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1983 280zx N/A poor throttle response, and backfire through intake

3K views 13 replies 6 participants last post by  palladin 
#1 ·
Hi, just like the title says, I've been getting shitty throttle resonse, and backfire through the intake. It backfires occasionally, and when I hit the throttle it feels like it will stall, and then it slowly picks up in the rpms. All thats been done to the engine us this-
-Injectors
-Ecu
-ICM
-Fuel filter
-air filter
-cap
-plugs and wires
Any input would be helpful, thanks!
 
#5 ·
Well that is opposite of what the issues usually describe. Typically its a lean condition for front fire (through the intake) as well as poor response. Whats the story here primus, how did you get to this point?
Good one PDX280!
 
#7 ·
Car has 200,000+ miles, no valve tick, injector six seems a little loud, compression test came back with
1 180
2185
3190
4190
5178
6180
plugs, wires were changed, as well as ignition module, injectors were also replaced and fuel filter and ecu. timing is set at 8 degrees BTDC when I hit the throttle it sort of lags and then starts to pick up, i attempted sea-foam, but i poured a drop in, and it literally threw up, like it shot it out the vacuum hose with quite some force.
P.S. I do hear a slight hissing sound near the pressure regulator before starting when the fuel pump primes the system, possibly a new FPR? but plugs say I'm running rich.
 
#8 · (Edited)
When seafoam is added its natural for the engine to sputter. The fpr does hiss, PDX told me that a while back on this forum. What is your fuel pressure? Did you look at the Fuel injection bible P40 and P44? More info can help us help you.
 
#12 ·
You should really narrow down whats going on before tearing into anything else. There are tons of issues with being overly rich on this site. Read the FSM and the Fuel injection bible. I will also advise you on the chts (Cylinder head temperature) sensor. If its wonky you will run rich too. Its cheaper than messing with an AFM.
Merry christmas
 
#13 ·
check your afm. Under the cap where the arm wipes across for the variable signal, I've seen it 'seperate' and lose contact at certain points although that's likely to produce a rich condition rather than lean.
 
#14 ·
Here is another possibility.....I set my timing per the book and it ran like crap. I too was getting backfire on startup. I did find vacuum leaks and correcting that made it better, but not 100%.

I don't know why I went here (I think the pulley was wobbling), but I removed the harmonic balancer and found that the woodruff key had sheared and the harmonic balancer shifted on the crank. Ran better after that was corrected.

As for the fuel level light....there is a sensor in the gas tank, it looks like a .38 special cartridge. It is hollow inside where it houses a wafer with two wires coming out; one wire is soldered to the end of the cartridge to ground it. When the wafer dries out, it makes contact and illuminates the light. If the wires pull out, there is no way of reattaching to the wafer that I know of. You cannot solder it and I know of no conductive paste. So it could be the one feeder wire is making contact to the ground. BTW, you cannot replace it, there is no part number. You have to salvage one off of another fuel level gauge.
 
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