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Discussion Starter #1
I have a 92 Sentra with a 1.6L Japanese 30k motor that I put in to it about 2 years ago.

There seems to be two distinct problems. One is a stutter during acceleration (1st, 2nd and 3rd gear) and the second is a lack of power under a load (4th and 5th gear). However I believe they are associated with each other.

For some time now I have noticed that when I am accelerating at a slow steady pace (1/4 to 1/2 peddle) I get some pulsing or stutter in the acceleration. Mostly noticeable when climbing a small incline. Best way to explain it is that it almost feels as if someone is turning the A/C on and off.

The problem has steadily gotten worse over the last few months. And has also caused the car to have no power. Hills that I use to be able to go up in 5th gear now require me to downshift to 4th. In fact the smallest incline at freeway speed requires me to go full throttle to stay at 60. I have also noticed that 1/2 throttle and full throttle don't seem to have any real big difference in acceleration. In addition, 1/2 to full throttle I don't seem to feel that pulsing or stutter in acceleration. But rather the motor just bogs down until I downshift. It's had to explain in words but the motor just does not have any power.

When I replaced the motor a few years ago I had the injectors cleaned. Well the guy who did them did a bad job and pinched off the bottom O rings allowing gas to dump on to the piston. At the time I pulled the one bad injector and replaced the O rings. Last week I pulled the other 3 injectors and replaced the O rings on them also as for they also showed damaged. I though for sure this was going to fix the problem. However it did not. I did notice on the end of the injectors there is a plastic cap. On a few of the injectors that cap is not centered and it looks like it "could" mess up how the gas is sprayed out of the injector. Don't know if that has any part of this problem or not.

I have done all the normal stuff. Plugs, Cap, Rotor, fuel filter and timing. None of which made any difference at all. I'm at a total loss of what to look for now. I could really use some help and suggestions. I keep thinking that this has something to do with fuel injection.


Thanks in advance.
 

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rodentkj said:
When I replaced the motor a few years ago I had the injectors cleaned. Well the guy who did them did a bad job and pinched off the bottom O rings allowing gas to dump on to the piston. At the time I pulled the one bad injector and replaced the O rings. Last week I pulled the other 3 injectors and replaced the O rings on them also as for they also showed damaged. I though for sure this was going to fix the problem. However it did not. I did notice on the end of the injectors there is a plastic cap. On a few of the injectors that cap is not centered and it looks like it "could" mess up how the gas is sprayed out of the injector. Don't know if that has any part of this problem or not.
Sounds like you already know where to start. More than likely, it's the injectors, fuel pressure or computer. Have you checked the pressure on the system?

Be careful about messing with the injectors, they are pretty tight mechanically on the limits and messing with them usually will cause you a lot of problems.

Regards,
Michael
 

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rodentkj said:
I have a 92 Sentra with a 1.6L Japanese 30k motor that I put in to it about 2 years ago.

There seems to be two distinct problems. One is a stutter during acceleration (1st, 2nd and 3rd gear) and the second is a lack of power under a load (4th and 5th gear). However I believe they are associated with each other.

For some time now I have noticed that when I am accelerating at a slow steady pace (1/4 to 1/2 peddle) I get some pulsing or stutter in the acceleration. Mostly noticeable when climbing a small incline. Best way to explain it is that it almost feels as if someone is turning the A/C on and off.

The problem has steadily gotten worse over the last few months. And has also caused the car to have no power. Hills that I use to be able to go up in 5th gear now require me to downshift to 4th. In fact the smallest incline at freeway speed requires me to go full throttle to stay at 60. I have also noticed that 1/2 throttle and full throttle don't seem to have any real big difference in acceleration. In addition, 1/2 to full throttle I don't seem to feel that pulsing or stutter in acceleration. But rather the motor just bogs down until I downshift. It's had to explain in words but the motor just does not have any power.

