Bad Vibrations at 2k in any gear

[J30_Kidd]

Trouble: Vibration that can be felt through whole car around 1600 - 2000 rpm

Conditions: Car 6 hours being used fully warmed up, short trips being made (pizza delivery)

Happens: In Every gear around same rpm, also has a less violent vibration in park and neutral around 2000 rpm.

I've looked at the engine while having it rev'd to 2000rpm and could notice the engine shaking(vibrating) in park and neutral as well.

I'm thinking this has to be either Engine or Torque converter or i guess the oil pump in the transmission as well.

Driving to and from day job, i haven't noticed this happening as bad as it did that last Saturday.

My Question of course, What does everyone else think. I want to take it in to get a pro to look at it, but as i said it's not constant or doesn't happen when it's cold from what i've seen this week. And they charge 95$ to look at it pretty much everywhere.

I'm on my last nerve with this money pit, seems one problem after another.

[GerryO]

Questions:
No CEL or codes?
Idle is smooth/normal?
How many miles on the engine/car?
What's the service history?

Repeated short trips will gum up an engine, especially an older one. Could be as "simple" as an engine miss due to a failing injector, coil pack, spark plug, PCV valve, IAC/AAC valve, Air Regulator valve or a vacuum leak. J30s run perform best when serviced at prescribed intervals (preventive maintenance), which can be prohibitively expensive after the warranty period expires. After that they can be fun to maintain yourself, though parts are fairly expensive.

[J30_Kidd]

No CEL or codes? Only code 14 for the VSS, i've replaced the sensor twice, has to be the buffer

Idle is smooth/normal? Idle is smooth and normal

How many miles on the engine/car? almost 217,000 now

What's the service history? Before i bought it, it was always serviced at a local garage in town (i have all the records they kept) After i bought it, i always use synthetic oil and change on time. I have since purchase replaced the transmission with a used one from LKQ and while i did that i had replaced all seals on the engine (excluding head gaskets), New timing belt, new water pump, new hoses all over, new egr valve and cleaned out tubes for the egr which cured my idle issues i had in the past. I think thats all i've done that has to do with the engine. I also put in a electric fan and removed the stock one.

Oh also new PCV valves, i cleaned out the IAC/AAC valve

I never had this issuse till now, i should also note i've been trying to find the culprit to why at around 50 to 55mph i let off the gas and it coast but the rpm jump from 2k to 1700 rpm, when this happens the car is in OD and foot off gas pedal no brakes but does it with brakes applied to.

[driverdriver]

Have you ohm checked the injectors?

One of them may be gone.

The injectors need to be in the 10-14 ohm range. Anyhing above or below means you need a new injector.

When an injector goes, the car vibrates. If more than one injector fails, the vibrates more violently.

[yodawill2000]

"Idle is smooth and normal"

Not sounding like an injector.
Still need to ohm to test coils though.

[J30_Kidd]

ya this is only happening 1600 to 2000 rpm and vibrates more under load aka in gear driving, what ohm value should the coil be in and could u refresh me on how to test them lol oh dear i forgot

[GerryO]

No CEL or codes? Only code 14 for the VSS, i've replaced the sensor twice, has to be the buffer

Idle is smooth/normal? Idle is smooth and normal

How many miles on the engine/car? almost 217,000 now

I never had this issuse till now, i should also note i've been trying to find the culprit to why at around 50 to 55mph i let off the gas and it coast but the rpm jump from 2k to 1700 rpm, when this happens the car is in OD and foot off gas pedal no brakes but does it with brakes applied to.

Your car sounds very well maintained.

No personal experience with the Vehicle Speed Sensor, but imagine the information it provides would affect rpms and transmission shifts, along with the TPS.

Can picture an injector working well enough to supply the engine with enough fuel to idle smoothly and even engines mis-firing engines tend to feel smoother at higher rpms. Know that an fully open coil with infinite resistance will cause the CEL to turn ON and that failing injectors will work intermittently, before finally failing completely. My first one failed at about 170K miles.

[driverdriver]

ya this is only happening 1600 to 2000 rpm and vibrates more under load aka in gear driving, what ohm value should the coil be in and could u refresh me on how to test them lol oh dear i forgot

The best way to test the ignition coil is by swapping them out.

[GerryO]

ya this is only happening 1600 to 2000 rpm and vibrates more under load aka in gear driving, what ohm value should the coil be in and could u refresh me on how to test them lol oh dear i forgot

The best way to test the ignition coil is by swapping them out.

You can also start by disconnecting and reconnecting coilpacks one at a time with the engine idling. If a cylinder is firing properly (injector/coilpack/spark plug/wiring harnesses/ECM) the idle speed will drop/roughen and then increase when the coilpack is reconnected. If there is a problem with a specific cylinder, the idle speed will not change at all.

[J30_Kidd]

swapping them out? A bit on the high price side for me to just go buy new ones lol.

@ Jerryo, The only weird thing is that the VSS code was around even before i did all the trans and engine work to it, when i bought the car it only had a code 14(VSS) and 34 (KS) and i did relocate the knock sensor and that code is gone but still the vss. I'll just STFU now and get to the point, I didn't have these weird things going on with that code in the past, this is all new stuff but yes i would also think maybe the vss is the cause if i hadn't had this code already.

