280z Troubles Again - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
User Tag List

Reply
 
LinkBack Thread Tools
post #1 of 74 (permalink) Old 08-19-2016, 11:58 PM Thread Starter
Senior Member
 
Join Date: Jun 2016
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
(Thread Starter)
280z Troubles Again

Didn't take long..

So I picked the car up from the mechanic today, all in time and great. He said it wasn't running right still, I said eh whatever I got this. So the idle adjustment screw was all the way out, and the AFM hose was off making a huge vacuum leak. So fixed those, drove the car around for a few minutes, got some new plugs since the old ones fouled (I assumed because I drove it to the mechanic out of time). Filled up with gas and sea foam and drove about 4 hours. No problems for the first little bit, but then the car started to backfire at higher RPMS in higher gears. Then it started to feel like it was missing a little when I was in high RPMS in lower gears, and then got to where I couldn't go past about 3k RPMS in 3rd or 4th, and I could hear little backfires coming out of the exhaust. No huge gun pops but just little ones. Checked the plugs, fouled again. So something is fouling my plugs. I got home, parked it and left it sit for a couple hours. Came back, tried to start it and it wouldn't start. Cranked and cranked. So I kicked the ECU a few times (LIGHTLY) with my foot, because making sure it was attached well last time had cured my injector problem, and sure enough it fired up. Drove it to my garage, and grabbed my handy dandy EFI Bible/FSM. Ran all the tests hoping to find what made me backfire. Two came back wrong, TPS at idle, and Pins 6-8 on the AFM (PDX, I know you're lurking going "I told you at least 3 times that one isn't the important one"). So I figured, well can't hurt to fix the TPS but that won't fix whats going on at higher RPM's. So I adjusted the little wiper to touch, put it all back together, and wouldn't start again. So I figured, ah what the ****, TPS isn't right, I'll just disconnect it again and go for a spin. So I took it off, sure enough started right up. Drove it around, no better than it was, and then almost back it died on me. After fooling around with it I finally got it back to where it was suppose to be and got the car to start with a few more kicks to the ECU. So after all this my question is, do you all think the TPS being off at idle would be enough to foul the plugs again, then cause me to backfire at higher RPMS/Gears (Because of fouled plugs not TPS)? If not, what should I be looking for? I've sprayed the car down with starting fluid and I'm pretty sure I don't have a leak.

All Tests are within FSM specs (EXCEPT 6-8 AFM, PDX GIVE ME THE PEACE AT MIND AND TELL ME HOW TO FIX IT )
Timing is 100% correct. Just had a mechanic do it.
Plugs are fouled
Getting 34 or 35PSI fuel pressure with no vacuum reference, 32 or so at idle.
I don't believe the TPS can "go bad" it seems to just be wipers? The middle wiper does move as it should.
Ignition system is pretty much all brand new, so it has adequate spark.

Felt pretty good to actually get to drive it around today though, glad it didn't cut out on me while I was farther away from home

Southern Indiana

1996 Z32 300zx Twin Turbo - SOLD!
1977 280z
Echutton is offline  
Sponsored Links
Advertisement
 
post #2 of 74 (permalink) Old 08-20-2016, 12:30 PM Thread Starter
Senior Member
 
Join Date: Jun 2016
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
(Thread Starter)
Just an update, car won't start this morning. If I unplug the TPS it will start, but won't even hold an idle, so if I floor it it'll barely stay running. Adjusted the TPS back to where it should be, now cleaning my old plugs and going to try them.

Hopefully, TPS at idle caused me to foul plugs, then fouled plugs caused loss of power/backfiring at higher rpms.

Adjusted TPS, clean plugs, same problem. I am very confused at this point

It'll run and idle (kinda. You gotta hold your foot on the gas very very little) and then if you give it any more gas it immediately dies

Well, after disconnecting my harness connector at the ECU and replugging it back in, I got it to run, wouldn't hold an idle. Drove it back to where it needed to be.

So now I have some time to sit down and go through what it could be. So what I know is,
Fuel pressure is perfect, 36PSI after cranking for a few seconds.
Spark is good, plugs were clean, maybe trying to replace again rather than clean could show something?
Timing is perfect.
ECU Harness tests all pass with AFM exception
Couldn't find any vacuum leaks, don't think its likely caused by a leak
No clue why it wont hold idle

Any possibility maybe bent connections in the ECU plug have anything to do with it, or maybe its the ECU itself?
No clue why it won't hold idle. You let off the gas=die. Yeah, driving that about 3 miles was fun. Lots of burnouts.

Southern Indiana

1996 Z32 300zx Twin Turbo - SOLD!
1977 280z

Last edited by Echutton; 08-20-2016 at 02:03 PM.
Echutton is offline  
post #3 of 74 (permalink) Old 08-20-2016, 03:10 PM
Senior Member
 
Join Date: Feb 2010
Location: Oregon
Posts: 3,336
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 565 Post(s)
Can't remember what your 6-8 AFM exception is about. Not going to search.

What does the tachometer do while it's running poorly? Does it follow the engine RPM or is it jumping around, reading high?

If you can find a spare ECU, it might be worth a try. That's why I collect spare parts when I can get them cheap.
pdx280 is offline  
post #4 of 74 (permalink) Old 08-20-2016, 03:32 PM Thread Starter
Senior Member
 
Join Date: Jun 2016
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
(Thread Starter)
Quote:
Originally Posted by pdx280 View Post
Can't remember what your 6-8 AFM exception is about. Not going to search.

What does the tachometer do while it's running poorly? Does it follow the engine RPM or is it jumping around, reading high?

