Rapid Compression Drop + Long list

[sideshowbob]

In two months and 60 or so miles my compression in all cylinders has dropped drastically<sp?>. From 170-160 across all cylinders it's become 140 to 150. <whimper>. My driving isn't that insane. I've made a mistake somewhere along the way.... THIS IS MY BIGGEST WORRY Will my engine be junk in another 60 miles? Help? Please?

Vacuum is still super low (it was when the compression was high, as well). It was at 14 steady when I bought it, now it's a twitchy 10. Hopefully the new intake gasket will fix that.

Oh, and injector 3 is doing something strange again, pull the ign wire and it stumbles, pull the injector clip and it does NOTHING (but yes, the injector is firing while it's plugged in.) Probably clogged again, here goes the fuel rail for the third time.

In the three months I've owned this car I've........

Rewired the Ignition Coil and replaced it

Made a new coil bracket

Adjust valves 3 times

Removed EGR blockoff plate and put it back in disgust at the black brake fluid mess from the MC leak

Sprayed Carb Cleaner into Intake while running (maybe bad? It stalled the motor.)

Cleaned throttle body

Replaced Harmonic Balancer

Changed Spark Plugs/Wires

Changed Dizzy cap and rotor

Played with timing adjustments

Moved the timing chain cam sprocket to the #2 position then back to #1

Removed the Cold start valve, tested, replaced

pulled the injector rail and injectors

cleaned the injectors using carb cleaner

replaced the injector hoses

replaced the injector connectors

replaced the injector rubber seals (Large and small)

replaces fusible link boxes with a Buick MAXIFuse unit

re-wired the starter to fusible link wiring with a single heavy wire

rewired alternator main wire and repaired bad splice

Replaced Air filter

Replaced fuel filter and fuel pump bracket

Melted a plastic bag to the headers and exhaust pipe (oops)

Screwed with the TVS, sometimes with good results, sometimes bad.

Scraped rust

Sprayed down the floorpans with rubberized spray

Ditto for the trunk area

Cleaned the injectors

Replaced the fuel pump bracket

Fuel filter

Cleaned up the valve cover and made it shine

wire brushed a good portion of the intake

polished the afm

repaired the dome light

Rewired alternator to fusible link wiring (the old was corroded into dust)

Shortened front bumper closer to the body

Somewhat straghtened the front splash pan

patched up the driver's fender

made a rust hole in the dogleg much bigger and fabricated a replacement piece

typed a lot of notes

replaced the outer window 'squeege' with something from the hardware store

Greased the driver's door locks

fixed the lock on the tailgate

played with the afm weight, killed the car twice, replaced the cover

replaced the afm to TB boot with a ZX unit

Removed countless leaves and insect carcasses

sprayed primer on a two panels and spray painted one to protect it from the rain

caught the kitchen on fire with the MIG welder (ok, the plastic shield I was using)

considered buying another Z several times

considered lighting the Z on fire several more times

Two compression checks with wildly varying results

Driven it more than 5 miles once

gotten various toxic fluids in my face at least twice

push started it three times

developed an even more colorful vocabulary of swear words

tried to figure out what the PO's were thinking a few dozen times

gazed at the motor sport catalog wistfully in the evenings

frowned at the clunking noise in the rear and shrugged

smelled burning tire everytime I've driven it

bought more odd and expensive tools that in the past five years combined, ok maybe not

drilled through a bolt to connect a fuel injector to a small tire type air compressor

wondered if, perhaps, I'd lost my mind

decided that a po must have done the same gas-squirting-from-the-cs-valve-hose I did, due to the odd location and shape of the underhood rust spots

watched the weather report with dread in my heart

torn apart the interior and partially reassembled it

ripped out the alpine tape player it came with

glued together the dash bezel

thrown away the AC compressor in a fit of rage

replaces vacuum hose/fuel hose and some indescribably hose-like hose

talked to a couple of hose

been asked if it's for sale 4 times in a month while screwing with it in the parking lot

dreamed of the V8 I'm going to be forced to put in when this 'rebuilt/rebored' engine falls apart

contemplated getting a job at a body shop to get free work done

inhaled far too many volatile compunds

just knew I was missing some simple, basic and stupid tuning procedure

gone through the EFI bible tests twice

replaced a few dozen bolts/nuts and made a few of my own

worn out a few wire brushes and a 3M 'paint-rust stripping wheel'

turned the kids into 'gophers'

lots of sanding (for just 3 panels)

slapped some vinyl on the fubared dash cap

slapped some vinyl on the rear deck

painted the window louvers

painted the hood louvers

wondered what the various odd smells were

re-attached various parts that were in the trunk when I bought it (headlights, clutch parts, ect)

called parts stores all around town without ever really buying much

desperately e-mailed salvage parts suppliers without getting replies

tried, in vain, to figure out what kind of differential the car has

cleaned lots of electrical connections, just to watch them corrode again within a month

replaced lots of electrical connections

used a pin from the spare wiper motor connector to replace one on a headlight that was only dust

nearly worn out my multimeter

zapped myself with the coil three times before finally changing out the wire to it

gone to the junkyard four times, returning vaugely depressed

hacked, slashed and burned

put heatshrink tubing in the obvious and most unlikely places

torn out all sorts of tar and fiberglass insulation

superglued my fingers together

lost all kinds of fasteners

made my very first dent in the door

spent far too much time searching and finding only answers to problems I didn't have yet

discovered that Mr. Humble bought his Z here in this city and must have gotten parts elsewhere

discovered that the true meaning of life the universe and everything=entropy

[Bubbleguinea]

wow. that was a great read.

you want to hear what happened to me?

i had 180PSI on my newley rebuilt bored over L28. after 6K miles, ive got 150psi...hmm..

well it was time for custom EFI manifold and SDS, so i took the head off to get fully ported out and what did i find?

well, hell. my "new" cylinder walls was gone. all the honing cross-hatches wasnt there, and i had horrible lines up and down the walls...i think i was running SO rich, that the rings got washed out during the break-in..

but dont worry, now ive got flattops, with good rings, and a perfect air-fuel ratio thanks to SDS...and a 13.9 second NA Z.

so im happy.