[Infinitiguy19]

Conditions: Car 6 hours being used fully warmed up, short trips being made (pizza delivery)

Maybe its pissed you use such a fine car to deliver Pizza's...Just kidding check the engine and transmission mounts

[J30_Kidd]

@ Paul, haha, i would use my truck but that sbf 351w is a thirsty beast lol.

A friend of mine told me to check the joints on the drive shaft for the clunk sound to so i'll have to jack it up and double check all that stuff.

But for today, it's my b/day i'm not doing crap lol

Finally a good excuse to be lazy hahaha

[J30_Kidd]

So ended up not being to lazy today and realized that i had never sea foamed the engine or used any cleaners in it at all.

So I put some Lucas fuel cleaner stuff in it and did the sea foam application via the vacuum hoses i could find to deliver to the whole engine, did pep it up but i'll see if it helped at all with my issues.

Now the hose i used to apply it was that huge rubber hose going right by the intake MAF that goes to the IAC valve in back, i couldn't help but notice when this hose was disconnected and i used my thumb to regulate the air flow into it, this caused my engine to have that vibe as i rev'd it. Not sure if i make sense but maybe this does have to do with those IACV things. Anyone know what i can do to test this theory?


Thanks! :-)

[1994 infiniti j30 190+]

clean the IACV and see if it fixes your vibration issue. if not you may have a driveline issue but who knows without accually being in the car. im just guessing what your issue could be, i could be totally wrong. i was also going to do the seafoam thing but in fear of making my engine run worse im not doin it cause who knows you could make it run worse after. especially a high mileage car. but might help you im not risking it though with the history of my car.

[GerryO]

A picture or two would be very helpful, and what are the chances that all this trying to diagnose car problems by exchanging words over the internet is ever going to work? I think I see one end of the hose in this photo. Pulling the plenum can be so much fun and very rewarding. Best of luck!

[J30_Kidd]

Sorry i've been absent on here, Got a new job and have been tinkering with my truck for a change. This J just wants to much attention LOL.

I'm using the pic you provided Gerryo but i circled in yellow the hose i was talking about when i did the seafoam application.

Do I have to pull the plenum again just to clean the IACV all over again? I'm trying to recall what all is connected back there. The engine was outta the car last time i pulled it. This was 3 months ago and i used MAF cleaner or was it throttle body cleaner? Well what ever i was told to use, anyways i sprayed it in every nook and nanny i could on the IACV.

If i recall The IACV actually attaches to the plenum and the other part the hose runs to before going to the upper tubing is just held on the plenum and acts like a choke or something? Am I right?

[GerryO]

I picked up a spare plenum, with IACV/Air Regulator a while back, along with a $9 hand gun cleaning kit that really helps when it comes to cleaning it.

Here are links to some good cleaning/adjustment instructions:
http://home.swipnet.se/e-solutions/IdleTech.html
http://home.swipnet.se/e-solutions/IdleTech2.html

You may also want to check your TPS first though.
http://www.wellsve.com/sft503/counterp_v2_i1_1998.pdf

[yodawill2000]

Cant you describe the hand gun cleaner ??
Haven't pulled my IACV/Air Regulator yet.

[GerryO]

Cant you describe the hand gun cleaner ??
Haven't pulled my IACV/Air Regulator yet.

Something similar to this and you may want to experiment with different diameter and shape copper wire brush attachments (sold separately). The copper wire is softer than SS, and less likely to scratch polished surfaces.



http://www.cabelas.com/cabelas/en/templ ... hasJS=true

[GerryO]

Do I have to pull the plenum again just to clean the IACV all over again? I'm trying to recall what all is connected back there. The engine was outta the car last time i pulled it.

If i recall The IACV actually attaches to the plenum and the other part the hose runs to before going to the upper tubing is just held on the plenum and acts like a choke or something? Am I right?

You'll probably want to disconnect a few other things to get at the IAC/Air Regulator and I have nightmares about dropping small connector clips and bolts.

Right. The IAC/Air Regulator routes air into the engine (after it passes through the MAF), in excess of what is passing through the closed (at idle and based on engine accessory load=alternator/AC/PS) butterflies on the throttle bodies, supporting a higher idle speed, especially when it's cold.

Some parts are fairly directly coolant temperature controlled (notice the length of tubing that sort of wraps around the Air Regulator) and others are controlled by the ECM based on other input information it's getting.

[J30_Kidd]

Thank you guys for all the help!

@ GerryO, Thanks a billion for those guides you got there with the links, i'll be checking those sensors and all for sure. Those articles make it so much easier to understand!

Another thought that has came to me after this week was maybe the engine is getting to hot. This week I've been tackling overheating problems in my truck which i had replaced the stock fan with a 16" electric fan. I also put one of these in the J30 during my transmission swap/engine gasket recondition, Taking the stock clutch fan out. I left the stock shroud in but mounted the fan directly to the radiator on both. Anyways yada yada i had problems recently with the truck due to the a/c being on and started noticing even with my a/c off i had temps in the 200+ f range on the truck.

