I have a 1990 300zx na. The chassis and most of the rest of the car has 260k miles on it. The engine was just recently replaced with a JDM engine with I don't know how many miles, but they (the mechanic shop) say that it is somewhere around 50k + or -. So, originally when I got it back it felt funny. I said something about it. they say it's the exhaust. Got that checked out. No issues there. A few days later I find my #5 cylinder fuel injector isn't even plugged in. Now it runs pretty good.
Have been driving the car now for about 2 weeks or so and now, when it's warm, it starts surging when idling from about 500rpm to 1200rpm. Not sure why. Anyone have an answer for me?
I've looked around on this forum but didn't find anything posted on this issue. No mods or deletes on my car. I do have 4" performance tail pipes, that the pipes from cat's to mufflers are 3" and from cats to engine are stock size.
Idle surging
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DCaff300ZX
- Posts: 4202
- Joined: Sun Jun 14, 2009 8:18 am
- Car: .
1993 CRP TT- Modified - Location: Tacoma, Washington
Re: Idle surging
Hmmm, most likely your issue is somewhere around the Idle Air Control Valve (IACV) and possibly a loose hose connection from the balance tube to the idle control valve. If not then check the connectors for corrosion and clean well if so, you may need to replace the connectors as they are brittle and may already be broken.
Another possibility should the above not help is your fuel pressure sensor regulator and/or the fuel pressure dampener. These are fairly common maintenance items at higher mileage intervals such as 60K, also be sure you have a fresh fuel filter on it since you are still using the 260K gas tank and fuel pump...a good area to spend some money!
Check these out and get back with the results...
Another possibility should the above not help is your fuel pressure sensor regulator and/or the fuel pressure dampener. These are fairly common maintenance items at higher mileage intervals such as 60K, also be sure you have a fresh fuel filter on it since you are still using the 260K gas tank and fuel pump...a good area to spend some money!
Check these out and get back with the results...
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Veeridian
- Posts: 13
- Joined: Sun Apr 12, 2015 3:14 pm
- Car: 1990 300zx NA 2+0
2004 JEEP Liberty Renegade - Location: Boise, ID
Re: Idle surging
Thank you. I'll look into those next week when I have time and then I will post results of what I find out.
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Veeridian
- Posts: 13
- Joined: Sun Apr 12, 2015 3:14 pm
- Car: 1990 300zx NA 2+0
2004 JEEP Liberty Renegade - Location: Boise, ID
Re: Idle surging
This has been more than a week I know... lol. But I put the car in the shop for a few days. They did a smoke test to check out for vacuum leaks. Found 3 of them. 1 was the PCV hose (balance bar to IACV) and the other 2 were both of my throttle bodies. PCV hose is now fixed. Haven't driven it much since then, so I'm not sure if that helped with the idle.
As far as the throttle bodies go, there doesn't seem to be any replacement parts to rebuild them. So I'll either have to replace with OEM parts (new is expensive and used... wonder if they'll have the same issue?) or replace with aftermarket ones that will need work done to them once bought to make them fit and work properly.
So now I'm just looking at my options. Any advice on the throttle bodies would be appreciated if anyone as had any experience with them.
As far as the throttle bodies go, there doesn't seem to be any replacement parts to rebuild them. So I'll either have to replace with OEM parts (new is expensive and used... wonder if they'll have the same issue?) or replace with aftermarket ones that will need work done to them once bought to make them fit and work properly.
So now I'm just looking at my options. Any advice on the throttle bodies would be appreciated if anyone as had any experience with them.