bad idle, dark smoke

[lyonsd]

This is what happened when I replaced the stock injectors with MSD 50s.

Before I did the injector swap, I put in the TurboLink boost sensinr harness and 3 bar MAP sensor. Car ran fine with that and stock injectors and JC chip.

Then I put in the MSD 50s and JC variable timing chip for 50lb injectors.

Started it up and it sounds like it's missing - idles like this: rump rump rump rump... Give it some gas and black smoke pours out the tailpipes.

Could I have gotten the plug wires crossed somewhere? Where is there a diagram that shows which plug goes with which terminal on the coil pack? I'll check that first.

What else could be wrong?

 

[Steve Wood]

coil pack should have numbers along the lower lip beside each plug wire tower showing what cylinder is what. Easy to cross them.

Did you make sure you put each injector to the correct connector in the fi harness?

 

[lyonsd]

Well, after letting it run a bit, the idle smoothed out. I guess what happened was an injector or two was blocked with vaseline.

So I took it for a ride. Pulls nice and hard at part throttle, but full throttle is starts seriously bogging. I'm thinking it might be running rich. I wonder if Jay sent me a chip for the wrong injectors.

Those good runs the 02 millivolts from the Scanmaster reads 600-800. Recall shows as low as 250.

How can I tell if I got the right chip for the injectors?

 

[lyonsd]

Lowered fuel pressure and tried again

Went from 44psi to 42psi. This time the O2 mV was ~850 with a minumum around 650.

Again, it ran good at part throttle. But at full throttle, serious bogging and cutting out. A sign of a rich condition, perhaps? What else could cause this?

Forgot to take notice of the exhaust this time.

Besides mV on the Scanmaster, what else should I be looking at for clues?

There were no malfunction codes.

Boost is set to ~19psi. 0 knock retard.

 

[lyonsd]

ttt

 

[lyonsd]

Needed some groceries, so I took the GN to test it again.

Dropped fuel pressure to 36psi.

First blast (I can't go WOT) got me 800-900 O2 volts and 3.3 knock retard. Let up.

I did some more tests. One had the O2 mV at 870, no knock.

I'm getting 0 or very low numbers for knock. But on these part-throttle blasts the O2 mv is in the 700s or 800s.

Just driving around and it's in the 600s usually. But really fluctuates.

 

[lyonsd]

new chip

Jay sent a a replacement chip to try. It arrived today. I knew the problem was gone when I started the car with the new chip. No more rough idle. It idled like stock. With the previous chip, the idle was rough when I started it cold but smoothed out.

So I took it for a ride. No more bogging at WOT. Although the Scanmaster showed the mV in the 800 range. This was with fuel pressure back up to 44psi. I raised the fuel pressure before I drove the car because I had previously reduced it to 36psi with the previous chip.

19psi, 0 knock.

So, either the previous chip was bad, or it wasn't for programmed 50lb injectors.

Thanks to everybody.

 

[Steve Wood]

We didn't help you but it does sound like you got the wrong chip or something. Jay's variable boost chips usually seem to work ok.

Glad it has come around.