7MGE rough running

[ochocinco5k]

Hey all, have a 1990 MKIII Supra, but is been giving me trouble lately. Other than this it has been completly reliable, got it water pump timing belted it, upgraded the stock slipping [ took 4.5 grand to get moving ] clutch with an ACT HDSS clutch. Well on the problem, sometimes and I say only sometimes because it will idle fine at some points but not others, its definately running rich, sputtering, has a high idle [ 2 - 3 grand ] , once your letting the clutch out with the high idle it goes down and if it dies it takes quite a while for it to start back up again. You can smell all the fuel when its cranking too. When its sputtering, you can gas it up to get it going and a puff of black smoke comes from the exhaust.


Any help is appreciated. I"ve already checked the AFM sweeping resistance as the door opens, continuity between te IAT sensor. I'm just stumped, the high idle would be explained by a vcuum leak but then why would it be only some of the time ?

 

[ochocinco5k]

Had a reoccurance of the issue. Stopped at a light, began dying, off the liht full throttle it was stuttering and blowin black smoke until I got to aout 50 -60 % throttle then it cleared up and off I went. I'm going to check the TPS and the wiring to the ECU for it once I can tear the dash apart

 

[f00g00]

check codes. Also its nice to have a spare AFM lying around thats been unopened which are usually available at your local pick a part.

 

[ochocinco5k]

It only throws codes when it stumbles' hard to check them while I'm moving.

I actually tested the AFM, increasing resistance as the door opens, continuity between the IAT.

 

[f00g00]

The ecu will store the codes, just jumper te1 and e1 as stated here and count the flashes to get the codes.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=23
Then check what you have and go from there.

 

[jetjock]

^ This. And the high idle can't be from a vacuum leak.

 

[ochocinco5k]

Finally got some usefull codes :

22 - Water temp sensor signal

41 - Thottle Position Sensor signal

Ok, so here's my hypothesis, in combination with the water temp sensor being open and causing the ECU to dump fuel and the lack of TPS signal is causing it to die off-throttle. The excessive fuel I hampering starting, and causes the black smoke when running and white smoke when attempting to start. The lack of TPS signal is causing the bucking and high idle, thinking its opening when it isn't.


Sound about right ? I'm going to test the TPS tommorow but I also had a question about setting it. I have read the manual and it gives two feeler guage readings or the GE. Can someone explain that ?

 

[hvyman]

Sounds like the tps took a dump making the idle high.

Bad water temp sensor or circuit would cause the richness keeping it in warm up mode.

Both can be tested using the online tsrm on how to do so.

 

[jetjock]

If we're talking hypothesis there's a fair chance both those codes are unrelated to your problem. They should still be fixed though. And the "dumping fuel" theory from code 22 is incorrect. In fact the opposite will occur.

 

[ochocinco5k]

So as far as I understand about setting the TPS, .001 feeler guage will result in a reading of 2.3 kiloOhms or less. While a .002 feeler guage will result in infinite ohms.

What setting should it be set at ? In step C itsays to turn the sensor clockwise until the ohm meter deflects, what does it mean by that ?

 

[jetjock]

Better check those feeler sizes again.

What you're doing is setting a switch inside the TPS to open just after the throttle comes off its stop and close again just before it hits the stop. The switch controls the IDL signal which is used by the ECU for several things, the most important of which is activating the Idle Speed Control System. The proper way to set everything is to first make sure the throttle plate is fully closed by adjusting its stop. The TPS is then set and finally the dashpot set, in that order.

"Deflect" refers to pointer deflection in an analog instrument. A digital meter going from near zero ohms to whatever infinity indication it uses (typically "OL") or back again is the equivalent. The TSRM procedure uses ohms but voltage can also be used to set the TPS by referencing IDL to ground. IDL will go low (near zero volts) when the switch is closed (throttle closed).

None of this is likely to resolve your problems or the code 41 however...

 

[ochocinco5k]

Ok, pulled the spark plugs, dripping with oil fouling them. Cleaned out the galleys and installed new plugs. Car ran fine until a little bit ago. Still running rich, cutting out, jerking, pulled #6 spark plug and its definately running rich.

Tested the TPS, still good, tested the coolant temp sensor 2.2 ohms, but I still got a code 22 for it when it died, no other codes though.

 

[ochocinco5k]

Ok, pulled the spark plugs, dripping with oil fouling them. Cleaned out the galleys and installed new plugs. Car ran fine until a little bit ago. Still running rich, cutting out, jerking, pulled #6 spark plug and its definately running rich.

Tested the TPS, still good, tested the coolant temp sensor 2.2 ohms, but I still got a code 22 for it when it died, no other codes though.

 

[jetjock]

At 2.2 ohms it's no wonder you have a code 22. And again, it's better to test voltage. The ECU doesn't deal in ohms. At least not directly.

 

[ochocinco5k]

My apologies, tested again 2.2 k Ohms. Tested the voltage 5 V going in the sensor, 0.0V from ground to the signal and 12.6 V on signal to power. This is with the connector disconnected.

At the ECU I got 5 volts between THW and E2 and 12.6V on both +B and +B1.

I suppose the only other thing left is to test the voltage drop from either E2 or THW to the actual ECU ? I didn't do this only because. Don't think my leads are long enough

 

[jetjock]

2.2k makes more sense. Your voltage measurement of THW at the ECU does not. Assuming it's accurate there's your code 22. Looks like THW is open. Don't need long leads...the car's chassis will do. I'd be looking at the sensor connector first though...

 

[ochocinco5k]

Turns out I forgot to reconnect the temp sensor. Once I put I back in and warmed the car up it sarted dropping down to what was suggested in the TSRM until..... it started reading 4.9 then down to 1.1 or whatever. The voltage drops coincided with it running shittier like a hunting idle. It would read 1.1 idle good, 4.9 idle higher then back down to 1.0 and on and on so you were correct.

Although even when it was reading 0.6V once it was warmed up it was still idling eye wateringly rich. Ill have to figure that one out once I get back from the field excersize were doing for the army. Tht and repair the harness

 

[Mk3turbo_newb]

Are you guys talking about the water temp sensor that's near the thermostat housing??? I was just informed that my car was running a little warmer than normal by the smog tech. And the wire does look a little tired. LoL

 

[jetjock]

Huh?