Hopefully you can help me. I've got an 87 Z28, 305 TPI, auto trans. Actually the wife's car (I'm such a nice guy). I replaced the motor and I'm trying to get it running correctly. At idle, the motor shakes like the timing is off. If I try to drive the car, it seems to ping, then sets a code 43. I replaced the ESC module, the knock sensor and the plugs. The wires are new, as are the cap and rotor. The timing is set at 6 degrees. The problem is that the car acts like it has a miss. I checked all of the wires and all of the plugs are getting spark. If I put a screwdriver against each injector, they feel like they are clicking. However, if I pull the connector off of the injectors, some will make the car idle rough, some won't. I can swap the connectors around ( 1 to 3, 5 to 7, etc.), but the problem stays the same. I've come to the conclusion that some of the injectors may be clogged. Aside from pulling the plenum and everything else off, is there any way to check to see if the injectors are all working? Also, would this cause a false knock (from the pinging) and set the code 43?

Sorry this was so long, but I wanted to make sure I got as much info in as possible.

 

Switching the injectors plugs around on respective sides won't really do anything becase the injectors batch fire (all left, all right, etc..). The only thing switching the plugs would help figure out is if you had a broken wire on one of them.

Just as a thought... over time sometimes, the outer ring of the balancer slips causing you to get a false timing reading. Right now on my camaro, the ring has slipped back to the point it's now rubbing the timing chain cover. Try backing off the timing some and see if that helps any. Also, sometimes (for me anyways..) it's really easy to mix up 2 plug wires and cause a miss/rough engine.

 

Like Deadbird said,

Verify All plug wires are Correct. 18436572 Clockwise around the Cap.

How did you set Timing, Was the EST Bypass Disconnected ?

A Code 43 is charatoristic of a bad Knock sensor. Was it installed correctly ?

If you go through all these steps and Nothing seems awry, You can verify the injectors by Checking their corresponding plugs. An injector not firing will leave the plug white, Lean.

It sounds to me however that You may Have a Timing Problem.

 

Timing was set by disconnecting the bypass connector, turning the distributor until the mark was at 6 degrees ( verified by timing light) and the car shut off. I tightened the distributor back down, started the car and verified the mark was still in the same spot. The knock sensor was brand new, no tape used on it, just the sealer that was on it when I pulled it from the box. I thought that maybe the plugs were fouled out, so I changed them. They were a tannish-brown color on the tips. Wires have been checked 4 times, by myself and others. I've tried the timing at 12 BTDC, 6 BTDC, 4 BTDC, TDC, 4ATDC and 6 ATDC. It runs the best at 4 or 6 BTDC. If I turn the motor by hand to TDC, the rotor is pointing at the number one cylinder and the number one tower on the cap. What else is left to check besides the ECM itself?

BTW, I've checked the resistance of the knock sensor, and it's 100k ohms. I've checked the ones at the parts stores and they are the same. I bypassed the knock sensor with resistors (3.7 and 4.1k ohms, the didn't have the correct ones to make up 3.9k ohms) and it did not seem to help at all. It still set a code 43 after the car warmed up.

Would it screw the computer up if the car actually had knock? that's the reason the motor was changed. Rod knock when I bought it. Probably why the car was only $400.

I just want to get this car finished so i can park my 82 and start working on my 83.

 

Do you have access to a Scan Tool ?

Have you set the TPS and Minimum Air ?

If the plugs are uniform, then all injectors are firing.

What is the idle speed set too... What is in your book a "rough idle"

No Vaccuum Leaks ?

Does the car perform well other wise, or is it down on power ?

Fuel Pressure ?

Verify Continuity Between the KS and the Module, and the Module and the ECM.

Verify 12v and ground at the Module.



Sounds like you have Coverd most of the basics, so Its on to the "fun"

lol

A Scantool Would REALLY help.

 

Digging this up from way back when. The problem was multiple things. The valves were adjusted wrong, that screwed the timing up, that fouled the plugs. On top of all that, the injectors were full of rust, causing only half to not spray. I've been told it's a common problem when you have steel injectors in an aluminum rail and the car sits for any length of time.