[ferrari21]

I have a 2000 infiniti g20 manual. I've been experiencing a strange bucking in the RPM on my car between 1700, and 2500 RPM when the car is sitting or is in first gear. No bucking or surge when driving normally (even in first gear for most cases, only when driving slow) or through any other gear.

So far I've replaced...
-dizzy cap and rotor
-plugs and wires
-tested 3 different MAFs (2 of them brand new)
-regrounded the MAF, and replaced the harness plug adapter (soldered and shrink wrapped the wires)
-adjusted TPS and set the based voltage at multiple points between .3v-.4v
-cleaned my TB
-cleaned and resoldered the crusty corroded wire in my fuse box feeding the iginition coil (the wires/box next to the battery under the hood)
-new fuel filter
-new refurbished/flow tested fuel injectors
-new OEM FPR
-new Bosch front and rear O2

Granted, all of these things have helped the car to run significantly better. But the surge bucking around the RPM range I stated is ALWAYS THE SAME. I think I'm narrowing it down to being a distributor issue. Anyone willing to confirm, is a good portion of the fuel map is also dependent upon the camshaft position sensor?

So I took the distributor cap off last night, to inspect the trigger wheel some more, and it appears maybe some debris could have been floating around chipping the outer edge of the optical camshaft position sensor wheel. On the 00-01 distributors, it looks like the frequency of notches for camshaft degree are a lot finer compared to other Nissan trigger wheels I've seen before in other distributors.

My question, anyone knowledgeable about this part of the car, and impact of the CAS trigger wheel willing to chime in on whether they think this could be causing the symptoms I've described? I'd hate to just keep throwing money at the problem, but lacking a good scanner to see exactly what the ECU is doing is probably not helping my cause either. All opinions welcome.

 

[Y2KG20]

I always keep an extra known good distributor on the shelf for diagnosis for weird crap like that. The distributor is one of the hardest parts to test. I have run into two bad ones so far, but they were dead not erratic like you describe. Unfortunately only the 2001,2002 have the newer hitachi ecu's that are easier to monitor live data at high speed. The wheels are pretty much the same pattern from the OBD1 to the newest vet/20V COP setup. Even if you have an old 90's SR20 distributor without built in coil you can wire in a blaster coil and MSD.

 

[ferrari21]

I always keep an extra known good distributor on the shelf for diagnosis for weird crap like that. The distributor is one of the hardest parts to test. I have run into two bad ones so far, but they were dead not erratic like you describe. Unfortunately only the 2001,2002 have the newer hitachi ecu's that are easier to monitor live data at high speed. The wheels are pretty much the same pattern from the OBD1 to the newest vet/20V COP setup. Even if you have an old 90's SR20 distributor without built in coil you can wire in a blaster coil and MSD.

Totally get what you are saying and thanks for the response. I’ll try to get some pictures of that trigger wheel up so you can see what I am talking about. I think the route I will end up taking is waiting for a CPO to go up in the next few months, maybe I can get lucky and find a working OE distributor on the cheap.

Off topic, running the green denso injectors as a drop in replacement for the stock black fbjc100s. I might have reached out to you before, they are a great alternative, the car ran noticeably better. I know based on my plugs cylinders 2, and 3 previously were running lean.

 

[cavern]

If your CAS trigger wheel is damaged from abuse or if the CPS is worn out, 100% could be causing your issue.

Before I went AEM I every so often had a similar issue with my VE. Never really could figure it out as it was once in a long time that it happened. Eventually, when I went with AEM and used my stock Nissan CAS wheel (120 count vs 24 count), while the car would run, at a specific RPM I would constantly get the car bucking, burping, stumbling, all around a specific RPM. I can't recall the specific RPM but it was highly noticeable on the freeway with light throttle input cruising. Full foot to the floor or full off and no issues. Eventually we dwindled it down to the CAS wheel (AEM wasn't specifying you needed a new one at the time), and swapped it for the AEM one and updated the config, everything became butter smooth.

Obviously AEM is different then stock, BUT the symptom mirrors your issues pretty close.

I'll look to see if I have a stock dizzy floating around with an OEM trigger wheel, at one point I had a 95,99 and 00 dizzy but I've been slowly cleaning out old stuff and may have gotten rid of it.

 

[ferrari21]

If your CAS trigger wheel is damaged from abuse or if the CPS is worn out, 100% could be causing your issue.

Before I went OEM I every so often had a similar issue with my VE. Never really could figure it out as it was once in a long time that it happened. Eventually, when I went with AEM and used my stock Nissan CAS wheel (120 count vs 24 count), while the car would run, at a specific RPM I would constantly get the car bucking, burping, stumbling, all around a specific RPM. I can't recall the specific RPM but it was highly noticeable on the freeway with light throttle input cruising. Full foot to the floor or full off and no issues. Eventually we dwindled it down to the CAS wheel (AEM wasn't specifying you needed a new one at the time), and swapped it for the AEM one and updated the config, everything became butter smooth.

Obviously AEM is different then stock, BUT the symptom mirrors your issues pretty close.

I'll look to see if I have a stock dizzy floating around with an OEM trigger wheel, at one point I had a 95,99 and 00 dizzy but I've been slowly cleaning out old stuff and may have gotten rid of it.

