Moderate vibration worsens at particular speeds...

[94RepoJ30t]

Newbie alert! 1994 J30t w/HICAS...196K miles and dandruff (paint peeling)...lol

I picked this car up as a repo in order to keep miles off of my new truck during some fairly long trips that are coming up soon. And, I have some issues...

The car has a vibration that can be felt throughout the car and with special regard in the steering wheel... it is worse within specific speed ranges, particularly over 65. The engine is noticeably missing, there's a lack of power, and the vibration is minimized when I romp it and hit 3500 to 5000 rpms. Also, it seems most noticeable once the transmission kicks up to Drive...

I have replaced spark plugs with factory spec NGK's (they were horrible, who knows how many miles on them), and I'm running a STP Complete FI Cleaner through the tank with 93 octane gas.

I believe there's a bad injector and will be confirming/replacing, but could that single injector be responsible for all of that vibration?!?!

Any other ideas of potential issues based on the symptoms described and your experiences?

I'm falling in love with this car, enough so to sand it down and repaint if I can work through these driveability issues!

[Infinitiguy19]

Sounds like a bad or even clogged injector, I would try some Redline S1 and BG44K.

You can run a power balance test using a laptop and a consult cable, the cable is $150 for the whole package or $88 for just the cable.

The power balance test will shut off each bank (Injector and Spark plug) and it will keep the AAC valve AKA IAC valve and timing the same so the resuts point to the bad cylinder.

Good Luck and welcome to NICO.

[driverdriver]

ohm test the injectors. They all should read between 10-14 ohms, anything above or below that range indicates injector failure. If its not a an injector it may be an ignition coil pack.

[94RepoJ30t]

Thanks for all of the insight, I will post again once I've attempted to diagnosis with the Consult cable I ordered through e-formance.

[94RepoJ30t]

Great news...I was able to replace the fuel injector thanks to the PDF I downloaded from another post here on the NicoClub website. I took longer than it probably should have, but I learned the importance of tossing all of my WD-40 cans and replacing with PB Blaster. ;-)

As for the car, it runs SO MUCH BETTER! I cannot believe that all of that vibration was caused by the bad injector.

Now, for the not as good news...

When I tested another one of the car's injectors....it's Ohms reading came up 66??? That's not within the 10-14 range that I have heard indicates a healthy injector. However, the injector I replaced read nothing...no sign of resistance at all. Is my 66 Ohm injector headed South too???

Also, my CEL light comes on intermittently now... Usually at lower speeds or when my RPM's stay below 2,500 for an extended period of time. No vibrations or audible engine missing sounds, but the light does come on regularly. I eagerly await the CONSULT cable that I ordered.

Any thoughts on that other injector or the intermittent CEL light?

Thanks again for all of the assistance so far, I am really starting to dig this car, except for the cramped leg room, but I can deal with that for now.

Trent

[yodawill2000]

The intermittent CEL light may be an EGR function.

The consult will tell you for sure.