When I replaced the motor a few years ago I had the injectors cleaned. Well the guy who did them did a bad job and pinched off the bottom O rings allowing gas to dump on to the piston. At the time I pulled the one bad injector and replaced the O rings. Last week I pulled the other 3 injectors and replaced the O rings on them also as for they also showed damaged. I though for sure this was going to fix the problem. However it did not. I did notice on the end of the injectors there is a plastic cap. On a few of the injectors that cap is not centered and it looks like it "could" mess up how the gas is sprayed out of the injector. Don't know if that has any part of this problem or not.

I have done all the normal stuff. Plugs, Cap, Rotor, fuel filter and timing. None of which made any difference at all. I'm at a total loss of what to look for now. I could really use some help and suggestions. I keep thinking that this has something to do with fuel injection.


Thanks in advance.
i had the same problem. what is was was the cat it was bad the way i was so sure is at nigh after driving if u pop the hood u could see that the manifold was bright cherry red if so then u know the cat is bad u either need to get rid of it or replace it let me know if that works
 

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MORTAL419 said:
i had the same problem. what is was was the cat it was bad the way i was so sure is at nigh after driving if u pop the hood u could see that the manifold was bright cherry red if so then u know the cat is bad u either need to get rid of it or replace it let me know if that works
If the catalytic converter (I'm assuming that's what you mean...) is bad, an easier way to check for backpressure is to hook up a vacuum gauge to the intake manifold and check to see if the pressures die and do not come back up. That would indicate the pistons are fighting against the backpressure. If your exhaust manifold is glowing, you're destroying your engine slowly, but surely.

Regards,
Michael
 

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Discussion Starter #5
MShorten said:
Sounds like you already know where to start. More than likely, it's the injectors, fuel pressure or computer. Have you checked the pressure on the system?

Be careful about messing with the injectors, they are pretty tight mechanically on the limits and messing with them usually will cause you a lot of problems.

Regards,
Michael
Not for sure how to check the fuel pressure. How do I do that? But I think you are correct. The Injectors should prob all be replaced. Some of the plastic is broken off of them. One of them even has a bent piece of metal on top.
 

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Discussion Starter #6
MShorten said:
If the catalytic converter (I'm assuming that's what you mean...) is bad, an easier way to check for backpressure is to hook up a vacuum gauge to the intake manifold and check to see if the pressures die and do not come back up. That would indicate the pistons are fighting against the backpressure. If your exhaust manifold is glowing, you're destroying your engine slowly, but surely.

Regards,
Michael
I know the cat has never been replaced. The car had 130k on it. Maybe I should just replace it?
 

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rodentkj said:
I know the cat has never been replaced. The car had 130k on it. Maybe I should just replace it?
The catalytic converter is expen$ive. Much cheaper to test for backpressure and see if you are restricting your exhaust somewhere else, if you think it's exhaust. However, KISS. Troubleshooting is about eliminating things one at a time, not buying everything under the sun. The catalytic convertor should last the life of the car and you've indicated that you know there are other problems.

I'm in agreement that if you can see your injectors are damaged, you need to replace them. You should also check your fuel pressure - I've not checked it on a Nissan, but a Chiltons should be able to guide you through the specifics. It's not too hard, either attach the gauge to a fitting or put it inline with the fuel line connecting to the fuel rail or throttle body.

If you're not a wrench, then take it to a decent mechanic (NAPA Autocare, perhaps) and have them take a look at it.
 

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Discussion Starter #8
MShorten said:
The catalytic converter is expen$ive. Much cheaper to test for backpressure and see if you are restricting your exhaust somewhere else, if you think it's exhaust. However, KISS. Troubleshooting is about eliminating things one at a time, not buying everything under the sun. The catalytic convertor should last the life of the car and you've indicated that you know there are other problems.

Well, I already bought a cat converter online. High flow for 60.00 bucks. Being shipped out today. I'm just going to replace it and eliminate the problem. In addition, I am going to replace the fuel injectors. Which will be a bit more expensive. Maybe even the o2 sensor.
 

