76 EFI help?

[Guest WaterDragon]

I know... do a search...

 

But this is where I am at. I just got the 76 280z and it runs and revs in nuetral when cold. Once it warms up it gets really choppy, wont rev and starves its self out or drowned its self (francly, witchever it prefers). I replaced the fuel pump, fuel filter, coil, cap and rotor, plug wires, plugs and drained the old gas and put new gas in. when you rev the engine it misses and smells like gas. If you try to drive it forward it wont rev and tries to die. Before I get the car the ECU and Injectors where replaced.

 

Any help please. I need this car for a daily untill I can get in a position for an SR or LS1 swap.

[RTz]

Unplug the water temp sensor and see if the car behaves the same.

 

[Guest WaterDragon]

I had not thought about that. I read the guide and then I combined the No Rev and the Sputtering trouble shoot section and combined the 2 to get comman problem areas... odviosly it didn't work and i'm here asking for help. ha ha, tangents.

I will definitly try that tomorrow.

 

One question, doesn't the water temp sensor stop workign after it gets warm? or is that another part?

[RTz]

One question, doesn't the water temp sensor stop workign after it gets warm?

 

No.

 

Spend some time reading the EFI bible.

[Guest WaterDragon]

No.

 

Spend some time reading the EFI bible.

 

 

I read that, did that, everything seams to be normal. We got it operate fine at rest but once you put a load on the car ei put it in fist and try to go, the car bogs and does not want to get RPM. it wont even go past 1500 RPM. Put it back into nuetral and let it idle for a minute and she runs ok but not back to good.

 

would a loose gas cap cause a vacum leak. we tested and fixed all the vacums leaks we could find.

[cygnusx1]

After a full tune-up...air filter, plugs, wires, cap, rotor, check ignition timing. Check operation of the AFM flap and confirm it works by checking with the factory FSM. Check all the sensors against the FSM, check grounds and connectors everywhere in the EFI system. Loose or ripped intake boots? Does the idle change when you unscrew the oil cap? It should stall.

 

You can get the FSM in the downloads section here at HBZ.

[Guest WaterDragon]

Thank you very mutch, The FSM should be a big help. I couldn't even find a chiltons anywhere and was going to have to order one online. Z's aren't all that big here in Albuquerque. And yes we have done a full tune up. Did all the tests in the EFI bible, all came up normal.

 

I appologize for the spelling: I've got the flue or something and am not thinking entirely straight.

[Guest WaterDragon]

After a full tune-up...air filter, plugs, wires, cap, rotor, check ignition timing. Check operation of the AFM flap and confirm it works by checking with the factory FSM. Check all the sensors against the FSM, check grounds and connectors everywhere in the EFI system. Loose or ripped intake boots? Does the idle change when you unscrew the oil cap? It should stall.

 

You can get the FSM in the downloads section here at HBZ.

 

 

pulled the oil cap: killed the engine almost right away.

[RTz]

I read that, did that, everything seams to be normal. We got it operate fine at rest but once you put a load on the car ei put it in fist and try to go, the car bogs and does not want to get RPM. it wont even go past 1500 RPM. Put it back into nuetral and let it idle for a minute and she runs ok but not back to good.

 

I'm not sure if you answered this or not... when you unplugged the WT sensor, did the car run the same or different? If it ran the same, there is a problem in that circuit (and quite common).

[mom'sZ]

Sounds like the throttle position sensor might be out of adjustment.

It has been my experience that when the water temp sensor goes bad, the system goes full rich. It won't run in gear and smokes badly (blue) won't idle and only runs half decent when you rev it up

Check the throttle position sensor. Don't replace it, check it for proper adjustment and readjust if neccesary. Here's how: Pop the cover off. Inside you will find two sets of contact switches. One should make contact when the car is at an idle and the other should make contact when the throttle is about three quarters open. They should not make contact at the same time and there should be some throttle travel between when the idle one opens and the WOT one makes contact. Adjust by turning the assembly (it has little set screws that can be loosened and the whole thing will turn slightly) and bending the contact arms (gently)

Also.. this sounds similar to when my stock ignition module went bad. In my case, the ignition module would go heywire when I revved the motor up close to redline. It (the ignition module) would overheat and the motor would barely run. Maybe in your case it is worse and it runs OK when first fired up but once it's run for a little while, module heats up and motor won't run right.

[Guest 52977]

My friend and I have been working on a 1977 280z, and have noticed the same symptoms. My friend knows a guy who worked on a lot of them and he said, "the car thinks it's cold." Just on a hunch, we pulled the connector off of the cold start injector and much to everyone's surprise, the car drove much better, but still bogged down at times. It was really hard to start, though (i wonder why:wink:). We plan on cleaning the connectors and replacing O2 and temp sensors within the week to get everything working as intended.

[woldson]

My friend and I have been working on a 1977 280z, and have noticed the same symptoms. My friend knows a guy who worked on a lot of them and he said, "the car thinks it's cold." Just on a hunch, we pulled the connector off of the cold start injector and much to everyone's surprise, the car drove much better, but still bogged down at times. It was really hard to start, though (i wonder why:wink:). We plan on cleaning the connectors and replacing O2 and temp sensors within the week to get everything working as intended.

 

Interesting, and insightful for your frist post. Cheers!

[mom'sZ]

People please... before you post a problem with your EFI 280z, get a can of electric contact cleaner and a toothbrush. Disconnect every connection in the EFI harness and spray - brush - clean each connection, there are only a few on the EFI harness. (it's a seperate harness from the rest of the car)

[Guest 52977]

Okay, here's my latest update:

The car runs b-e-a-utifully... for 15 to 18 minutes on the road at 35-40 mph, then when I try to accelerate, i can feel the car decelerating unless I accelerate very slowly. We have cleaned all of the connectors. The spark plugs seem dry and not carbon covered.

[WizardBlack]

You AFM won't actuate through it's whole range of motion. Take the cover off the AFM and clean, lube and test function.

[Guest 52977]

I forgot about this until now, but when slowing down or shifting, the engine stays at a fairly high idle until I come to a complete stop. Could this be explained by a sticky AFM as well?

[WizardBlack]

I forgot about this until now, but when slowing down or shifting, the engine stays at a fairly high idle until I come to a complete stop. Could this be explained by a sticky AFM as well?

 

Hmm, that could be a stuck throttle. A stuck AFM would just make it run a bit rich (or really rich depending on how bad). You may very well have both. I'd definitely get both the throttle and AFM cleaned and working freely. AFM's are notorious for sticking open, sticking shut, not shutting all the way, not reading all the way, etc. etc. etc.

 

EDIT: Thinking back to a stock Z (it's been a while), I am not sure how stuck the throttle can get with the solid throttle linkage, but there is a bi-metal idle control device on top of the intake manifold that could be out of adjustment, etc. Could be the throttle stop as well, I suppose.