Enough bout the truck though what makes me think the car maybe be getting to hot is last week i forgot to turn the fan on one day and the temp gauge didn't show it getting hotter then usual but the a/c kept kicking off on me and later found out whoops the after market fan wasn't turned on.

now i know it's been getting freaking hotter here in Texas the past month which may be bringing up these overheating issues now and not previously. I would think though if the a/c was kicking off due to the engine getting to hot i would of seen the gauge go up further then usual but didn't. now i suspect a faulty temp gauge and a hot engine which could cause issues. last weekend i did see it started acting up again around 4 pm when it was the hottest part of the day here.

Sorry for this long post but just want to put that out there for future reference.

So i'll be installing the factory fan back in and testing the tps and other sensors before re cleaning the iACV and ya, gonna go step by step.

i'll bring back details but i may take a while, two jobs working everyday and trying to make time for car work is a Betch for sure!

[yodawill2000]

Hard to beat the OEM fan assuming the clutch is good.
It moves a HUGE amount of air.
Much more than an electric.

[J30_Kidd]

Don't rub it in yoda lol, i was just going for better fuel economy and thought this would take a load off the engine, i might of made things worse lol.

i never had problems with the OEM, just wanted to go electric, well i'm letting her cool down right now before i go burn my hands. I wonder if i have enough room to keep the electric fan on and install the oem back on as well. this is what i did with the truck lol. Actually i have 2 10" fans on my condenser, a 16" on the radiator and the stock clutch fan on my truck, Can Anyone say overkill? haha

[yodawill2000]

your putting a huge load on the alternator !!
That's taking HP from the motor ya' know ..

[J30_Kidd]

Well i only had enough time to get the OEM fan back on, but was also able to leave the electric fan in place as well, i know this car will never over heat lol. I had to take extra time rigging the shroud back on nice and tight, as you know these plastic pieces where the bolts go always break at this age. Some zip ties made it nice in tight.

Well tomorrow at work i'll see if this fixed my problems, if not then i'll do the sensor testing step tomorrow after work.

[J30_Kidd]

your putting a huge load on the alternator !!
That's taking HP from the motor ya' know ..

I just realized your talking bout the truck and all the fans lol, after i had originally put the 16" on it was doing the job but with the a/c on my temp got high and that truck is a 86 and was designed to run r-12 but with the conversion to r-134a it probably requires more cooling power, which is why i put the two 10" fans on before putting the stock one back on, for now i'm experimenting on it to see it the two 10's and the stock well make do or etc. maybe i just need to build a custom shroud lol but thats all in another forum haha.

But i agree my radar detector shows voltage and i've noticed the draw on it in both the car and truck and especially using the car in pizza delivery on the weekends with the start and stopping alot probably hurts it more so i may be better with the stock fan. At least on the J30 it already has a electric fan for the condenser so no woe's thar!

I'll update tomorrow on my results though

[J30_Kidd]

Hey guys still haven't gotta a chance to test all those sensors, been working to much trying to get out projects at work and just feel to much like crap to do anything else. But when i get to it i'll post back.

[J30_Kidd]

OK Guys finally got off my azz and did it.

results i got on sensors were:

Coolant Temp Sensor: .66k Ohm's @ bout 130* F (PASS)

TPS: Idle position @ .40 V WOT @ 3.80 V (PASS)

Power balance test came back as all Good for me, every coil i disconnected changed the idle dramatically, this left me to the conclusion that the Coils, Injectors and Newer NGK Spark Plugs are Good (PASS)

CAS: No Test Done, Didn't feel the need to.

MAS: No Test Done but i have cleaned the unit recently (I'll have to look into which wires to measure for voltage readings)

Fuel: Not a problem

PCV: New on both sides

IAA-Unit
FICD: 23 Ohms (PASS) AAC: 11 Ohms (PASS)

Air Reg: It's not idling High after warm up (PASS)

Throttle Bodies: Clean (PASS)

Idle Adjustment: Eyeballed to 720rpm with AAC disconnected, rpm jumped up once connected back to AAC. (PASS)

-I ran outta time tonight but I still want to test the Voltage of the MAS and possible clean it again just to make sure.

-I found no loose hoses and i'm 99.99% sure no vacuum leaks are present but i'll double check once more tomorrow.

-Also realized i have a loose heat shield on my exhaust pipe rattling away, Great one more thing to do now lol.

-I'm also curious as to what type of compression readings i would get as well but i gotta buy a gauge for that first. Maybe i'll pick one up this week.

Besides the lack of testing of the MAS, I'm now back to point one on why i get this problem. I really would think the MAS would cause problems all over the board not just at 2K RPM. I kinda wish i would of found a bad Sensor at this point. At least i'd have something to go on.....

[J30_Kidd]

update, i'm noticing my power just gos away at times as if the timing is retarded to the max and even past 3k rpm at times. But other times it feels like a just had a shot of NOS on it. I was told maybe my MAS is bad but i have yet been able to test the voltage.

[yodawill2000]

Try wiggling the MAF connector while the engine is running.
If it changes RPM the connector may need a good cleaning and dielectric grease.