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I've had the same thing happen with my car this is what i've changed so far
1- Catilytic converter
2- Spark Plugs
3- Fuel Filter
4- Timing Checked
5- Cap & Rotor
6- TPS Adjusted
7- IAC cleaned out
8- New Air Filter
Obviously alot of this is standar replacement stuff however none of it really had an efftect on the car it still ran the exact smae way, i'm still trying to figure it out! Left to replace that may be the problem
1- o2 Sensor
2- Spark Plug Wires
3- Fuel Injectors
4- Fuel Pump ( called my local Nissan dealer $450.00 CAD Damn)
Anyway's be sure to leave us feedback as i will do the same maybe this gremlin can be beat!
 

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Discussion Starter #10 (Edited)
I have a couple more things I though about that I wanted to add.

1. When I replaced the spark plugs they had a very odd color to them. Bright red. I showed them to a couple of other motor head friends and they said they had never scene that before. I don't add any additive to my gas. See the picture below.

2. When I took off the plentum to work on the injectors I noticed the plentum gasket had a lot of oil on it. I kind of forgot about it at the moment but now I am questioning wheather or not this means something. I did not take a close look at the inside of the plentum. I guess I should have.

Any comments?


 

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I remember a few years ago i had my 5.0 rebuilt before selling it and i broke it in properly etc. i had put about 10,000. kms on it before i finally let it go. When the deal went through some aftermarket parts were removed, long story short i removed my throttle body and noticed ALOT of oil in the upper intake you put your hand in there and came out with oil all over it! I talked to a few guys and they figure it was blow by, the rings were allowing all that oil in there. The shop obviously did a bad hone or ring install since everything was new and/or machined, the point being the rings are due for replacement probably but that's just a thought not a fact! Check into it though call a shop tell them what your getting and they'll give you some ideas!
 

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Just a guess on the plugs but maybe it's running hotter then normal? Could do a search on the web maybe it'll show the same thing!
 

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Discussion Starter #14 (Edited)
new94 said:
Just did a search and it say's that the colour your seeing is from fuel additive's!
Ya, thats what may friends first said also. But I don't put additives in my gas. So, it must be the gas I use. No biggie I suspect.
 

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Discussion Starter #15
new94 said:
I remember a few years ago i had my 5.0 rebuilt before selling it and i broke it in properly etc. i had put about 10,000. kms on it before i finally let it go. When the deal went through some aftermarket parts were removed, long story short i removed my throttle body and noticed ALOT of oil in the upper intake you put your hand in there and came out with oil all over it! I talked to a few guys and they figure it was blow by, the rings were allowing all that oil in there. The shop obviously did a bad hone or ring install since everything was new and/or machined, the point being the rings are due for replacement probably but that's just a thought not a fact! Check into it though call a shop tell them what your getting and they'll give you some ideas!
Well, it was not alot of oil. And the engine is not burning any. So who knows.
 

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rodentkj said:
I have a couple more things I though about that I wanted to add.

1. When I replaced the spark plugs they had a very odd color to them. Bright red. I showed them to a couple of other motor head friends and they said they had never scene that before. I don't add any additive to my gas. See the picture below.

2. When I took off the plentum to work on the injectors I noticed the plentum gasket had a lot of oil on it. I kind of forgot about it at the moment but now I am questioning wheather or not this means something. I did not take a close look at the inside of the plentum. I guess I should have.

Any comments?


That looks like a BOSCH spark plug... you know they make better plugs for your Nissan. By the look of the plug I'd say it misfires at high speeds you may want to consider a colder plug... make it NGK this time.
 

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The intake plenum will have oil in it if you use one of those oil treated filters but that won't affect engine's performance in any way... the oil in the filter pleats actually helps a lot in the filtering process.
 

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Discussion Starter #19
Twiz said:
That looks like a BOSCH spark plug... you know they make better plugs for your Nissan. By the look of the plug I'd say it misfires at high speeds you may want to consider a colder plug... make it NGK this time.

Yup, Bosch. I'll put in NGK when I start working on it.
 

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Discussion Starter #20
What do you guys think about mixing OEM injectors with the Bosch repalcments? For example using two of each.
 
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