Bigport Tvis 4ag Diagnostic Mode

[capt. crunch]

Ok so I've queried in a few places but still havn't really gotten an answer yet. but when i went to set my timing I noticed that my car does not advance as you rev it. I also read that there is a diagnostic terminal that needs to be bridged, by this I assume it is meant that I have to connect the blue/white wire in this port to the brown earth wire, correct or incorrect?

 

I also used the pin out table for the ecu and traced the diagnostic connector wire to the engine bay, and found it was leading to the four pin plug next to the two pin plug that i was under the impression i should be bridging.

 

Am I meant to be earthing this red/white (diagnostic connector) wire instead of the blue wire in the two pin plug? or am I meant to connect the red/white from the four pin plug to the blue/white from the two pin plug?

 

Also I was informed that the engine has like a fail safe type of thing going on, which when the engine isn't getting a ignition signal from the ecu it will run at a set ignition timing without any advance through the revs (which seems to be my problem). Does this mean the ignitor wire from the ecu might not be connected properly?

Or which wires are the ones I should investigate to solve this issue of no advance?

[parrot]

http://www.aeu86.org/index/technical-ae86-...at/9/topic=5158

[Trev]

Factory wiring or a conversion?

[capt. crunch]

Factory wiring or a conversion?

 

 

Sorry it is a conversion into a KE70, i pulled motor out of an AE71 so I did not do the initial conversion. but those plugs appear not to be tampered with, and looking at photos of other plugs online the colour coding of the wires are the same?

 

 

so in regards to that ignition not advancing I should check the IGN wire from ecu to the igniter first I suppose?

 

and thanks a lot parrot, I've been hunting for manuals like those for way too long!

[ke70dave]

i think your first step is to get the check engine light wired in

 

then get it into diagnostic mode.

 

and it will tell you the reason why it isnt advancing the ignition. the error codes are pretty specific and they will tell you what signal it hasnt got etc.

 

the check engine light ecu output is an earth, so you just get a bulb, put one side to +12, the other side to the ecu output. and it should work for you. (Was it you that had the thread on check engine lights? i think i forgot to reply with this answer, if so sorry!)

[capt. crunch]

Hey Dave I wired up the check light as you said, did it last night and when i bridged the terminals all I was getting was one flash every ~3 seconds at a constant rate... which is telling me it is 'normal" with no errors if I am reading that right.

[Trev]

Hey Dave I wired up the check light as you said, did it last night and when i bridged the terminals all I was getting was one flash every ~3 seconds at a constant rate... which is telling me it is 'normal" with no errors if I am reading that right.

 

Yes.

 

So the timing does not move when it is not in diagnostic mode and you rev it while pointing a timing light on the pulley?

[capt. crunch]

Yes.

 

So the timing does not move when it is not in diagnostic mode and you rev it while pointing a timing light on the pulley?

 

 

it doesnt move regardless of whether or not i am in diagnostic mode.

 

however today i did look at the IGN and IGF wires as well as the 3 distributor wires and found the distributor wires were a bit frayed and after crimping on new terminals and plugging it all back up, i took it for a drive and the whole car felt a lot smoother and it felt good through out the rev range compared to before where it was a little hesistant below 2500rpm.

 

running out to the shop tonight to grab some batteries so i can get the timing light running again and see if my problem was fixed.

[ke70dave]

ah interesting.

 

i would have throught that would have thrown up an ECU error.

 

oh well learn something new everyday.

 

interesting to see what the timing light sais.

[capt. crunch]

yeah I'm confused as to why no errors came up as well...

 

When I checked the tps it says the earth and IDL pins should have <2.3 kilo Ohms with a .35mm spacer, mine was only getting 0.02. it was the highest I could get it as well so that is looking like a potential problem as well. I mean it does say less than 2.3 k ohm but 0.02 k ohm is ridiculously lower.

[ke70dave]

what you could try just to double check your check engine light and diagnostic mode.

