Cbystrack

update everyone

Hook'd up the snap-on diagnostic scanner and had the whole read out on display. Heated o2's are giving bad readings, some evap is low or no readings, and the best of all the spark advance is 21 degrees with the key off..... so im looking about 2 teeth advanced on the cam gear. just wish i had known about it all last week when putting the opti in but oh well should've scanned the car to begin with.

Thanks everyone for the help/suggestions ill post back as soon as its fast again lol.

bw_hunter

Check compression to confirm before tearing it apart....

mrmint69

Is the car a 96 or 97?

Cbystrack

yes correction sorry for any confusion it is indeed a 1997 lt1 ws6 6 speed

Injuneer

I'm trying to figure out how the scanner can determine that your cam is advanced 21* with the key off. It has two pieces of data - the four pulses of the crank sensor and the 8 pulses of the low res cam position from the Opti - it only gets those with the engine running. Generally, the spark advance the scanner shows is what the PCM is reading off the spark timing tables, as a function of RPM and MAP, plus a couple variable offsets.

Cbystrack

it should 0 out with car off in acc mode with key in ignition its not. that tells us cam timing is off, also with car running it will only advance maybe 12-14 before it stops. All in all something is not right and monday it'll be going back to the surgeon to rip it all apart again lol

Guest47904

That spark advance reading is arbitrary until the engine is running. In other words, it means nothing. Fred tried to tell you that.

You are jumping to conclusions.

Why don't you do this. When a particular cylinder is at TDC, the rotor should be pointing in the direction of the contact inside the distributor cap.

Look at this
http://shbox.com/1/opti_cyl.jpg
When #1 is at TDC, the rotor will be just slightly to the left of 6 O,Clock position. Look and see. That's a hole lot easier than going all the way to the timing chain. The benefit is you get to see all the crud inside the cap too.

Cbystrack

okay i understand what your saying now i do understand it, we'll compression check it tomm once we get it on the lift. Im pointing hard towards cam timing to be off seeing how the prev owner says he's not sure if it was right or not after swaping the gears.

if compression is in fact low we'll go further into it as your telling me. either way ill know something later on in the day mon or tues. Keeping fingers crossed for full power!

Again everyone here thanks so much for help and support through this, cant wait to have a nice tight 4th gen!

Cbystrack

compression is fine, still tore it down and only to find it is timed correct.... what can my issue be?

Recent parts,
opti
wires
plugs
crank sensor



Getting ready to test fuel pressure i guess... im lost at words i sold a turn key 400+ hp car for this slug which i thought would be a quick fix...... any more input?

Cbystrack

checked fuel pressure and its 31 psi...... did i just find my issue?

bw_hunter

How did you checkit? At idle with the vacuum line off the regulator and plugged you should be between 41 and 47 psi.....

mrmint69

Have you replaced the fuel filter lately? Have you tested the 02's after the car was warmed up?

Injuneer

Earlier you indicated the scanner showed the O2 sensors were "giving bad readings". What were the readings, exactly?

You need to test the fuel pressure on the road, with an attempt to exceed at least 5,000RPM at WOT. Pressure should not drop below 40psi under that load.

mrmint69

Went back over all your posts. You neglected to do any of the easy tests suggested and went right for the complicated stuff. Fuel pressure test was listed first and done last and appears to be your issue, as well as possibly bad O2 sensors, which both will make that car run bad. Don't just replace the fuel pump because it reads bad. A fuel filter that was left in too long and is partially blocks will make pressure low. $15 and easy to replace. Start there and then retest the fuel pressure correctly as stated.

Cbystrack

Okay everyone here goes. The lower end was from a caprice classic police car. The alum heads from the orginal motor were put on the donor motor. Now one thing that drew my attention is the cam........are they all the same. As far as lt1s??? If not than that could be an issue im having right? Computer getting confused maybe? And yes i shouldve checked fuel pressure right off the bat. I assumed it was fine seeing the car runs good just has no power.