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Jay
Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 19483
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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Sentra: I have a 93 1.6 Sentra that won't accelerate when climbin

Customer Question

I have a 93 1.6 Sentra that won't accelerate when climbing hills
Submitted: 1 year ago.
Category: Nissan
Expert:  Mike V. replied 1 year ago.
Hi there, Just to be clear, it accelerates on a flat road without any issues at all?
Customer: replied 1 year ago.
If u push the gas slow it's ok
If u push it too fast it bogs down
Expert:  Mike V. replied 1 year ago.
Ok, sounds like your maf might be the problem even though it is new, however, if the car has a plugged converter you might have the same symptom. If possible disconnect the front pipe before the converter and see if the car has better acceleration. if it does then you know the converter is blocked. It's going to be loud of course, but it's a good way to test it.Please try it and let me know.Thanks.
Customer: replied 1 year ago.
I removed the cat and test
At idle no load revs up fine.has a slight hesitation if u push the throttle fast.
At idle under load if push the throttle fast it will hesitate at 1800 rpm
If I push it slow it will go to bout 2000-2200 steady for bout 4-5 seconds and drop back to 1800 with hesitation
Expert:  Mike V. replied 1 year ago.
Is the check engine light on?
Customer: replied 1 year ago.
No check engine light
Expert:  Mike V. replied 1 year ago.
You need to check the timing at this point. With a timing light it should be about 15 BTDC, it sounds like the timing is not advancing. This could be a problem with the distributor or the ecm, if it's not advancing that is.
Customer: replied 1 year ago.
Is there a way to test if the ecm is advancing.
Also can you tell me the proper way to adjust the timing on this vehicle.
Expert:  Mike V. replied 1 year ago.
The only way to tell if the timing is being advanced is with a scan tool that can see the timing that the computer is seeing.HERE is a link to setting the timingWhat happens next:Just Answer will now charge you for the full amount of your question.My goal is to provide you with 5-star service. If you cannot rate me at least 3-5 stars, we will keep working on this.Just Answer does not compensate me for my time and effort; you do with a 3-5 star rating.Follow up questions are included in your question price even after rating.
Customer: replied 1 year ago.
I will try a ecm
Does it need to be programmed
Can u give me a connector end view of the ecm.93 Sentra a.t. 1.6l
Expert:  Mike V. replied 1 year ago.
No programming is needed on one this old, it should just plug and play. I added a diagram of the ecm connector view, I hope it's what you are looking for.
Customer: replied 1 year ago.
I just replaced the ecm with a used one.still same problem although sometimes it can rev pass 2000 when holding brk under load/same as before.
Expert:  Mike V. replied 1 year ago.
Did you put a timing light to the car to first determine if the timing was on?
Customer: replied 1 year ago.
Yes I did the timing again got it to 10 degrees.
Expert:  Mike V. replied 1 year ago.
Ok, if you had to reset the timing then I am thinking the distributor is no good. Once you lock it in it should stay there. If you are having to reset it, then there is either an issue with the distributor or the timing chain
Customer: replied 1 year ago.
I don't think it moved. I just wanted to do it again following ur post
Expert:  Mike V. replied 1 year ago.
hmm, ok.No check engine light usually limits our possibilities.I would say next we have to check the fuel pressure to see if the issue lies there. Also, check the fuel pressure regulator vacuum line and make sure there isn't any fuel in it.Fuel pressure should run about 40 psi when the engine is at idle, 36 would be acceptable as well.
Customer: replied 1 year ago.
Ok how do you test the fuel regulator
Expert:  Mike V. replied 1 year ago.
The fuel pressure regulator is just a vacuum diaphram, if there is fuel in the vacuum line then its not any good. Also, you can unplug the vacuum line and see if the fuel pressure increases, if it does, then the regulator is doing its job.
Customer: replied 1 year ago.
Fuel pressure is at 36 psi at idle.
Regulator disconnected goes to 45 psi.
At 1800 rpm with hesitation goes to 45 psi
Expert:  Mike V. replied 1 year ago.
Nothing wrong with that at all.I am going to open this up for the other experts as I am out of ideas. Please don't reply or it will lock it back to me and they won't see the question or be able to reply.
Expert:  Jay replied 1 year ago.
Hi, My name is*****'m happy to help you. During our conversation, I may be presenting you with different things to try, and ask you some Questions to get a better understand of the issue so I can answer your question properly. So stick with me to the end, and I am sure we should be able to get this issue resolved for you! Based on the description on how it will accelerate when lightly applied but bogs when heavier applied does sound like a MAF sensor. I know you replaced it. Can you tell me where you brought it? Let me know, Thanks Jay!
Customer: replied 1 year ago.
I got the maf from a running vehicle
Same kind car and engine
Same part number
Customer: replied 1 year ago.
Hello is anyone there
Expert:  Jay replied 1 year ago.
I take it you don't have a scanner to monitor fuel trim readings right?
Customer: replied 1 year ago.
I have a scanner that can monitor fuel trims
Expert:  Jay replied 1 year ago.
Wow.. Perfect! .. Can you give me the Short Term Fuel Trim readings at idle when warmed up? I will be online tomorrow evening around 7 pm EST and be online till around 11 or 12 at night. Let me know..
Customer: replied 1 year ago.
The short term trim is 100% at idle
The long term is 120
Customer: replied 1 year ago.
The pid is showing st alpha
Expert:  Jay replied 1 year ago.
Cool, the alpha readings are around 100? Ignore long term right now.. Only Alpha... That is around 100% at idle?
Customer: replied 1 year ago.
Yes st alpha is 100% at idle
Expert:  Jay replied 1 year ago.
i would think you have a exhaust restriction maybe. I would try dropping the exhaust and see if that helps.
Drop it after the catt converter.
Let me know..
Customer: replied 1 year ago.
I dropped the exhaust after the cat same prob
Hesitates at 1800 rpm under load while holding brake
Expert:  Jay replied 1 year ago.
if the catt is clogged dropping the exhaust after it won't change the condition. You want to drop it before the catt
Customer: replied 1 year ago.
I dropped it before the cat already still same problem
Expert:  Jay replied 1 year ago.
Is the Alpha Moving or is it locked at a 100% at idle?
Expert:  Jay replied 1 year ago.
Oh .. You mentioned you replaced the MAF sensor didn't you!.... Where did you get it?
Customer: replied 1 year ago.
Yes st alpha is locked at 100%
I got the maf from a running vehicle same part#same car and engine
Can it be knock sensor?
Expert:  Jay replied 1 year ago.
No, if it's locked that means the 02 sensors are not working either. This sounds like it maybe a after market MAF sensor. They tend to do this and can cause this type of running issue. I would recommend getting a MAF sensor from the dealer, after market ones never work right. After Market MAF sensors never tend to meter air properly and if they do, they lock around 100% and flat line 02 sensor operation which makes you think it's something else when it's the MAF sensor all along. If you have any more questions on this, please feel free to ask. If not, and you're satisfied with my help, please Rate me. I hope I have provided you with Excellent Service. Thanks Jay!