THE EXACT ISSUE I AM EXPERIENCING (all caps for stressing my excitement). Yep, foot to the floor and pulls really nice all the way up through 7k (I try to avoid the redline on the RR)

Yes, please LMK if you have something laying around, I'll try to get a picture up soon of the trigger wheel in my distributor. It isn't physically causing driveability issues, nor am I throwing any CEL's so not in a huge rush to fix, but also don't like running any of my cars with problems like this either. Thank you.

 

[dfddfd2]

Have you checked the ECU for codes? It could be a leak in the EGR system or the EGR control solenoid or control valve.

 

[ferrari21]

Have you checked the ECU for codes? It could be a leak in the EGR system or the EGR control solenoid or control valve.

Late response here, I actually have my EGR blocked off. I'm actually running a 16.9k ohm resistor in my egr temp sensor plug, with the egr tube blocked off, and plate blocking to prevent vacuum leak on the IM.
https://www.b15sentra.net/forums/showthread.php?t=57557&page=13

I picked up a second hand distributor, my cap and rotor are clean, swapped out mine (which I thought was causing the problem), and after the car warms up and is parked (in neutral), I still get idle surge only when the car is revved up past 1500 RPM. So I'm taking the distributor out of the equation.

My engine was ran with bad plugs, bad cap and rotor, and clogged injectors for who knows how long by the previous owner. The only other thing I haven't swapped/tested out yet is the TPS, which I think could be impacting this issue. After that, IDK, I don't have any codes giving me any insight on what's happening at this point. If it was knock I would think I would be getting a CEL for that right?

 

[MFNchip]

If you have a consult , you can download the free version of nistune and hook up to your ecu and download your maps. Can compare to a ton of different maps also. And can obviously see why you can't just use an w10 ecu in the p10+T safely it's to much timing. The only spots i see in the ecu is around 2800 . 3000. Where it stops using o2 signal, mine would jump there, and still kind of does unless it's wot. Or if you wot from dead stop. 65% load will pull out about 150 timing until you reach about 3800 rpm. Check o2s and exhaust leaks . And is the dizzy cap tight on the shaft for the rotor. 1 of mine came little loose and rotor was walking off the shaft.

O never mind it's a2000. Or ecu swap

 

[MFNchip]

1 more i use a tuner pro app on windows xp. It's free and i got a few xdf files for b13, p10, w10, 11 s14. The nistune only has a few minutes trial. My tuner pro is always open to use it with the FIC6. Can email if you want. You have to use the right xdf with whatever bin file you load from nistune onto the tuner pro

 

[ferrari21]

If you have a consult , you can download the free version of nistune and hook up to your ecu and download your maps. Can compare to a ton of different maps also. And can obviously see why you can't just use an w10 ecu in the p10+T safely it's to much timing. The only spots i see in the ecu is around 2800 . 3000. Where it stops using o2 signal, mine would jump there, and still kind of does unless it's wot. Or if you wot from dead stop. 65% load will pull out about 150 timing until you reach about 3800 rpm. Check o2s and exhaust leaks . And is the dizzy cap tight on the shaft for the rotor. 1 of mine came little loose and rotor was walking off the shaft.

O never mind it's a2000. Or ecu swap

Thanks for the feedback, a consult is definitely something I do need at this point. Currently, I'm limited to torque lite on bluetooth through an android phone, and its pretty limited in terms of sensors I can monitor.

I do have the cap and rotor that I removed from the rotor that is now on my car. Looks a little worn out but I'm sure I can clean it up. I am using the same cap and rotor I purchased from Autozone about a year or so back, everything visually looks real clean... but maybe, could be causing this problem if it isn't seated right. I'll give it a try tomorrow.

 

[MFNchip]

Actually the only time i ever had the bucking like you say, was misfire, it happened with 1 bad plug wire, and again with stupid #2 injector. Wouldn't feel it when revving but i didn't rev it much when it started. If you got those ngk wires ditch them for a set of scrap yard OEM. Difference is night and day even when all of then work. The manual lists ohm spec, and maybe check gaps in the plug. .035 for copper. Now im just ranting . Suppose to be warm all week good luck.

 

[ferrari21]

Actually the only time i ever had the bucking like you say, was misfire, it happened with 1 bad plug wire, and again with stupid #2 injector. Wouldn't feel it when revving but i didn't rev it much when it started. If you got those ngk wires ditch them for a set of scrap yard OEM. Difference is night and day even when all of then work. The manual lists ohm spec, and maybe check gaps in the plug. .035 for copper. Now im just ranting . Suppose to be warm all week good luck.

I actually just ordered some OE platinums, and I have used OE wires in my parts bin, I'll give those a try. But the more you mention possible issues, the more I'm leaning towards ignition/misfire. Also much more prominent when the engine gets warm/hot, so again very well could be a misfire maybe even a small knock at those lower RPMs. I'll play around with this some more tomorrow, watching my 1 yr/old all day today, so not going to have any time.

 

[Cheezit]

What turned out to be causing this "strange bucking between 1700 and 2500 RPM, when the car is idling or in first gear"?