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Tim Mohr
Tim Mohr, ASE MASTER TECH
Category: Nissan
Satisfied Customers: 560
Experience:  30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
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92 nissan D21 pickup. Standard cab. 4 cyl. Manual trans.

Customer Question

92 nissan D21 pickup. Standard cab. 4 cyl. Manual trans. changed the fuel filter and fuel pump. It starts, runs for 10 minutes and shuts down as if turned off the key. next step was to turn the key on without starting, to build up pressure in fuel system at which time it will start and run for 10 min and shut down.
Submitted: 10 months ago.
Category: Nissan
Expert:  Jay replied 10 months ago.

Hello my name is ***** ***** thank you for your question.

Do you happen to know if you have any codes?

Customer: replied 10 months ago.
no codes. the owner, a friend on whose behalf I'm asking the question says the engine needs to be up to temp to throw codes, not sure why 15 minutes at 1800 didn't bring it up to temperature though. So he says no codes. What do you think?
Customer: replied 10 months ago.
he says he will try to get codes next
Expert:  Jay replied 10 months ago.

If there is a fault in a circuit, it would produce a code quick. So if you can, have him double check. If he doesn't know how to manually check for codes let me know. I will supply the steps.

This sounds like a distributor issue.

Let me know..

Customer: replied 10 months ago.
He says he will try to get codes tonight after work. He didn't ask how to manually retrieve codes when I told him you would provide the procedure so I guess he knows how. I'm a little curious about it though. He says the unit related to codes is under the driver's seat. Is there another place, with blinking lights perhaps, where you read the code manually? I have a 1984 Porsche 944 that I've had for 25 years and I had what I thought was a fuel problem when the car wouldn't start if left out in the cold overnight, unless you gave it a shot of starter fluid. I replaced just about everything in the Bosch fuel injection system but unfortunately started at the back instead of the front. It turned out to be the computer, the last thing left to replace. In 1984 the system didn't throw codes. You had to manually test every component in the system. I will be back in touch when he double checks for codes. We are on Alaska standard time.
Expert:  Jay replied 10 months ago.

not a problem. Let me know if he has codes. Also have him check for spark and injector pulse if he can.

Talk to you later.

Yes, these older vehicles with computers there were much more testing required to isolate issues.

Customer: replied 10 months ago.
The car starts, idles normally and then dies.... restart same thing. He ran it at 1800 rpm for 15 minutes. That requires spark and injector pulse. When you say "check" that what exactly do you mean?
Expert:  Jay replied 10 months ago.

92 may be the cut off year. Does this have the 2 injectors in the throttle chamber or does it have 4 injectors 1 per cylinder?

Customer: replied 10 months ago.
I think I asked him if it's throttle body or multi-port injection but that was a week or so ago and I don't think he answered me yet. I will ask him again.
Expert:  Jay replied 10 months ago.

The throttle chamber on some of the old trucks had 2 injectors that mount in the top of the throttle chamber. Later they took the two injectors out, and put 1 per cylinder. I don't have to much data on these older trucks. I have from 94 and up. So I am working off memory of these trucks.

Expert:  Jay replied 10 months ago.

If this truck has the 2 injectors in the throttle chamber, I have seen them dump to much fuel which drowns out the truck.

Other wise, it could be a MAF sensor issue.

Customer: replied 10 months ago.
I suppose it could be the MAF sensor or any number of other things or even a combination of things. But idling for five minutes dying and restarting only to repeat cycle might be a commonly reported pproblem
Expert:  Jay replied 10 months ago.

I have seen ports in the intake get all carboned up which can keep the truck from running when it warms up.

Either that or a fuel pump maybe. It has fuel pressure as the pump warms it looses pressure.

It could be a number of things. The first thing we need to check is to see if it can produce a code.

Expert:  Jay replied 10 months ago.

MAF sensor has a heated element. When cold it could run but as it warms it dies.

Customer: replied 10 months ago.
Does only at idle five minutes in runs at 1800 rpm at least 15 min after which owner shut it off
Customer: replied 10 months ago.
As noted fuel pump is new and filter
Expert:  Jay replied 10 months ago.

Codes?

Expert:  Jay replied 10 months ago.

He is giving it gas to run at 1800 rpms? it will only start and idle on it's own for around 5 mins?

Customer: replied 10 months ago.
gives gas to 1800 rpm dies at idle but restarts dies again after 5. Still waiting to get codes its 3:30pm here. No throttle body multi port injection
Expert:  Jay replied 10 months ago.

It has the 4 injectors?

Customer: replied 10 months ago.
Expert:  Jay replied 10 months ago.

Waiting on codes...

Customer: replied 10 months ago.
Me too
Expert:  Jay replied 10 months ago.

Any idea when he will check?

Customer: replied 10 months ago.
He is having trouble getting codes. The slotted screw in the ECU is broken and he can't turn it fast enough to set the diagnostic mode, he said. He says he will need to remove the seat and set the ECU up where he can get to it, or maybe replace it entirely. I have suggested to him that he first try replacing the O2 sensor. It's available for $5 to $10 dollars. As you probably know, that sensor is not used by the ECU on cold starts and as the engine warms it takes over the air/fuel mixture (with input from coolant temperature sensor). If it isn't working the ECU stays at rich mixture that could kill the engine at idle. When the engine is up to speed the O2 sensor is again not used (or so I've read) which could explain why the engine runs at 1800 rpm and doesn't die. The over rich fuel mixture would cause more fuel consumption, which the owner also noticed before this dying at idle problem made the car basically unusable. If that turns out not to be the problem then he can look elsewhere, maybe even replace the ECU at $50 -$75 for a used unit with a 90-day warranty. Then he can get codes.
Expert:  Jay replied 10 months ago.

The 02 sensor is used in all situations. It has a heater to help it warm up faster to get to operating temp. The readings it produces from the exhaust tell the computer if it's running to rich or to lean so it can try to make adjustments to balance the fuel trim if it can.

I would rather not throw any parts at the truck till we can read the codes.

Customer: replied 10 months ago.
The newer O2 sensors have a heater. The older ones do not. This is an older one. 1992 Nissan D21 ONE WIRE. Like the O2 sensor in my old Porsche, it is heated by the EXHAUST and does not send a signal when starting a cold engine. At high engine speeds the O2 reading is ignored according to what I have read:When an internal combustion engine is under high load (e.g. wide open throttle), the output of the oxygen sensor is ignored, and the ECU automatically enriches the mixture to protect the engine, as misfires under load are much more likely to cause damage. This is referred to as an engine running in 'open-loop mode'. Any changes in the sensor output will be ignored in this state. In many cars (with the exception of some turbocharged models), inputs from the air flow meter are also ignored, as they might otherwise lower engine performance due to the mixture being too rich or too lean, and increase the risk of engine damage due to detonation if the mixture is too lean.
Customer: replied 10 months ago.
I think at this point we should close out the question. Thank you for trying to help.
Expert:  Jay replied 10 months ago.

I would agree. It seems since you are the man in the middle of this and since we can not read the codes yet. It is making this more difficult for both of us.

https://dl.dropboxusercontent.com/u/105565483/0a.jpg

That is the operation of the 02 sensor. So you know what it does for this vehicle.

Thanks Jay!

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