If you can find a spare ECU, it might be worth a try. That's why I collect spare parts when I can get them cheap.
AFM between 6-8 measures 300Ohms rather than continuity, you told me that wasn't the important of the 3.

Tach works good, follows it around.

I'll see if I can find any for sale.

Southern Indiana

1996 Z32 300zx Twin Turbo - SOLD!
1977 280z
Echutton is offline  
post #5 of 74 (permalink) Old 08-20-2016, 03:51 PM
Senior Member
 
Join Date: Feb 2010
Location: Oregon
Posts: 3,336
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 565 Post(s)
6-8 should be 180 ohms. It's shown on page 74 of the guide I linked to in the "EFI missing pins" thread.

As I recall, your critical AFM numbers were 100 and 180 way back in one of your early posts. I think that you might be losing track of your numbers.
pdx280 is offline  
post #6 of 74 (permalink) Old 08-20-2016, 05:03 PM Thread Starter
Senior Member
 
Join Date: Jun 2016
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
(Thread Starter)
Quote:
Originally Posted by pdx280 View Post
6-8 should be 180 ohms. It's shown on page 74 of the guide I linked to in the "EFI missing pins" thread.

As I recall, your critical AFM numbers were 100 and 180 way back in one of your early posts. I think that you might be losing track of your numbers.
Ah maybe I put the wrong pin numbers, one of them measures approximately 180Ohms, one approximately 100Ohms and one to be continuity, the one that measures continuity measures 300Ohms.

At least thats what my EFI Bible states. I believe its 6-8=Continuity (300 for me), 7-8=180, 8-9=100?

And then the continuity for the pump contact.

Southern Indiana

1996 Z32 300zx Twin Turbo - SOLD!
1977 280z
Echutton is offline  
post #7 of 74 (permalink) Old 08-20-2016, 05:07 PM
Senior Member
 
Join Date: Sep 2015
Location: Central FL
Posts: 424
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
if its fouling plugs again, did you check the cold start injector to make sure its off? maybe injector is stuck open or the thermotime switch may be stuck closed.


Carbon fouled plugs mean serious over rich condition. did you confirm the temp sensor again at the ECU for resistance/temp (if the cold start is not the issue).


do you have a vaccum gauge, check that. for some reason 32psi seems high with it at idle. thinking maybe could be a problem with either a vacuum leak or a fuel regulator.
Dave M is offline  
post #8 of 74 (permalink) Old 08-20-2016, 05:15 PM Thread Starter
Senior Member
 
Join Date: Jun 2016
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
(Thread Starter)
Quote:
Originally Posted by Dave M View Post
if its fouling plugs again, did you check the cold start injector to make sure its off? maybe injector is stuck open or the thermotime switch may be stuck closed.


Carbon fouled plugs mean serious over rich condition. did you confirm the temp sensor again at the ECU for resistance/temp (if the cold start is not the issue).


do you have a vaccum gauge, check that. for some reason 32psi seems high with it at idle. thinking maybe could be a problem with either a vacuum leak or a fuel regulator.
Didn't check anything that wasn't in the FSM, I know the cold start valve passed the FSM test, showed 0V at first and then battery voltage after 3 seconds or so. I can always unplug it. I installed it brand new a few weeks ago. Thermotime may be broken, I just changed its connector last week, but didn't run any tests on it. The temp sensor is working perfectly, I do know that.

I do have a gauge, I'll check it out when I have a few minutes

Southern Indiana

1996 Z32 300zx Twin Turbo - SOLD!
1977 280z
Echutton is offline  
post #9 of 74 (permalink) Old 08-20-2016, 05:24 PM
Senior Member
 
Join Date: Sep 2015
Location: Central FL
Posts: 424
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
one thing you can do to be sure its not the cold start, just clamp the hose that feeds it. You really should not even need it at all during the summer. You need to test things even new to make sure they work, just imagine if the brand new cold start was stuck open pouring fuel in the manifold. I don't trust stuff just cause its new.
Dave M is offline  
post #10 of 74 (permalink) Old 08-20-2016, 05:29 PM Thread Starter
Senior Member
 
Join Date: Jun 2016
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
(Thread Starter)
Quote:
Originally Posted by Dave M View Post
one thing you can do to be sure its not the cold start, just clamp the hose that feeds it. You really should not even need it at all during the summer. You need to test things even new to make sure they work, just imagine if the brand new cold start was stuck open pouring fuel in the manifold. I don't trust stuff just cause its new.
Good point, I wouldn't ever need it anyways I don't think. I have no reason to drive the 280 when its cold. As for vacuum pressure do you know the PSI off the top of your head? I don't think I've ever seen a number in the FSM but I recall something like 18PSI at idle from reading somewhere.

Southern Indiana

1996 Z32 300zx Twin Turbo - SOLD!
1977 280z
Echutton is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



  Similar Threads
Thread Thread Starter Forum Replies Last Post
EFI Troubles - Revisited - 77 280Z JoelR 70-83 Tech Discussion Forum 9 10-02-2010 12:27 AM
1978 280z running troubles gofastnoslippy 70-83 Tech Discussion Forum 5 10-07-2008 04:33 PM
280z Brake troubles AlabamaZNut 70-83 Tech Discussion Forum 3 07-29-2005 07:17 AM
78 280z steering troubles mauicowi 70-83 Tech Discussion Forum 5 02-29-2004 01:37 AM
more engine troubles 78 280z mllcb42 70-83 Tech Discussion Forum 4 07-13-2002 09:24 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
 


Content Relevant URLs by vBSEO 3.6.1