KA24E Hesitation at 3000 RPM in 5th and Burning Gas - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Datenshi · 01-17-2011, 02:56 PM

Okay, well for the last few days I've been searching for what could be causing this problem and I've not really found anyone with a similar problem. There is lots of information listing many reasons, but usually the OP has a different problem than I, yet somewhat similar. So here it goes.

Sorry if this is long, I want to give you guys as much details as possible.. About a week ago I noticed that my car idles pretty rough when I start it. Keep in mind I live in Canada, and winter is pretty cold so I chalked it up to that at first.. but I noticed when I drive about 120km/h in 5th around 3000 RPM it feels like theres much less power than there used to be and if I let off the gas quickly it feels very jerky. If I lightly push the throttle when its around there sometimes it lets out a sound like quick misfires. (My car has always let one pop from the exhaust depending on what gear/RPM I'm in. Usually around like 3500-4500 in first or second. When its about about 3000 RPM though in 5th, if I'm just driving normally and maintaining speed it feels like sometimes the car is getting pushed.. sort of like what cruise control feels like.. that automatic pushing effect. When the car is turning on and warming up/idling it sounds like I have aggressive cams, it goes from about 600-800 rpm's bouncing back and forth. When the car is warm and at a stop, if I rev the car slightly.. say to 2000RPM and just let off the gas completely the revs dive to like 400-500 and then back up to normal idle. When the car is warmed up and sitting and idle, it's completely normal but the hesitation is always there. Also, I seem to be burning a lot of fuel compared to normal.. I'm getting half the fuel mileage I used to a week ago. Which is probably about 100 miles out of a full tank of gas.

I was reading 240sx.org and reading a few things on there to see if I could find a common solution. The only thing I found that sort of sounds like the issue I'm having is this Checking the Engine Ground which tells me to check my engine grounds but that is the closest I can find to a problem that sounds similar. Does anyone have any other solutions? I'm researching this at work and will be trying everything tonight when I get home.. so any help is appreciated.

Cliff Notes:
Hesitation at 3000 RPM in 5th gear
Feel somewhat automatic push around 3000 RPM in 5th (Like cruise control)
Burning double the gas I used to
Revs bounce from 600-800 on start (sounds like aggressive cams)
At a stop if you Rev engine, and let off gas -- rev's dive to 400-500 RPM then back to normal (feels like about to stall)

Car is a 1989 240sx hatch with a stock ka24e at 250000 KM's, with no aftermarket mods. It's completely stock and has had a timing chain rattle for a month or two.

Datenshi · 01-18-2011, 07:30 AM

No one has any ideas?

nicho919 · 01-18-2011, 07:37 AM

Sounds to me like it's either a vacuum leak, a leaky injector, or a bad iacv.

Datenshi · 01-18-2011, 10:34 AM

I found six grounds in the FSM for the engine bay. Any I'm missing? 5 body grounds and 1 engine ground?

ILoveMyRHS13 · 01-18-2011, 11:32 AM

Your motor has probably skipped a tooth of timing. My car runs IDENTICAL to what you described, and I'm 99% sure it skipped a tooth; there's no other explanation. All my injectors are good, and it's not a vacuum leak, seeing as I don't have any emissions equipment.

nicho919 · 01-18-2011, 12:16 PM

Saying you don't have any emissions equipment so you won't have vacuum leaks is just stupid, and ignorant. There are LOTS of places where air can get in, like under the caps you used to seal the vacuum ports on the intake manifold, the throttle body, and the throttle body seal, and the block to intake manifold seal. Skipping timing with a chain? Really?

01-17-2011, 02:56 PM	#1
Datenshi Leaky Injector Join Date: Jul 2010 Location: Toronto Posts: 91 Trader Rating: (0) Feedback Score: 0 reviews	KA24E Hesitation at 3000 RPM in 5th and Burning Gas Okay, well for the last few days I've been searching for what could be causing this problem and I've not really found anyone with a similar problem. There is lots of information listing many reasons, but usually the OP has a different problem than I, yet somewhat similar. So here it goes. Sorry if this is long, I want to give you guys as much details as possible.. About a week ago I noticed that my car idles pretty rough when I start it. Keep in mind I live in Canada, and winter is pretty cold so I chalked it up to that at first.. but I noticed when I drive about 120km/h in 5th around 3000 RPM it feels like theres much less power than there used to be and if I let off the gas quickly it feels very jerky. If I lightly push the throttle when its around there sometimes it lets out a sound like quick misfires. (My car has always let one pop from the exhaust depending on what gear/RPM I'm in. Usually around like 3500-4500 in first or second. When its about about 3000 RPM though in 5th, if I'm just driving normally and maintaining speed it feels like sometimes the car is getting pushed.. sort of like what cruise control feels like.. that automatic pushing effect. When the car is turning on and warming up/idling it sounds like I have aggressive cams, it goes from about 600-800 rpm's bouncing back and forth. When the car is warm and at a stop, if I rev the car slightly.. say to 2000RPM and just let off the gas completely the revs dive to like 400-500 and then back up to normal idle. When the car is warmed up and sitting and idle, it's completely normal but the hesitation is always there. Also, I seem to be burning a lot of fuel compared to normal.. I'm getting half the fuel mileage I used to a week ago. Which is probably about 100 miles out of a full tank of gas. I was reading 240sx.org and reading a few things on there to see if I could find a common solution. The only thing I found that sort of sounds like the issue I'm having is this Checking the Engine Ground which tells me to check my engine grounds but that is the closest I can find to a problem that sounds similar. Does anyone have any other solutions? I'm researching this at work and will be trying everything tonight when I get home.. so any help is appreciated. Cliff Notes: Hesitation at 3000 RPM in 5th gear Feel somewhat automatic push around 3000 RPM in 5th (Like cruise control) Burning double the gas I used to Revs bounce from 600-800 on start (sounds like aggressive cams) At a stop if you Rev engine, and let off gas -- rev's dive to 400-500 RPM then back to normal (feels like about to stall) Car is a 1989 240sx hatch with a stock ka24e at 250000 KM's, with no aftermarket mods. It's completely stock and has had a timing chain rattle for a month or two.

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01-18-2011, 07:30 AM	#2
Datenshi Leaky Injector Join Date: Jul 2010 Location: Toronto Posts: 91 Trader Rating: (0) Feedback Score: 0 reviews	No one has any ideas?

01-18-2011, 07:37 AM	#3
nicho919 Leaky Injector Join Date: Jun 2010 Location: Raleigh, NC Age: 31 Posts: 51 Trader Rating: (0) Feedback Score: 0 reviews	Sounds to me like it's either a vacuum leak, a leaky injector, or a bad iacv.

01-18-2011, 10:34 AM	#4
Datenshi Leaky Injector Join Date: Jul 2010 Location: Toronto Posts: 91 Trader Rating: (0) Feedback Score: 0 reviews	I found six grounds in the FSM for the engine bay. Any I'm missing? 5 body grounds and 1 engine ground?

01-18-2011, 12:16 PM	#6
nicho919 Leaky Injector Join Date: Jun 2010 Location: Raleigh, NC Age: 31 Posts: 51 Trader Rating: (0) Feedback Score: 0 reviews	Saying you don't have any emissions equipment so you won't have vacuum leaks is just stupid, and ignorant. There are LOTS of places where air can get in, like under the caps you used to seal the vacuum ports on the intake manifold, the throttle body, and the throttle body seal, and the block to intake manifold seal. Skipping timing with a chain? Really?