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When I had a bad coil pack it tested fine according to the fsm, and readings as the new one. But since you're getting randoms instead of just one cylinder it's more likely something affecting everything like the fuel system
I believe so, I ran the car while using it and it was pulling RPMs, and other information from several sensors... is there something you want me to look for?
Originally Posted by cswlightning
When I had a bad coil pack it tested fine according to the fsm, and readings as the new one. But since you're getting randoms instead of just one cylinder it's more likely something affecting everything like the fuel system
My fuel was low last night and the stuttering went crazy, as soon as I put fuel in it, it was almost driving normal and it crunk up a lot faster immediately after a refuel. I have a 10:30am EST meeting, when that's over I'll check the fuel sending units to see if they're working properly. I read somewhere that someone had a similar P0300 problem and when they checked the the fuel pump on the sending unit, it was barely hanging on or something and all they had to do is put it back together. We'll see.
If you can read freeze frame data you want to see at what conditions the P0300 and P0171 codes are occurring. If your car is under load and it was not getting the required fuel that is a sign of fuel delivery issue. You can test fuel pressure, but you need an adapter. Z1 sells a pretty nice one, but it's like 60-70 bucks.
You'd also want to check your short-term and long-term fuel trims to see how the fuel mixture is working. You want your long-term (base fuel delivery) to be close to 0, however, +-10% is considered acceptable. The short-term is instant fuel levels. So, if you're at idle and it's like +25% that means it's adding extra fuel due to unmetered air getting in the system.
The 3-4 seconds to start though is also a sign of fuel delivery issues as well. It could either not be keeping a prime, weak, or on it's way out. There is also a rubber grommet in the fuel pump that can cause a lot issues it's about 10 bucks to order from Z1.
Before I decided to hook more stuff up to the car, I decided to look at the fuel lines... and I noticed something didn't look like every other fuel system I've seen on here. What the hell is going on here? I could tell whomever had this car before me did some mods... there's cut outs in the trunk for what I believe was a rear strut bar, you can tell there was a strut bar in the front from wear on the plenum cover. Radiator hoses are aftermarket as well. Does anyone have any idea what's going? I'm not even sure how to get this back to factory. Everything under the hood looks fine.
What are these? They are not on factory sending units.
That looks like maybe an aftermarket fuel filter? The stock car has sending units on the side of the pump. The other side of the car has another sending unit. The only filter with stock is the small sock on the fuel pump. If that's an aftermarket filter that could be one problem.
I can't really tell, but you can try taking the hose going in off the filter. Then take the other hose and put it on the pump housing connection.
Last edited by coffeysm; Aug 26, 2018 at 11:50 AM.
So I pulled both fuel sending units... my fuel gauge was reading incorrectly as well. The weird thing that was on the passenger side had these ID # on it
0280160575
4.0 bar (pressure)
Made in Germany
050
One tube was routed to the front of the car but I'm not sure where. It was connected to the open port shown in the picture . Why would someone install a secondary fuel pressure regulator?
I thought I posted but evidently it didn't. So I replaced the fuel sending unit (used the existing O-rings...will change later). My car is back to normal. It did have a CEL for P1273 (Air Fuel: Lean), but I did an A/F mixture reset and that cleared that code up. It's running like a champ now.
This is what happened and what I did to remedy.
Car did not throw a CEL, but would hesitate and stutter during acceleration. It also had extremely long start ups.
Thought it was the cam shaft and crankshaft position sensors. Swapped them out with aftermarket, No change in horrible performance. Swapped them out with OEM, No change in horrible performance.
Checked coil packs. They looked like they were in good order. Replaced spark plugs with NGK Laser Platinums. No change in horrible performance.
Installed new PCV valve. No change in horrible performance.
Installed new throttle body and MAF sensor. No change in horrible performance
Installed a used fuel sending unit (55k miles on it) from a 350z. Cranked right up... after a idle relearn and a A/F mixture relearn, my car is back to normal. The fuel pump was the culprit. I could hear a difference in the way it the new one operated (very quiet) versus the loud old one.
I ended up returning all the parts that I didn't need with exception to the position sensors and the spark plugs. Thanks for all your help everyone.
Awesome you solved your problem after all this time, enjoy your G! This site has been amazing for me as a college student working on my G and I've learned a lot on here too. Now go rip your G
