Help! 89 L98 Running on 4 cylinders.

[jgmotto]

Anybody have any idea about what is causing this problem? 1989 L98 started to misfire while driving down the road. This is what I checked so far:

-No codes registered.
-Checked all ignition wires with inductive timing light. All flashed OK.
-Fuel pressure OK (50 psi +/-)
-Replaced distributor cap and rotor.
-Checked TPS OK (0.525 v)
-Pulled all spark plugs. All on the left side OK. All on the passenger side - black, carbon deposits.
-Checked all fuel injector resistances - OK (17.0 ohms +/-)

I think the key here is one bank of cylinders appears to be rich/misfiring. I'm running out of ideas for what else to check. Any suggestions?

 

[joe j]

joe j

On my 91 there is a fuse for each bank of injectors any chance you have a blown fuse?

 

[boomdriver]

Anybody have any idea about what is causing this problem? 1989 L98 started to misfire while driving down the road. This is what I checked so far:

-No codes registered.
-Checked all ignition wires with inductive timing light. All flashed OK.
-Fuel pressure OK (50 psi +/-)
-Replaced distributor cap and rotor.
-Checked TPS OK (0.525 v)
-Pulled all spark plugs. All on the left side OK. All on the passenger side - black, carbon deposits.
-Checked all fuel injector resistances - OK (17.0 ohms +/-)

I think the key here is one bank of cylinders appears to be rich/misfiring. I'm running out of ideas for what else to check. Any suggestions?

You only have 2 inj circuits...they ARE bank fired. When one fires they ALL fire (on that bank)...when one shorts they ALL short. Simple system.
D/C ONE passenger side inj at a time until the rest start working......pull 1 off the replace it and pull the next so there are always 7 connected.
One is likely shorting either thru the plug, inj body arcing to ground, or the wire harness (which is basically 8 wires split from 2).

Go to the parts store and buy or rent a NOID lite to test the inj to see if they are getting the signal. IF they are NOT, look at fuses, and finally ECM. A scan tool would indicate if there were a driver failure.

 

[jgmotto]

Thanks for the suggestions, guys. I'll try them all and let you know what I find.

 

[jgmotto]

Checked fuses - both OK
Started up with new spark plugs.
Disconnected one injector at a time on passenger side.
Seems to be running on at least 7 cylinders now. I think I've isolated it to one injector not working.
I'll pick up a noid light and check the signal asap.
If one injector is bad, do you recommend replacing just one or should I spring for all new ones?
Where is the best place to purchase?

 

[G Winter]

Replace them all , been the route of replacing only bad injectors. Money was a problem. I ended up
replacing the rest 2 yrs later.

If you need injectors check out Fuel Injector Connection
I got a set of his reconditioned Bosh III . My corvette never ran as smooth
or had as much power as it does with those injectors.
Many people on this site will give them a thumbs up.

Glenn

 

[aklim]

For bank fired, I don't think it is likely, although possible, that every injector on that side failed. More likely is you have a break in the wiring or a blown fuse or ECM.

 

[1989landjet]

I agree with aklim.Both the ecm and wiring are the first things I'd check.The only other thing I can think of would be a kink in one of the fuel rail crossover tubes or maybe a clogged tube or rail.Those are pretty much the only possibilities if one side of the motor is having issues. Good luck to ya.