when going to full throttle at low rpms but this seems to be a common issue?
My conclusion is that everything actually works just wish I could find a reasonable explanation to why the AFR is OK at idle but not at no load@2500rpm?
The plan to pass inspection is to lean out the no load cells with the piggyback, should work.
/Dea
12-23-2012, 06:40 AM
#38
Racer
Thread Starter
So what happened.....
The car is not dumped in a lake as can be seen in the pictures
Since I couldn't find the problem I decided to take it to the annual inspection anyway, expecting to fail but I would at least get two month of legal driving on the road to do some more logging.
To my surprise they skipped the 2500rpm elevated idle test and the car passed the inspection with an extra plus for the excellent idle exhaust values
Still not working:
- AFR at 2500rpm elevated idle, not in closed loop
- Adding the piggy-back makes the AFR values go nuts... it stays in closed loop under boost??
Otherwise it's running fine, response is improved compared to the original set-up.
/Dea
The car is not dumped in a lake as can be seen in the pictures
Since I couldn't find the problem I decided to take it to the annual inspection anyway, expecting to fail but I would at least get two month of legal driving on the road to do some more logging.
To my surprise they skipped the 2500rpm elevated idle test and the car passed the inspection with an extra plus for the excellent idle exhaust values
Still not working:
- AFR at 2500rpm elevated idle, not in closed loop
- Adding the piggy-back makes the AFR values go nuts... it stays in closed loop under boost??
Otherwise it's running fine, response is improved compared to the original set-up.
/Dea
