Discussion
i ve put new maf in reset ecu and a little bit better but still wont boost spluters and holds back at about 3 grand iam starting to get a little disheartened with this now ive also changed knock sensor does any one know how to check coil packs as ive tried with a plug in it all 4 are sparking a nice blue spark is there any other way i can check tomorrow i will rip rad out to check timing all lines up and also try another set of injectors thanks every one mike
Your problem is electrical/sensor based.
When i came down to see you we unplugged the MAF and your car revved 100% better, in fact as i would expect it to rev normally but it idled badly and hunted up and down (Did you clean out the IACV valve as i suggested?).
Unplugging the MAF sends the car into like an SD (speed density mode) like MAFless tuned scoobs so it doesn't use the MAF to check airflow instead using just RPM and Manifold Absolute Pressure to guesstimate engine VE but it can also send the car into Limp mode which stops it revving over about 3000rpm.
You've changed the MAF sensor and you say it's a little bit better. It would be good to know in what way it's better.
We unplugged your Lambda sensor and there was no check engine light. I would expect to see a check engine light when you unplug it. Likely there is an issue there of some sort but without spending a day on it to check everything out it's difficult to say. Have you got another Lambda sensor to plug in and try?
I can't remember if you said there is no rear O2 sensor on it. There should be so is there a resistor mod/fix on the connector the rear O2 sensor plugs in to?
There is really not much more to check on it sensor wise. You have just the crank sensor to check but it won't start up without it so i presume from that it's working fine because it starts fine. Your injectors are OK otherwise you would have problems whether your MAF is or isn't plugged in so i would forget about those.
I strongly suspect issues with either the MAF sensor wiring, and/or Lambda sensor wiring. Equally it's worth checking your ECU to see if it's been chipped or not. If it has been it could be an issue with that. The car has been modified with induction kit and decat exhaust. It should have been mapped but i suspect it may have been chipped and therein could be some or all of your problems.
Edited to add: You said you checked the error codes and it was coming up OK. I have to say baring in mind we got no check engine light when you unplugged the Lambda sensor there is something definitely suspect there and i would want to check the error codes again. Are you sure you read them right because with the running problems you car has it must be throwing up some sort of error. The fact there are no error codes is a worry.
When i came down to see you we unplugged the MAF and your car revved 100% better, in fact as i would expect it to rev normally but it idled badly and hunted up and down (Did you clean out the IACV valve as i suggested?).
Unplugging the MAF sends the car into like an SD (speed density mode) like MAFless tuned scoobs so it doesn't use the MAF to check airflow instead using just RPM and Manifold Absolute Pressure to guesstimate engine VE but it can also send the car into Limp mode which stops it revving over about 3000rpm.
You've changed the MAF sensor and you say it's a little bit better. It would be good to know in what way it's better.
We unplugged your Lambda sensor and there was no check engine light. I would expect to see a check engine light when you unplug it. Likely there is an issue there of some sort but without spending a day on it to check everything out it's difficult to say. Have you got another Lambda sensor to plug in and try?
I can't remember if you said there is no rear O2 sensor on it. There should be so is there a resistor mod/fix on the connector the rear O2 sensor plugs in to?
There is really not much more to check on it sensor wise. You have just the crank sensor to check but it won't start up without it so i presume from that it's working fine because it starts fine. Your injectors are OK otherwise you would have problems whether your MAF is or isn't plugged in so i would forget about those.
I strongly suspect issues with either the MAF sensor wiring, and/or Lambda sensor wiring. Equally it's worth checking your ECU to see if it's been chipped or not. If it has been it could be an issue with that. The car has been modified with induction kit and decat exhaust. It should have been mapped but i suspect it may have been chipped and therein could be some or all of your problems.
Edited to add: You said you checked the error codes and it was coming up OK. I have to say baring in mind we got no check engine light when you unplugged the Lambda sensor there is something definitely suspect there and i would want to check the error codes again. Are you sure you read them right because with the running problems you car has it must be throwing up some sort of error. The fact there are no error codes is a worry.
Edited by ScoobieWRX on Tuesday 4th December 22:08
hi ya mate rear 02 is not there also has nothing in plug if its the round plug by boost solinoid its just disconnected i dont have a lambda sensor handy it seems to run a little bit better with maf in rev a little more smoothly cleaned iacv how can investagate the ecu mate thanks
there was no error code i will try with lambda disconnected tomorrow just flashed steady
also is it possiable for me to test wireing for maf where would i find info on doing this
there was no error code i will try with lambda disconnected tomorrow just flashed steady
also is it possiable for me to test wireing for maf where would i find info on doing this
Edited by SCOBBYMIKE on Tuesday 4th December 22:37
Edited by SCOBBYMIKE on Tuesday 4th December 22:39
Disconnect the Lambda sensor and check for error codes.
If you get no codes showing up then you have some wiring or ECU issues. I'm less inclined to think it is ECU issues because removing the MAF sensor not only lets the car rev properly but also if i remember right it does actually throw a check engine light when disconnected so this may well be linked to just the Lambda sensor/wiring.
As for the ECU, it's under the front passenger footwell carpet, under a plate bolted to the firewall/bulkhead. Disconnect your battery first, then disconnect the ECU connectors. Take the screws out holding down the ECU cover and remove the cover.
This is what your board looks like.
Look where is says IC Socket on the picture, that's where i expect to see a chip, either soldered to the board, or a chip carrier soldered to the board with the chip sitting on it, if it's chipped.
