Cascade Crew

aaron_sK · Posted: Mon Aug 13, 2007 10:18 am Post subject: Hydrocarbons part 2

Okay, here goes:

Stock was around 740 hc at idle, and about 83 at 2200rpm.

Swapped out leaking injectors for a used LT1 set (yeah, I'm poor right now). New plugs (Autolite 25's) and new PCV.

That caused the idle hc to go up to around 760, but the 2200rpm reading stayed about the same. It did however drop the idle CO by about 50%.

Found some split plug wires, so I bought a cheapo set to see if that was the problem, and pulled the timing back from -6 to -1.

That dropped the reading at idle down to about 450. However that's still twice the legal limit (damn Californians).

I also noticed that on the last time thru, the lady had me run the load test in third rather than second. That dropped the RPM's down to around 1900, which caused the HC at load to jump by about 20%. So... lower idle = more unburnt gas? Confused

Right now I'm about out of ideas, aside from just replacing random parts. Anything I should look at? No codes are being thrown, car runs fine otherwise, cap, rotor, plugs, wires, coil and all fluids are new. All tests were run with the car at around 200-210F.

TecherB · Posted: Tue Aug 14, 2007 10:04 am Post subject:

do you have any vaccume leaks? how new is your catalitic converter?

Twilightoptics · Posted: Tue Aug 14, 2007 8:46 pm Post subject:

Egads! That's worse than I've ever been.

You might consider checking the valve lash ? Shot in the dark! LOL

This is a TPI car?

Aren't the LT1 Injectors rated differently than than stockers? Might be spitting out more fuel than it should. Do you have an adjustable fuel pressure regulator? Pressure might be too high. Also o2 could be culpret.

Get back to me on the answers to those questions.

aaron_sK · Posted: Wed Aug 15, 2007 6:47 pm Post subject:

Hmm... think I found the problem, but I'll run through these questions:

Techer: Vacuum check comes back at around 22, and steady with RPM. It drops and snaps up normally when I flip the throttle as well. The cat has quite a few miles on it, but the fact that the car has around 80HC ppm at 2200rpm, and almost ten times that at idle makes me think the cat is okay.

Paul: The stock TPI is still there, although it has been ported. Correct me if I'm wrong, but '87 was a hydraulic lifter?

The LT1's are a touch larger (two pounds) than the L98's, but I watched a mere 3 ppm increase at 2200rpm with them over the smaller injectors.

While resetting the timing today I noticed an occasional misfire on the #1 cylinder. Decided to test a couple more cylinders and they all occassionally drop one fire randomly. Swapped the coil with another one I had on the shelf (also used) and that made the problem even worse. Aside from the coil (which is getting tossed tomorrow) what would cause random firing drops at idle, but not at higher rpms?

aaron_sK · Posted: Thu Aug 16, 2007 11:31 am Post subject:

It's not the coil. Swapped in a brand new Schmucks coil and it's exactly the same. Put the timing light on it and held the throttle up to about 1K and it was dropping out quite a bit, like a second with no fire, followed by a series of rapid fires.

Plugs are new, wires are new, coil is new, cap and rotor have less than 1500 on them, and look brand new. What else is there? Pickup? Module? Crank sensor? The timing is rock-solid, so I don;t think there's anything physically wrong with the dizzy.

Twilightoptics · Posted: Thu Aug 16, 2007 5:22 pm Post subject:

aaron_sK · Posted: Thu Aug 16, 2007 8:39 pm Post subject:

Hmm... could kill all three birds, but also my wallet:

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=A1C&MfrPartNumber=301830&PartType=218&PTSet=A

BigDaddyVu · Posted: Fri Aug 17, 2007 10:14 am Post subject:

This raises a question i have. I have talk to the emissions tech and he said your car has to pass the emissions standards of the year your car was made not to the current standards of todays emision requirements. Where do i find the the values or charts for are years of of our f-bodies???