 

unplug your tps or Map sensor, fire it up, it may not run very well. then do the diagnostic mode, just to check that the diag mode is working.

 

Actually i just remembered, when i first got my 4age going, i couldnt work out what was going on, turned out to be a stuffed TPS, but there was no error code thrown up...though my engine refused to idle steady and would rev up and down like crazy for no reason.

 

also your engine should run fine without a TPS plugged in, the revs will just drop fairly slowly when you free rev. but other than that it runs fine. (i ran mine like this, while i was waiting for a replacement TPS)

[capt. crunch]

what you could try just to double check your check engine light and diagnostic mode.

 

unplug your tps or Map sensor, fire it up, it may not run very well. then do the diagnostic mode, just to check that the diag mode is working.

 

Actually i just remembered, when i first got my 4age going, i couldnt work out what was going on, turned out to be a stuffed TPS, but there was no error code thrown up...though my engine refused to idle steady and would rev up and down like crazy for no reason.

 

also your engine should run fine without a TPS plugged in, the revs will just drop fairly slowly when you free rev. but other than that it runs fine. (i ran mine like this, while i was waiting for a replacement TPS)

 

 

yep i did that to check yesterday, unplugged the TPS and also the vacuum sensor and the corresponding error codes came up.

my idle is fairly consistant at the moment, but when i just cruise along then come to a stop it will sit at around 12-1300 then blip the accellerator and it drops to 1000.

 

so when it says below 2.3 k ohm roughly what kind of figure am i expecting?

[ke70dave]

i don't really know, but there is a way to calibrate your TPS.

 

ive not personally done it, but it should be in the 4age manual (big blue book). ive heard guys having success doing it.

 

you turn it aorund till you have Xohms etc. might be worth looking into?

 

http://www.ae92gts.com/ae92gts_tps.html

 

the IDL is your idle switch, which clicks on when your throttle is in the "idle" position. if you fiddle with the TPS while the engine is running, you can hear the idle switch clicking in/out etc. I'm not sure what it changes, i assume something with the timing advance.

 

i assume the 2.3K ohm thing that when the IDL switch is open there should be no resistance (ie <2.3K) but when its closed it should be more than this. you can see in that link it gives a value of "infinity" when the TPS is at 0.59mm, so it reckons that when the butterfly is open 0.59mm the ecu recognises that the engine isnt at idle anymore. which makes sense i think.

[capt. crunch]

i don't really know, but there is a way to calibrate your TPS.

 

ive not personally done it, but it should be in the 4age manual (big blue book). ive heard guys having success doing it.

 

you turn it aorund till you have Xohms etc. might be worth looking into?

 

http://www.ae92gts.com/ae92gts_tps.html

 

the IDL is your idle switch, which clicks on when your throttle is in the "idle" position. if you fiddle with the TPS while the engine is running, you can hear the idle switch clicking in/out etc. I'm not sure what it changes, i assume something with the timing advance.

 

i assume the 2.3K ohm thing that when the IDL switch is open there should be no resistance (ie <2.3K) but when its closed it should be more than this. you can see in that link it gives a value of "infinity" when the TPS is at 0.59mm, so it reckons that when the butterfly is open 0.59mm the ecu recognises that the engine isnt at idle anymore. which makes sense i think.

 

yep i get it.. Even though I couldn't get a value closer to the 2.3k yesterday I set it at 0.03 which was the highest I could get it when using the .35mm feeler.

 

but hey presto after fixing up those dizzy wires everything is working a treat!

 

going into diagnostic DOES make my ignition timing retard by ~5 degrees

when not in diagnostic mode i AM getting timing advance when revving.

and it is the timing is sitting perfectly without any fuss at 900rpm.

 

thanks for all the help guys, would never of checked the ecu - distributor and ecu - igniter wires if no one suggested it!

[Trev]

Future reference for broken wiring:

 

http://www.rollaclub.com/board/index.php?showtopic=23020