1990 GTR Running SUPER rich HELP!!

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Rebel13
Posts: 3
Joined: Sat Dec 16, 2017 10:35 pm
Car: 1990 R32 GTR

1990 GTR Running SUPER rich HELP!!

Postby Rebel13 » Sat Dec 16, 2017 10:48 pm

So I bought a 1990 GTR last week and I have been cursed by bad coils and plugs but got all that replaced and tested And all is good there. But the car is still running ungodly rich at idle and through the revs. It’s spitting out fuel right out the pipe. Car will back fire and so I looked into the MAFs and used a multimeter to check the signal wires and power/ground and I’m getting about 1.2V at idle (1200rpm) out of the signal wires coming back from the MAFs as well. But the weird part is I disconnected the MAFs and the condition stayed the same. Also I’m getting 0V coming off my TPS at any throttle position. I’ve heard temp sensors can cause issues but the car does it cold and hot so I’m stumped.Hope someone can help me thanks so much!

Rebel :gotme


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asoomal
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Joined: Tue Feb 26, 2008 4:45 pm
Car: 2001 Subaru Impreza L 5MT (Daily)
1992 Nissan 240SX SE 5MT w/HICAS (Being restored)
Location: Canada

Re: 1990 GTR Running SUPER rich HELP!!

Postby asoomal » Sun Dec 17, 2017 8:47 am

Does the engine coolant temp sensor's output change as the engine warms up?

Rebel13
Posts: 3
Joined: Sat Dec 16, 2017 10:35 pm
Car: 1990 R32 GTR

Re: 1990 GTR Running SUPER rich HELP!!

Postby Rebel13 » Sun Dec 17, 2017 10:33 am

I have not check that out at all. Does it matter even if the car cold or does the car think it’s overheating? Is there a resistance range I should look for over the sensor? Thanks.

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asoomal
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Joined: Tue Feb 26, 2008 4:45 pm
Car: 2001 Subaru Impreza L 5MT (Daily)
1992 Nissan 240SX SE 5MT w/HICAS (Being restored)
Location: Canada

Re: 1990 GTR Running SUPER rich HELP!!

Postby asoomal » Tue Dec 19, 2017 8:03 pm

There should be two sensors, one for the gauge and one for the ECU.

If I recall correctly, the sensor is sort of fail safe in a way. When the sensor fails, the engine should dump more fuel as the sensor will output it's max voltage.

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M35Squirrel
Posts: 185
Joined: Wed Jul 16, 2014 8:35 am
Car: 1990 GT-R, 2011 M37
Location: Houston, TX

Re: 1990 GTR Running SUPER rich HELP!!

Postby M35Squirrel » Wed Dec 20, 2017 8:24 am

The coolant temp sensor is an identical sensor to the air temp sensor next to it mounted on the plenum. You can just swap the two and see if anything changes. A 19mm long socket and you can take it off in 5 seconds. Also listed in the FSM there is a voltage or resistance range for the sensor, just dip it in hot water and you can measure.

TPS really should not be 0v. So that can be your problem right there.

The solders on R32 MAF do come loose with age, it's a known and common problem. I believe if you google you can find a couple different write ups on how to crack it open and re-solder.

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EstoMax
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Re: 1990 GTR Running SUPER rich HELP!!

Postby EstoMax » Wed Dec 20, 2017 2:53 pm

when i had my z32 MAF wired wrong back in the day it was always telling the engine about 20% load, even at idle, and it ran rich (or not at all really). If the wiring is all OEM then that shouldnt have been messed with, but look at the voltage going back to the ECU (consult FSM)

Rebel13
Posts: 3
Joined: Sat Dec 16, 2017 10:35 pm
Car: 1990 R32 GTR

Re: 1990 GTR Running SUPER rich HELP!!

Postby Rebel13 » Thu Dec 21, 2017 4:17 pm

Checked voltage and it’s all in spec with the car running. Also I halve a Haltech platinum pro with a base tune for a 26 on it and looked at all my sensors and they all read properly to include throttle position and about 49 to 54hg a at idle. I’m going to do a compression test later and get back to you guys. I’m wondering if I should hold unplug my o2 sensors as well to make it go open loop. This thing is taking me for a run. I’ll get back to you guys with results.in in the army and family time is priority right now. MERRY Christmas!


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