[sideshowbob]

Now that you mention it that nasty little gas smell is back. I had that problem fixed before and no I'm not sure how. Thing is, the car doesn't run rich. At least, not enough to carbon up the plugs much and the injectors don't leak under pressure, either. How did you get the new rings in/block honed? I've done this bit before but only on a fully dissasembled engine and that's not an option right now. Really, doing it in the engine bay would be seriously iffy right now too.

Oh yeah.... maybe replacing the master cyl was a bad idea. It might be that I was getting good compression because the brake fluid was sealing up the rings. Unlikely, but something that strange wouldn't surprise me at this point.

[sideshowbob]

I'm so terribly embarassed. I have the same problem. I pulled the fuel rail a few minutes ago and (after moving it 5 parking slots) there was gas dripping from the fuel injectors when I pulled it and the raw fuel smell (well, maybe stale fuel) from the cylinders was terrible. Apparently my injectors have been leaking down while it sits and removing that 'oh-so-important' film of oil between the rings and cylinder walls causing some bad contact. With luck, it's salvageable enought to go untill I get a garage and a yard to stick the kids in while I work. Thank god this car is just an unneccesary frivolity (so the wife says) and not what I'm driving every day. Oh, and it looks like it was used badly in a major war somewhere with 6 colors and a big rust hole! Anyway, stay tuned while I use a tire air compressor and a 555 timer IC with a 9 volt to fire all six injectors simultaneously into a large, oval cookpot. The fireworks could be spectacular!! Maybe I'll do this outside this time....

So like the commercial said.. Starting Tony's Motor Is The Worst Thing He Can Do To It

[sideshowbob]

Bad FPR. Checked using a tire air pump (eeelectric). That would have been so much easier if I had a fuel pressure guage. I could have done this on-vehicle, but I feared the worst (6 new injectors). Silly me.

[sideshowbob]

Oops. I had the compressor connected to the RETURN line. No wonder it held pressure. I've reversed the connection and discovered that two injectors very slowly leak down. CRAP. The rest may just not have enough fuel to hear it. Time to test them individually. I'm fearing the worst again. Should have listened to myself before. I never get off THAT easy.

What I don't understand is that when testing number 3 by itself, there was no leak. Now it's the worst offender behind #1 (which seems to be leaking from the body! Though, more slowly.)

The entire rail has only lost about 7lbs in the last 20 minutes, which doesn't seem too bad, but this does appear to be the source of my woes anyway.

Comments? Related EFI experiences? Anyone?

[smokingwheels]

Yep a good read, just picked my self up off the floor

Ive had Days like that too, dont give up

sounds like the bores have a few vertical lines this could be from the pistions being too tight,

one idear

try getting an ultra bright led ,pulse driving from your 555 at 100 mA for a 1mS or so increase the intentsy, use some cat 5 cable or single conductor wire,

then put it in the plug hole, i dont know it you will see much but try it at night

Ps buy 2 leds incase you burn the first one out, if was me i would get 4

then you could use 2 or 3 in a bunch stagger them.

In the past I have used a dash board globe and a 8 mm steel rod to get the chain tensioner back in its place several times, sure beats the hell out of removing the cover.

Ive even shaped lumps of hard wood and an old lawn mower blade to mount the block of wood in place then using the head bolt to secure the blade and hold the wood behind the slack side of the chain, put the tensioner back in place and its good for another 3000 km

simple just keep making bigger ones,

ill upload a pic of the biggest one soon

its taken me 3 years to work another head

I am finding similar problems

the plugs are carboning up again,

Bosch tell me that i need to cut down on the fuel supply, so i guess i will rip the stock carby apart and block off all jets but at least 50%

then lower the float level

then use a 555 to pulse the fuel pump into the carby every so often.

in the other head i had, the ratio was ~ 11.5:1 and the std heat plugs lasted less than 15 mins, around the block spin the wheels and get sum fuel .

I started replacing all sorts of electrical stuff

got spark plugs 3 heat ranges up and still only got 1000 km before missfiring

this head used made the engine knock above 3000 rpm with 5 degrees total advance

with it sitting in the drive way.

I worked the head somthing cruel,it used to knock very hard with stock dissy

The new recon motor chewed all the con rod bearings out in a few weeks

what have i done ......

so i lowered the compression to 8:1

used 20" and 30" oversizre bearings on the rods.

After 3 years of working on my program,

I now know that under WOT it would of been 7 degrees on the other side

No nobody has made a engine like this before, i think

Wrote a computer program to time the engine (in basic) using the parrell port

the engine lasted for another 9 months.

Then it started to make lots of noise again which intensty increased with rpm in disgust in 2003 we diched the hole lot out

so now i have another one not as good as the first though but its just a matter of making the ports larger and remembring what i did 5 years ago to the nearest .1 of mm

its really hard to recall the exact port size that i had before

I guess that will teach me for cutting sick with a die grinder

But worse of all i threw out my work of art.

[sideshowbob]

I love it! Finnaly a use for that lot of 25 LED's I ordered from mouser. They're red but should work. I was also going to attach 6 to the injector wiring to watch them flash, but maybe not.