Car idles but dies when I give it gas.

[dylancorrea1]

I just had the car running, but the other day when I went to start it, it just wouldn’t start. Today I attempted to get it running but to no avail. I ended up getting it to idle healthy, it smells rich but other than that idle is great. But as soon as I give it gas it begins to sputtering and giving front afm backfire. (Adjust the afm to get it to idle by adjusting the fuel mix). 1978 280z
 
 
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[cgsheen1]

10 minutes ago, dylancorrea1 said:

it smells rich but other than that idle is great.

🤣

[SteveJ]

Start with checking the basics.

1. Does the timing at idle match factory specs?
2. What is your fuel pressure?
3. Have you checked the valve lash?

[dylancorrea1]

Start with checking the basics.

1. Does the timing at idle match factory specs?
2. What is your fuel pressure?
3. Have you checked the valve lash?

I can check timing again, I checked about a month ago and timing was matching factory. I haven’t checked my fuel pressure, I actually just got a new FPR because Ive been upgrading some parts. Its a factory FPR and was thinking of installing it, and then checking pressure. Haven’t checked valve lash.

[cgsheen1]

Go through the EFI troubleshooting basics in the FSM and triple check your EFI wiring and connectors - make sure everything is CLEAN. Check your EFI coolant sensor for correct Ohm reading.

Please don't touch the AFM until you've literally done everything else (unless someone else already screwed you by messing with it). Vacuum leaks will completely throw the ECU out of whack. If you've had a windshield leak in the left bottom corner be sure to pull out the ECU and check the connector and all the pins for corrosion.

L Series love a rich condition - up to a point.

[kickstand80]

A bad connection at the AFM will do this. The car will start even with the AFM wire disconnected but will die if you give it gas. I agree cgsheen1 about DONT mess with the AFM. Nothing good can come of it. They are pretty reliable and most of the time issues with these cars have nothing to do with the AFM but people go after them. Once you have messed with it it will be very difficult to get it back to factory settings and once you have figured out what is really wrong then your AFM will be out of adjustment and then it will be the issue.

Vac leaks will also cause this type of engine behavior. Check the connection for the coolant temp sensor, the one that feeds the ECU.

[dylancorrea1]

A bad connection at the AFM will do this. The car will start even with the AFM wire disconnected but will die if you give it gas. I agree cgsheen1 about DONT mess with the AFM. Nothing good can come of it. They are pretty reliable and most of the time issues with these cars have nothing to do with the AFM but people go after them. Once you have messed with it it will be very difficult to get it back to factory settings and once you have figured out what is really wrong then your AFM will be out of adjustment and then it will be the issue.
Vac leaks will also cause this type of engine behavior. Check the connection for the coolant temp sensor, the one that feeds the ECU.

I’ll avoid messing around with the afm from now on, what’s the ohm reading I should get from the coolant temp sensor? I still have to check for vacuum leaks.


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[kickstand80]

The OHM reading changes as the engine warms up. Cold sensor high ohm. Hot sensor low OHM. I know the Coolant temp sensor and a Cylinder head sensor are really close when it comes to the OHM values. I have a 1981 and a 1983 car so I have CHTS, not coolant sensor but the ohm value should be around 7000 if you put it in ice water and around 200 in boiling water.

Tried to upload a picture of the graph but keep getting errors. If you go to this site:

http://xenonzcar.com/s130/FSM/1981fsm.php

Look at page 18 of the Engine Fuel section you will find the graph.