Like i said, i think it's doubtful the ECU is the problem, more like a wiring issue somewhere, and there is so much stuff badly modified before you got the car, and connectors disconnected that i don't think should be, it wouldn't surprise me if it's a bunch of issues all relating to the problem you have now.
I'm not down your way or anywhere near for a while so i've no idea when i can come back down and have another look without taking a whole day out to try and get your car running right.
If you get no codes showing up then you have some wiring or ECU issues. I'm less inclined to think it is ECU issues because removing the MAF sensor not only lets the car rev properly but also if i remember right it does actually throw a check engine light when disconnected so this may well be linked to just the Lambda sensor/wiring.
As for the ECU, it's under the front passenger footwell carpet, under a plate bolted to the firewall/bulkhead. Disconnect your battery first, then disconnect the ECU connectors. Take the screws out holding down the ECU cover and remove the cover.
This is what your board looks like.
Look where is says IC Socket on the picture, that's where i expect to see a chip, either soldered to the board, or a chip carrier soldered to the board with the chip sitting on it, if it's chipped.
Like i said, i think it's doubtful the ECU is the problem, more like a wiring issue somewhere, and there is so much stuff badly modified before you got the car, and connectors disconnected that i don't think should be, it wouldn't surprise me if it's a bunch of issues all relating to the problem you have now.
I'm not down your way or anywhere near for a while so i've no idea when i can come back down and have another look without taking a whole day out to try and get your car running right.
I think it's definitely in limp mode and it could well be linked to the Lambda sensor and why we aren't seeing a check engine light when it's disconnected. Just see what happens when you disconnect the Lambda sensor and see if you are getting any error codes. If no error codes there is a more serious issue going on, likely with wiring somehow.
![](http://thumbsnap.com/sc/oGXauRaH.jpg[/img]</a> <a href="http://thumbsnap.com/OQnr4A1A" Target="_blank">[img]http://thumbsnap.com/sc/OQnr4A1A.jpg)
It seems you have a Z4 ECU. This ECU is calibrated to make 260bhp with supporting mods.
Based upon your mods, although you're kind of heading in the right direction with this ECU you have to bare in mind you have a fully decat exhaust system and induction kit therefore beyond what the Z4 can do for you. Your ECU needs remapping and the only way forward on that is with an ESL Daughterboard, and you could do with the 1.74bar MAP sensor from a V3/V4 97/98 classic. The Z4 ECU was calibrated to run with 2 factory cats and factory airbox so your tuning needs sorting.
As for your wiring you need to have a look at a manual for your year car that comes with schmatics. You can check all the sensors one by one to make sure they are all getting the right supply voltages and are giving back the right signal voltages to the ECU. I've got a 1996 manual which will be spot on for your car.
I can let you download off one of my servers. Let me see if i've got your email addy and i'll send you a link.
Did you say you disconnected the Lambda sensor and checked for error codes? If you did check did you get any error codes?
Based upon your mods, although you're kind of heading in the right direction with this ECU you have to bare in mind you have a fully decat exhaust system and induction kit therefore beyond what the Z4 can do for you. Your ECU needs remapping and the only way forward on that is with an ESL Daughterboard, and you could do with the 1.74bar MAP sensor from a V3/V4 97/98 classic. The Z4 ECU was calibrated to run with 2 factory cats and factory airbox so your tuning needs sorting.
As for your wiring you need to have a look at a manual for your year car that comes with schmatics. You can check all the sensors one by one to make sure they are all getting the right supply voltages and are giving back the right signal voltages to the ECU. I've got a 1996 manual which will be spot on for your car.
I can let you download off one of my servers. Let me see if i've got your email addy and i'll send you a link.
Did you say you disconnected the Lambda sensor and checked for error codes? If you did check did you get any error codes?
hi mate no codes from lambda when its unpluged ok mate so in the future i need sa mapping on car where to go from now i will check all senso etc if you could send me data that would be great my email is sk8street@hotmail.com thanks hopeing to get car done before the nice weather thanks mate
Well that's possibly your problem then. You should be getting a check engine light with it unplugged and definitely some error codes when unplugged so there is something screwy going on there. You should also have a rear Lambda sensor in the exhaust and if unplugged the only way to sort it is with a resistor mod. You need to check if the connector is just sitting there with nothing plugged in. If so that's wrong and needs to be sorted.
You'll have to go through the car with a fine tooth comb and check any and all disconnected connectors to see where they are meant to be plugged into and if not have they been modified with a resistor like the rear O2 sensor connector should be.
Check all that first then look at wiring. I'm just about to send you the link for the workshop manual to your email address.
You'll have to go through the car with a fine tooth comb and check any and all disconnected connectors to see where they are meant to be plugged into and if not have they been modified with a resistor like the rear O2 sensor connector should be.
Check all that first then look at wiring. I'm just about to send you the link for the workshop manual to your email address.
hi mate checked all plugs etc only one with nothing in is a round plug by the boost solinoid has just been disconnected nothing ion there etc just as ive rear sensor removed and left unpluged should i put a rear o2 in or is it pointless with a decat there is a thread in my down pipe by the tuirbo flange with a blank in it i take it this is where the rear sensor goes thanks mike
The rear O2 sensor goes into the exhaust further down the exhaust, somewhere near the back of of your gearbox. I've got a problem uploading this workshop manual to my server. Leave it with me and i'll get this link over to you as soon as i've sorted my server problem. Probably tomorrow now.
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