Im stumped

[WillWorkFoBoost]

Okay so I posted about this before and I still havent been able to solve this. car starts up fine but once it gets up to temp it hesitates on any sort of throttle, not just boost, and has poor acceleration. then when you come down to idle it idles badly, occasionally coming out of it. It throws no codes,nor are there any stored. Ive tried o2,cps and retimed it, tps, afm, plugs, coilpacks, ive retqd the head, ( has mhg and arps) looked at vac lines and for boost leaks, probably a couple other things too im forgetting but cant seem to figure it out. one thing I noticed is when its missing at idle, you unplug the o2 and it idles fine. once again I tried a good o2 on it, it seems to be that when you unplug o2 it goes into default ignition and fuel values, and the car idles great. (havent tried driving with o2 unplugged,) but Im about to take it somewhere to diagnose it as i cant seem to figure it out. anyone have any idea what could be bad that would mess with ignition when o2s plugged in?

josh

 

[lewis15498]

What mods if any are you running?

 

[WillWorkFoBoost]

What mods if any are you running?

3 inch turbo back, apexi power intake, hardpipes and fmic, gates timing belt, arps and hks 1.2mhg on a fresh head and low mileage block, 10 psi.

 

[89supracrazy]

Check between vf1 and e1 at the diagnostic block and see what your vf reading is. That is your oxygen sensor reading. I would also check your water temperature sensor on your thermostat housing. It tells the computer when the vehicle is at operating temp. Scroll down on this link.

http://www.supramania.com/forums/showthread.php?39712-MAP-ECU-Tuning&p=547633#post547633

 

[jetjock]

Actually Ox is the sensor. Not that he couldn't use Vf, just that he'd have to go into diag mode and be off idle...

 

[89supracrazy]

Hey jj I'm glad you chimed in. How can you actually check the ox at the diag. block. Every where I read it shows the vf1 and e1 to test the oxygen sensor. I have seen the ox in the block but that is as far as I get. Maybe I'm looking in the wrong place.

 

[WillWorkFoBoost]

thing is Im led to believe that its something else, something ignition related that is effed, but is being reverted back to default values when I unplug the o2. I tried a good o2 and it didnt help. it runs fine until it is up to temp. also it doesnt seem to be overly rich... actually the o2 itself looks on the lean side of things. not terrible but definitely not overfueling. Wouldnt the water temp sensor cause it to tell me that im cold on the guage? cuz it doesnt. my point is it definitely knows that its up to temp cuz thats when it starts to be shitty. Il definitely check the o2 signal out though thanks.

 

[89supracrazy]

No it will not show on the guage. It has one for the guage and one for the ecu. The one for the guage is one wire and the one for the ecu is two wire. Check the value on the sensor. It is located toward the bottom left of the housing. The water temp. sensor resistance increases as the engine warms up. If your sensor does not increase then your ecu thinks it is still cold and your other sensors is saying it is warm. It is something to check into.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=113

 

[jetjock]

Hey jj I'm glad you chimed in. How can you actually check the ox at the diag. block. Every where I read it shows the vf1 and e1 to test the oxygen sensor. I have seen the ox in the block but that is as far as I get. Maybe I'm looking in the wrong place.

1) Ox is raw signal. It's a direct connection to the sensor's output.

2) When not in diag mode Vf outputs learned value.

3) In diag mode with the idle contact open Vf outputs an emulated O2 signal.

4) In diag mode with idle closed Vf outputs a signal that shows if codes are present or absent.

A scope or DMM with a Min/Max/Avg recording function can be used with situations 1 or 3 to monitor the sensor during normal operation or while preforming any of the well known diagnostic tests eg; driving the sensor hard over with snap throttle or using artificial enrichment. Or the sensor can be checked off the car using a propane torch. In all cases the heater needs to be tested separately.

 

[89supracrazy]

I see. The ox is before it is processed. Do you know what the raw value would be. Is it measured in volts.

 

[jetjock]

Ya gotta work with me Sparky. The internet can be much more than a global pornography network you know:

http://en.wikipedia.org/wiki/Oxygen_sensor

It's a run-of-the-mill NB zirconia...

 

[89supracrazy]

Thanks for the link. Maybe now I can test the ox and see what the results are. I figured searching the web I would be going around in circles. I need to give it a try ever once in awhile.

 

[7mturbo]

umm. why would you have a 1.2mm headgasket? i thought stock it was 1.37mm and you had to machine the head and block therefore needing a bigger one...........?

 

[WillWorkFoBoost]

yea stock is 1.3 and the head was planed, the block didnt need to be planed its cast iron, if it moves I think youve got a problem. so yea ive got slightly higher compression than stock.