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280zx sputtering problems/backfiring while driving.


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Well this is a problem i've been battling for a few months and I decided to see if you guys could help me out because i'm confounded.

 

I have a 83 280zx with a 81 zxt swap in it. The car starts up, used to run great but now it drives like crap.

 

When I go to drive, 80% of the time the car will bog down, stutter alot, possibly backfire and just generally run like crap. The noise it makes is hard to describe.... It's like if you made a farting noise with your tongue.. lol

(I can throw something on youtube if you guys want to hear it)

 

I can get through it sometimes by pressing the pedal but most of that time it just backfires and sounds god awful.

 

I have replaced the fuel pump with a walboro, tps, fuel filter, switched over to a 83 dizzy, head temp sensor, double checked all my wires, triple checked my timing and checked for boost leaks.

 

Have any of you heard heard of something like this? The only thing I haven't changed out yet is my afm. It was obviously opened before I bought it, but seemed to work great.

 

Like I said.. this just started happening out of nowhere and my wallet is beginning to get unhappy from parts and shipping costs :D

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  • 3 weeks later...
Well this is a problem i've been battling for a few months and I decided to see if you guys could help me out because i'm confounded.

 

I have a 83 280zx with a 81 zxt swap in it. The car starts up, used to run great but now it drives like crap.

 

When I go to drive, 80% of the time the car will bog down, stutter alot, possibly backfire and just generally run like crap. The noise it makes is hard to describe.... It's like if you made a farting noise with your tongue.. lol

(I can throw something on youtube if you guys want to hear it)

 

I can get through it sometimes by pressing the pedal but most of that time it just backfires and sounds god awful.

 

I have replaced the fuel pump with a walboro, tps, fuel filter, switched over to a 83 dizzy, head temp sensor, double checked all my wires, triple checked my timing and checked for boost leaks.

 

Have any of you heard heard of something like this? The only thing I haven't changed out yet is my afm. It was obviously opened before I bought it, but seemed to work great.

 

Like I said.. this just started happening out of nowhere and my wallet is beginning to get unhappy from parts and shipping costs :D

 

it could be the afm. My afm has the tendency to get stuck open and the car either dies or runs like crap. Have you double checked for vacuum leaks?

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I recently replaced my afm and coil with a msd blaster 2 and it didn't make a bit of difference.

 

Right now i'm leaning towards a screwy ecu or maybe the valves need readjusted...

 

The only thing I haven't replaced atm is my injectors, but i can't really see them doing that.

 

Also.. I did buy a ecu out of a 83 turbo from a junkyard but it starts the car and instantly dies the seconds i give it gas. They absolutely refuse to take it back so that was 70 bucks down the drain.

 

This is annoying too because the Z is so fun to drive with the ttops off. We don't really have many around iowa do to rust and crappy winters.

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you might open the junkyard dizzy and check the innards. Look for burnt diodes and/or conductors on the board the have scorched. I have had success by running a piece of 22 ga stranded to replace blown board conductors. Replace diode if burnt. Need a 25 watt solder iron and electronic duty solder. anything heavier than 25 watt do more damage and no repair. pic of one that I resurrected.

15105_thumb.attach

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checked both boards and I don't see any questionable places. Everything all pretty and new looking,:mrgreen:

 

Could the valves be causing that kind of problem or does it sound more electrical? To me it seems electrical since the car starts, runs, revs and the problem kind of comes and goes as it pleases.

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I had really weird driveability issues with my motor (83 L28ET). My fuel pump died; so I put a Walbro external pump on it. Then (now) the car would barely turn over or idle and cut out while driving. checked a half million voltages and resistances. All good. If i held the AFM flapper door in a little bit it would idle. End result hooked a fuel pressure gauge and got an initial reading of a hose on the gauge instantly swelling and blew before I could get the key off. Did it again and got about 135psi. I think thats about 100 more than I need. Unhooked the return and put it in a gas can and pressure dropped to about 26 psi at idle. (Pressure was @ 37 psi with no vacuum line hooked to regulator) I havent found the blockage in the return line yet but Im guessing it will solve the majority of my FI issues. Its VERY worth checking out. I live outside DM if you needed to use the gauge or anything. Ive been chasing these problems since the last time I talked to you, just figured it all out last night. Best of Luck, A.J.

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Well i bought a fp tester and at idle the car sits right around 30 and when i give the engine gas it will go up to around 38-39.

 

There is a noticeable stutter in the gauge though thats pretty consistent. It will idle at 30 and every 3 seconds or so it will hiccup and stutter for a sec and the gauge will dip down to 28 and back up to 30. You can hear the sloshing inside the gauge when it happens.

 

I can't think of anything else that could be wrong... I'm really hesitant to buy another ecu just for testing purposes because the last one I bought was dead and the junkyard pretty much told me "tough luck..."

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When I removed the obstruction in my return line the pressure dropped from 135psi to about 29psi. With the vacuum line removed from the FPR the pressure was about 38psi. With 10 Hg of vacuum on the FPR it was about 33 Psi. I was thinking my fuel pressure seemed low as well but the car seems to run fine? The gauge deffinately had a costant flicker to it. Jumped around a .5 PSI or so constantly. It wasn't like you described though; mine was just constant fluctuation between 29 & 30 PSI. Im going to try a new FPR and see what happens.

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I got my fuel pressure to stay around 39-42 by pulling the float in my trunk, removing the filter and cleaning it. I used some dawn dish soap + a toothbrush for 5 minutes or so and now I can see through the filter again.

 

Hopefully something dumb like this will help you out.

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The car has been running perfect since I cleaned it out. It's hard to believe that something so small could F my cars performance up so bad.

 

Is there any Z following in des moines now? It would be so cool to get about 10+ people together and go on a Z cruise.

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