My 7MGE will not idle correctly, runs rich

[Trefer84]

Hello I am having a hell of a time with my Supra. This has become very expensive and time consuming working on her.

I have taken off the intake manifold to reveal the engine block and tested every sensor, and found 1 broken VSV fuel pressure up and replaced it with a brand new OEM one. Double checked all vacuum and tested each hose for leaks with compressed air. All new gaskets and mating surface clean.

Car fires up cold and goes to 840 -930 and starts moving from 840-930 slowly. ISCV clicks when car turns off and just installed a new one 2k miles ago.
There are no engine codes. Plugs become carbon fouled and have to be cleaned the car is running so rich.

Also have checked timing marks are 100% correct and vehicle runs at 10 with timing light/ECU check connected.


#1 Resistance checked ISCV and bench tested - Passed & Cleaned. reinstalled with toyota gasket
#2 Replaced TPS and calibrated - passed
#3 replaced MAF - passed
#4 Replaced VSV fuel pressure up
#5 Vacuum tested EGR modulator and EGR valve, also cleaned and reinstalled with new Toyota Gaskets
#6 Compression tested motor 140-155 from 1-6
#7 Checked valve clearance - checked out close to spec
#8 Resistance checked Ignitor, distributor, EFI main fuse, Fuel pump solenoid and resistor, all grounds, every electrical item under hood and inside vehicle all checked good, any bad replaced new.
#9 Replaced Oxygen Sensor
#10 Replaced Fuel Pressure regulator
#11 Replaced Fuel Pressure damper
#12 Replaced Cold Start Injector time switch
#13 Replaced Engine coolant Temperature Sensor
#14 New NGK Spark Plugs and Wires with correct Gap and part numbers. .43
#15 Tested to make sure fuel injectors where not stuck open and cleaned each one.
#16 Has new Fel Pro head gasket & ARP head studs,, did not blow but did it to be safe. Ran perfect and drove 500 miles home and parked it, went out and fired it up and this problem is now present.

There are no vacuum leaks present at all. Vacuum testing motor reads 13 which slowly moves from 13-14. I am at 5600 elevation so take 1 HG per 1k elevation and subtract from 17-21 on a good engine.



At this point the only thing I can see it being is the ECU. I have taken the cover off and inspected it but it looked brand new inside with no burns or smell.

What in the hell could this be????????

 

[Nick M]

Your vacuum is low, 5600 feet or not. That indicates a worn engine, assumign it is also low and you are correct about 10 with TE1 and E1 connected. I wonder how you determine the air flow meter works correctly. It has a spring loaded door with a potentiometer that tells the PCM how far the door is open. If you loosen the spring tension, like I have seen people do, the car will run rich and even smoke. Do you have black smoke?

 

[jetjock]

Radiator cap...

 

[Trefer84]

It turns out the car needed to relearn idle procedures again.........runs amazing now that all the iffy and broken parts where fixed.

Takes about 20 minutes before the car idles correctly and stops with the rich smell. Checked vacuum at it is steady at 15 with no fluctuations anymore. Not bad for 5600 elevation and 105k miles.

I checked the MAF sensor using my voltmeter and reading the resistance values at temperatures and changes during the lid being opened. The old Maf had dead spots during that test, so I got a new one. I am sure I didnt need a TPS but figured it would probably die on me soon anyway since this car is falling apart before my eyes.


-Why would u say radiator cap as the cause of the issue?