90 Z Running Bad

[mchall629]

Good afternoon folks,

I have been picking your brains for years and you didn't even know it. Most of the time I can just search for my answers, but working 7 days a week and traveling all the time has me limited in how much time I can actually search.

Last night I got the car out and everything seemed fine. After about 20 minutes or so it started to chug and buck at about 60 mph in high gear. I pretty much had to run 4th or 5th gear the rest of the way home. As I downshifted to get off the freeway and came to the end of the off ramp it seemed to straighten up. So I decided to pull out and get on it a little bit. Was strong through first, but about mid way through the rpm range in second it started doing it again. I pushed the clutch in and revved it some and it had a "flutter" in it.

We had just replaced the plugs and coil packs. Also replaced the valet switch. It had a chip from Mark in it, which I just replaced with the stock since it looked like the prom from Mark seemed to have a crack in it, but the problem persisted. This problem seems to come and go today so it isn't a constant.. Any ideas would be greatly appreciated.

Any suggestions for a good Z mechanic between Nashville TN and Bristol TN?

[tomtom72]

My first thought is it sounds like it could be the OEM injectors....if you still have them? When the alcohol finally gets to the coil windings' insulation that is what they behave like...a miss from nowhere. I would think that they could start out as if they were failing intermittently I suppose. I know they get progressively worse as the coils short to greater degrees.

Beyond that first thought I don't have much else to contribute to the diagnostics....it sure seems that something is starting in soft failure mode.


Tom

Just had a BFO.....how good are your fuel pumps? Sorry I left that out of this reply.

[Kevin]

sounds like injectors. check the voltage with an omh meeter. they should be between 12.5 and 15omz

[mchall629]

I was thinking after all the reading I have done in the past about injectors. Unfortunately I am going to have to take it to my mechanic since I won't have time to fool with this myself. I will have him check fuel pressure and ohm out the injectors.

Any suggestions on injectors and price?

Thanks for the replies..

[sammy]

jon at ficinjectors has rebuilts w/a 3 year warrenty for about 380 to your door also i think has some new boschs for about 550-600. wish i could do the link deal but am a newbe at this stuff . i have jons injectors in both my cars and love them

[Kevin]

Originally Posted by mchall629

I was thinking after all the reading I have done in the past about injectors. Unfortunately I am going to have to take it to my mechanic since I won't have time to fool with this myself. I will have him check fuel pressure and ohm out the injectors.

Any suggestions on injectors and price?

Thanks for the replies..

doing the ohming isn't hard, should take about 10-15 minutes. replacing them is pretty easy too. I know RC has injectors for these cars and there was another company that I can't remember right now.

[tomtom72]

Jon @ FIC has rebuilt & new
Accel also I think, but I don't know the P/N's.
And RCEngineering, aka RC injectors, or just RC's.

I believe I listed them from lowest prices to highest. Gaskets can be had from Jerry or Kurt, they both sell a top end set that comes with all you need to do an injector swap.

If I were to trust a non-ZR-1 owner to do this job I would give them my FSM to use. It is not brain surgery, but it's different enough from a L98/1/4 to have some unique traps waiting for the tech without a FSM. JMHO


Tom

[A26B]

Remember that injectors have 2 components to failure, electrical & mechanical. The early, 90~92 are the most prone to failure as they do not have SS trim in the injector. Ethanol & water are soluble which translates into rust & corrosion to the non-ss trim.

What does this mean? Just because the resistance checks out, does not mean the injector is good. It just means the electrical component is OK.

Leak-down & flow testing are the only way to check the mechanical component. Best done on a flow tester.

[george henry]

Accell part number is 150121. For the primaries or secondaries, I can't remember which, you just have to cut off a little plastic nub on the clip so they fit the harness. You should probably replace the o-rings also. Replaced mine 3 years ago and no problems.

[bldavis11]

my bet is on the fuel pump(s) or fuel filter. Sounds like a fuel flow problem. Would a failing injector REALLY cause the bucking? Seems that's more like all eight "failing" at once (e.g. problem delivering fuel to the injectors, not through the injectors).

Well that's my .02.
-Doc